Electrical Properties of New Brounmillerite-type Ba2In2-x(Zn, Zr)xO5 System

In order to investigate the relationship of oxide-ion conduction between the brownmillerite-type and perovskite-type structures, the solid solution system Ba2In2-x(Zn1/2Zr1/2)xO5 was investigated. The orthorhombic phase was obtained in the range of 0.0≤x≤0.3, while the cubic phase was obtained in the range, 0.4≤x≤2.0. The transition temperature from orthorhombic to cubic phases shifted to the lower temperature than that of Ba2In2O5 with increasingx. The temperature dependence of electrical conductivity after the phase transition in the composition range (0.1≤ x ≤ 0.3) agreed with the conductivity of the high temperature Ba2In2O5 which was extrapolated to the low temperature region. In order to investigate in more detail the crystal structure at high temperatures, high temperature X-ray diffraction was carried out. It was clarified that the crystal phase of sample of x = 0.3 transformed from orthorhombic to tetragonal at 973K. As a result, the substitution of (Zn, Zr) into the In site lowered the phase transition-temperature.