Scientific Articles

By selecting a field of Application
By selecting a product
By typing in your keyword : (Keyword can be a particular word, an author, a journal, etc.)
5631 articles

E0338 – Silica doped bismuth lead oxyfluoride glass ionic conductors

Doping of bismuth lead oxyfluorides by silica (30 at.%) makes it possible to stabilize a large vitreous domain. The presented study relates to the stability of the vitreous phase and the variation of conductivity versus temperature, as well as composition. DTA heating analyses evidenced the temperature of vitreous transition followed by the material recrystallization. The crystallized phase was identified by high temperature Guinier Lenné pattern. The best conductivity, about 3 × 10? 3 Scm? 1 at 220 °C, was obtained for the fluorine richest material.
Claudine Follet-Houttemane, Michel Drache, Pierre Conflant, Solid State Ionics 181 (2010) 37–40

E0337 – Thermal and optical investigation of EuF3-doped lead fluorogermanate glasses

Europium-doped lead germanate and lead fluorogermanate glasses are studied by using differential thermal analysis, X-ray diffraction, photoluminescence and fluorescence lifetimes measurements of the 5Dj, j = 0, 1, 2 levels. PbF2 addition increases the thermal stability of the lead germanate glass, while Eu3+ ions promote the crystallization of ?-PbF2:Eu3+ nano-crystals embedded in a glassy matrix. In the lead fluorogermanate glasses, Eu3+ ions exhibit a strong affinity for F? ions although oxygen ions are much more numerous. It appears that luminescence concentration quenching is not important, while cross relaxation is very efficient in the glasses. The results allow to propose for these glasses a molecular model in which small fluorine rich island, incorporating the Eu3+ ions in low symmetry sites, are separated from each other by chains of germanate (GeO4)4? ions linked together.
C. Bensalem, M. Mortier, D. Vivien, M. Diaf, Journal of Non-Crystalline Solids 356 (2010) 56–64

E0336 – Phase equilibria in the FeO1+x–UO2–ZrO2 system in the FeO1+x-enriched domain

Experimental results of the investigation of the FeO1+x–UO2–ZrO2 system in neutral atmosphere are presented. The ternary eutectic position and the composition of the phases crystallized at this point have been determined. The phase diagram is constructed for the FeO1+x-enriched region and the onset melting temperature of 1310 °C probably represents a local minimum and so will be a determining factor in this system and its application to safety studies in nuclear reactors.
V.I. Almjashev, M. Barrachin, S.V. Bechta, D. Bottomley, F. Defoort, M. Fischer, V.V. Gusarov, S. Hellmann, V.B. Khabensky, E.V. Krushinov, D.B. Lopukh, L.P. Mezentseva, A. Miassoedov, Yu.B. Petrov, S.A. Vitol, Journal of Nuclear Materials 400 (2010) 119–126

E0335 – Physical properties and MAS-NMR studies of titanium phosphate-based glasses

In this study, for a series phosphate-based glasses ((P2O5)0.45(CaO)0.3(Na2O)0.25?x(TiO2)x, 0 ? x ? 0.15), their degradation, ion release, surface and thermal properties have been determined. The results show that adding TiO2 was associated with a significant increase in density and glass transition temperature, but a decrease in degradation rate and ion release. 31P solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) showed that the local structure of the glasses changes with increasing TiO2 content. As TiO2 is incorporated into the glass, the phosphate connectivity increases as Q1 units transform to Q2, confirming that an increase in the nominal TiO2 content correlates unequivocally with an increase in glass stability. As reported for titania–silica gels, Ti4+ is clearly adopting a network former role in these phosphate-based glasses. 23Na MAS-NMR results corroborate this phenomenon with a marked upfield trend of the 23Na isotropic chemical shift suggesting that the local Na–O bond distances are decreasing within a more condensed glass network upon increased incorporation of TiO2.
Azadeh Kiani, Lindsay S. Cahill, Ensanya Ali Abou Neela, John V. Hanna, Mark E. Smith, Jonathan C. Knowles, Materials Chemistry and Physics 120 (2010) 68–74

HE009 – Hypercrosslinked polyanilines with nanoporous structure and high surface area: potential adsorbents for hydrogen storage

A method for the preparation of an entirely new type of nanoporous material, hypercrosslinked polyaniline, with permanent porous structure and specific surface areas exceeding 630 m2 g21 has been developed. The hypercrosslinking reaction was carried out with commercial polyaniline and diiodoalkanes or paraformaldehyde using both conventional and microwave assisted processes. Polyaniline swollen in an organic solvent was hypercrosslinked to form a rigid, mesh-like structure with permanent porosity and a high surface area. The resulting materials were characterized using infrared spectroscopy and elemental analysis. Porous properties were determined by means of scanning electron microscopy as well as nitrogen and hydrogen adsorption. Short crosslinks such as those formed using paraformaldehyde and diiodomethane led to materials with the highest surface areas. Surface area also increased with the concentration of polyaniline in solution used during preparation. The hydrogen storage capacities of these materials were also tested and a capacity of 2.2 wt% at 77 K and 3.0 MPa was found for the best adsorbent. Hypercrosslinked polyanilines exhibit a remarkably high affinity for hydrogen, which results in enthalpies of adsorption as high as 9.3 kJ mol21 (exothermic), in sharp contrast with hypercrosslinked polystyrenes and metal–organic frameworks for which significantly lower enthalpies of adsorption, typically in the range of 4–7 kJ mol21, are measured.
Jonathan Germain, Jean M. J. Fréchet and Frantisek Svec, J. Mater. Chem., 2007, 17, 4989–4997

HE0019 – In situ synthesis and hydrogen storage properties of PdNi alloy nanoparticles in an ordered mesoporous carbon template

Organized mesoporous carbon has been used as a nanoreactor to prepare PdNi metallic particles using an incipient wetness method starting from Pd and Ni salts. The final composite material consists of nanosized metallic particles of an alloy with composition Pd0.60Ni0.40 highly dispersed within the carbon host structure. The thermodynamic hydrogenation properties of both the PdNi-free OMC and the Pd0.60Ni0.40- OMC composite have been determined by hydrogen isotherm sorption measurements. The introduction of the palladium–nickel alloy into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 2 MPa, since the hydrogen uptake is mainly attributed to physisorption on the carbon surface. However, at room temperature and moderate pressure (0.5 MPa), the filling of the OMC with nanocrystalline Pd0.60Ni0.40 results in larger hydrogen uptake than that of the PdNi-free OMC.
R. Campesi, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Microporous and Mesoporous Materials 117 (2009) 511–514

HE008 – Hydrogen storage behavior of ZrNi 70/30 and ZrNi 30/70 composites

The Zr–Ni compositional alloys, namely (i) ZrNi 70/30 and (ii) ZrNi 30/70 (both by weight) have been investigated for the reversible hydrogenation behavior. These composites show Zr–Ni intermetallic multi-phase formation as explored by X-ray diffraction studies. The sorption kinetics of ZrNi 70/30 seems much faster (?3–4 times) than that of ZrNi 30/70 alloys. The initial desorption rate increasing with an increase in temperature. A well-defined plateau region was obtained for the ZrNi 70/30 with an equilibrium pressure range from <1 bar (300 ?C) to 10 bars (390 ?C). For ZrNi 30/70, the sloppy plateau region extends to higher equilibrium pressures. It is estimated that the total effective hydrogen concentration for ZrNi 70/30 (?1.0 wt.%) is at least 2 times that of ZrNi 30/70 (?0.5 wt.%) composites. From the PCT isotherms, the enthalpy of reaction ( H) has been calculated to be ?39 kJ/mol H2 for the ZrNi 70/30. The surface morphologies of the hydrogenated materials exhibit the presence of cracks and particle size pulverization in comparison to the pristine alloys
Diego Escobar, Sesha Srinivasan, Yogi Goswami, Elias Stefanakos, Journal of Alloys and Compounds 458 (2008) 223–230

HE0018 – Hydrogen storage properties of Pd nanoparticle/carbon template composites

Theoretical studies predict improved hydrogenation properties for hybrid carbon/metal composites. The hydrogen storage capacity of ordered porous carbon containing Pd clusters was measured. The C/Pd composite was obtained by chemical impregnation of an ordered porous carbon template (CT) with a H2PdCl4 solution followed by a reduction treatment. 10 wt.% of palladium clusters were introduced in the carbon porosity; the Pd clusters (2 nm in size) being homogeneously distributed. Thermodynamic hydrogenation properties of both Pd-free CT and the Pd–10 wt.% CT composite have been determined by hydrogen isotherm sorption measurements and thermal desorption spectroscopy (TDS) analysis. The introduction of the palladium into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 1.6 MPa, since here the hydrogen uptake is being attributed to physisorption on the carbon. However, at room temperature and moderate pressure (0.5 MPa), the filling of the CT with 10 wt.% nanocrystalline Pd results in an hydrogen uptake eight times larger than that of the Pd-free CT. After the second cycle, a good reversibility is observed. TDS measurements confirm that the sharp increase of the hydrogen uptake is due to the presence of the Pd clusters in the carbon porosity.
R. Campesi, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Carbon 46 (2008) 206-214

HE007 – Polyaniline-based nanocomposite materials for hydrogen storage

Nanomaterials have diverse tunable physical properties as a function of their size and shape due to strong quantum confinement effect and large surface to volume ratio. On basis of these facts, nanocomposite materials can be considered as strong candidates for hydrogen storage. In the present work, we report a novel conducting polymeric nanocomposite material for hydrogen storage. Conducting polymer-based nanocomposites were modified using carbon nanotubes as filler material. This further increased the porous structure of the nanocomposite and the number of binding sites, which in turn enhances the hydrogen storage capacity. Additionally, fine aluminum powder was added to the polymeric nanocomposite, which further increased the hydrogen sorption of the material. The modified conducting polymeric nanocomposites were characterized with various analytical techniques including FTIR, DSC, TGA and SEM. Adsorption and desorption experiments are conducted using a Sieverts-type volumetric PCT instrument. Further experiments are in progress to understand the hydrogen storage mechanism in the proposed conducting polymer nanocomposites.
Michael Ulrich Jurczyk, Ashok Kumar, Sesha Srinivasan, Elias Stefanakos, International Journal of Hydrogen Energy 32 (2007) 1010 – 1015

HE0028 – Mg–Ni–Cu mixtures for hydrogen storage: A kinetic study

Mg-based ternary mixtures (40 Mg wt% 80) containing increasing amount (up to 30 wt %) of Ni and Cu were prepared by ball milling (BM) under Ar for 16 h and subsequently activated at high temperature (623 K) by charging/discharging cycles at H2 pressure of 50 bar/0.7 bar. The work aims to analyze the influence of the mixtures’ composition on the storage properties (H2 intake and sorption kinetics) and to describe the role played by an ad-hoc activation in reaching these same properties. The storage capacity of the mixtures decreases by decreasing the Mg starting content, the H2 active phases being ‘‘free Mg’’ and the ‘‘bonded Mg’’ intermetallic compounds Mg2Ni and Mg2Cu. After full activation (3 charging/ discharging runs), ‘‘free Mg’’ hydrogenates 10 times quicker than the ‘‘bonded Mg phases’’, while the discharging of both ‘‘free’’ and ‘‘bonded’’ Mg hydrides takes place simultaneously with similar kinetics. The best kinetic performance is shown by the samples with Mg ¼ 60 wt% and 70 wt% and the highest Ni content (30% and 20% respectively), with sorption rates up to 7 times higher than those of the pure Mg/ MgH2 system. Ó
C. Milanese, A. Girella, G. Bruni, P. Cofrancesco, V. Berbenni, P. Matteazzi, A. Marini, Intermetallics xxx (2009) 1–9

HE0017 – Novel Sieverts’ type volumetric measurements of hydrogen storage properties for very small sample quantities

Novel volumetric analysis instrument for studying hydrogen storage property of very small quantities (?mg) of samples was developed and tested. Small pressure change arising from hydrogen uptake or release are precisely measured and equated to the change in the sample’s hydrogen content using the gas lawequation.Very small volume pressure reservoir enables these precise measurements, and all internal volumes are calibrated with high-purity helium gas. Capacity, equilibrium isotherm, and kinetic measurements can be performed in the pressure range of vacuum to 4MPa and the temperature range from cryogenic-673 K. Test measurements were made on small carbon nanotube samples and measurement of less than ?3 g of hydrogen uptake was demonstrated, which corresponds to an accuracy of better than 0.15 wt% for a 2 mg sample.
Yong-Won Lee, Bruce M. Clemens, Karl J. Gross, Journal of Alloys and Compounds 452 (2008) 410–413

