Preparation, structure and electrical conductivity of pyrochlore-type Gd1−xEu2xSm1−xZr2O7 ceramics with a constant lattice parameter

A novel series of Gd1−xEu2xSm1−xZr2O7 (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 Gd1−xEu2xSm1−xZr2O7 ceramics have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis. Gd1−xEu2xSm1−xZr2O7 ceramics exhibit a single phase of pyrochlore-type structure. The total conductivity of Gd1−xEu2xSm1−xZr2O7 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 Gd1−xEu2xSm1−xZr2O7 ceramics. Gd1−xEu2xSm1−xZr2O7 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 Gd1−xEu2xSm1−xZr2O7 ceramics is about 1.01 × 10−2 S cm−1 at 1173 K in air.

► Dense Gd1−xEu2xSm1−xZr2O7 were firstly prepared by pressureless-sintering.
► The total conductivity of Gd1−xEu2xSm1−xZr2O7 increases with temperature.
► Gd1−xEu2xSm1−xZr2O7 are oxide-ion conductors in low oxygen partial pressure.
► The composition has little effect on the total conductivity of Gd1−xEu2xSm1−xZr2O7.