Excellent upconversion luminescence and temperature sensing performance of CdMoO₄:Er³⁺,Yb³⁺ phosphors

In this paper, Er³⁺/Yb³⁺ co-doped CdMoO₄ phosphors were prepared by a traditional high temperature solid state reaction method. Based on the 3D network structure of the CdMoO₄ host and the efficient Er³⁺/Yb³⁺ upconversion luminescence combinations, excellent green emission properties were observed when the prepared sample is irradiated with a laser at about 980 nm. For optical temperature sensors based on the fluorescence intensity ratio (FIR), the prepared phosphors have excellent sensitivity to temperature in the range of 293 to 473 K. With increasing environmental temperatures, the absolute sensitivity of the CdMoO₄:0.02Er³⁺,0.08Yb³⁺ sample reached a maximum at about 473 K (S_a = 1.388% K^-1). The calculated relative sensitivity of the optical temperature sensor was S_r = 1.631% K^-1 at 293 K. This is due to the sensitive thermally coupled energy levels (TCLs) of the Er³⁺ ions (²H_11/2 and ⁴S_3/2) in the CdMoO₄ structure. Therefore, it is shown that the prepared CdMoO₄:0.02Er³⁺,0.08Yb³⁺ phosphor has excellent applications in non-contact optical temperature measurement.