Multiple phase separation of super-abundant-vacancies in Pd hydrides by all solid-state electrolysis in moderate temperatures around 300 degrees C

作者：Fukada Yoshiki; Hioki Tatsumi; Motohiro Tomoyoshi

来源：Journal of Alloys and Compounds, 2016, 688: 404-412.

DOI：10.1016/j.jallcom.2016.07.176

• Metal hydrides
• Solid-electrolyte
• Electrical transport
• Hydrogen-induced-vacancies
• X-ray diffraction
• Electrolysis

The dynamics of hydrogen-induced vacancies are the key for understanding various phenomena in metal -hydrogen systems under a high hydrogen chemical potential. In this study, a novel dry-electrolysis experiment was performed in which a hydrogen isotope was injected into a Pd cathode and time-resolved in situ monochromatic X-ray diffraction measurement was carried out at the Pd cathode. It was found that palladium-hydride containing vacancies forms multiple phases depending on the hydrogen chemical potential. Phase separation into vacancy-rich, vacancy-poor, and moderate-vacancy-concentration phases was observed when the input voltage was relatively low, i.e., similar to 0.5 V. The moderate-vacancy-concentration phase may be attributed to Ca7Ge or another type of super-lattice Pd(7)VacH(D)(8). Transition from the vacancy-rich to the moderate-vacancy-concentration phase explains the sub-micron void formations without high temperature treatment that were observed at the Pd cathode but have never been reported in previous anvil experiments.

• 出版日期2016-12-15