Search

Abstract: The effects of zinc oxide (ZnO) additive on the crystal structure, densification, and electrical conductivity of the GdSmZr2O7 ceramic have been examined. The GdSmZr2O7 ceramic with and without the addition of 1 wt.% ZnO sintered at temperatures between 1773 and 1973 K exhibits a single cubic pyrochlore-type phase. ZnO is very effective as a sintering aid for the GdSmZr2O7 ceramic, and it reduces the sintering temperature by about 200 K with a positive effect on the total conductivity. The total conductivity of the ZnO-modified GdSmZr2O7, as measured by A.C. impedance spectroscopy under an air atmosphere, is higher than that of the unmodified GdSmZr2O7 at identical temperature levels. At 1173 K, the highest total conductivity of the ZnO-modified GdSmZr2O7 is about fifteen percent higher than that of the unmodified GdSmZr2O7. The 1 wt.% ZnO-modified GdSmZr2O7 is one of good oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10−4 to 1.0 atm at different test temperatures. [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]

Abstract: The GdSmZr2O7 ceramic is prepared by pressureless-sintered method under different conditions as a possible solid electrolyte. The crystal structure, microstructure and electrical properties are characterized by the X-ray diffraction, field-emission scanning electron microscopy and ac impedance spectroscopy, respectively. The GdSmZr2O7 ceramic exhibits a single phase of the pyrochlore-type structure. The total conductivity of the GdSmZr2O7 ceramic obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173K. The GdSmZr2O7 ceramic is an oxide-ion conductor in the oxygen partial pressure range of 1.0×10−4 to 1.0atm at all test temperature levels. According to the experimental results of the present work, the maximum value of the total conductivity for the GdSmZr2O7 ceramic is about 1.01×10−2 Scm−1 at 1173K. [Copyright &y& Elsevier]