TANG An, ZHANG Hongsong
(School of Mechanical Engineering Henan Institute of Engineering, Zhengzhou 451191, Henan, China)

Abstract: Pure (Sm_0.5Gd_xYb_0.5-x)₂Ce₂O₇ ceramics with single fluorite-type structure were prepared successfully by solid reaction method using Sm₂O₃, Gd₂O₃, Yb₂O₃ and CeO₂ as reactants. The synthesized products has densified microstructure and the grain boundaries are very clean. Because of the decreasing atomic-weight difference between the substituting and substituted atoms, the thermal conductivity increase gradually with the increasing content of Gd-doping content, and their thermal conductivity is lower than that of Sm₂Ce₂O₇. The thermal expansion coefficient decreases gradually due to the relatively high electrical-negativity of Gd and Yb, and their thermal expansion coefficient is greater than that of YSZ.

Key words: A₂B₂O₇ oxide; thermal conductivity; thermal expansion coefficient