Upconversion luminescence and temperature sensing performance of Er3+ ions doped self-activated KYb(MoO4)2 phosphors

In this work, a series of self-activated KYb(MoO4)(2) phosphors with various x at% Er3+ doping concentrations (x = 0.5, 1, 3, 5, 8, 10, 15) was synthesized by the solid-state reaction method. The phase structure of the as-prepared samples was analyzed by X-ray diffraction (XRD), XRD Rietveld refinement and Fourier transform infrared (FT-IR) spectroscopy. The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er3+ doping concentration up to 15 at%. High-purity upconversion (UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er3+ ions in the self-activated KYb(MoO4)(2) host is revealed as 3 at%. The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra. In addition, the fluorescence intensity ratios (FIRs) of the two thermally-coupled energy levels, namely H-2(11/2) and S-4(3/2), of Er3+ ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample. The maximum relative sensitivity (S-R) is determined to be 0.0069 K-1 at 300 K and the absolute sensitivity (S-A) is determined to be 0.0126 K-1 at 300 K. The S-A of self-activated KYb(MoO4)(2):Er3+ is almost twice that of traditional KY(MoO4)(2):Er3+/Yb3+ codoping phosphor. The results demonstrate that Er3+ ions doped self-activated KYb(MoO4)(2) phosphor has promising application in visible display, trademark security and optical temperature sensors. (c) 2023 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.