An energy self-compensating phosphosilicate material applied to temperature sensors

For years, researchers have been exploring effective methods of sustaining the emission intensity of phosphors with increasing temperature by suppressing emission loss. In this work, we developed a multi-cationic site and lattice-distorted phosphosilicate phosphor, Ca₈Al₂P₆SiO₂₈:Ce, Eu. To obtain luminous-self-healing properties, we attempted to change the energy depths and density distributions of the traps to achieve self-suppression of emission loss by energy compensation from the traps or energy transfer between Ce³⁺ and Eu²⁺/Eu³⁺. The temperature-dependent emission spectra indicate that the luminescence of Ce³⁺ presents similar change trends in both single and co-doped samples. Meanwhile, the change trends of the Eu²⁺/Eu³⁺ emission intensities show obvious differences. Combined with the thermoluminescence curves, decay times, temperature-dependent fluorescence characteristics and cathodoluminescence spectra, we speculate that the traps play an important role in the luminescence of Ce³⁺ due to the smaller energy difference of the Ce³⁺ excited states and the conduction band. The abnormal luminescence of Eu²⁺/Eu³⁺ mainly results from the energy transfer of Ce³⁺ to Eu²⁺/Eu³⁺. For this phenomenon, a high thermal sensitive fluorescence intensity ratio is obtained in a broad temperature range, which implies that this material can be applied in temperature sensors.