Enhancing the temperature sensing property of a CaBiErYbMoO phosphor local symmetry distortion and reduction in non-radiative channels.

We demonstrate an enhancement in the upconversion (UC) emission and temperature sensing property of a CaMoO:Er/Yb phosphor distortion of the local symmetry environments and reduction in no-radiative channels. Bi ion co-doping creates a local distortion while the average tetragonal structure of CaMoO remains intact. This creates asymmetry around the Er ions which improves the UC emission. Furthermore, our calculations on XRD data show a reduction in the dislocation density and the micro-strain in the crystal with the introduction of Bi, which also favours the enhancement of UC emission as it reduces the non-radiative channels. Furthermore, the effect of this enhancement on the temperature sensing property of Er ion has also been revealed. Our results show that the UC emission is enhanced about 25 times for Bi co-doped samples which improves the temperature sensitivity significantly. The samples, both with and without Bi co-doping, exhibited relative sensitivities of 0.0068 K at 300 K and 0.0057 K at 298 K which is a significant improvement and indicates the potential of the material for temperature sensing applications. This proof-of-concept provides a deeper understanding of the effect of Bi doping on UC emission and opens new avenues for the development of high-performance temperature sensing materials.