Novel AMoO4:Eu3+ (A = Ca and Ba) optical thermometer: Investigation of effect of local ionic coordination environment on optical performance and temperature measurement sensitivity

https://doi.org/10.1016/j.ceramint.2023.05.217

A range of Eu³⁺-doped AMoO₄ (A = Ca and Ba) phosphors were successfully synthetized, and their crystal structures, optical performance, and temperature measurement sensitivities were investigated in detail. Peak doping concentration of CaMoO₄:Eu³⁺ phosphor was 0.18, while peak doping concentration of BaMoO₄:Eu³⁺ phosphor may be greater than 0.18. Then, temperature-dependent photoluminescence emission spectra of representative CaMoO₄:0.09Eu³⁺ and BaMoO₄:0.03Eu³⁺ phosphors were recorded. CaMoO₄:0.09Eu³⁺ phosphor exhibited abnormal thermal quenching, which was attributed to defects caused by heterovalent substitution of ions and increase in the temperature, and good thermal stability. Finally, the possibility of using both phosphors as optical thermometers was discussed, which exhibited good temperature sensitivity. However, CaMoO₄:0.09Eu³⁺ phosphor exhibited two peak absolute (Sa, 1.28 %K⁻¹ and 1.39 %K⁻¹) and relative sensitivities (Sr, 1.21 %K⁻¹ and 1.20 %K⁻¹). In addition, variation trend of Sr value with temperature was considerably peculiar. Two optimum Sa and Sr values were attributed to abnormal thermal quenching of CaMoO₄:0.09Eu³⁺ phosphor. Peak Sa and Sr values of BaMoO₄:0.03Eu³⁺ phosphor was 12.39 %K⁻¹ and 0.89 %K⁻¹, respectively. In addition, Sa of AMoO₄:Eu³⁺ phosphor was negatively related to Eu³⁺ central asymmetry, while peak Sr value was more inclined to appropriate ionic central asymmetry.