Electrical conductivity and thermal expansion of neodymium–ytterbium zirconate ceramics

(Nd1−xYbx)2Zr2O7 (0 ≤ x ≤ 1) ceramics were prepared by pressureless-sintering to obtain dense bulk materials. The electrical conductivity of (Nd1−xYbx)2Zr2O7 was investigated by complex impedance spectroscopy over a frequency range of 20 Hz to 2 MHz from 723 to 1173 K in air. A high-temperature dilatometer was used to analyze thermal expansion coefficient of (Nd1−xYbx)2Zr2O7 in the temperature range of 373–1523 K. The measured electrical conductivity obeys the Arrhenius relation. The grain conductivity of each composition in (Nd1−xYbx)2Zr2O7 gradually increases with increasing temperature. A decrease of about one order of magnitude in grain conductivity is found at all temperature levels when the Yb content increases from x = 0.3 to x = 0.5. The highest electrical conductivity value obtained in this work is 9.32 × 10−3 S cm−1 at 1173 K for (Nd0.7Yb0.3)2Zr2O7 ceramic. (Nd1−xYbx)2Zr2O7 ceramics are oxide-ion conductors in the oxygen partial pressure range from 1.0 × 10−4 to 1.0 atm at all test temperature levels. Thermal expansion coefficients of (Nd1−xYbx)2Zr2O7 gradually decrease with increasing ytterbium content at identical temperature levels.