Phase-structural transformation of erbium trihydride studied by thermal desorption spectroscopy

Abstract

Thermal desorption behaviours of erbium trihydride (ErH3) powders were studied using simultaneous thermogravimetry and thermal desorption spectroscopy (TG-TDS) method. The crystal structures and chemical compositions of the samples were investigated by X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Two-peak structures were observed in the hydrogen desorption spectra and the corresponding activation energies were determined to be 160.7 and 212.3 kJ/mol, respectively. The phase transformation sequences during thermal desorption process were established by combining the changing trends in the temperature/hydrogen content with the Er–H phase diagram. It was established that the low-temperature and high-temperature peaks were related to the β + γ → β and α + β → α phase transformation steps, respectively. The origins of the observed TDS peaks and shoulders were attributed to the equilibrium hydrogen pressures of the phase regions that the decomposition reaction passed through.