Influence of MoO3 doping on structure and electrical conductivity of defect fluorite-type Gd2Zr2O7

In this paper, we report the preparation, structure and electrical conductivity of MoO3-doped zirconates with a nominal chemical formula of Gd2(Zr1−xMox)2O7+2x (x = 0, 0.1, 0.2). X-ray diffraction measurements indicate that Gd2Zr2O7 exhibits a defect fluorite-type structure, and Gd2(Zr1−xMox)2O7+2x (x = 0.1, 0.2) have a single phase of pyrochlore-type structure. The alternating current (AC) impedance measurements show that the electrical conductivity of Gd2(Zr1−xNbx)2O7+2x ceramics obeys the Arrhenius equation, and gradually increases with increasing temperature from 673 to 1173 K. The activation energy and pre-exponential factor for electrical conductivity gradually decrease with the increase of MoO3 content. Gd2(Zr1−xMox)2O7+2x 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 electrical conductivity of defect fluorite-type Gd2Zr2O7 is not improved by MoO3 doping.

Research highlights▶ Gd2(Zr1−xMox)2O7+2x (x = 0.1, 0.2) have a single phase of pyrochlore-type structure, while Gd2Zr2O7 exhibits a single phase of defect fluorite-type structure. Gd2(Zr1−xMox)2O7+2x 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 electrical conductivity of defect fluorite-type Gd2Zr2O7 is not improved by MoO3 doping.