Effect of lattice defects on thermal conductivity of Ti-doped, Y2O3-stabilized ZrO2

The evolution of lattice structure and thermal conductivity has been studied systematically for a range of Ti-doped, Y2O3-stabilized ZrO2 (YSZ) solid solutions. The mechanism of reducing the thermal conductivity by Ti doping has been determined. Ti4+ mainly substitutes for Zr4+ below a critical composition factor (x ⩽ 0.08), above which the interstitial Ti4+ need to be considered separately. The effect of lattice defects caused by mass and radius differences between Ti4+ and Zr4+ ions on the phonon scattering coefficient was discussed quantitatively. And the reduction of oxygen vacancy by interstitial Ti4+ ions which increases the thermal conductivity at high Ti doping content was also determined. Concerning the integrated phase stability and thermo-mechanical properties, Ti-doped YSZ is believed to be a promising candidate for thermal barrier coatings at higher temperature.