Enhancing the temperature sensing property of a Ca(0.79−x)Bi(x)Er(0.01)Yb(0.2)MoO(4) phosphor via 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(4):Er/Yb phosphor via distortion of the local symmetry environments and reduction in no-radiative channels. Bi(3+) ion co-doping creates a local distortion while the average tetragonal structure of CaMoO(4) remains intact. This creates asymmetry around the Er(3+) 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(3+), 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(3+) ion has also been revealed. Our results show that the UC emission is enhanced about 25 times for Bi(3+) co-doped samples which improves the temperature sensitivity significantly. The samples, both with and without Bi(3+) co-doping, exhibited relative sensitivities of 0.0068 K(−1) at 300 K and 0.0057 K(−1) 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(3+) doping on UC emission and opens new avenues for the development of high-performance temperature sensing materials.