Low Thermal Conductivity of SnO2-Doped Y2O3-Stabilized ZrO2: Effect of the Lattice Tetragonal Distortion

Considering the phonon scattering effect and the stability of t zirconia, Sn4+ ion is recognized as an appropriate dopant to achieve the best combination of thermal insulating capability and durability of yttria-stabilized zirconia thermal barrier coatings (TBCs). In this research, unusual lattice expansion and strong structural disordering were observed in a series of SnO2-doped Y2O3-stabilized ZrO2 compounds, which are caused by the tetragonal distortion of oxygen coordination. Phonon scattering due to the structural disordering rather than point defects of Sn4+ substitutions predominates in reducing the thermal conductivity. However, deterioration of the thermal properties was observed at high doping content, which may be attributed to the t-m phase transformation during the measurements. Considering the structure stability and thermal properties, SnO2-doped Y2O3-stabilized ZrO2 compounds can be promising candidates for TBCs.