The average and local structure of TiVCrNbD<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si47.svg"><mml:msub><mml:mrow /><mml:mi>x</mml:mi></mml:msub></mml:math> (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"><mml:mrow><mml:mi>x</mml:mi><mml:mo linebreak="goodbreak">=</mml:mo><mml:mn>0</mml:mn><mml:mo>,</mml:mo><mml:mn>2.2</mml:mn><mml:mo>,</mml:mo><mml:mn>8</mml:mn></mml:mrow></mml:math>) from total scattering and neutron spectroscopy

The volumetric hydrogen density of 160 kg H/m3 in TiVCrNbH8 is among the highest for interstitial hydrides, but reported reversible capacity only about 2/3 full theoretical at room temperature. In present work we have investigated local structure TiVCrNbDx, x=0, 2.2, 8 with aim to unravel how remaining sites can be destabilized respect hydrogen/deuterium occupation using total scattering measurements and Reverse Monte Carlo (RMC) modelling. Our analysis indicates that partially desorbed deuteride (x=2.2) adopts a body-centred tetragonal (I4/mmm) where deuterium atoms occupy both tetrahedral octahedral interstices low occupancies. There significantly higher portion occupied nearest-neighbour metals valence-electron concentration VEC. This observation used motivate strategies further destabilization hydride. Inelastic neutron (INS) functional theory (DFT) calculations indicate vibrational states very diverse TiVCrNbH2.4, it suggested might mobile between nearby interstices.