Influence of La₂O₃ addition on thermophysical properties of ZrO₂–4 mol %Y₂O₃ ceramics fabricated by spark plasma sintering

Abstract

The influence of La₂O₃ addition on the thermal diffusivity and thermal conductivity of ZrO₂ ceramics has been investigated. Porous and dense ZrO₂ ceramics were fabricated by spark plasma sintering at 1100 and 1500°C. The porosity of ZrO₂ ceramics sintered at 1100°C increased with increasing 0–5 mol % La₂O₃ addition. In contrast, ZrO₂ ceramics sintered at 1500°C showed full density regardless of the amount of La₂O₃ addition. The La₂Zr₂O₇ of crystalline pyrochlore phase was formed by reaction between La₂O₃ and ZrO₂. The XRD peak of the La₂Zr₂O₇ phase increased with increasing La₂O₃ addition. The thermal diffusivity and thermal conductivity of sintered ZrO₂ decreased with increasing La₂O₃ addition. In addition, the thermal conductivity of the present samples decreased remarkably with increasing the porosity.