Scalable synthesis of ytterbium and erbium codoped calcium molybdate phosphors as upconversion luminescent thermometer

Luminescent thermometry is a noninvasive method of temperature detection with high sensitivity and response speed. The present study demonstrated the process-intensified synthesis of ytterbium and erbium codoped calcium molybdate phosphors (CaMoO 4 :Yb 3+ /Er 3+ ). The experiment involved the initial premixing of the precursors using a high-gravity rotating packed bed (RPB) reactor and subsequent calcination processing. The pronounced mass transfer and micromixing of the reactants in the RPB facilitated the scalable and controllable synthesis of CaMoO 4 :Yb 3+ /Er 3+ particles with submicron sizes and regular morphologies. The CaMoO 4 :Yb 3+ /Er 3+ particles exhibited a bright-green emission with temperature-dependent luminescence characteristics under 980 nm laser irradiation. Furthermore, the maximum absolute sensitivity was determined to be 0.02837 K −1 . These results indicated that the synthesized product was a suitable candidate for application in upconversion luminescent thermometers capable of temperature sensing at the microscale.