Simultaneous enhancement of emission and thermal sensitivity via phase transition in Gd2(MoO4)3:Yb3+/Er3+ crystals

Abstract The effects of site symmetric distortion induced by the phase transition on up‐conversion emission and thermal sensing performance of Gd 2 (MoO 4 ) 3 :Yb 3+ /Er 3+ (GMO) crystals were elaborately studied by minimizing interference from many factors. Monoclinic GMO showed a much stronger fluorescence intensity and larger fluorescence intensity ratio under the irradiation of 980 nm laser in comparison to the orthorhombic counterpart. These remarkable up‐conversion properties stemmed from the low site symmetry with large site symmetric distortion in monoclinic GMO. Moreover, the thermal sensing property of the samples was assessed based on the fluorescence intensity ratio technique, where monoclinic GMO exhibited much higher maximum absolute sensitivity ( S a = 0.0257 K −1 at 510 K) due to the site symmetric distortion, which was further explained by the Judd–Ofelt theory and polarizability of the chemical bond volume model. Results opened an efficient avenue for achieving highly sensitive thermometry in many daily scenarios via finely tailoring the local site symmetry.