Crystal Structure and Transport Properties of Oxygen-Deficient Perovskite Sr0.9Y0.1CoO3-δ

The present work reports a systematic study on temperature-dependent local crystal structure, oxygen stoichiometry, and electrical/electrochemical properties of an oxygen deficient Sr0.9Y0.1CoO3-delta (SYC10) perovskite using variable temperature neutron diffraction (VTND), thermal gravimetric analysis, and electrical/electrochemical methods, respectively. The VTND reveals that the crystal symmetry of SYC10 remains P4/mmm tetragonal up to 900 degrees C. The tetragonal symmetry reflects the net effects of temperature and oxygen stoichiometry on crystal symmetry. The observed p-type electronic conductivity behavior originates from the charge-ordering between the two distinctive Co-sites. The partial oxide-ion conductivity and diffusivity obtained from oxygen permeation measurements are 2.3 x 10(-2) S cm(-1) and 7.98 x 10(-8) cm(2)/s at 800 degrees C in air, respectively. The electrochemical oxygen reduction reaction kinetics of the SYC10 cathode is primarily limited by the charge-transfer process at low temperatures (600-650 degrees C) and oxide-ion migration from the cathode into the electrolyte at high temperatures (700-800 degrees C).