Creating Deep Traps in Yttrium Aluminum Garnet for Long-Term Optical Storage and Afterglow-Intensity-Ratio-Based Temperature Sensing

Abstract

Deep traps are needed for electron-trapping-based long-term optical storage due to its resistance to thermal erasure. Current electron trapping materials have the erasing temperatures hardly beyond 600 K, limiting its storage time. Herein, an electron trapping material containing deep traps is achieved by co-doping Tb and Eu in Y₃Al₅O₁₂ via solid-state reaction in reducing atmosphere. After 254 nm UV charging, strong thermoluminescence of Tb³⁺ with the glow curve peaking at 600, 693, and 765 K is observed. The comparative studies of the as-made and the air-annealed samples suggest that these new traps are related to the complex defects containing oxygen vacancy with adjacent Eu²⁺ and the charging process is the photoionization of Tb³⁺ with subsequent electron trapping. The 693 and 765 K thermoluminescence glow peaks in the charged sample show almost no decrease during 108 h storage in dark at room temperature. Images write-in and read-out via 808 nm laser stimulation are realized. Furthermore, the present phosphor also exhibits temperature-sensitive afterglow spectra in the range of 553–803 K with the sensing span of 250 K wider than other afterglow thermometers. These findings indicate the great application potentials of Y₃Al₅O₁₂:Tb,Eu phosphor in long-term optical storage and temperature sensing.