Influence of Defect Structure on the Thermal Conduction Characteristic of YSZ Polycrystalline

Abstract

Based on author's research data obtained by using microstructure-controlled sintered dense yttria–stabilized zirconia (YSZ) pellets and porous YSZ pellets, influence of defect structure on the thermal conduction characteristic of dense YSZ polycrystalline and porous YSZ polycrystalline is explained. The difference in the specific heat capacity between 3YSZ (Y₂O₃/ZrO₂ = 3/97 (mol)) and 8YSZ (Y₂O₃/ZrO₂ = 8/92 (mol)) is discussed from the point of view of the number of lattice defects introduced to YSZ by doping Y₂O₃. Thermal diffusivity in a high temperature region and a low temperature region is explained separately, respectively. Contributions of phonon diffusion and photon heat radiation in YSZ grain and pore to temperature dependency of the thermal diffusivity of 3YSZ and 8YSZ are clarified. In order to interpret their contributions, porosity, pore size, and grain–boundary concentration are used as a key factor.