High-Quantum-Efficiency Pr3+-Doped Li7La3Zr2O12 Garnet and Associated Temperature-Sensing Performance

The understanding of energy transfer mechanisms between different excited states of Pr3+ is closely bound up with exploiting high-quantum-efficiency Pr3+-doped luminescent thermometers and optimizing their temperature-sensing performances. Herein, we propose a new-type Pr3+-doped tetragonal-phase Li7La3Zr2O12 (Pr3+:LLZO) garnet luminescent thermometer and study accompanied photoluminescence (PL) properties. Combining composition optimization, we gain a fantastic room-temperature PL quantum efficiency within Pr3+:LLZO phosphors (77.48%), a value obviously superior to those of traditional Pr3+-doped garnet-type phosphors. The thermally induced fluorescence quenching of 3P0 emissions within Pr3+:LLZO mainly originates from phonon-assisted thermal ionization, differing from the Pr3+-doped Y3Al5O12 garnet. By contrast, the 1D2 case is akin to most Pr3+-doped materials in that the quenching behavior is seriously associated with the cross-relaxation between the 3P0 and 1D2 states. On that basis, we propose a Pr3+:LLZO luminescence thermometry strategy by utilizing different quenching mechanisms of steady-state 3P0 and 1D2 emissions, performing a comparable temperature-sensing capability to those Pr3+-based garnet-type luminescent thermometers. Our findings strengthen the importance of discerning the quenching mechanisms of Pr3+ emissions and provide a valuable perspective for designing high-quantum-efficiency Pr3+-doped garnet-type luminescent materials and relevant luminescence thermometry.