Theoretical and experimental studies of doping effects on thermodynamic properties of (Dy, Y)-ZrO2

Ionic oxide materials play a vital role in technical applications owing to their high-temperature capability and when used as thermal barrier coating (TBC) materials, for example, they have environmentally friendly effects such as improved fuel efficiency and reduced emissions. Doped ZrO2 based solid solution is attracting attention, whereas doping effects on thermodynamic properties are not well understood. This work reports the synthesis and characterization of doped ZrO2 with Dy3+ and Y3+ via a sol-gel route. The relationship between chemical composition and thermodynamic properties is investigated via experiment and molecular dynamics (MD) simulation. MD simulation has been employed to theoretically explore the crystal structure and to calculate the intrinsic thermal conductivity, which agrees well with the experiment measurement. The thermal conductivity of dense samples is lower than that of conventional 6–8 wt.% Y2O3 stabilized ZrO2 (equivalent to 4 mol% Y2O3 stabilized ZrO2, 4YSZ) at room temperature. The coefficient of thermal expansion is higher due to the doping Dy3+ ion compared with that of 4YSZ. The thermochemical compatibility of Dy0.06Y0.072Zr0.868O1.934 with Al2O3 which is critical for the durability of the TBC system has been studied and can be maintained up to 1500 °C.