Effect of alumina addition on the phase evolution and thermal conductivity of ZrO2–NdO1.5 ceramics

Abstract

The ZrO 2 –NdO 1.5 –AlO 1.5 ceramics were synthesized by solid-state reaction at 1600 °C for 10 h in air to fabricate dense bulk ceramics. The relative density, structure and thermal diffusivity of different ZrO 2 –NdO 1.5 –AlO 1.5 ceramics were investigated by the Archimedes method, X-ray diffraction (XRD), scanning electron microscopy (SEM), laser Raman spectroscopy and laser-flash method. The thermal conductivity was calculated from density, specific heat and thermal diffusivity in a temperature range of room temperature to 1400 °C. The Nd 2 Zr 2 O 7 ceramics doped without alumina only exhibit a pyrochlore-type lattice. The 47.1ZrO 2 –47.1NdO 1.5 –5.8AlO 1.5 and the 44.2ZrO 2 –44.2NdO 1.5 –11.6AlO 1.5 ceramics (mol%) consist of both perovskite-like NdAlO 3 and pyrochlore structures. However, the 41.3ZrO 2 –41.3NdO 1.5 –17.4AlO 1.5 ceramics consist of both perovskite-like NdAlO 3 and fluorite (F-ZrO 2 ) structures, and the 38.4ZrO 2 –38.4NdO 1.5 –23.2AlO 1.5 ceramics consist of perovskite-like NdAlO 3 , F-ZrO 2 and hexagonal β-Al 2 O 3 -type structures. The thermal conductivities of different ZrO 2 –NdO 1.5 –AlO 1.5 ceramics increase with the increase of alumina concentration in raw materials under identical temperature conditions. The thermal conductivities of ZrO 2 –NdO 1.5 –AlO 1.5 ceramics in this investigation were located in the range of 1.50–3.22 W m −1 K −1 from room temperature to 1400 °C.