Phase transitions in the H+-conducting perovskite ceramics by the quasi-elastic neutron and high-pressure Raman scattering

摘要

H+-containing lanthanide-doped perovskites A(Ba, Sr etc.)B(Zr, Ce, Ti etc.)O3 are potential ceramic membranes for fuel cell and medium temperature water electrolysis (300–800 °C). The comparison studies of the hydrated and non-hydrated Yb-doped BaZrO3 and SrZrO3 were performed by thermal expansion, medium–high temperature neutron and room-temperature high-pressure Raman scattering. Neutron diffraction and elastic/quasi-elastic studies carried out for BaZrO3 ceramic show the presence of the protons, their successive diffusion above ～600 °C, and then their departure above 750 °C (under vacuum). Phase transitions and their modification by proton insertion are discussed. A high-pressure Raman study of SrZrO3 performed at room temperature in the diamond anvil cell reveals the presence of two pressure-induced phase transitions at about 5 and 22 GPa and confirms that proton insertion modifies the phase transition sequences.