ABSTRACT
Stabilized cubic zirconia is used for thermal barrier coatings, and its thermal conductivity has been measured with conflicting results. To understand its behavior it is here calculated from thermal conductivity theory. The intrinsic thermal conductivity, which is not accessible to measurement, is estimated to be 1700/T W/m∙K (T in Kelvin), in line with the measured value of 2800/T for titania. Point defect scattering of phonons is then estimated for additions of Y2O3, CaO, MgO and CeO2, taking account of the vacancies which accompany the first three of these solute cations. The consequent thermal conductivity reductions are calculated. Grain boundary scattering and possible reductions by two-level tunnel states give further reductions. Theoretical values are compared with observations. There is rough agreement at low temperatures, but theory predicts larger decreases in conductivity than have been observed at high temperatures. This may be due to internal radiation.
