Influence of various additions of Ti4+ substitution Ce4+ on high-temperature phase stability of co-precipitation Ti4+and Ce4+ co-doping YSZ powders

In this work, the Ce4+ and Ti4+ co-doped YSZ powders (Ce0.08-xTixY0.08Zr0.88O2.04) with various additions of Ti4+ substitution Ce4+ are prepared by the co-precipitation method. The microstructure, phase and chemical composition, phase transformation process, and phase stability after repeated calcination at 1300 °C of the powders have been investigated. The crystal structure of co-doping YSZ depends on the addition of Ti4+ substitution Ce4+ in the Ce0.08-xTixY0.08Zr0.88O2.04. When the doping molar ratio of Ce4+ to Ti4+ is 3:1 or 1:1, the ZrO2 can be stabilized to form the t′-phase and show better thermal stability, according to the TG-DSC and XRD results. Ti4+ enters the ZrO2 lattice in the form of substitution or interstitial. The oversized radius cation and undersized-radius cation co-stability can be induced by co-doping of Ti4+ and Ce4+. Thereby, the t′-ZrO2 is stabilized after repeated calcination at 1300 °C for 120 h. The co-doping of oversized radius cations and undersized-radius cations can further improve the t′-ZrO2 stability of YSZ, while the role of oversized radius cations is dominant.