Optical thermometry based on different luminescence thermal responses of matrix and doped ions in CaMoO4: Sm3+ phosphors

In this experiment, Sm³⁺ doped CaMoO₄ phosphors of scheelite structure with body-centered tetragonal phase were acquired via hydrothermal method, and the Sm³⁺ doping concentrations were 0.05 %, 0.1 %, 0.3 %, respectively. The temperature-dependent emission spectra of phosphors show that as the temperature rose from 303 K to 503 K, the luminescence intensity of MoO₄²⁻ decreased all the time due to the thermal quenching, while the luminescence intensity of Sm³⁺ exhibited a new phenomenon of initial increase and then decrease. The reason for the above new situation is the combined effect of the enhanced energy transfer efficiency of MoO₄²⁻ to Sm³⁺ with increasing temperature and the thermal quenching effect of Sm³⁺ luminescence. The FIR of Sm³⁺ and MoO₄²⁻ can be utilized to represent the temperature and achieve optical temperature sensing with high relative sensitivity. The maximum relative sensitivity of CaMoO₄: 0.3 %Sm³⁺ phosphor is 6.07 % K⁻¹ at 303 K. In conclusion, CaMoO₄: Sm³⁺ phosphor has great potential for development in temperature-sensitive materials.