Preparation and thermophysical properties of NdxZr1−xO2−x/2 (x = 0.1, 0.2, 0.3, 0.4, 0.5) ceramics

Ceramic powders of NdxZr1−xO2−x/2 (x = 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by chemical-coprecipitation followed by calcination method. The ceramic powders of NdxZr1−xO2−x/2 were pressureless-sintered at 1600 °C for 15 h in air to fabricate dense bulk ceramics. The relative density of sintered samples was measured by the Archimedes method. Structures of the synthesized powders and sintered ceramics were identified by X-ray diffractometer. The morphologies of ceramic powders were observed by transmission electron microscope. Various thermal analysis methods were used for thermal expansion coefficient, specific heat, thermal diffusion coefficient and DSC measurements in a temperature range of room temperature to 1400 °C. The thermal conductivity was calculated from thermal diffusivity, density and specific heat. Nd0.1Zr0.9O1.95 ceramics consist of both monoclinic and tetragonal structures. However, Nd0.2Zr0.8O1.9 and Nd0.3Zr0.7O1.85 ceramics only exhibit a single fluorite structure. Nd0.4Zr0.6O1.8 and Nd0.5Zr0.5O1.75 ceramics have a pyrochlore-type lattice. With the increase of Nd2O3 concentration, the thermal expansion coefficients of NdxZr1−xO2−x/2 ceramics increase. The thermal conductivities of NdxZr1−xO2−x/2 ceramics were located in the range of 1.50-2.01 W m−1 K−1 from room temperature to 1400 °C.