Effects of dopants and excitation wavelength on the temperature sensing of Ln3+-doped 7YSZ

Rare-earth ions doped yttrium-stabilized zirconia (7YSZ) has been proven as a promising candidate in temperature sensing of TBCs. In this work, the influences of different dopants and the excitation wavelength on the temperature sensing of Ln3+-doped 7YSZ are investigated. The luminescence from 7YSZ doped with trivalent rare-earth ions, Sm3+, Eu3+, and Er3+, was measured both at room temperature and up to 1200 °C. Strong luminescence was observed in all the three materials using either 532 nm or 355 nm excitation, indicating little effect of excitation wavelength on the luminescence temperature sensing. Sm3+, Eu3+ doping is found to give rise to superior luminescence decay characteristics to temperatures up to 1000 °C, while the sample doped with Er3+ shows longer decay time above that temperature and measurement can be made up to 1200 °C. The luminescent lifetime-temperature dependences for all the three materials were also discussed based on the multi-phonon relaxation model.