Reversible regulation of upconversion luminescence in new photochromic ferroelectric materials: Bi4−xErxTi3O12 ceramics

Abstract

Reversible upconversion (UC) luminescence modulation by external stimuli (i.e. electric field, magnetic field, and light irradiation) is extremely attractive for applications in a broad range of fields, such as photoswitches, high-density optical data storage devices, and optical sensing. In this work, one kind of novel phosphor, Er³⁺-doped Bi₄Ti₃O₁₂ (Bi_4−xEr_xTi₃O₁₂) ceramics, prepared by a conventional solid-state reaction approach, is reported which exhibits both bright UC luminescence and a remarkable photochromic (PC) effect. The UC luminescence, PC effect, and the coupling between UC and PC performances were investigated in detail. It is found that the UC luminescence could be readily modulated by alternating visible light irradiation and a thermal stimulus, and a large reversible luminescence regulation has been achieved based on the PC reaction. Meanwhile, the modulation of UC luminescence was shown to tightly depend on the irradiation time and thermal treatment processes. In addition, the coloration and decoloration processes also exhibited good fatigue resistance. The mechanisms related to the UC emissions, PC processes, and luminescence modulation are also discussed. These results indicated that Bi_4−xEr_xTi₃O₁₂ samples could be potentially utilized as a kind of optical data storage material.