Photochromic induced dual‐mode luminescence modulation of CaWO4: Yb3+, Ho3+, Bi3+ ceramics for anticounterfeiting agent

Photochromic reaction‐induced reversible luminescence materials have attracted extensive attention and research in information storage, anticounterfeiting and other aspects. The reversible luminescence regulation could induced photochromic reaction by external fields stimulation. However, most of the bleaching methods stay in the high temperature thermal stimulation bleaching, which has low efficiency and long reaction time, thus limiting its application. In this work, the CaWO4: Yb3+, Ho3+, Bi3+ ceramics were prepared to realize the reversible regulation of photoluminescent and photochromism by light stimulation. The CaWO4: Yb3+, Ho3+, Bi3+ ceramics turn gray after being exposed to 254 nm ultraviolet light for 25 min, and then turn white under the irradiation of 532 nm laser for 10 s to restore to the original state. The cation vacancies and oxygen vacancies formed in co‐doped Bi3+ CaWO4 ceramics lead to photochromic effect. CaWO4: Yb3+, Ho3+, Bi3+ ceramics realize reversible dual mode upconversion and downconversion luminescence, improving security and reliability in anticounterfeiting. The reversibility photoluminescent and photochromism of CaWO4: Yb3+, Ho3+, Bi3+ ceramics was verified by 245‐nm ultraviolet coloration and 532‐nm laser bleaching, which indicates that CaWO4: Yb3+, Ho3+, Bi3+ ceramics have potential application prospects as anticounterfeiting agents.