In situ high temperature X-ray diffraction studies of mixed ionic and electronic conducting perovskite-type membranes

摘要

Phase structure and stability of three typical mixed ionic and electronic conducting perovskite-type membranes, SrCo_(0.8)Fe_(0.2)O_(3-delta) (SCF), Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-delta) (BSCF) and BaCo_(0.4)Fe_(0.4)Zr_(0.2)O_(3-delta) (BCFZ) were studied by in situ high temperature X-ray diffraction at temperatures from 303 to 1273 K and under different atmospheres (air, 2 percent O_2 in Ar and pure Ar) at 1173 K. By analyzing their lattice parameters the thermal expansion coefficients (TECs) of BSCF, SCF and BCZF are obtained to be 11.5 X 10~(-6) K~(-1), 17.9 X 10~(-6) K~(-1) and 10.3 X 10~(-6) K~(-1), respectively. A relationship between phase stability and TEC was proposed: the higher is the TEC, the lower is the operation stability of the perovskite materials.