Structure and thermal conductivity of Gd2(TixZr1-x)2O7 ceramics

The Gd-2(TixZr1-x)(2)O-7 (x=0, 0.25, 0.50, 0.75, 1.00) ceramics were synthesized by solid state reaction at 1650 degrees C for 10 h in air. The relative density and structure of Gd-2(TixZr1-x)(2)O-7 were analyzed by the Archimedes method and X-ray diffraction. The thermal diffusivity of Gd-2(TixZr1-x)(2)O-7 from room temperature to 1400 degrees C was measured by a laser-flash method. The Gd2Zr2O7 has a defect fluorite-type structure; however, Gd-2(TixZr1-x)(2)O-7 (0.25 <= x <= 1.00) compositions exhibit an ordered pyrochlore-type structure. Gd2Zr2O7 and Gd2Ti2O7 are infinitely soluable. The thermal conductivity of Gd-2(TixZr1-x)(2)O-7 increases with increasing Ti content under identical temperature conditions. The thermal conductivity of Gd-2(TixZr1-x)(2)O-7 first decreases gradually with the increase of temperature below 1000 degrees C and then increases slightly above 1000 degrees C. The thermal conductivity of Gd-2(TixZr1-x)(2)O-7 is within the range of 1.33 to 2.86 W m(-1) K-1 from room temperature to 1400 degrees C (C) 2008 Elsevier B.V. All rights reserved.