Upconversion properties and temperature sensing behaviors in visible and near-infrared region based on fluorescence intensity ratio in LuVO4: Yb3+/Er3+

A high temperature solid state method was used to synthesize the Yb3+ and Er3+ codoped LuVO4. The efficient energy transfer (ET) processes from Yb3+ to Er3+ has been demonstrated by upconversion (UC) spectra, near-infrared (NIR) spectra and lifetime curves. The optimal doping concentration for Yb3+ and Er3+ is 20 mol % and 2 mol %, respectively. Meanwhile, the temperature sensing behaviors in visible and NIR region based on fluorescence intensity ratio (FIR) have been explored in detail. In visible region, the optical thermometry of LuVO4: Yb3+/Er3+ is investigated via the FIR of the two thermally coupled energy levels H-2(11/2) and S-4(3/2) of Er3+, accompanying with a maximal absolute sensitivity S-A of 0.82% K-1 at 423 K. In NIR region, the FIRs of Peak 1 (located at 1595 nm) to Peak 3 (located at 1660 nm) and Peak 2 (located at 1637 nm) to Peak 3, which are all assigned to I-4(13/2) -> I-4(15/2) transition of Er3+, can be well fitted related to the temperature, with the maximal S-A of 1.85% K-1 and 0.62% K-1 respectively. All the results suggest that LuVO4: Yb3+/Er3+ powders is a potential material for optical thermometry in both visible and NIR region based on FIR. (C) 2018 Elsevier B.V. All rights reserved.