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

Abstract

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; Bi 3+ , Tb 3+ , Ga 3+ , or Ge 4+ doped LiTaO 3 perovskite storage and ML phosphors. Their photoluminescence, thermoluminescence (TL), and ML properties are studied. The charge carrier trapping and release processes in the Bi 3+ , Tb 3+ , Ga 3+ , or Ge 4+ doped LiTaO 3 are explained by using the constructed vacuum referred binding energy diagram of LiTaO 3 including the energy level locations of unintended defects, Tb 3+ , Bi 3+ , and Bi 2+ . The ratio of the TL intensity after X-ray charging of the optimized LiTaO 3 :0.005Bi 3+ ,0.006Tb 3+ ,0.05Ga 3+ , or LiTaO 3 :0.005Bi 3+ ,0.006Tb 3+ ,0.05Ge 4+ to that of the state-of-the-art BaFBr(I):Eu 2+ is ≈1.2 and 2.7, respectively. Force induced charge carrier storage phenomena is studied in the Tb 3+ , Bi 3+ , Ga 3+ , or Ge 4+ doped LiTaO 3 . Proof-of-concept compression force distribution sensing and X-ray imaging is demonstrated by using optimized LiTaO 3 :0.005Bi 3+ ,0.006Tb 3+ ,0.05Ga 3+ 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 + ,Mn 2+ with optimized LiTaO 3 :0.005Bi 3+ ,0.006Tb 3+ ,0.05Ge 4+ in an epoxy resin disc.

Novel spectral band: ultraviolet A mechanoluminescence from Bi3+-doped LiYGeO4

“…3a, when monitored at λ em = 355 nm, the PLE spectrum shows a broad band in the 250–330 nm region peaked at 303 nm. In addition to the peak at 303 nm, when monitored at λ em = 725 nm, other two 1–39 peaks at 615 and 655 nm are observed, which are ascribed to the 2 P 1/2 → 2 P 3/2 transition of Bi 2+ . PL spectra at room temperature of Li x Y 0.995 GeO 4 :0.005Bi 3+ ( x = 0.898, 0.991, 0.994, 0.997, 1.000 and 1.003) are shown in Fig.…”

“…21 In 2022, Lyu et al reported the ML perovskite materials Bi 3+ , Tb 3+ , Ga 3+ , or Ge 4+ doped LiTaO 3 , and studied the force induced charge carrier storage phenomenon in detail. 22 The reports mentioned above have proved that Bi 3+ ion doped ML materials are feasible to a certain extent, and although theoretically possible, ML in the UV spectral band has not been achieved by the Bi 3+ ion yet.…”

Pressure- and Rate-Dependent Mechanoluminescence with Maximized Efficiency and Tunable Wavelength in ZnS: Mn2+, Eu3+

“…In this work, we systematically studied pressure- and rate-dependent ML behavior of Mn 2+ , Eu 3+ co-doped ZnS at different compression rates by employing a dynamic diamond anvil cell (dDAC), lab-built microsecond time-resolved fluorescence, in situ high-pressure synchrotron X-ray diffraction (XRD), PL, and thermoluminescence. We chose Mn 2+ , Eu 3+ co-doped ZnS phosphor rather than ZnS: Mn 2+ , as the optical performance can be improved by co-doping transition-metal ions or rare-earth-metal ions to increase the defect concentration. ,, It is revealed that pressure and compression rate have great influence on the ML emission efficiency and wavelength via the pressure-induced enhancement of the interaction between the host lattice and doped luminescent ions. Our findings not only open a new door for exploiting the relationship between structural stability and optical performance under high pressure, as well as pressure- and rate-dependent ML, but also show the multifunctional potential applications of ZnS: Mn 2+ , Eu 3+ in new pressure sensors, dynamic pressure visualization, and stress distribution.…”

Tunable and enhanced mechanoluminescence in LiYGeO4:Tb3+via Bi3+ → Tb3+ energy transfer

“…1 Due to the linear relationship between luminescence intensity and load, ML materials have potential applications in lighting and displaying, high-level information storage, artificial intelligent skin, health monitoring and wearable devices. [2][3][4][5][6][7][8] In particular, by using the luminescence signals as the medium, ML could enable in situ, remote, distributed and visualized stress sensing for different kinds of interfaces. 9 So far, ML has been classified into two categories of deformation-ML and tribo-ML (TML).…”

“…Thereinto, hosts with abundant intrinsic defects may be suitable for Tb 3+ ions to emit high intensity ML emissions, because it is generally acknowledged that both long persistent luminescence (PersL) and ML depend on defects to accommodate the carriers. 26 Therefore, deep defects in PersL materials can be directly used, and the ML performance can be enhanced by reasonably adjusting the defect concentration and distribution. 27 In recent years, research studies on LiYGeO 4 -based PersL materials have indicated that they have excellent PersLs with the afterglow time ranging from dozens of hours to hundreds of hours after irradiation by UV light.…”