In-situ EXAFS study on the thermal decomposition of TiH2

TL;DR

This study uses in-situ EXAFS to analyze the thermal decomposition of TiH2, revealing how decomposition temperature depends on conditions and detailing the phase transformation sequence during decomposition.

Contribution

It provides detailed in-situ EXAFS analysis of TiH2 decomposition, including hydrogen stoichiometry and phase changes under different atmospheres, which was not previously characterized in detail.

Findings

Decomposition temperature varies with atmosphere (300°C in vacuum, 400°C in helium).

Phase transformation sequence of TiH2 during decomposition is mapped.

Structural information of hydrogen in TiH2 is effectively detected.

Abstract

Thermal decomposition behaviors of TiH2 powder under a flowing helium atmosphere and in a low vacuum condition have been studied by using in-situ EXAFS technique. By an EXAFS analysis containing the multiple scattering paths including H atoms, the changes of hydrogen stoichiometric ratio and the phase transformation sequence are obtained. The results demonstrate that the initial decomposition temperature is dependent on experimental conditions, which occurs, respectively, at about 300 and 400 degree in a low vacuum condition and under a flowing helium atmosphere. During the decomposition process of TiH2 in a low vacuum condition, the sample experiences a phase change process: {\delta}(TiH2) - {\delta}(TiHx) - {\delta}(TiHx)+{\beta}(TiHx) - {\delta}(TiHx)+{\beta}(TiHx)+{\alpha}(Ti) - {\beta}(TiHx)+{\alpha}(Ti) - {\alpha}(Ti)+{\beta}(Ti). This study offers a way to detect the structural information of hydrogen. A detailed discussion about the decomposition process of TiH2 is given in this paper.