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Abstract: A series of zirconate compounds with the general formula Sm2– x La x Zr2O7 (0⩽ x ⩽1.0) were prepared by pressureless-sintering method at 1973K for 10h in air. The relative density, structure and electrical conductivity of Sm2– x La x Zr2O7 ceramics were investigated by the Archimedes method, X-ray diffraction and impedance spectroscopy measurements. Sm2– x La x Zr2O7 (0⩽ x ⩽1.0) ceramics exhibit a pyrochlore-type structure. The measured electrical conductivity of Sm2– x La x Zr2O7 ceramics obeys the Arrhenius relation and gradually increases with increasing temperature from 673 to 1173K. Sm2– x La x Zr2O7 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0×10−4 to 1.0atm at all test temperature levels. The electrical conductivity of Sm2– x La x Zr2O7 ceramics decreases with increasing lanthanum content at identical temperature levels. [Copyright &y& Elsevier]

Abstract: (Nd1−x Yb x )2Zr2O7 (0≤ x ≤1) ceramics were prepared by pressureless-sintering to obtain dense bulk materials. The electrical conductivity of (Nd1−x Yb x )2Zr2O7 was investigated by complex impedance spectroscopy over a frequency range of 20Hz to 2MHz from 723 to 1173K in air. A high-temperature dilatometer was used to analyze thermal expansion coefficient of (Nd1−x Yb x )2Zr2O7 in the temperature range of 373–1523K. The measured electrical conductivity obeys the Arrhenius relation. The grain conductivity of each composition in (Nd1−x Yb x )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 Scm−1 at 1173K for (Nd0.7Yb0.3)2Zr2O7 ceramic. (Nd1−x Yb x )2Zr2O7 ceramics are oxide-ion conductors in the oxygen partial pressure range from 1.0×10−4 to 1.0atm at all test temperature levels. Thermal expansion coefficients of (Nd1−x Yb x )2Zr2O7 gradually decrease with increasing ytterbium content at identical temperature levels. [Copyright &y& Elsevier]

The effects of a single additive (SnO 2 , Ta 2 O 5 , or WO 3 ) on the crystal structure, densification, and electrical conductivity of the GdSmZr 2 O 7 ceramic have been examined. The GdSmZr 2 O 7 ceramic with or without a single additive of 1 wt.% SnO 2 , Ta 2 O 5 , or WO 3 sintered at temperatures between 1773 and 1973 K exhibits a single cubic pyrochlore-type phase. The relative densities of different compositions increase with increasing sintering temperature. The total conductivity of different samples obeys the Arrhenius relation. The total conductivity of the GdSmZr 2 O 7 ceramic is not improved by the addition of 1 wt.% SnO 2 , Ta 2 O 5 , or WO 3 . A single additive, SnO 2 , Ta 2 O 5 , or WO 3 , is not an effective sintering aid for the GdSmZr 2 O 7 ceramic. [ABSTRACT FROM AUTHOR]

Abstract: Sm2Zr2O7 co-doped with and without 5mol.% Yb2O3 and 5mol.% Gd2O3 were prepared by a pressureless-sintering method at 1973K for 10h in air. The relative density, structure and electrical conductivity were investigated by the Archimedes method, X-ray diffraction, scanning electron microscopy and impedance spectra measurements. Both Sm2Zr2O7 and (Sm0.9Gd0.05Yb0.05)2Zr2O7 ceramics exhibit a single phase of pyrochlore-type structure. The grain conductivity, grain-boundary conductivity and total conductivity obey the Arrhenius relation, respectively, and gradually increase with increasing temperature from 723 to 1173K. (Sm0.9Gd0.05Yb0.05)2Zr2O7 ceramic is the oxide-ion conductor in an oxygen partial pressure range of 1.0×10−4 to 1.0atm at all test temperature levels. The grain conductivity, grain-boundary conductivity and total conductivity of (Sm0.9Gd0.05Yb0.05)2Zr2O7 with dual Yb3+ + Gd3+ doping are higher than those of undoped Sm2Zr2O7 at identical temperature levels. [ABSTRACT FROM AUTHOR]