Sensitization of Ti3+ Persistent Luminescent Lifetime-Based Thermometer by Ln3+ Co-Doping

Abstract

Co-doping of phosphors to induce energy transfers is a recognized approach to sensitize lifetime-based luminescent thermometers. However, introducing an additional depopulation channel is usually associated with a significant shortening of lifetime over the entire temperature range, which hinders the reliability of the temperature readout with respect to unco-doped counterparts. In this work, I analyzed the influence of the co-doping of lanthanide (Ln3+) ions on the thermometric performance of the LaAlO3: 10% Ti3+ phosphor, in which the average lifetime of the 2E excited state reaches almost 30 ms at room temperature. To optimize the sensitization strategy, I discuss the role of Ti3+ → Ln3+ and Ln3+ → Ti3+ energy transfers in the thermal evolution of Ti3+ lifetimes, where Ln3+ = Pr3+, Nd3+, Eu3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+. The next step is the verification of the effect of the concentration of Tm3+ and Pr3+ ions as co-dopants on thermal quenching. The research allowed improvement of the relative sensitivity of the luminescent thermometer by more than 250%, exceeding 5% K–1.