A multi-mode optical thermometer based on the up-conversion Ca3Y2Ge3O12: Er3+, Yb3+ phosphor

In order to develop a new up-conversion luminescent temperature measurement material with a garnet structure, Ca3Y2Ge3O12: Er3+, Yb3+ phosphors were prepared by a simple high temperature solid phase method. The structural phase and luminescence characteristics of the samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy and photoluminescence spectra. It can be observed that the characteristic emission of Er3+ ion appears in the sample under 980 nm excitation, and it's up-conversion emission intensity increases with the increase of Yb3+ ion concentration. The maximum relative sensitivity is 1.29 %K−1, 1.09 %K−1 and 1.03 %K−1 based on the different temperature dependence of the thermal coupled energy levels (TCELs), non-thermal coupled energy levels (NTCELs) and the fluorescence lifetime (FL) of 4S3/2 state, respectively. The results show that Ca3Y2Ge3O12: Er3+, Yb3+ phosphor is excellent a material for optical temperature measurement. •Proposed a multi-mode optical thermometer which can measure temperature in three ways: FL, FIR based on TCELs and NTCELs.•Novel garnet structured thermometer Ca3Y2Ge3O12: Er3+, Yb3+ shows high relative sensitivity of 1.29 %K−1.•Ca3Y2Ge3O12: Er3+, Yb3+ have potential uses for self-referenced optical thermometry.