Nanoscale-hydride formation at dislocations in palladium: Ab initio theory and incoherent inelastic neutron scattering measurements

TL;DR

This study combines ab initio modeling and neutron scattering to investigate how hydrogen forms nanoscale hydrides at dislocations in palladium, revealing temperature-dependent trapping and dissociation behaviors.

Contribution

It introduces a predictive ab initio hydrogen potential energy model and correlates it with neutron scattering data to understand nanoscale hydride formation at dislocations.

Findings

Hydrogen forms nanometer-sized hydrides at dislocation cores at 0K.

Increased temperature dissolves hydrides, dispersing hydrogen in palladium.

The model accurately predicts vibrational spectra matching experimental measurements.

Abstract

Hydrogen arranges at dislocations in palladium to form nanoscale hydrides, changing the vibrational spectra. An ab initio hydrogen potential energy model versus Pd neighbor distances allows us to predict the vibrational excitations for H from absolute zero up to room temperature adjacent to a partial dislocation and with strain. Using the equilibrium distribution of hydrogen with temperature, we predict excitation spectra to explain new incoherent inelastic neutron-scattering measurements. At 0K, dislocation cores trap H to form nanometer-sized hydrides, while increased temperature dissolves the hydrides and disperses H throughout bulk Pd.