HE006 – LaMg2PdH7, a new complex metal hydride containing tetrahedral [PdH4]4? anions

Hydrogenation of the intermetallic compound LaMg2Pd at 200 ?C and 10 bar leads to a complex metal hydride of composition LaMg2PdH7. Its structure has orthorhombic symmetry and displays tetrahedral [PdH4]4? anions. The Pd–H bond distances as measured on the deuteride range from 1.71 to 1.78 °A and the H–Pd–H bond angles from 95? to 122?. Three additional hydride anions H? occupy La2Mg2-type interstices having tetrahedral metal configurations. Band structure calculations suggest the hydride to be non-metallic and to have a band gap of ?1.0 eV. The compound desorbs hydrogen at 125 ?C yielding a pressure of more than 1 bar absolute.
K. Yvon, J.-Ph. Rapin , N. Penin, Zhu Mab, M.Y. Choub, Journal of Alloys and Compounds 446–447 (2007) 34–38

HE0027 – Synthesis of carbon nanotube–TiO2 nanotubular material for reversible hydrogen storage

A material consisting of multi-walled carbon nanotubes (MWCNTs) and larger titania (TiO2) nanotube arrays has been produced and found to be efficient for reversible hydrogen (H2) storage. The TiO2 nanotube arrays (diameter ?60 nm and length ?2–3 ?m) are grown on a Ti substrate, and MWCNTs a few ?m in length and ?30–60 nm in diameter are grown inside these TiO2 nanotubes using chemical vapor deposition with cobalt as a catalyst. The resulting material has been used in H2 storage experiments based on a volumetric method using the pressure, composition, and temperature relationship of the storage media. This material can store up to 2.5 wt% of H2 at 77 K under 25 bar with more than 90% reversibility.
Amrita Mishra, Subarna Banerjee, Susanta K Mohapatra, Olivia A Graeve and Mano Misra, Nanotechnology 19 (2008) 445607

HE0016 – Heat of adsorption for hydrogen in microporous high-surface-area materials

The automated Sieverts PCTPro2000 was used with a so-called Microdoser (MD) from HyEnergy, USA. This Microdoser offers the possibility to measure the hydrogen uptake of very small amounts of material. Therefore the MD includes a 0.51 ml reservoir, a pressure sensor and minimizes the sample cell volume to 1.2ml. The sample mass was between 99 mg and 400 mg and the samples have been activated in high vacuum according to table 1. Adsorption isotherms (0-20 bar) were measured at liquid nitrogen, liquid argon and temperatures above 87 K. Latter is realized by heating the sample cell in a dewar cooled by liquid nitrogen. The temperature was controlled to +/- 1 K.
B. Schmitz, U. Müller, N. Trukhan, M. Schubert, G. Férey, M. Hirscher, ChemPhysChem 2008

HE005 – National Testing Laboratory for Solid-State Hydrogen Storage Technologies

Develop and operate a national-level testing and core reference laboratory aimed at assessing and validating the performance of emerging solid-state hydrogen storage materials and full-scale systems. Establish and validate measurement techniques for hydrogen sorption and related performance metrics.
Michael A. Miller and Richard A. Page FY 2006 Annual Progress Report DOE Hydrogen Program 529-534

HE0026 – Effect of the substrate on the thermodynamic properties of PdHx films studied by hydrogenography

We investigated the influence of the substrate on the thermodynamic properties of metal hydride thin films by hydrogenography, using PdHx as a model system. After appropriate hydrogen cycling, reproducible hydrogenation properties are found at the same equilibrium pressure for all substrates studied. Comparing these thin films with free-standing films—measured both by hydrogenography and by Sievert’s method—we find a very similar behavior. Hence, thin films can be used to study the hydrogenation behavior of the corresponding bulk materials.
Y. Pivak, R. Gremaud, K. Gross, M. Gonzalez-Silveira, A. Walton, D. Book,H. Schreuders, B. Dama and R. Griessen, Scripta Materialia xxx (2008) xxx–xxx

HE0015 – Heat of Adsorption for Hydrogen in Microporous High-Surface-Area Materials

The heat of adsorption for hydrogen is determined over a wide range of surface coverages for activated carbon and several metal–organic frameworks. Heat determination is based on hydrogen adsorption measurements performed at temperatures between 77 and 296 K (see figure, BTC=benzene-1,3,5-tricarboxylate). The materials with smaller cavities show a higher heat of adsorption for hydrogen.
Barbara Schmitz, Ulrich Müller, Natalia Trukhan,Markus Schubert,Gérard Férey and Michael Hirscher, ChemPhysChem 2008

HE004 – Dependence of dissociation pressure upon doping level of Ti-doped sodium alanate—a possibility for ‘‘thermodynamic tailoring’’ of the system

Pressure–concentration isotherms have been recorded for NaAlH4 with different doping levels of titanium. It is well known that titanium accelerates the hydrogenation and dehydrogenation reactions in this system. Our studies have shown that the titanium doping also significantly alters the thermodynamics of the system, which is demonstrated by the change of the dissociation pressure with doping level. This can be explained by changes in the systems energy by dilution of the TiAl-alloy present after doping: Such an alloy forms as a result of the doping reaction. Aluminum generated during the dehydrogenation reaction dilutes this alloy, which gives an additional contribution to the free energy of the system.
Guido Streukens, Borislav Bogdanovic, Michael Felderhoff and Ferdi Schüth, Phys. Chem. Chem. Phys., 2006, 8, 2889–2892

HE0025 – Reactivity and hydrogen storage performances of magnesium–nickel–copper ternary mixtures prepared by reactive mechanical grinding

Ternary Mg-based mixtures (50 Mg weight% 80) containing increasing amount of Ni (up to 30 wt%) and Cu (up to 20 wt%) have been prepared by ball milling in hydrogen reactive atmosphere ðPH2 ¼ 5 barÞ to determine the effects of both the processing conditions and the concurrent presence of the two transition metals on the sorption mechanisms and the storage properties of the Mg/MgH2 system. Combined SEM, TG and XRPD analyses showed that the processing time tBM (¼3 h, 8 h and 16 h) strongly affects the properties of the ‘‘as milled powders’’ (average particle sizes and microstructure, nature of the phases, amount of hydrogen absorbed upon milling, and desorption characteristics). However, after a combined high temperature/high pressure activation cycle, all the charged samples were composed of MgH2, Mg2NiH4 and MgCu2 while the discharged samples contained ‘‘free Mg’’ and the intermetallic compounds Mg2Ni and Mg2Cu (‘‘bonded Mg’’): in all cases the definitive storage performances are related only on the relative amounts of these three phases that, in turn, depend on the starting composition of the mixtures. Both Ni- and Cu-containing phases hydrogenated/dehydrogenated according to their own sorption reaction schemes; however, Mg2NiH4 and MgCu2 destabilized each other, with the beneficial effect of rising the desorption plateau pressures of the ‘‘bonded Mg’’ with respect to binary Mg–Ni and Mg–Cu mixtures. On the contrary, Ni- and Cu-containing phases did not exert any appreciable destabilizing effect towards ‘‘free MgH2’’.
C. Milanese, A. Girella, G. Bruni, P. Cofrancesco, V. Berbenni, M. Villa, P. Matteazzi, A. Marini , International Journal of Hydrogen Energy 33 (2008) 4593-4606

HE0014 – Improved hydrogen storage properties of a V decorated Mg nanoblade array

An ultra-thin layer of V has been coated onto the surface of individual Mg nanoblades by dynamic shadowing growth. This 2.25 at% V decorated Mg nanoblade array can absorb and desorb hydrogen rapidly at temperatures T 500 K after activation by one hydrogen cycle, with a low hydrogen absorption activation energy of 35.0 ± 1.2 kJ per mol H2 and a desorption activation energy of 65.0 ± 0.3 kJ per mol H2. The improved hydrogen sorption kinetics is attributed to both the catalytic effect of the V coating and the unique nanoblade morphology with a large surface area and small hydrogen diffusion length
Yuping He and Yiping Zhao, Phys. Chem. Chem. Phys., 2009

HE003 – Independent verification of the saturation hydrogen uptake in MOF-177 and establishment of a benchmark for hydrogen adsorption in metal–organic frameworks

Hydrogen isotherms for MOF-177, Zn4O(1,3,5-benzenetribenzoate)2, crystals were independently measured by volumetric and gravimetric methods at 77 K to confirm its hydrogen uptake capacity and to establish the importance of calibrating gas adsorption instrumentation prior to evaluating H2 storage capacities. Reproducibility of hydrogen adsorption experiments is important because non-systematic errors in measurements can easily occur leading to erroneous reports of capacities. The surface excess weight percentage of hydrogen uptake in MOF-177 samples is 7.5 wt% at 70 bar, which corresponds to an absolute adsorbed amount of 11 wt%. These values are in agreement with our previous report and with those found independently by Southwest Research Institute. Considering its well-known structure and its significant H2 uptake properties, we believe MOF-177 is an excellent material to serve as a benchmark adsorber.
Hiroyasu Furukawa, Michael A. Miller and Omar M. Yaghi J. Mater. Chem., 2007, 17, 3197–3204

HE0024 – Hydrogen storage properties of 2LiNH2 + LiBH4 +MgH2

We have investigated the ternary mixture of complex hydrides with stoichiometry 2LiNH2 + LiBH4 +MgH2, and have identified a set of novel hydrogen storage reactions. One of these reactions involves the known reversible reaction Mg(NH2)2 + 2LiH?Li2Mg(NH)2 +2H2. Previous studies have shown that initiating this reaction from the binary mixture 2LiNH2 +MgH2 results in poor hydrogen desorption kinetics and a small amount of NH3 release. In contrast to this behavior, here we demonstrate that by starting from the ternary mixture 2LiNH2 + LiBH4 +MgH2, the above reaction can proceed at lower temperatures and with improved kinetics, while maintaining reversibility. The advantage of starting with the ternary mixture can be traced to the subsequent formation, melting, and reaction of Li4BH4(NH2)3 with MgH2 to form the mixed imide phase Li2Mg(NH)2, which acts as a seed for the reversible reaction, and is at least partly responsible for the improved kinetic response
Jun Yang, Andrea Sudik, Donald J. Siegel, Devin Halliday, Andy Drews, Roscoe O. Carter III, Christopher Wolverton, Gregory J. Lewis, J.W.A. Sachtler, John J. Low, Syed A. Faheem, David A. Lesch, Vidvuds Ozolins, Journal of Alloys and Compounds 446–447 (2007) 345–349

HE0013 – The formation of MgH2 nanowires during the hydrogenation of Ti-doped Mg film

A unique diffusion barrier structure, consisting of layers of a Ti nanorod array and Ti film, has been fabricated on Si substrate for a subsequent 2 at.% Ti-doped Mg film deposition using a combinational technique of multilayer growth, co-deposition and dynamic shadowing growth. The hydrogenation of the Ti-doped Mg film on such a barrier structure shows that the barrier can prevent direct Mg–Si contact and suppress the formation of Mg2Si alloy in a high-temperature process. When this film has been hydrogenated at temperatures T 300 ?C for approximately 150 h, tetragonal single-crystal MgH2 nanowires are formed on the surface of the Ti-doped Mg film. The hydrogenation time and temperature are the two main factors for the nanowire formation. The doping of Ti also plays a significant role. This result reveals that complicated dynamic processes could occur during the hydrogenation of Ti-doped Mg film when Mg2Si formation can be eliminated by an effective diffusion barrier layer
Yuping He, Yongjun Liu and Yiping Zhao, Nanotechnology 19 (2008) 465602

HE002 – Thermodynamische und katalytische Eigenschaften von Titan- und Cer-dotierten komplexen Aluminiumhydriden

x
Thesis of Guido Streukens Fakultät für Chemie der Ruhr Universität Bochum Germany 2007

HE0023 – Activation of hydrogen storage materials in the Li–Mg–N–H system:Effect on storage properties

