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.