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

Herein, a series of novel Y 2 GeO 5 : Er 3+ , Yb 3+ 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 Er 3+ and Yb 3+ of all the samples were combined to explore their properties as optical thermometer. By exciting 980 nm laser, strong UC luminescence of Er 3+ ions was emitted at 522, 546, and 652 nm, and by increasing the Er 3+ , Yb 3+ ions co-doped concentration, the UC luminescence intensity of Er 3+ ions was greatly enhanced. By using two different techniques, a dual-mode temperature sensor was explored based on the FIR of thermal coupling ( 2 H 11/2 / 4 S 3/2 ) and non-thermal coupling ( 2 H 11/2 / 4 F 9/2 ) 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 Y 2 GeO 5 : Er 3+ , Yb 3+ phosphors are prospective applications in temperature sensing. • Proposed a three-mode temperature sensor based on the fluorescence lifetime and the FIR of TCEL and NTCEL. • Y 2 GeO 5 : Er 3+ shows high signal discriminability in the green regions. • Y 2 GeO 5 : Er 3+ , Yb 3+ have potential uses for self-referenced optical thermometry.