We investigate the thermodynamics, kinetics, and capacity of the hydrogen storage reaction: Li2Mg(NH)2 +2H2?Mg(NH2)2 + 2LiH. Starting with LiNH2 and MgH2, two distinct procedures have been previously proposed for activating samples to induce the reversible storage reaction. We clarify here the impact of these two activation procedures on the resulting capacity for the Li–Mg–N–H reaction. Additionally, we measure the temperature-dependent kinetic absorption data for this hydrogen storage system. Finally, our experiments confirm the previously reported formation enthalpy ( H), hydrogen capacity, and pressure–composition–isotherm (PCI) data, and suggest that this system represents a kinetically (but not thermodynamically) limited system for vehicular on-board storage applications.
Jun Yang, Andrea Sudik, C. Wolverton, Journal of Alloys and Compounds 430 (2007) 334–338

HE0012 – Hydrogenation of Mg film and Mg nanoblade array on Ti coated Si substrates

The hydrogenation of Mg film and Mg nanoblade array fabricated on Ti coated Si substrates has been studied and compared. The nanoblades start to absorb hydrogen at a temperature between 250 and 300 °C, which is much lower than 350 °C for Mg film. However, the saturated total hydrogen uptake in nanoblades is less than half of that in the film, resulting from MgO formation by air exposure. The nanoblade morphology with large surface area and small hydrogen diffusion length, and the catalytic effect of Ti layer, are two main reasons for the nanoblade hydrogenation behavior.
Yuping He, Yiping Zhao, Liwei Huang, Howard Wang, and Russell J. Composto, APPLIED PHYSICS LETTERS 93, 163114 2008

HE001 – Crystal structure determination and reaction pathway of amide–hydride mixtures

Combined synchrotron in situ X-ray diffraction and neutron diffraction studies were performed on 2:1 mixtures of lithium amide and magnesium hydride, which have shown promise as solid-state hydrogen storage materials. The dehydrogenated product is a mixed lithium and magnesium imide, Li2Mg(NH)2, whose crystal structure has not heretofore been determined. Furthermore, at elevated temperatures, Li2Mg(NH)2 undergoes two structural transitions from an orthorhombic structure to a primitive cubic structure at intermediate temperature (350 ?C) followed by a facecentered cubic crystal structure at high temperature (500 ?C). Disordering of the Li, Mg and cation vacancies as a function of temperature drives the structural transitions.We report the reaction pathway from in situ X-ray diffraction studies and the crystal structures of the three structural variants of Li2Mg(NH)2 as determined by high-resolution X-ray and neutron powder diffraction. We also report the hydrogen storage reaction pathways for mixtures with other cation ratios.
Job Rijssenbeek, Yan Gao, Jonathan Hanson, Qingzhen Huang, Camille Jones, Brian Toby Journal of Alloys and Compounds xxx (2007) xxx–xxx

HE0022 – Nanocatalyst doping of Zn(BH4)2 for on-board hydrogen storage

In this work, we report the synthesis and characterization of Zn(BH4)2, a new class of complex borohydrides for on-board hydrogen storage. The thermal decomposition of Zn(BH4)2 comprises of not only the evolution of H2, but also an appreciable amount of B–H (borane) compounds. Lowering the decomposition temperature by catalytic doping may lead to negligible release of boranes. An amount of 1.5 mol% nanoNi was estimated and found to be the optimum concentration for nanocatalyst doping of Zn(BH4)2. Significance of the nanoNi doping, lowers the melting and thermal decomposition temperatures (at least 20–40 ?C) of Zn(BH4)2 as evidenced from the calorimetric analysis. At these low temperatures, the nanocatalyzed Zn(BH4)2 exhibits reduction in the amount of borane gases released by a factor of 20 as compared to the undoped sample
Sesha Srinivasan, Diego Escobar, Michael Jurczyk, Yogi Goswami, Elias Stefanakos, Journal of Alloys and Compounds 462 (2008) 294–302

HE0011 – Ternary nitrides for hydrogen storage: Li–B–N, Li–Al–N and Li–Ga–N systems

This paper reports an investigation of hydrogen storage performance of ternary nitrides based on lithium and the Group 13 elements boron, aluminum and gallium. These were prepared by ball milling Li3N together with the appropriate Group 13 nitride.BN, AlN or GaN. Powder X-ray diffraction of the products revealed that the ternary nitrides obtained are not the known Li3BN2, Li3AlN2 and Li3GaN2 phases. At 260 .C and 30 bar hydrogen pressure, the Li.Al.N ternary system initially absorbed 3.7wt.% hydrogen, although this is not fully reversible. We observed, for the first time, hydrogen uptake by a pristine ternary nitride of Li and Al synthesized from the binary nitrides of the metals. While the Li.Ga.N ternary system also stored a significant amount of hydrogen, the storage capacity for the Li.B.N system was near zero. The hydrogenation reaction is believed to be similar to that of Li3N, and the enthalpies of hydrogen absorption for Li.Al.N and Li.Ga.N provide evidence that AlN and GaN, as well as the ball milling process, play a significant role in altering the thermodynamics of Li3N.
Henrietta W. Langmi, G. Sean McGrady, Journal of Alloys and Compounds 466 (2008) 287–292

G0014 – Technological plasticity studies of the FeAl intermetallic phase-based alloy

Results of hot torsion tests of the Fe-40Al-5Cr-0.2Mo-0.2Zr-0.02B alloy are presented in the paper. The alloy was obtained by melting in an induction furnace. The tests were carried out using a plastometer of the Sataram type in the temperature range of 1123-1273 K and strain rates of 0.06, 0.24, 0.48 and 2.42 s-1 that were close to those used in plastic working processes. In the alloy studied the super-plasticity phenomenon was observed. The shape of the flow curves indicated that dynamic recrystallisation occurred during the super-plastic deformation. This was confirmed by studies of the alloy structure. Also traces of dynamic recovery were observed. The value of the activation energy Q=343 kJ/mol for dynamical recrystallisation is close to the activation energy of aluminium diffusion in the FeAl phase. The results have revealed that cast FeAl-based alloy can be process by superplasic forming in the range 1123-1223 K at strain rates about 1 s-1.
M. Kupka, Intermetallics 12 (2004) 295-302

HE0021 – Hydrogen Storage in a Microporous Metal-Organic Framework with Exposed Mn2+ Coordination Sites

Use of the tritopic bridging ligand 1,3,5-benzenetristetrazolate (BTT3-) enables formation of [Mn- (DMF)6]3[(Mn4Cl)3(BTT)8(H2O)12]2â42DMFâ11H2Oâ20CH3OH, featuring a porous metal-organic framework with a previously unknown cubic topology. Crystals of the compound remain intact upon desolvation and show a total H2 uptake of 6.9 wt % at 77 K and 90 bar, which at 60 g H2/L provides a storage density 85% of that of liquid hydrogen. The material exhibits a maximum isosteric heat of adsorption of 10.1 kJ/mol, the highest yet observed for a metal-organic framework. Neutron powder diffraction data demonstrate that this is directly related to H2 binding at coordinatively unsaturated Mn2+ centers within the framework.
Mircea Dinca ,Anne Dailly, Yun Liu, Craig M. Brown, Dan. A. Neumann and Jeffrey R. Long, J. AM. CHEM. SOC. 2006, 128, 16876-16883

HE0010 – Nanoporous Polymers for Hydrogen Storage

The study clearly demonstrates that hypercrosslinked nanoporous polymers with high hydrogen adsorption capacity are good candidates for use in future hydrogen storage systems. The major advantages of nanoporous polymers are light weight, and rapid complete adsorption and desorption with no appreciable hysteresis. Using a variety of well known reaction, these synthetic polymers can be easily modified and their adsorption ability further tuned.
Jonathan Germain, Jean M. J. Fréchet and Frantisek Svec, Polymeric Materials: Science & Engineering 2007, 97, 272

G0013 – Application des mesures magnétiques à la métallurgie

E. Alff and Cl. Bronner, Conférence au Cercle d'Etudes des Métaux (1973) 1-34

HE0020 – An overview of advanced materials for hydrogen storage

In a future sustainable energy system based on renewable energy, environmentally harmless energy carriers like hydrogen will be of crucial importance. One of the major impediments for the transition to a hydrogen-based energy system is the lack of satisfactory hydrogen storage alternatives. In the last years, the possible to store hydrogen in various materials was extensively studied. This paper is a preliminary study with the focus on advanced nanostructured materials such as solids of large surface area based on carbon structures, metals and different types of metal alloys, other intermetallic compounds, etc. as possibilities for hydrogen storage. The newest materials used for hydrogen storage are light metal alloys. We have so far focused in this review almost exclusively on experimental studies. Also there are presented the most important characteristics of these materials such as mechanical strength, porosity and affinity to hydrogen, and also the recent developments in the search for innovative materials with high hydrogen-storage capacity and our contribution in this field.
Michael A. Miller and Richard A. Page FY 2006 Annual Progress Report DOE Hydrogen Program 529-534

HE0041 – The Investigation of MgH2and LiBH4Mixtures Potential for Hydrogen Storage

MgH2has been examined as a potential hydrogen storage due to its high gravimetric capacity of 7.6 wt.%; however, its kinetics is slow. LiBH4has even higher capacity, 13.9 wt.% when it decomposes to LiH; unfortunately, this reaction requires high temperature exceeding 400oC. ?Destabilization of LiBH4with MgH2[1] and also of MgH2with LiBH4[2], have been reported. Vajo et al. [1] reported thermodynamic improvement of the hydrogen storage performance of MgH2destabilized with LiBH4; however, no kinetic improvement was observed. The reaction pathway through Mg and then MgB2corresponding to a two-step desorption was suggested. The MgB2formation was believed to improve the reversibility [3]. Johnson et al. [2] reported kinetic improvement of the hydrogen storage performance of LiBH4destabilized withMgH2. The presence of Li+in the crystal structure was suggested to be the reason for this enhancement. However, evidence of thermodynamic enhancement from LiBH4addition was not observed. ?We have examined if there is a “eutectic” molar ratio existing between MgH2and LiBH4that may improve both kinetic and thermodynamic hydrogen storage performances. We have found that a 3:1 mole ratio of MgH2and LiBH4mixture has the fastest desorption rate and highest hydrogen desorption capacity. The 3:1 mixture was doped with TiCl3and the result shows good reversibility and cycle stability.
Uncharat Setthanan, G. Sean McGrady, Poster

HE0030 – Hydrogen storage properties of Pd nanoparticle/carbon template composites

Theoretical studies predict improved hydrogenation properties for hybrid carbon/metal composites. The hydrogen storage capacity of ordered porous carbon containing Pd clusters was measured. The C/Pd composite was obtained by chemical impregnation of an ordered porous carbon template (CT) with a H2PdCl4 solution followed by a reduction treatment. 10 wt.% of palladium clusters were introduced in the carbon porosity; the Pd clusters (2 nm in size) being homogeneously distributed. Thermodynamic hydrogenation properties of both Pd-free CT and the Pd–10 wt.% CT composite have been determined by hydrogen isotherm sorption measurements and thermal desorption spectroscopy (TDS) analysis. The introduction of the palladium into the carbon matrix does not increase the hydrogen storage capacity at 77 K and 1.6 MPa, since here the hydrogen uptake is being attributed to physisorption on the carbon. However, at room temperature and moderate pressure (0.5 MPa), the filling of the CT with 10 wt.% nanocrystalline Pd results in an hydrogen uptake eight times larger than that of the Pd-free CT. After the second cycle, a good reversibility is observed. TDS measurements confirm that the sharp increase of the hydrogen uptake is due to the presence of the Pd clusters in the carbon porosity
R. Campesia, F. Cuevas, R. Gadiou, E. Leroy, M. Hirscher, C. Vix-Guterl, M. Latroche, Carbon 46 (2008 ) 206 –214

