Preparation, structure and electrical conductivity of pyrochlore-type samarium–lanthanum zirconate ceramics

A series of zirconate compounds with the general formula Sm2–xLaxZr2O7 (0 ⩽ x ⩽ 1.0) were prepared by pressureless-sintering method at 1973 K for 10 h in air. The relative density, structure and electrical conductivity of Sm2–xLaxZr2O7 ceramics were investigated by the Archimedes method, X-ray diffraction and impedance spectroscopy measurements. Sm2–xLaxZr2O7 (0 ⩽ x ⩽ 1.0) ceramics exhibit a pyrochlore-type structure. The measured electrical conductivity of Sm2–xLaxZr2O7 ceramics obeys the Arrhenius relation and gradually increases with increasing temperature from 673 to 1173 K. Sm2–xLaxZr2O7 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 Sm2–xLaxZr2O7 ceramics decreases with increasing lanthanum content at identical temperature levels.

► Dense Sm2–xLaxZr2O7 ceramics were prepared by pressureless-sintering at 1973 K. ► Sm2–xLaxZr2O7 ceramics have a single phase of pyrochlore-type structure. ► The electrical conductivity of Sm2–xLaxZr2O7 increases with increasing temperature. ► Sm2–xLaxZr2O7 ceramics are oxide-ion conductors in low oxygen partial pressure. ► The electrical conductivity of Sm2–xLaxZr2O7 decreases with increasing La content.