Preparation, structure and electrical conductivity of pyrochlore-type Gd_1-xEu_2xSm_1-xZr₂O₇ ceramics with a constant lattice parameter

A novel series of Gd_1-xEu_2xSm_1-xZr ₂O₇ (x = 0, 1/3, 1/2, 2/3, 1) ceramics with a constant lattice parameter are prepared by solid-state reaction, and are then evaluated as possible solid electrolytes. The microstructure and electrical properties of Gd_1-xEu_2xSm_1-xZr₂O₇ ceramics have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis. Gd _1-xEu_2xSm_1-xZr₂O₇ ceramics exhibit a single phase of pyrochlore-type structure. The total conductivity of Gd_1-xEu_2xSm_1-xZr ₂O₇ ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. At 973-1173 K, the composition has little effect on electrical conductivity of Gd _1-xEu_2xSm_1-xZr₂O₇ ceramics. Gd_1-xEu_2xSm_1-xZr₂O ₇ ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10^-4 to 1.0 atm at all test temperature levels. The maximum total conductivity of Gd_1-xEu_2xSm _1-xZr₂O₇ ceramics is about 1.01 × 10 ^-2 S cm^-1 at 1173 K in air.