HE0051 – Iodide substitution in lithium borohydride, LiBH4–LiI

The new concept, anion substitution, is explored for possible improvement of hydrogen storage properties in the system LiBH4–LiI. The structural chemistry and the substitution mechanism are analyzed using Rietveld refinement of in situ synchrotron radiation powder Xray diffraction (SRPXD) data, attenuated total reflectance infrared spectroscopy (ATRIR), differential scanning calorimetry (DSC) and Sieverts measurements. Anion substitution is observed as formation of two solid solutions of Li(BH4)1?xIx, which merge into one upon heating. The solid solutions have hexagonal structures (space group P63mc) similar to the structures of hLiBH4 and bLiI. The solid solutions have iodide contents in the range ?0–62 mol% and are stable from below room temperature to the melting point at 330 ?C. Thus the stability of the solid solutions is higher as compared to that of the orthorhombic and hexagonal polymorphs of LiBH4 and ? and ? LiI. Furthermore, the rehydrogenation properties of the iodide substituted solid solution Li(BH4)1?xIx, measured by the Sieverts method, are improved as compared to those of LiBH4. After four cycles of hydrogen release and uptake the Li(BH4)1?xIx solid solution maintains 68% of the calculated hydrogen storage capacity in contrast to LiBH4, which maintains only 25% of the storage capacity after two cycles under identical conditions.
Line H. Rude, Elena Groppo, Lene M. Arnbjerg, Dorthe B. Ravnsbæk, Regitze A. Malmkjær, Yaroslav Filinchuk, Marcello Baricco, Flemming Besenbacher, Torben R. Jensen, Journal of Alloys and Compounds 509 (2011) 8299– 8305

HE0040 – Ammine Magnesium Borohydride Complex as a New Material for Hydrogen Storage: Structure and Properties of Mg(BH4)2·2NH

The ammonia complex of magnesium borohydride Mg(BH4)2 · 2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2 · 6NH3 (II), which crystallizes in the cubic space group Fm¯3m with unit cell parameter a ) 10.82(1) Å and is isostructural to Mg(NH3)6Cl2. We solved the structure of I that crystallizes in the orthorhombic space group Pcab with unit cell parameters a ) 17.4872(4) Å, b ) 9.4132(2) Å, c ) 8.7304(2) Å, and Z ) 8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2 · 2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by N-H· · ·H-B dihydrogen bonds. Complex I decomposes endothermically starting at 150 °C, with a maximum hydrogen release rate at 205 °C, which makes it competitive with ammonia borane BH3NH3 as a hydrogen storage material.
Grigorii Soloveichik, Jae-Hyuk Her, Peter W. Stephens, Yan Gao, Job Rijssenbeek, Matt Andrus, and J.-C. Zhao, Inorg. Chem., 2008, 47 (10), 4290-4298

HE0029 – H2 sorption performance of NaBH4–MgH2 composites prepared by mechanical activation

The current research on solid state hydrogen storage materials for on-board applications is focused on reactive hydrides composites (RHC), i.e. systems based on the improvement of the dehydrogenation thermodynamic of a complex hydride when one (generally the light hydride MgH2) or more hydrides take part to the reaction. The extent of the destabilization, as well as the sorption characteristics of the composites, strongly depends on the structural and nanostructural properties of the constituent hydrides, which are in turn affected by the preparation route. The aim of this work is to evaluate the influence of different mechanical activation conditions on the storage properties of NaBH4 – MgH2 composites, up to now scarcely explored in literature. The first results regard composites with 2:1 and 1:2 stoichiometry milled under different atmosphere (Ar or H2). X-ray powders diffraction analysis shows that milling does not lead to the formation of any new phase, but it reduces the average crystallite size of the powders down to nanometric scale. All the mixtures release an H2 amount close to the theoretical value expected for the full dissociation of both the hydrides and much higher than the target fixed by the US Department of Energy for on-board application. The thermal programmed desorption profiles of the mixtures clearly show two steps, with MgH2 dissociating first and with higher rate and NaBH4 gradually dehydrogenating at temperatures close to 400°C. Concerning the 2:1 stoichiometry, when the samples are processed under Ar the two dehydrogenation processes are characterized by a lower starting temperature but also by a lower average rate with respect to the sample milled in H2. The 1:2 sample milled under Ar shows the best kinetic performance. Unfortunately, also for this mixture more than 10 h are required to obtain full desorption at a temperature as high as 450°C.
C. Milanese, A. Girella, G. Mulas, S. Enzo, S. Medici, S. Garroni, M. D. Barò, S. Suriñach & A. Marini, Ecosystems and Sustainable Development VII 389

HE0050 – Metal Organic Frameworks as Adsorbents for Hydrogen Purification and Precombustion Carbon Dioxide Capture

Selected metal organic frameworks exhibiting representative properties—high surface area, structural flexibility, or the presence of open metal cation sites—were tested for utility in the separation of CO2 from H2 via pressure swing adsorption. Single-component CO2 and H2 adsorption isotherms were measured at 313 K and pressures up to 40 bar for Zn4O(BTB)2 (MOF-177, BTB3 = 1,3,5-benzenetribenzoate), Be12(OH)12(BTB)4 (Be-BTB), Co(BDP) (BDP2 = 1,4-benzenedipyrazolate), H3[(Cu4Cl)3(BTTri)8] (Cu-BTTri, BTTri3 = 1,3,5-enzenetristriazolate), and Mg2-(dobdc) (dobdc4 = 1,4-dioxido-2,5-benzenedicarboxylate). Ideal adsorbed solution theory was used to estimate realistic isotherms for the 80:20 and 60:40 H2/CO2 gas mixtures relevant to H2 purification and precombustion CO2 capture, respectively. In the former case, the results afford CO2/H2 selectivities between 2 and 860 and mixed-gas working capacities, assuming a 1 bar purge pressure, as high as 8.6 mol/kg and 7.4mol/L. In particular, metal organic frameworks with a high concentration of exposed metal cation sites, Mg2(dobdc) and Cu-BTTri, offer significant improvements over commonly used adsorbents, indicating the promise of such materials for applications in CO2/H2 separations.
Zoey R. Herm,Joseph A. Swisher,Berend Smit,Rajamani Krishna, Jeffrey R. Long, J. Am. Chem. Soc.2010

HE0039 – Room temperature reversible hydrogen storage in polyaniline (PANI) nanofibers

We report for the first time the reversible hydrogen storage behavior at room temperature in polyaniline nanofibers. The rate of hydrogen sorption during the initial run was very rapid and an extended plateau pressure of about 30 bars was obtained from the pressure-composition isotherm profiles of these polyaniline nanofibers. The reversible cycling capacity of ~3-4 wt.% was demonstrated at room temperature and have been attributed due their unique microstructural and surface properties
Michael U. Jurczyk, Sesha S. Srinivasan, Ayala R. Phani, Ashok Kumar, D. Yogi Goswami, Elias K. Stefanakos

HE0049 – Mg-Ni-Cu mixtures for hydrogen storage: A kinetic study

Mg based ternary mixtures containing increasing amounts of Ni and Cu were prepared by ball milling under argon for 16 hours and then activated at high temperature (623K) by charging-discharging cycles at H2 pressures of 50 bar/0.7 bar. The work aims to analyze the influence of the mixture composition on the storage properties (H2 intake and sorption kinetics).
C. Milanese, A. Girella, P. Cofrancesco, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, Intermetallics 18 (2010) 203-211

HE0038 – High-surface area biocarbons for reversible on-board storage of natural gas and hydrogen

An overview is given of the development of advanced nanoporous carbons as storage materials for natural gas (methane) and molecular hydrogen in on-board fuel tankss for next generation clean automobiles.
Peter Pfeiffer and al, Mater. Res. Soc. Symp. Proc. Vol. 1041 © 2008 Materials Research Society

HE0048 – Effect of C (graphite) doping on the H2 sorption performances of the Mg-Ni storage system

The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the sorption performances of the Mg-Ni system.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy 35 (2010) 1285-1295

HE0037 – Hydrogen Storage Properties of Ternary Nitrides Prepared by Mechanochemical Milling

Lithium nitride reacts with many elements or binary nitrides to form ternary nitrides. Synthesis procedures for ternary nitrides often involve solid-state reactions that require high temperatures. In the current work we prepare, for the first time, ternary nitrides based on both Li and Group 13 elements by mechanochemical milling of Li3N and the Group 13 nitrides – BN, AlN and GaN. The ternary nitrides obtained are not the known Li3XN2 systems and we have tentatively designated them as Li–X–N (where X = B, Al or Ga). We report here an investigation of the hydrogen absorption–desorption behaviour of the Li–X–N ternary nitrides.
Henrietta W. Langmi, G. Sean McGrady, Poster

HE0047 – Synergetic effect of C (graphite) and Nb2O5 on the H2 sorption properties of the Mg-MgH2 system

Ternary Mg-Nb2O5-graphitic C mixtures were prepared by high energy ball milling under Ar for different times and charcaterized especially by the calorimetric technique.The aims of the work are to assess the effect of the simultaneous presence of the two dopants on the reactivity and the sorption properties of the Mg-MgH2 system, to study the influence of the milling time on the performances of the mixtures.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy 35 (2010) 9027-9037

HE0036 – Mixed–Metal Li3N–Based Systems for Hydrogen Storage: Li3AlN2 and Li3FeN2

The concept of destabilization has been employed by several groups working in the area of hydrogen storage by metal hydrides to identify and pursue systems with lower H2 desorption temperatures.
Henrietta W. Langmit, Scott D. Culligan and G. Sean McGrady, Poster

HE0057 – The effect of V, VCl3 and VC catalysts on the MgH2 hydrogen sorption properties

MgH2 based composites processed by mechanical alloying with the addition of 5 wt.% of V, VCand VCl3 were evaluated for their absorption/desorption hydrogen capacities at 300 and 350°C. These composites were investigated by the following techniques: X-ray diffraction, XRD, Pressure–Composition Isotherms, PCI and Differential Scanning Calorimetry, DSC. It was observed that the addition of V, VC and VCl3 compounds improves hydrogen absorption and desorption kinetics in comparison to the MgH2. The MgH2-5 wt.% VCl3 composite showed the faster absorption kinetics which absorbed 6.0 wt.% of H2 in 7.5 min at 350°C. The desorption activation energy of the composite containing VCl3 (47 kJ mol 1) is smaller than VC (63 kJ mol 1). This indicates that this catalyst is more effective to be used in hydrogen storage system.
M.O.T. da Conceição, M.C. Brum, D.S. dos Santos, Journal of Alloys and Compounds (2013)

HE0046 – A Reversible Nanoconfined Chemical Reaction

Hydrogen is recognized as a potential, extremely interesting energy carrier system, which can facilitate efficient utilization of unevenly distributed renewable energy. A major challenge in a future “hydrogen economy” is the development of a safe, compact, robust, and efficient means of hydrogen storage, in particular, for mobile applications. Here we report on a new concept for hydrogen storage using nanoconfined reversible chemical reactions. LiBH4 and MgH2 nanoparticles are embedded in a nanoporous carbon aerogel scaffold with pore size Dmax 21 nm and react during release of hydrogen and form MgB2. The hydrogen desorption kinetics is significantly improved compared to bulk conditions, and the nanoconfined system has a high degree of reversibility and stability and possibly also improved thermodynamic properties. This new scheme of nanoconfined chemistry may have a wide range of interesting applications in the future, for example, within the merging area of chemical storage of renewable energy.
Thomas K. Nielsen, Ulrike Bösenberg, Rapee Gosalawit, Martin Dornheim, Yngve Cerenius, Flemming Besenbacher, Torben R. Jensen, ACS Nano, Vol. 4, N° 7, 3903–3908 (2010)

HE0035 – Sorption properties of NaBH4/MH2 (M[Mg, Ti) powder systems

The sorption properties of NaBH4/MH2 (M ¼ Mg, Ti) powder systems prepared by highenergy ball milling have been thoroughly investigated. Concerning the systems containing MgH2, the 2:1 and 1:2 molar compositions have been studied and both lead to a multistep desorption pathway, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the MgH2-rich system (composition 1:2) if compared with the NaBH4-rich system (composition 2:1). Even though full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. During absorption, the unsuspected formation of the perovskite-type hydride NaMgH3 is detected and it is showed that this ternary phase contributes to reduce the gravimetric capacity of the systems. Conversely, in the 2NaBH4/ TiH2 system, there is no formation of the intermetallic compound TiB2. Furthermore, a decrease in the sorption kinetics is found in comparison with the systems based on MgH2
S. Garroni, C. Milanese, A. Girella, A. Marini, G. Mulas, E. Menendez, C. Pistidda, M. Dornheim, S. Surinach, M.D. Baro, International journal of hydrogen energy 35 (2010) 5434-5441

