Microstructure and electrical property of GdSmZr2O7 doped by rare-earth Ce

Abstract

GdSm(Zr1–xCex)2O7 solid solutions are successfully prepared by a conventional solid-state sintering method for intermediate-temperature solid oxide fuel cells. The effect of cerium content on the microstructure and electrical conductivity of the GdSmZr2O7 ceramic is studied. The phase composition, morphology and electrical conductivity are investigated by means of X-ray diffraction, scanning electron microscopy and electrochemical impedance spectroscopy. GdSm(Zr1–xCex)2O7 solid solutions exhibit a single phase structure. With the increase of cerium content, GdSm(Zr1–xCex)2O7 solid solutions change from pyrochlore-type structure to defect fluorite-type structure. The lattice parameters of GdSm(Zr1–xCex)2O7 solid solutions approximately linearly increase with the increase of cerium content. The relative densities of GdSm(Zr1–xCex)2O7 solid solutions are over 91%. The grains of GdSm(Zr1–xCex)2O7 solid solutions are inhomogeneous and the grain boundaries can be observed clearly. The relationship between grain conductivity of GdSm(Zr1–xCex)2O7 solid solutions and test temperature conforms to Arrhenius equation and the curve is approximately linear. The grain conductivity increases with the increase of temperature for each composition. At the same test temperature, the grain conductivity of GdSm(Zr1–xCex)2O7 solid solutions decreases firstly and then increases or maintains steady with the increase of cerium content.