Effect of point defects on the thermal conductivity of Sc ₂ O ₃ -Y ₂ O ₃ co-stabilized tetragonal ZrO ₂ ceramic materials

In this paper, the reduction mechanism in thermal conductivity of a series of Sc ₂ O ₃ -Y ₂ O ₃ co-stabilized tetragonal ZrO ₂ ceramics is systematically discussed. The thermal conductivity is approximately 20–28% lower than that of 6–8 wt.% yttria-stabilized zirconia (YSZ). A phonon scattering model, on account of the influence of oxygen vacancy variation and cation mass fluctuation, is optimized and utilized to depict the thermal conductivity of these materials. For the samples with the same amount of oxygen vacancy, Sc ³⁺ is more effective in lowering thermal conductivity than Y ³⁺ due to the large mass difference with Zr ⁴⁺ , as evidenced by the scattering model and phonon vibrational density of states. The experimental and calculation results suggest that this optimized model is proved to be more effective in predicting the thermal conductivity of binary or multiple rare earth oxides co-doped tetragonal ZrO ₂ and guiding the compositional design of thermal barrier materials.