Near infra-red luminescence thermometer based on Y₃Al₅O₁₂: Yb³⁺, Cr⁴⁺

Research on luminescence thermometers has predominantly centered around visible-light thermometers, susceptible to significant impact from Raleigh scattering (similar to lambda(-4)). In this work, a Cr4+ and Yb3+ co-doped Y3Al5O12 thermometer is reported. Both emission and excitation are in the IR range, which makes this thermometer much less affected by Raleigh scattering compared to traditional visible-light thermometers. The non-overlapping of Yb3+ and Cr4+ emissions in the photoluminescence (PL) spectrum is also a major advantage over conventional thermometers. By calculating the PL intensity ratio of Yb3+ and Cr4+ as a function of temperature, the maximum relative sensitivity reaches 1.60% K-1 at 200 K. In addition, Cr4+ and Yb3+ co-doped Y3Al5O12 as a thermometer based on Cr4+ luminescence lifetime exhibits a relative sensitivity of 0.56% K-1. This work provides inspiration for the design of transition metal and rare-Earth co-doped dual-mode thermometers.