HE0056 – Hydrogen sorption–desorption studies on ZrCo–hydrogen system

The ZrCo–H2 system was investigated in this study owing to its importance as a suitable candidate material for storage, supply, and recovery of hydrogen isotopes. Desorption hydrogen pressure-composition isotherms were generated at six different temperatures in the range of 524–624 K. A van’t Hoff plot was constructed using the plateau pressure data of each pressure-composition isotherms and the thermodynamic parameters were calculated for the hydrogen desorption reaction of ZrCo hydride. The enthalpy and entropy change for the desorption of hydrogen were found to be 83.7 ± 3.9 kJ mol-1 H2 and 122 ± 4 J mol-1 H2 K-1, respectively. Hydrogen absorption kinetics of ZrCo–H2 system was studied at four different temperatures in the range of 544–603 K and the activation energy for the absorption of hydrogen by ZrCo was found to be 120 ± 5 kJ mol-1 H2 by fitting kinetic data into suitable kinetic model equation.
Ram Avtar Jat, S. C. Parida, J. Nuwad, Renu Agarwal, S. G. Kulkarni, J Therm Anal Calorim, 2012

HE0045 – Confinement of MgH2 Nanoclusters within Nanoporous Aerogel Scaffold Materials

Nanoparticles of magnesium hydride were embedded in nanoporous carbon aerogel scaffold materials in order to explore the kinetic properties of hydrogen uptake and release. A new modified procedure for the synthesis of magnesium hydride nanoparticles is presented. The procedure makes use of monoliths ( 0.4 cm3) of two distinct types of nanoporous resorcinol formaldehyde carbon aerogels loaded with dibutylmagnesium, MgBu2. Excess MgBu2 was removed mechanically, and the increase in mass was used as a measure of the amount of embedded MgH2. Energy-dispersive spectrometry revealed that MgH2 was uniformly distributed within the aerogel material. In situ synchrotron radiation powder X-ray diffraction showed that MgBu2 transformed directly to MgH2 at T 137 °C and p(H2) 50 bar. Two distinct aerogel samples, denoted X1 and X2, with pore volumes of 1.27 and 0.65 mL/g and average pore sizes of 22 and 7 nm, respectively, were selected. In these samples, the uptake of magnesium hydride was found to be proportional to the pore volume, and aerogels X1 and X2 incorporated 18.2 and 10.0 wt % of MgH2, respectively. For the two samples, the volumetric MgH2 uptake was similar, 12 vol %. The hydrogen storage properties of nanoconfined MgH2 were studied by Sieverts’ measurements and thermal desorption spectroscopy, which clearly demonstrated that the dehydrogenation kinetics of the confined hydride depends on the pore size distribution of the scaffold material; that is, smaller pores mediated faster desorption rates possibly due to a size reduction of the confined magnesium hydride.
Thomas K. Nielsen, Kandavel Manickam, Michael Hirscher, Flemming Besenbacher, Torben R. Jensen, ACS Nano, Vol. 3, N°. 11, 3521–3528 (2009)

HE0034 – Effect of C (graphite) doping on the H2 sorption performance of the Mg–Ni storage system

Binary Mg–Ni mixtures and ternary Mg–Ni–C (graphite) samples with fixed proportions of metals (Mg 85%–Ni 15% by weight) and amount of C increasing in increments of 5 wt % from 5 wt % to 15 wt % were prepared by high energy ball milling (BM) in Ar for tBM ¼2 h. The purpose of the study was to evaluate the effect of C addition on the reactivity, the sorption activation and the storage performance of the Mg–Ni system. Increasing the amount of C had the effect of decreasing (from 10 to 3) the number of cycles needed for activation (performed at 623 K and 40 bar/0.9 bar charging/discharging H2 pressure). After full activation, the 5 wt % C-containing sample exhibited the best absorption kinetics performance: the average rate to charge up to 5 wt % H2 was about 3 times higher than that observed for the undoped sample. Unfortunately, increasing the amount of C had a negative impact on the desorption behaviour, causing an increase in the dehydrogenation activation energy and a decrease in the discharging rates. Within the present study, C reacted neither with H2 nor with the H2 active phases (the two discharged phases Mg and Mg2Ni and the related hydrides) and consequently did not lead to variation in the sorption enthalpies of the Mg–Ni system. But, its presence did cause a small increase (4 K at 0.9 bar H2) in the minimum desorption temperatures of the hydrides and a consequent minor decrease (0.2 bar) in the equilibrium pressures. The best sorption properties were obtained for the 5 wt % C-sample, that on the whole worked better than the binary mixture.
C. Milanese, A. Girella, S. Garroni, G. Bruni, V. Berbenni, P. Matteazzi, A. Marini, International journal of hydrogen energy xx (2009) 1-11

HE0055 – Direct Synthesis of Amine-Functionalized MIL-101(Cr) Nanoparticles and Application to CO2 Capture

The synthesis of amine-functionalized metal-organic framework was obtained with chromic nitrate hydrate, 2-aminoterephthalic acid and and sodium hydroxide.. The adsorption isotherms of the probe gas CO2, N2 and CH4 (purity of 99.99) were measured using volumetric technique by an apparatus from SETARAM France (PCTpro-E&E). Before each measurement, the sample was evacuated at 150°C?? for 12 h. The adsorbed amounts ( Qi ) were calculated by the volumetric method. The ideal selectivity (?) of the sample was defined as: ? (A/B)= QA / QB , where QA is the adsorption uptake for gas A, and QB is the adsorption uptake for gas B.
Yichao Lin, Chunlong Kong, Liang Chen

HE0044 – Improved Hydrogen Storage Kinetics of Nanoconfined NaAlH4 Catalyzed with TiCl3 Nanoparticles

Nanoparticles of NaAlH4 have been infiltrated in nanoporous carbon aerogel with TiCl3 nanoparticles in order to explore possible synergetic effects between nanoconfinement and a functionalized catalytic scaffold. Resorcinol formaldehyde carbon aerogels with an average pore size of 17 nm and total pore volume of 1.26 mL/g were infiltrated with TiCl3 to obtain an aerogel doped with 3.0 wt %TiCl3 nanoparticles. NaAlH4 was melt-infiltrated into the functionalized carbon aerogel at 189 C and p(H2) ? 186 199 bar. Energy-dispersive spectrometry (EDS) combined with focused ion beam (FIB) techniques revealed the presence of Na, Al, Ti, and Cl inside the aerogel scaffold material. The infiltrated NaAlH4 was X-ray amorphous, whereas 27Al magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH4. Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH4 TiCl3 material as compared to nanoconfined NaAlH4 without the catalysts TiCl3 and to bulk ball-milled samples of NaAlH4 TiCl3. We find that the onset temperature for hydrogen release was close to room temperature (Tonset = 33 C), and the hydrogen release rate reached a maximum value at 125 C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.
Thomas K. Nielsen, Marek Polanski, Dariusz Zasada, Payam Javadian, Flemming Besenbacher, Jerzy Bystrzycki, Jørgen Skibsted, Torben R. Jensen, ACS Nano

HE0033 – Thermodynamics of hydrogen adsorption in MOF-177 at low temperatures:measurements and modelling

Hydrogen adsorption measurements and modelling for the Zn-based microporous metal–organic framework (MOF) Zn4O(1,3,5-benzenetribenzoate)2, MOF-177, were performed over the 50–77 K and 0–40 bar ranges. The maximum excess adsorption measured under these conditions varies over about 105–70 mg g?1. An analysis of the isotherms near saturation shows that hydrogen is ultimately adsorbed in an incompressible phase whose density is comparable to that of the bulk liquid. These liquid state properties observed under supercritical conditions reveal a remarkable effect of nanoscale confinement. The entire set of adsorption isotherms can be well described using a micropore filling model. The latter is used, in particular, to determine the absolute amounts adsorbed and the adsorption enthalpy. When expressed in terms of absolute adsorption, the isotherms show considerable hydrogen storage capacities, reaching up to 125 mg g?1 at 50 K and 25 bar. The adsorption enthalpies are calculated as a function of fractional filling and range from 3 to 5 kJ mol?1 in magnitude, in accordance with physisorption. These results are discussed with respect to a similar analysis performed on another Zn-based MOF, Zn4O(1,4-benzenedicarboxylate)3, IRMOF-1, presented recently. It is found that both materials adsorb hydrogen by similar mechanisms.
Eric Poirier and Anne Dailly, Nanotechnology 20 (2009) 204006

HE0054 – New compounds in the potassium-aluminium-hydrogen system observed during release and uptake of hydrogen

Three new compounds are observed in the potassium-aluminium-hydrogen system, which are characterised using in-situ synchrotron radiation powder X-ray diffraction (SR-PXD), thermal analysis (TG and DSC) and Siverts measurements (PCT). All three new compounds (denoted 1, 2 and 3) are observed during release and uptake of hydrogen in the potassium- aluminium-hydrogen system and may be new intermediates. All three compounds were indexed and the following unit cells were found, 1: cubic, a = 17.0248(9) A° , 2: cubic, a = 14.2746(4)A° and 3: orthorhombic, a = 10.46(1), b = 6.661(6) and c = 6.173(5)A° . Formation and observation of 1, 2 and 3 depends on the mechano-chemical sample preparation (ball milling), temperature, (heating rate), and hydrogen pressure (and temperature for pressure change). Compound 1 is often observed in the temperature range 55e150 "C for a medium ball-milled sample heated under a constant hydrogen pressure of 50 bar 1 is clearly an intermediate for formation of KAlH4 and may have the composition KyAlHx with 1 < y < 3 and 4 < x < 6. Applying hydrogen pressure abruptly at elevated temperatures leads to faster hydrogenation, which can then be performed at lower hydrogen pressures. In the latter case, 1 is only observed shortly in a few PXD patterns. Compounds 2 and 3 are mainly observed during dehydrogenation of KAlH4 in the temperature ranges of ca. 200 to 350 "C and 200 to 390 "C respectively, as relatively weak Bragg diffraction peaks.
Lene Mosegaard Arnbjerg, Torben R. Jensen, International journal of hydrogen energy 37 (2012) 345-356

HE0043 – Processing analysis of the ternary LiNH2–MgH2–LiBH4 system for hydrogen storage

In this article, we investigate the ternary LiNH2–MgH2–LiBH4 hydrogen storage system by adopting various processing reaction pathways. The stoichiometric ratio of LiNH2:MgH2:- LiBH4 is kept constant with a 2:1:1 molar ratio. All samples are prepared using solid-state mechano-chemical synthesis with a constant rotational speed, but with varying milling duration. Furthermore, the order of addition of parent compounds as well as the crystallite size of MgH2 are varied before milling. All samples are intimate mixtures of Li–B–N–H quaternary hydride phase with MgH2, as evidenced by XRD and FTIR measurements. It is found that the samples with MgH2 crystallite sizes of approximately 10 nm exhibit lower initial hydrogen release at a temperature of 150 C. Furthermore, it is observed that the crystallite size of Li–B–N–H has a significant effect on the amount of hydrogen release with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160 C and the other around 300 C. The main hydrogen release temperature is reduced from 310 C to 270 C, while hydrogen is first reversibly released at temperatures as low as 150 C with a total hydrogen capacity of w6 wt.%. Detailed thermal, capacity, structural and microstructural properties are discussed and correlated with the activation energies of these materials.
Michael U. Niemann, Sesha S. Srinivasan, Ashok Kumar, Elias K. Stefanakos, D. Yogi Goswami, Kimberly McGrath, International Journal of hydrogen energy, xxx (2009) 1-8

HE0032 – Structure and Charge Control in Metal–Organic Frameworks Based on the Tetrahedral Ligand Tetrakis(4-tetrazolylphenyl)methane

Use of the tetrahedral ligand tetrakis(4-tetrazolylphenyl)methane enabled isolation of two three-dimensional metal–organic frameworks featuring 4,6- and 4,8-connected nets related to the structures of garnet and fluorite with the formulae Mn6-(ttpm)3·5DMF·3H2O (1) and Cu-(Cu4Cl)(ttpm)2]2·CuCl2·5DMF·11H2O (2) (H4ttpm=tetrakis(4-tetrazolylphenyl) methane). The fluorite-type solid 2 displays an unprecedented post-synthetic transformation in which the negative charge of the framework is reduced by extraction of copper(II) chloride. Desolvation of this compound generates Cu4(ttpm)2·0.7CuCl2 (2d), a microporous material exhibiting a high surface area and significant hydrogen uptake
Mircea Dinca, Anne Dailly and Jeffrey R. Long, Chem. Eur. J. 2008, 14, 10280 – 10285

HE0053 – Recommended Best Practices for the Characterization of Storage Properties of Hydrogen Storage Materials

