Microstructure and electrical property of GdSmZr ₂ O ₇ doped by rare-earth Ce

GdSm(Zr _1–x Ce _x ) ₂ O ₇ 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 GdSmZr ₂ O ₇ 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(Zr _1–x Ce _x ) ₂ O ₇ solid solutions exhibit a single phase structure. With the increase of cerium content, GdSm(Zr _1–x Ce _x ) ₂ O ₇ solid solutions change from pyrochlore-type structure to defect fluorite-type structure. The lattice parameters of GdSm(Zr _1–x Ce _x ) ₂ O ₇ solid solutions approximately linearly increase with the increase of cerium content. The relative densities of GdSm(Zr _1–x Ce _x ) ₂ O ₇ solid solutions are over 91%. The grains of GdSm(Zr _1–x Ce _x ) ₂ O ₇ solid solutions are inhomogeneous and the grain boundaries can be observed clearly. The relationship between grain conductivity of GdSm(Zr _1–x Ce _x ) ₂ O ₇ 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(Zr _1–x Ce _x ) ₂ O ₇ solid solutions decreases firstly and then increases or maintains steady with the increase of cerium content.