High-Performance Pr³⁺-Doped Scandate Optical Thermometry: 200 K of Sensing Range with Relative Temperature...

Nowadays, for lanthanide fluorescence thermometry, high relative temperature sensitivity (S_r) and wide sensing range are urgently required in practical applications. Herein, a Pr³⁺-doped scandate (Pr³⁺:CaSc₂O₄) luminescent thermometer is proposed, and the related crystal-field splitting of Pr³⁺ ions is systematically discussed. The 4f5d-4f and 4f-4f emissions of Pr³⁺ ions in CaSc₂O₄ basically present positive and negative correlation relationships with the increase in temperature, respectively. The different changing tendencies in relation to temperature for the two kinds of transitions are mainly derived from the effects of the thermally activated trap energy levels and the crossover process between 5d and 4f energy states of Pr³⁺ ions and are beneficial for the enhancement of relevant temperature sensitivities. The obtained experimental results manifest that Pr³⁺:CaSc₂O₄ owns a maximum relative temperature sensitivity S_r of 2.49%·K^-1 (at 390 K) and a low temperature uncertainty (around 0.1 K from 275 to 490 K). Moreover, it is also able to keep a relatively high S_r (not lower than 2%·K^-1) over a wide temperature sensing range (∼200 K), which is more excellent than those of reported luminescent thermometric materials (∼100 K). Hence, what discussed in this study might provide a useful design perspective for the exploration and development of high-performance luminescent thermometers with a wide applicable temperature range.