This Recommended Practices for the Characterization of Hydrogen Storage Materials document provides an introduction to and overview of the recommended best practices in making measurements of the hydrogen storage properties of materials. Due to the breadth of the subjects covered, material will be presented in its most concise and accessible form. The authors will use examples from literature to add clarity to key topics and to provide the reader with avenues for further detailed inquiry into a specific subject. The Recommended Practices document is divided into an introductory section and will be followed by four or more chapters that cover the topic areas of:concentration and capacity, kinetics, thermodynamics and cycle life measurements of hydrogen storage materials as well as other important hydrogen storage materials properties.
Karl J. Gross, K. Russell Carrington, Steven Barcelo, Abhi Karkamkar, Justin Purewal,

HE0042 – Novel catalytic effects of fullerene for LiBH4 hydrogen uptake and release

The addition of catalysts to complex hydrides is aimed at enhancing the hydrogen absorption desorption properties. Here we show that the addition of carbon nanostructure C60 to LiBH4 has a remarkable catalytic effect, enhancing the uptake and release of hydrogen. A fullerene–LiBH4 composite demonstrates catalytic properties with not only lowered hydrogen desorption temperatures but also regenerative rehydrogenation at a relatively low temperature of 350 ?C. This catalytic effect probably originates from C60 interfering with the charge transfer from Li to the BH4 moiety, resulting in a minimized ionic bond between Li+ and BH4 , and a weakened covalent bond between B and H. Interaction of LiBH4 with an electronegative substrate such as carbon fullerene affects the ability of Li to donate its charge to BH4, consequently weakening the B–H bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H2. Degradation of cycling capacity is observed and is probably due to the formation of diboranes or other irreversible intermediates
Matthew S. Wellons, Polly A Berseth, Ragaiy Zidan, Nanotechnology 20 (2009) 204022

HE0031 – Ternary nitrides for hydrogen storage: Li–B–N, Li–Al–N and Li–Ga–N systems

This paper reports an investigation of hydrogen storage performance of ternary nitrides based on lithium and the Group 13 elements boron, aluminum and gallium. These were prepared by ball milling Li3N together with the appropriate Group 13 nitride—BN, AlN or GaN. Powder X-ray diffraction of the products revealed that the ternary nitrides obtained are not the known Li3BN2, Li3AlN2 and Li3GaN2 phases. At 260 ?C and 30 bar hydrogen pressure, the Li–Al–N ternary system initially absorbed 3.7wt.% hydrogen, although this is not fully reversible. We observed, for the first time, hydrogen uptake by a pristine ternary nitride of Li and Al synthesized from the binary nitrides of the metals. While the Li–Ga–N ternary system also stored a significant amount of hydrogen, the storage capacity for the Li–B–N system was near zero. The hydrogenation reaction is believed to be similar to that of Li3N, and the enthalpies of hydrogen absorption for Li–Al–N and Li–Ga–N provide evidence that AlN and GaN, as well as the ball milling process, play a significant role in altering the thermodynamics of Li3N.
Henrietta W. Langmi, G. Sean McGrady, Journal of Alloys and Compounds 466 (2008) 287–292

HE0052 – Carbon monoliths for CO2 adsorption

In this article we present the characterization of some carbon monoliths, which have an open and permeable structure. Due to electrical and thermal conductivity of the carbon fibers these composites could be electrically desorbed. The monoliths were prepared from milled carbon fibers and a phenolic resin. The obtained monolithic composites were carbonized up to 650°C and then the composites were steam activated at 800°C. By activation, the adsorption capacity of carbon dioxide was improved. The carbon fibers composites were characterized using scanning electron microscopy, atomic force microscopy, X-ray diffraction, BET surface area analysis and volumetric measurements of gas adsorption.
C. Banciu, A. Bara, L. Leonat, D. Patroi, Optoelectronics and Advanced Materials – Rapid Communications Vol. 5, No. 12, December 2011, p. 1341 - 1345

HE0073 – Nanoconfined 2LiBH4-MgH2-TiCl3 in carbon aerogel scaffold for reversible hydrogen storage

Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ?1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (?2.5 and 7 h, respectively) and bulk material (?23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively
Rapee Gosalawit-Utke, Chiara Milanese, Payam Javadian, Julian Jepsen, Daniel Laipple, Fahim Karmi, Julian Puszkiel, Torben R. Jensen, Amedeo Marini, Thomas Klassen, Martin Dornheim, International journal of hydrogen energy 38 (2013) 3275-3282

HE0062 – Hydrogen storage in 2NaBH4 + MgH2 mixtures: Destabilization by additives and nanoconfinement

We focus on the H2 desorption properties of the 2NaBH4 + MgH2 system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF5 was tested as catalyst in both the preparations. Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics.
G. Mulas, R. Campesi, S. Garroni, E. Napolitano, C. Milanese, F. Dolci, E. Pellicer, D. Baró, A. Marini, Journal of Alloys and Compounds 536S (2012) S236– S240

HE0072 – Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1 xNix)2

The crystal structures of hydrogenated and unhydrogenated Sc(Al1?xNix)2 Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A2B2-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H2. It is shown that these compounds share the same local coordination as Frank–Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures
Martin Sahlberg, Jonas Angström, Claudia Zlote, Premysl Beran, Michel Latroche, Cesar Pay Gomez, Journal of Solid State Chemistry 196 (2012) 132–137

HE0061 – Influence of the substitution of V by Nb in the structure and properties of hydrogen absorption/desorption of TiCr1.1V0.9 alloy

The partial substitution of V by Nb in the TiCr1.1V0.9 alloy was performed generating four different compounds. The thermal stability, the hydrogen storage capacity as well as the kinetics of absorption/desorption were studied. It was observed that the addition of Nb decreases the hydrogen absorption capacity from 3.6 wt% to 2.5 wt%, but it increases the kinetic. The desorption performance improves above 373 K.
A. Martínez, D.S. dos Santos, Journal of Alloys and Compounds 536S (2012) S231– S235

HE0071 – Fully reversible hydrogen absorption and desorption reactions with Sc(Al1 xMgx), x¼0.0, 0.15,0.20

The hydrogen storage properties of Sc(Al1?xMgx), x=0.0, 0.15, 0.20, have been studied by X-ray powder diffraction, thermal desorption spectroscopy, pressure-composition-isotherms and scanning electron microscopy techniques. Hydrogen is absorbed from the gas phase at 70 kPa and 400 °C under the formation of ScH2 and aluminium with magnesium in solid solution. The reaction is fully reversible in vacuum at 500 °C and shows the hydrogenation–disproportionation–desorption-recombination (HDDR) behaviour. The activation energy of desorption was determined by the Kissinger method to 185 kJ/mol. The material is stable up to at least six absorption–desorption cycles and there is no change in particle size during cycling.
Martin Sahlberg, Claudia Zlote, Michel Latroche, Yvonne Andersson, Journal of Solid State Chemistry 184 (2011) 104–108

HE0060 – Reprint of: CO2/CH4, CH4/H2 and CO2/CH4/H2 separations at high pressures using Mg2(dobdc)

High-pressure separations of binary and ternary mixtures of CO2, CH4, and H2 are relevant to carbon dioxide capture as well as hydrogen and natural gas purification. Metal–organic frameworks represent a class of porous materials that could be used to accomplish these separations, and Mg2(dobdc) (dobdc4? = 1,4-dioxido-2,5-benzenedicarboxylate), also sometimes referred to as Mg–MOF-74 or CPO-27–Mg, is an especially lightweight metal–organic framework with a high concentration of coordinatively-unsaturated metal sites decorating its interior surfaces. High pressure CH4 adsorption isotherms presented here, together with CO2 and H2 adsorption behavior, are analyzed using the Ideal Adsorbed Solution Theory to model CO2/CH4, CH4/H2, and CO2/CH4/H2 mixture separations using Mg2(dobdc). The selectivities, working capacities and breakthrough performances for these three mixtures are reported, and Mg2(dobdc) is shown to outperform zeolite 13X in each scenario.
Zoey R. Herm, Rajamani Krishna, Jeffrey R. Long, Microporous and Mesoporous Materials 157 (2012) 94–100

HE0081 – Ammonia-free infiltration of NaBH4 into highly-ordered mesoporous silica and carbon matrices for hydrogen storage

In this work we focused on nanoconfinement of NaBH4 into highly-ordered Si-based mesoporous scaffold and its carbon replica by ammonia-free wet chemical impregnation. Structural and morphological characterization, performed by X-ray diffraction and transmission electron microscopy enabled us to confirm the effectiveness infiltration procedure. Desorption properties tested by temperature programmed desorption analyses highlighted a noticeable shift towards lower temperature compared to both bulk material and samples of similar systems referred to in the bibliographical data.
F. Peru, S. Garroni, R. Campesi, C. Milanese, A. Marini, E. Pellicer, M.D. Baró, G. Mulas, Journal of Alloys and Compounds 580 (2013) S309–S312

HE0070 – Ball-milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

Among the borohydrides proposed for solid state hydrogen storage, Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 + MgB2 system from which Ca(BH4)2 and MgH2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB2 with AlB2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions
B. Schiavo, A. Girella, F. Agresti, G. Capurso, C. Milanese, Journal of Alloys and Compounds 509S (2011) S714– S718

HE0059 – Sorption of hydrogen onto titanate nanotubes decorated with a nanostructured Cd3[Fe(CN)6]2 Prussian Blue analogue

Nanostructured films of cadmium hexacyanoferrate (III), Cd3[Fe(CN)6]2 have been deposited on the surface of titanate nanotubes (TiNT) by ion exchange with CdSO4, followed by reaction with K3[Fe(CN)6] in an aqueous suspension. The composite demonstrates a significantly higher hydrogen storage uptake than pure Cd3[Fe(CN)6]2 and TiNT. At a temperature of 77 K and a pressure 100 bar, the hydrogen uptake for the composite is approximately 12.5 wt %, whereas only 4.5 wt % and 4 wt % are achieved for the TiNT and Cd3[Fe(CN)6]2 respectively. Electron microscopy and infrared spectroscopy show that Cd3[Fe(CN)6]2 is uniformly distributed on the surface of the nanotubes forming a discontinuous nanostructured film with a well developed interface, which allows efficient interaction with the support. The possible reasons for the high uptake of hydrogen in the composite are discussed
A.A. Al-Hajjaj, B. Zamora, D.V. Bavykin, A.A. Shah, F.C. Walsh, E. Reguera, International journal of hydrogen energy 37 (2012) 318-326

HE0080 – Structural evolution upon decomposition of the LiAlH4+LiBH4 system

In the present work we focus the attention on the phase structural transformations occurring upon the desorption process of the LiBH4 + LiAlH4 system. This study is conducted by means of manometric–calorimetric, in situ Synchrotron Radiation Powder X-ray Diffraction (SR-PXD) and exsitu Solid State Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) measurements. The desorption reaction is characterized by two main dehydrogenation steps starting at 320 and 380 °C, respectively. The first step corresponds to the decomposition of LiAlH4 into Al and H2via the formation of Li3AlH6 whereas the second one refers to the dehydrogenation of LiBH4 (molten state). In the range 328–380 °C, the molten LiBH4 reacts with metallic Al releasing hydrogen and forming an unidentified phase which appears to be an important intermediate for the desorption mechanism of LiBH4–Al-based systems. Interestingly, NMR studies indicate that the unknown intermediate is stable up to 400 °C and it is mainly composed of Li, B, Al and H. In addition, the NMR measurements of the annealed powders (400 °C) confirm that the desorption reaction of the LiBH4 + Al system proceeds via an amorphous boron compound
S. Soru, A. Taras, C. Pistidda, C. Milanese, C. Bonatto Minella, E. Masolo, P. Nolis, M. D. Baró, A. Marini, M. Tolkiehn, M. Dornheim, S. Enzo, G. Mulas, S. Garroni, Journal of Alloys and Compounds (2013)

HE0069 – Chloride substitution in sodium borohydride

The dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH4)1?xClx is studied. The dissolution reaction is facilitated by two methods: ball milling or combination of ball milling and annealing at 300 °C for three days of NaBH4–NaCl samples in molar ratios of 0.5:0.5 and 0.75:0.25. The degree of dissolution is studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction (SR-PXD) data. The results show that dissolution of 10 mol% NaCl into NaBH4, forming Na(BH4)0.9Cl0.1, takes place during ball milling. A higher degree of dissolution of NaCl in NaBH4 is obtained by annealing resulting in solid solutions containing up to 57 mol% NaCl, i.e. Na(BH4)0.43Cl0.57. In addition, annealing results in dissolution of 10–20 mol% NaBH4 into NaCl. The mechanism of the dissolution during annealing and the decomposition pathway of the solid solutions are studied by in situ SR-PXD. Furthermore, the stability upon hydrogen release and uptake were studied by Sieverts measurements.
Dorthe B. Ravnsbæk,Line H. Rude,Torben R. Jensen, Journal of Solid State Chemistry 184(2011)1858–1866

