LiTaO₃:Bi³⁺,Tb³⁺,Ga³⁺,Ge⁴⁺: A Smart Perovskite with High Charge Carrier Storage Capacity for X-Ray Imaging, Stress Sensing, and Non-Real-Time Recording

Developing X-ray or UV-light charged storage and mechanoluminescence (ML) materials with high charge carrier storage capacity is challenging. Such materials have promising utilization in developing new applications, for example, in flexible X-ray imaging, stress sensing, or non-real-time recording. Herein, the study reports on such materials; Bi³⁺, Tb³⁺, Ga³⁺, or Ge⁴⁺ doped LiTaO₃ perovskite storage and ML phosphors. Their photoluminescence, thermoluminescence (TL), and ML properties are studied. The charge carrier trapping and release processes in the Bi³⁺, Tb³⁺, Ga³⁺, or Ge⁴⁺ doped LiTaO₃ are explained by using the constructed vacuum referred binding energy diagram of LiTaO₃ including the energy level locations of unintended defects, Tb³⁺, Bi³⁺, and Bi²⁺. The ratio of the TL intensity after X-ray charging of the optimized LiTaO₃:0.005Bi³⁺,0.006Tb³⁺,0.05Ga³⁺, or LiTaO₃:0.005Bi³⁺,0.006Tb³⁺,0.05Ge⁴⁺ to that of the state-of-the-art BaFBr(I):Eu²⁺ is ≈1.2 and 2.7, respectively. Force induced charge carrier storage phenomena is studied in the Tb³⁺, Bi³⁺, Ga³⁺, or Ge⁴⁺ doped LiTaO₃. Proof-of-concept compression force distribution sensing and X-ray imaging is demonstrated by using optimized LiTaO₃:0.005Bi³⁺,0.006Tb³⁺,0.05Ga³⁺ dispersed in a hard epoxy resin disc and in a silicone gel film. Proof-of-concept color-tailorable ML for anti-counterfeiting is demonstrated by admixing commercial ZnS:Cu⁺,Mn²⁺ with optimized LiTaO₃:0.005Bi³⁺,0.006Tb³⁺,0.05Ge⁴⁺ in an epoxy resin disc.