Up-conversion luminescence and temperature sensing properties based on Y2GeO5: Er3+, Yb3+ phosphors for three-mode optical thermometry

Abstract

Herein, a series of novel Y2GeO5: Er3+, Yb3+ phosphors were prepared through traditional high-temperature solid-state reactions under an air atmosphere. During whole experiments, the fluorescence intensity ratio (FIR), crystal structure, up-conversion (UC) luminescence, and energy transmission between Er3+ and Yb3+ of all the samples were combined to explore their properties as optical thermometer. By exciting 980 nm laser, strong UC luminescence of Er3+ ions was emitted at 522, 546, and 652 nm, and by increasing the Er3+, Yb3+ ions co-doped concentration, the UC luminescence intensity of Er3+ ions was greatly enhanced. By using two different techniques, a dual-mode temperature sensor was explored based on the FIR of thermal coupling (2H11/2/4S3/2) and non-thermal coupling (2H11/2/4F9/2) energy levels. And the maximal relative sensitivities of thermal coupling and non-thermal coupling were 1.17%·K−1 and 1.71%·K−1, respectively. In addition, the fluorescence lifetime was used as the third temperature detection signal. And the maximum of relative sensitivity based on fluorescence lifetime was 1.81%·K−1. All the above research shows that Y2GeO5: Er3+, Yb3+ phosphors are prospective applications in temperature sensing.