HE0058 – Synthesis and characterization of mesoporous PdPtCr alloy and its influence on the hydrogen kinetics in MgH2

The compounds made of MgH2 and (1 and 5 wt.%) Pd40Pt30Cr30 catalyst by mechanical milling were tested for their ability to absorb and desorb hydrogen. The mesoporous Pd40Pt30Cr30 was obtained by the reduction of chloride complexes and using a surfactant solution. The absorption kinetic tests showed that the MgH2 + 1 wt.% Pd40Pt30Cr30 sample attained 90% of hydrogen capacity around 10 min, at 350°C. The desorption tests showed that the MgH2 + 5 wt.% Pd40Pt30Cr30 sample desorbed completely in about 5 min at the same temperature. The highest hydrogen capacity, 6.8 wt.% of H2, was determined by absorption/desorption P-C-Isotherm curves at 300°C for MgH2 + 1 wt.% Pd40Pt30Cr30 sample. The MgH2 + 5 wt.% Pd70Pt30 was used in the hydrogenation tests to elucidate the fact that the presence of CrCl3 in the Pd40Pt30Cr30 alloy mixed to MgH2, leads to an increase in the hydrogen total capacity of absorption.
M.O.T. da Conceicão, M.C. Brum, C.S. Guimarães, D.S. dos Santos, Journal of Alloys and Compounds 536S (2012) S255– S258

HE0079 – In situ synchrotron radiation powder X-ray diffraction study of the 2LiNH2 + LiH + KBH4 system

In the present work we focus on the 2LiNH2 + KBH4 + LiH system: the phase-structural transformations occurring during the desorption process on the powder mixture are described by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), high-pressure differential scanning calorimetry and manometric measurements. It is observed that LiNH2 transforms into Li2NH during heating, at about 160 °C, while the reflections related to KBH4 disappeared at 380 °C. At higher temperature, the formation of Li3BN2 is detected, together with an evident increase of the background, ascribable to the presence of a further phase in the molten state. Patterns at room temperature, after cooling down the sample, confirm the presence of Li3BN2 and KH as reported in the theoretical study. For the as prepared mixture it is possible to achieve the theoretical hydrogen gravimetric capacity of 7.4 wt%.
Maddalena Sale, Claudio Pistidda, Alessandro Taras, Emilio Napolitano, Chiara Milanese, Fahim Karimi, Martin Dornheim, Sebastiano Garroni, Stefano Enzo, Gabriele Mulas, Journal of Alloys and Compounds 580 (2013) S278–S281

HE0068 – An experimental investigation on the poor hydrogen sorption properties of nano-structured LaNi5 prepared by ball-milling

Nano-structured LaNi5 hydrogen storage materials prepared by ball-milling is analysed using differential scanning calorimetry (DSC) and x-ray photoelectron spectroscopy (XPS). DSC results indicate a partial elimination of defects at 500 °C in a more efficient way for the short-time ball-milled powders compared to the long-time ball-milled ones. XPS results show almost no change in the core-level electronic structure for La and Ni of LaNi5 in the bulk and the nano-structured forms, but gives an indication that the self-restoring mechanism of the active surface observed in the bulk sample (Siegmann et al. Phys. Rev. Lett. 40, 972) may not be occurring in the nano-powders. Results from the X-ray diffraction and the local structural studies together with the above observations suggest that the reduced unit-cell volume and the enhanced atomic disorder in the nano-structured LaNi5 cause a larger energy barrier for the hydrogen sorption reactions of the long-time ball-milled samples.
B. Joseph, B. Schiavo, G. D’Al? Staiti, B.R. Sekhar, International journal of hydrogen energy 36 (2011) 7914-7919

HE0078 – Catalysis and hydrolysis properties of perovskite hydride NaMgH3

The addition of NaH by ball milling is shown to greatly improve the hydrogen storage properties and the hydrolysis properties of MgH2, which is related to the formation of ternary hydride NaMgH3 with specific perovskite structure. The MgH2–10%NaH mixture exhibits better hydriding and dehydriding kinetics than the MgH2–10%LiH mixture, in which the LiMgH3 with perovskite structure could not be formed. The catalytic role of NaMgH3 is attributed to fast hydrogen mobility in the perovskite structure, which provides fast hydrogen diffusion pathways for the hydriding and dehydriding of MgH2. The NaMgH3 also shows fast hydrolysis reaction kinetics without any passivation. Our work shows that such perovskite-type hydride demonstrates great potential as efficient catalysts for the high-capacity hydrides for whether reversible or irreversible hydrogen storage.
H. Wang, J. Zhang, J.W. Liu, L.Z. Ouyang, M. Zhu, Journal of Alloys and Compounds 580 (2013) S197–S201

HE0067 – Hydrogen Adsorption in Zeolite Studied with Sievert and Thermogravimetric Methods

Natural clinoptilolite (mixture from clinoptilolite, quartz and muscovite) is activated with palladium and tested for hydrogen adsorption capability at temperatures RT - 200°C. Thermogravimetric and volumetric methods showed that zeolite activated with palladium (1.25%wt) shows markedly high hydrogen adsorption capacity - up to 3 wt%. Lower amount of adsorbed hydrogen (~1.5 wt%) was found for raw zeolite and activated with higher amount of palladium sample. Hypothesis is proposed that the heating of zeolite in argon atmosphere forms and activates the pore structure in zeolite material, where hydrogen encapsulation (trapping) is believed to occur when cooling down to room temperature. An effect of catalyst (Pd) on hydrogen sorption capability is explained by spillover phenomena were less-porous fractions of natural clinoptilolite sample (quartz and muscovite) are involved.
P. Lesnicenoks, A Sivars, L Grinberga, J Kleperis, IOP Conf.Series : Materials Science and Engineering 38 (2012) 012060

HE0077 – Surface properties of V40(TiCr)51Fe8Mn alloy during hydrogenation/dehydrogenation cycles

The bcc alloy V40(TiCr)51Fe8Mn shows a high reversible hydrogen capacity of 2.22 mass% at room temperature and is therefore expected to be applied as a hydrogen storage material. During the first 10 hydrogenation/dehydrogenation cycles, the capacity decreases markedly from 2.22 to 1.86 mass%. Possible reasons are both internal (including lattice variation, strain, phase transformation, phase disproportion, etc.) and external factors (poisoning by impurities in the gas after decades of cycles mainly). In this work, the surface properties of the V40(TiCr)51Fe8Mn alloy during 20 hydrogenation/dehydrogenation cycles were investigated by XPS analysis. During hydrogenation/dehydrogenation cycles, the surface becomes oxidized. Particular oxides were known to block hydrogen uptake and might thus be responsible for the capacity decay. It was found that Cr is enriched at the surface. Dense and passive chromia forms thereafter around alloy particles and hinder further oxidation and therefore stops further degradation of the hydrogen capacity of the alloy.
Chaoling Wu, Andreas Borgschulte, Urs Frischknecht, Yigang Yan, Fei Yang, Linshan Luo, Yungui Chen, Andreas Züttel, Journal of Alloys and Compounds 580 (2013) S156–S158

HE0066 – Increased volumetric hydrogen uptake of MOF-5 by powder densification

The metal-organic framework MOF-5 has attracted significant attention due to its ability to store large quantities of H2 by mass, up to 10 wt.% absolute at 70 bar and 77 K. On the other hand, since MOF-5 is typically obtained as a bulk powder, it exhibits a low volumetric density and poor thermal conductivity—both of which are undesirable characteristics for a hydrogen storage material. Here we explore the extent to which powder densification can overcome these deficiencies, as well as characterize the impact of densification on crystallinity, pore volume, surface area, and crush strength. MOF-5 powder was processed into cylindrical tablets with densities up to 1.6 g/cm3 by mechanical compaction. We find that optimal hydrogen storage properties are achieved for ? ? 0.5 g/cm3, yielding a 350% increase in volumetric H2 density with only a modest 15% reduction in gravimetric H2 excess in comparison to the powder. Higher densities result in larger reductions in gravimetric excess. Total pore volume and surface area decrease commensurately with the gravimetric capacity, and are linked to an incipient amorphization transformation. Nevertheless, a large fraction of MOF-5 crystallinity remains intact in densities up to 0.75 g/cm3, as confirmed from powder XRD. Predictably, the radial crush strength of the pellets is enhanced by densification, increasing by a factor of 4.3 between a density of 0.4 g/cm3 and 0.6 g/cm3. Thermal conductivity increases slightly with tablet density, but remains below the single crystal value.
J.J. Purewal, D. Liu, J. Yang, A. Sudik, D.J. Siegel, S. Maurer, U. Müller, International journal of hydrogen energy 37 (2012) 2723-2727

HE0076 – New directions for hydrogen storage: sulphur destabilised sodium aluminium hydride

Aluminium sulphide (Al2S3) is predicted to effectively destabilise sodium aluminium hydride (NaAlH4) in a single-step endothermic hydrogen release reaction. The experimental results show unexpectedly complex desorption processes and a range of new sulphur containing hydrogen storage materials have been observed. The NaAlH4–Al2S3 system releases a total of 4.9 wt% of H2 that begins below 100 °C without the need for a catalyst. Characterisation via temperature programmed desorption, in situ synchrotron powder X-ray diffraction, ex situ x-ray diffraction, ex situ Fourier transform infrared spectroscopy and hydrogen sorption measurements reveal complex decomposition processes that involve multiple new sulphur-containing hydride compounds. The system shows partial H2 reversibility, without the need for a catalyst, with a stable H2 capacity of 1.6 wt% over 15 cycles in the temperature range of 200 °C to 300 °C. This absorption capacity is limited by the need for high H2 pressures (>280 bar) to drive the absorption process at the high temperatures required for reasonable absorption kinetics. The large number of new phases discovered in this system suggests that destabilisation of complex hydrides with metal sulphides is a novel but unexplored research avenue for hydrogen storage materials.
Drew A. Sheppard, Lars H. Jepsen, Torben R. Jensen, Mark Paskeviciusa, Craig E. Buckley, J. Mater. Chem. A, 2013, 1, 12775

HE0065 – The effects of halide modifiers on the sorption kinetics of the Li-Mg-N-H System

The effects of different transition metal halides (TiCl3, VCl3, ScCl3 and NiCl2) on the sorption properties of the 1:1 molar ratio of LiNH2 to MgH2 are investigated. The modified mixtures were found to contain LiNH2, MgH2 and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl3 > ScCl3 > VCl3 > NiCl2. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. X-ray diffraction and Raman spectroscopy identified the cycled material to be composed of LiH, MgH2, Mg(NH2)2 and Mg3N2
Christine Price, Joshua Gray, Robert Lascola Jr., Donald L. Anton, International journal of hydrogen energy 37 (2012) 2742-2749

HE0075 – Affects of mechanical milling and metal oxide additives on sorption kinetics of 1:1 LiNH2/MgH2 mixture

The destabilized complex hydride system composed of LiNH2:MgH2 (1:1 molar ratio) is one of the leading candidates of hydrogen storage with a reversible hydrogen storage capacity of 8.1 wt%. A low sorption enthalpy of ~32 kJ/mole H2 was first predicted by Alapati et al. utilizing first principle density function theory (DFT) calculations and has been subsequently confirmed empirically by Lu et al. through differential thermal analysis (DTA). This enthalpy suggests that favorable sorption kinetics should be obtainable at temperatures in the range of 160 °C to 200 °C. Preliminary experiments reported in the literature indicate that sorption kinetics are substantially lower than expected in this temperature range despite favorable thermodynamics. Systematic isothermal and isobaric sorption experiments were performed using a Sievert’s apparatus to form a baseline data set by which to compare kinetic results over the pressure and temperature range anticipated for use of this material as a hydrogen storage media. Various material preparation methods and compositional modifications were performed in attempts to increase the kinetics while lowering the sorption temperatures. This paper outlines the results of these systematic tests and describes a number of beneficial additions which influence kinetics as well as NH3 formation
Donald L. Anton, Christine J. Price, Joshua Gray,Energies 2011, 4(5), 826-844

