Synthesis of Y-doped BaZrO3 proton conducting electrolyte material by a continuous hydrothermal process in supercritical conditions: Investigation of the formation mechanism and electrochemical performance

Abstract

In this work, BaZr0.85Y0.15O3-δ was elaborated by a continuous hydrothermal process in supercritical conditions (410 °C/30.0 MPa). X-Ray diffraction, Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy analysis allowed to propose a description of the formation mechanism for this oxide in supercritical water. This mechanism consists in the precipitation of core-shell nanoparticles in which, the core is a Ba-deficient perovskite and the shell an oxyhydroxide species of Y and Zr. Then, Ba2+, Zr4+ and Y3+ are incorporated in the perovskite from the solution and from the shell. After an annealing treatment at 1000 °C for 1 h to homogenize the composition, the powder was pressed into a pellet and sintered at 1550 °C for 5 h to analyze its electrochemical properties. The total conductivity of this oxide is 2.5 × 10-3 S cm-1 at 600 °C in wet H2 (3% H2O). Furthermore, electrochemical impedance spectroscopy measurements showed that its conduction is mainly protonic at a temperature lower than 575 °C.