We study deuterated tetrahydroborate LiBH4 in the low-temperature (LT) phase, focusing on the BH ... more We study deuterated tetrahydroborate LiBH4 in the low-temperature (LT) phase, focusing on the BH (BD) stretching vibrations, by infrared (IR) and IR-pump-probe spectroscopy. Calculated infrared spectra by density functional theory allow us to disentangle the contributions coming from all the coexisting BH4-nDn (n = 0…4) molecular units. We report on anharmonicity and vibrational lifetime (1.6 ps) of the BD vibrations, as well as on the BH2D2 orientational relaxation by polarization anisotropy IR-pump-probe measurements. We find a constant anisotropy for at least 5 ps confirming the slow reorientational motion and low thermal disorder of the BH4 unit in the LT phase of this potential hydrogen storage material.
In this proceeding, we discuss measurements of the vibrational properties of hydrides using inela... more In this proceeding, we discuss measurements of the vibrational properties of hydrides using inelastic neutron scattering (INS) and the impact of the vibrational modes on the thermodynamic properties. We compare the heat capacity of PdH0.63 and LiBH4 as measured calorimetrically to that derived form INS spectra. We show that the vibrational properties of Ca(BH4)2 depend on the specific phase and hitherto determine their stability.
... Robin Gremaud*, Andreas Borgschulte, Oliver Friedrichs, and Andreas Z ttel. Empa, Swiss Feder... more ... Robin Gremaud*, Andreas Borgschulte, Oliver Friedrichs, and Andreas Z ttel. Empa, Swiss Federal Laboratories for Materials Testing and Research, Hydrogen & Energy, berlandstrasse 129, CH-8600 D bendorf, Switzerland. J. Phys. Chem. ...
The search for new lightweight metal hydride storage materials is essentially like looking for a ... more The search for new lightweight metal hydride storage materials is essentially like looking for a needle in a haystack. Over the years, a number of combinatorial methods have been developed to scan the properties of materials in an efficient way. We demonstrate that combinatorial techniques are also applicable for the search of suitable hydrogen storage materials. This applies especially to hydrogenography, a novel optical screening method that measures simultaneously the enthalpy of hydride formation of thousands of materials on a single thin film wafer.
We investigated the influence of the substrate on the thermodynamic properties of metal hydride t... more 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 sa
The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectros... more The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectroscopy. The measurements give direct evidence of a macroscopic diffusion of BH ions as well as atomic exchange of hydrogen between the anions. An effective tracer diffusion coefficient of deuterium in LiBH(4) of D approximately 7 x 10(-14) m(2) s(-1) at 473 K is derived. The direct exchange rate of hydrogen between BH(4) units is 10 orders of magnitude slower, i.e. the relatively fast effective hydrogen diffusion has its origin in the fast diffusion of BH(4) units.
We study deuterated tetrahydroborate LiBH4 in the low-temperature (LT) phase, focusing on the BH ... more We study deuterated tetrahydroborate LiBH4 in the low-temperature (LT) phase, focusing on the BH (BD) stretching vibrations, by infrared (IR) and IR-pump-probe spectroscopy. Calculated infrared spectra by density functional theory allow us to disentangle the contributions coming from all the coexisting BH4-nDn (n = 0…4) molecular units. We report on anharmonicity and vibrational lifetime (1.6 ps) of the BD vibrations, as well as on the BH2D2 orientational relaxation by polarization anisotropy IR-pump-probe measurements. We find a constant anisotropy for at least 5 ps confirming the slow reorientational motion and low thermal disorder of the BH4 unit in the LT phase of this potential hydrogen storage material.
In this proceeding, we discuss measurements of the vibrational properties of hydrides using inela... more In this proceeding, we discuss measurements of the vibrational properties of hydrides using inelastic neutron scattering (INS) and the impact of the vibrational modes on the thermodynamic properties. We compare the heat capacity of PdH0.63 and LiBH4 as measured calorimetrically to that derived form INS spectra. We show that the vibrational properties of Ca(BH4)2 depend on the specific phase and hitherto determine their stability.
... Robin Gremaud*, Andreas Borgschulte, Oliver Friedrichs, and Andreas Z ttel. Empa, Swiss Feder... more ... Robin Gremaud*, Andreas Borgschulte, Oliver Friedrichs, and Andreas Z ttel. Empa, Swiss Federal Laboratories for Materials Testing and Research, Hydrogen & Energy, berlandstrasse 129, CH-8600 D bendorf, Switzerland. J. Phys. Chem. ...
The search for new lightweight metal hydride storage materials is essentially like looking for a ... more The search for new lightweight metal hydride storage materials is essentially like looking for a needle in a haystack. Over the years, a number of combinatorial methods have been developed to scan the properties of materials in an efficient way. We demonstrate that combinatorial techniques are also applicable for the search of suitable hydrogen storage materials. This applies especially to hydrogenography, a novel optical screening method that measures simultaneously the enthalpy of hydride formation of thousands of materials on a single thin film wafer.
We investigated the influence of the substrate on the thermodynamic properties of metal hydride t... more 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 sa
The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectros... more The hydrogen tracer diffusion in LiBH(4) has been determined by spatially resolved Raman spectroscopy. The measurements give direct evidence of a macroscopic diffusion of BH ions as well as atomic exchange of hydrogen between the anions. An effective tracer diffusion coefficient of deuterium in LiBH(4) of D approximately 7 x 10(-14) m(2) s(-1) at 473 K is derived. The direct exchange rate of hydrogen between BH(4) units is 10 orders of magnitude slower, i.e. the relatively fast effective hydrogen diffusion has its origin in the fast diffusion of BH(4) units.
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