HE0064 – Kinetic and thermodynamic studies of hydrogen adsorption on titanate nanotubes decorated with a Prussian blue analogue

In this paper, the kinetic and thermodynamic hydrogen adsorption characteristics of a novel composite comprising TiNT decorated with the Prussian blue analogue Cd3FeIII are investigated at high pressures and different temperatures. It is shown that boundary-layer (film) diffusion does not play a limiting role in the mass transport of hydrogen inside the composite material. The diffusion coefficient and time constant at different temperatures and pressures are calculated using an intra-particle diffusion model. The results suggest that molecular diffusion dominates Knudsen diffusion in the composite material. There are clear improvements in the mass transport characteristics compared to bulk Cd3FeIII. The Gibb's free energy is estimated by fitting isotherm equilibrium data to the Dubinin–Astakhov model and is used to calculate the enthalpy and the entropy of adsorption. The calculated value of enthalpy is characteristic of a physisorption process and is considerably higher than the activation energy for intraparticle diffusion, suggesting that the rate-limiting step of hydrogen is not mass transport to the adsorption sites.
B. Zamora, A.A. Al-Hajjaja, A.A. Shahc, D.V. Bavykina, E. Reguerab, International Journal of Hydrogen Energy, Volume 38, Issue 15, 20 May 2013, Pages 6406–6416

HE0074 – The Affects of Halide Modifiers on the Sorption Kinetics of the Li-Mg-N-H System

In this present work, the affects of different transition metal halides (TiCl3, VCl3, ScCl3 and NiCl2) on the sorption properties of the 1:1 molar ratio of LiNH2 to MgH2 are investigated. The modified mixtures were found to contain LiNH2, MgH2 and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl3>ScCl3>VCl3>NiCl2. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. XRD and Raman spectroscopy identified the cycled material to be composed of LiH, MgH2, Mg(NH2)2 and Mg3N2.
Christine J. Erdy-Price, Joshua R. Gray, Robert J. Lascola, Donald L Anton, Publication of Savannah River National Laboratory

HE0063 – Enhanced dehydrogenation properties of LiBH4 compositing with hydrogenated magnesium-rare earth compounds

LiBH4 is regarded as a promising hydrogen storage material due to its high hydrogen density. In this study, the dehydrogenation properties of LiBH4 were remarkably enhanced by doping hydrogenated Mg3RE compounds (RE denotes La, Ce, Nd rare earth metals), which are composed of nanostructured MgH2 and REH2+x (denoted as H ? Mg3RE). For the LiBH4 + H ? Mg3La mixture, the component LiBH4 desorbed 6 wt.% hydrogen even at a relatively low temperature of 340 °C, far lower than the desorption temperature of pure LiBH4 or the 2LiBH4 + MgH2 system. This kinetic improvement is attributed to the hydrogen exchange mechanism between the H ? Mg3La and LiBH4, in the sense that the decomposition of MgH2 and LaH2+x catalyzed the dehydrogenation of LiBH4 through hydrogen exchange effect rather than mutual chemical reaction requiring higher temperature and hydrogen pressure. However, prior to fast hydrogen release, the hydrogen exchange effect suppressed the dehydriding of MgH2 and elevated its desorption temperature. It is expected to strengthen the hydrogen exchange effect by compositing the LiBH4 with other nanosized metal hydrides and to obtain better dehydrogenation properties
C. Luo, H. Wang, T. Sun, M. Zhu, International journal of hydrogen energy 37 (2012) 13446-13451

L0019 – Processing and characterization of La2O3/Al2O3/B2O3 based glass-ceramics for LTCC application

A lead-free, non-alkali and low-sintering temperature, La2O3-Al2O3-B2O3 (LAB) glass with Al2O3 filler had been investigated for LTCC application. The glass melting, processing window of tape casting, and sintering of the LAB glass-ceramic systems the wetting behaviors of the LAB glass on alumina plate, and the crystallization kinetics in the LAB/Al2O3 glass-ceramics were also studied. Moreover, systematic studies of thermal characteristics, phase transformation and microstructures during different heat-treatments were investigated by DTA, XRD, TMA, SEM/EDS, TEM, and AEM. The densification and crystallization temperatures of LAB glass performed between 800°C-850°C. Additionally, the sintering and dielectric properties of layer LAB/Al2O3 glass-ceramics with Ag electrode were also measured. The densification kinetics and possible defects during the cofiring will be reported.
C-L.B. Chen, W-C.J. Wei and A. Roosen

L0008 – Effect of Yttrium doping on sintering of fine grained alumina

E. Sato and C. Carry, Third Euro-Ceramics 1 (1993) 691-696

HE0083 – Muon spin relaxation reveals the hydrogen storage mechanism in light alkali metal fullerides

We report a muon spin relaxation investigation of Li6C60 and Na10C60 fullerides, which have been recently demonstrated to be efficient and reversible H2 absorbers above 570 K. We prove that, differently from other fullerides, a sizeable fraction of implanted muons form C60 muonium adduct radicals, with hyperfine coupling depending on the C60 hydrogen coverage. Surprisingly, the fraction of radicals was found to increase up to 65% when lowering T to 5 K in Na10C60Hy. This indicates that hydrogen interaction in these systems is enhanced even at cryogenic temperatures, while the high T needed for hydrogen absorption is only required to overcome the H2 dissociation barrier mediated by alkali metals.
M. Aramini, M. Gaboardi, G. Vlahopoulou, D. Pontiroli, C. Cavallari, C. Milanese, M. Ricco, Carbon 67 (2014) 92-97

L0018 – The linear thermal expansion and the thermal diffusivity measurements for near-stoichiometric (U, Ce)O2 solid solutions

The thermal diffusivities of near-stoichiometric (U, Ce)O2 solid solutions containing CeO2 up to 22 mol% were investigated in the temperature range of 298-1273 K using the laser flash method. Also, linear thermal expansion measurements were performed in the temperature range of 298-1673 K using a thermomechanical analysis. The thermal conductivities were determined by a calculation of the thermal diffusivity, the density and the specific heat. The thermal conductivities of the tested samples could be expressed as a function of the temperature by the phonon conduction equation k = (A + BT)-1. The thermal conductivity decreased gradually with an increasing Ce content. This was attributable to the increasing lattice defect thermal resistance caused by the U4+, Ce4+ and O2- ions as phonon scattering centers.
D-J. Kim, Y-S. Kim, S-H. Kim, J-H. Kim, J-H. Yang, Y-W. Lee and H-S. Kim, Thermochimica Acta 441 (2006) 127-131

L0007 – BaTiO3 ceramics. Sintering and residual carbon content.

C. Le Calvé-Proust, E. Husson, G. Blondiaux, J.P. Coutures, Third Euro-Ceramics 1 (1993) 799-804

HE0082 – Catalysis and evolution on cycling of nanostructured magnesium multilayer thin films

This paper explores the hydrogen cycling properties of Mg/Cr and Mg/V multilayer thin films and studies the effect of chromium and vanadium transition metal catalysts on the cycling properties of thick magnesium coatings. Two transition-metal catalysed magnesium-based multilayer PVD coatings are compared with a non-catalysed magnesium control sample. The (micro-)structural evolution of the thin film coatings into fine, flakey powders is studied in-depth using XRD, SEM and TEM and the hydrogen storage properties of all three materials are assessed using volumetric, gravimetric and calorimetric methods focussing on the effect of the microstructure and composition of the coatings on the hydrogen storage kinetics. It was found that the chromium-catalysed coating had the most favourable hydrogen storage kinetics with an activation energy for the dehydrogenation reaction of 65.7 ± 2.5 kJ mol?1 and a hydrogen capacity of 6.1 ± 0.3 wt%. The mechanism of the dehydrogenation reaction of the catalysed samples was studied using the CV and JMAK kinetic models and it was found that the catalyst material influenced not only the hydrogen storage kinetics but also the mechanism of the reaction
Christopher M.P. Fry, David M. Grant, Gavin S. Walker, International Journal of Hydrogen Energy (2013) 1-12

L0017 – Low-temperature synthesis and sintering of y-Y2Si2O7

In this article, a novel pressureless solid-liquid reaction method is presented for preparation of yttrium disilicate ( -Y2Si2O7). Single-phase -Y2Si2O7 powder was synthesized by calcination of SiO2 and Y2O3 powders with the addition of LiYO2 at 1400°Cfor 4 h. The addition of LiYO2 significantly decreased the synthesis temperature, shortened the calcination time, and enhanced the stability of -Y2Si2O7. The sintering of these powders in air and O2 was studied by means of thermal mechanical analyzer. It is shown that the -Y2Si2O7 sintered in oxygen had a faster densification rate and a higher density than that sintered in air. Furthermore, single-phase -Y2Si2O7 with a density of 4.0 g/cm3 (99% of the theoretical density) was obtained by pressureless sintering at 1400°Cfor 2 h in oxygen. Microstructures of the sintered samples are studied by scanning electron microscope.
Z. Sun, Y. Zhou and M. Li, Journal of Materials Research 21 (2006) 1443-1450

L0006 – Grain growth and swelling of hot pressed BaTiO3 during annealing treatments

M. Demartin, C. Herard, J. Lemaitre and C. Carry, Third Euro-Ceramics 1 (1993) 775-780

L0016 – Effect of alumina concentration on thermal and structural properties of MAS glass and glass-ceramics

Magnesium aluminum silicate (MAS) glass samples with different concentrations of alumina (7.58 to 14.71 mol%) were prepared by melt and quench-technique. Total Mg content in the form of MgF2+MgO was kept constant at 25 mol%. MAS glass was converted into glass-ceramics by controlled heat treatment at around 950°C. Crystalline phases present in different samples were identified by powder X-ray diffraction technique. Dilatometry technique was used to measure the thermal expansion coefficient and glass transition temperature. Scanning electron microscopy (SEM) was employed to study the microstructure of the glass-ceramic sample. It is seen from X-ray diffraction studies that at low Al2O3 concentrations (up to 10.5 mol%) both MgSiO3 and fluorophlogopite phases are present and at higher Al2O3 concentrations of 12.3 and 14.7 mol%, fluorophlogopite and magnesium silicate (Mg2SiO4), respectively are found as major crystalline phases. The average thermal expansion co-efficient (avg) of the glass samples decreases systematically from 9.8 to 5.5 x 10^(-6)°C-1 and the glass transition temperature (T g) increases from 610.1 to 675°C with increase in alumina content. However, in glass-ceramic samples the avg varies in somewhat complex manner from 6.8 to 7.9 x 10^(-6)°C-1 with variation of Al2O3 content. This was thought to be due to the presence of different crystalline phases, their relative concentration and microstructure.
M. Goswami, A. Sarkar, B.I. Sharma, V.K. Shrikande and G.P. Kothiyal, Journal of Thermal Analysis and Calorimetry 78 (2004) 699-705

L0005 – Sintering, grain growth and de-sintering processes in un-doped BaTiO3

M. Demartin, G. Pethybridge and C.Carry, Third Euro-Ceramics 1 (1993) 787-792

L0026 – High temperature properties of SiC and diamond CVD-monofilaments

The chemical, structural and thermomechanical properties of SiC and diamond CVD-monofilaments have been investigated. Electron and Raman microprobe analyses showed graded radial atomic and phase distributions in the SiC filaments. Thermomechanical investigations (tensile/bending elastic modulus/creep tests) were carried out on single filaments and these properties were correlated with the physicochemical features. The thermal behaviour of the CVD-SiC filaments is strongly related to the nature and the amounts of intergranular secondary phases (free carbon or silicon). The strong covalent bonds and the microcrystalline state of the CVD-diamond filaments give rise to an outstanding thermal behaviour.
G. Chollon, R. Naslaina, C. Prentice, R. Shatwell, P. May, Journal of the European Ceramic Society 25 (2005) 1929-1942

L0015 – Thermal analysis of coal minerals, ash and slag

J.D. Saxby, S.P. Chatfield, AIE 8th Australian Coal Science Conference (1998) 57-63

L0004 – Preparation of dense tetragonal zirconia ceramics from ZrO2 micropowders

A. Smith, B. Cales and J.F. Baumard, Journal de Physique, Colloque C1, supplément au n°2, Tome 47 (1986) 237-241