Novel Strategy for Designing Photochromic Ceramic: Reversible Upconversion Luminescence Modification and Optical Information Storage Application in the PbWO₄:Yb³⁺, Er³⁺ Photochromic Ceramic

Inorganic photochromic material is an available medium to obtain optical information storage. The photochromic property of the inorganic material is mainly from the defects of the host. However, the formation of defects in the host is uncontrollable, in particular, the revisable formation and removement of defects are difficult. Thus, there are few inorganic materials with the revisable photochromism upon the entire light stimulation. Therefore, it is an urgent need to find a suitable approach to design inorganic photochromic materials. Here, the photochromic PbWO₄:Yb³⁺, Er³⁺ ceramic was designed with the help of valence state change of W⁶⁺ → W⁵⁺ and Pb²⁺ → Pb⁴⁺. Upon the 532 nm laser stimulation, the photochromism of the PbWO₄:Yb³⁺, Er³⁺ ceramic was obtained based on the Pb²⁺ + hν (532 nm) → Pb⁴⁺ + 2e^- and W⁶⁺ + e^- + hν (532 nm) → W⁵⁺ reaction, resulting in the optical information writing. Under the stimulation of an 808 nm laser, the written optical information was erased based on the W⁵⁺ + hν (808 nm) → W⁶⁺ + e^- and Pb⁴⁺ + 2e^- + hν (808 nm) → Pb²⁺ reaction. In addition, the photochromism-induced upconversion emission modification was obtained in the PbWO₄:Yb³⁺, Er³⁺ ceramic, realizing the effective and nondestructive reading out of optical information. The cyclic experiment demonstrated a good reproducibility of both photochromism and upconversion emission modification, exhibiting the potential application of the PbWO₄:Yb³⁺, Er³⁺ ceramic as the optical data storage medium.