Observation of Rapid Change of Crystalline Structure during the Phase Transition of the Palladium-Hydrogen System

TL;DR

This study used X-ray diffraction to observe rapid changes in the crystalline structure of palladium during hydrogen absorption and desorption, revealing phase transition dynamics and lattice behavior.

Contribution

It provides detailed experimental insights into the crystalline lattice behavior during phase transitions in the Pd-H system, highlighting rapid phase growth and lattice changes.

Findings

Rapid growth of β phase at specific hydrogen concentrations

Lattice compression at high hydrogen levels

Post-cycle lattice expansion and line width increase

Abstract

We performed an X-ray diffraction experiment while palladium bulk absorbed and desorbed hydrogen to investigate the behavior of the crystalline lattice during the phase transition between the $\alpha$ phase and $\beta$ phase. Fast growth of $\beta$ phase was observed around x=0.1 and x=0.45 of PdH$_x$. In addition, slight compression of the lattice at high hydrogen concentration and increase in the lattice constant and the line width of the $\alpha$ phase after a cycle of absorption and desorption of hydrogen was observed. These behavior correlated with the change in the sample length, which may infer that the change in shape was related to the phase transition.