Low temperature reliability and high sensitivity of dual-channel up-conversion thermometry phosphor optimized by heterovalent ions

摘要

Poor or absent sensitivity at low temperature, as a vital deficiency of up-conversion (UC) luminescence materials, has been restricting the optimization of temperature sensing performance. Herein, UC luminescence, low temperature sensitivity and reliability were optimized concurrently by first doping Nb5+ ions in CaWa(4):Er3+/Yb3+ phosphor. The UC intensity was greatly improved by heterovalent ions (Li+/Nb5+) doping, which was mutually verified with the extended decay life. Simultaneously, near constant sensitivity 0.0070K(-1) was obtained based on the sublevels H-2(11/2(3))/S-4(3/2(1)). Moreover, a high absolute sensitivity 0.0104 K-1 and a high relative sensitivity 0.0243 K-1 based on the separated levels H-2(11/2)/S-4(3/2) were achieved. More importantly, regardless of the strategy, the temperature uncertainty delta T at low temperatures was less than 0.5 K, and the new temperature sensor also had good repeatability ( 3%). The above results indicate that this material is an optical temperature sensor with good application prospect, especially in low temperature demand.