Comparative study on upconversion and downconversion luminescence of Er3+, Yb3+ co-doped BaY0.67Mo0.33O3 phosphors for optical thermometry

This study presents a comparative analysis of upconversion and downconversion luminescence of Er³⁺,Yb³⁺ co-doped BaY_0.67Mo_0.33O₃ phosphors for potential application in optical thermometry. The phosphors were synthesized via a conventional solid-state reaction method and characterized using photoluminescence spectroscopy and temperature-dependent emission studies. Under near-infrared excitation (980 nm), intense green and red upconversion emissions were observed. An efficient energy transfer from Yb³⁺ to Er³⁺ ions. Simultaneously, near-infrared downconversion emissions were obtained under 980nm excitation. The intensity ratio of thermally coupled levels ²H_11/2(⁴S_3/2)→⁴I_15/2 exhibited strong temperature sensitivity, enabling precise optical temperature readout. The results demonstrate that BaY_0.67Mo_0.33O₃:Er³⁺,Yb³⁺ is a promising dual-mode luminescent material for advanced non-contact temperature sensing applications.