Gradient Deep-Trap Engineering in Terbium-Doped LiYF<sub>4</sub> Nanocrystals for Reconfigurable Multiplexed Encrypted Data Storage.

Xiao, Qin; Fan, Bao; Guo, Dongxin; Liao, Hong; Chen, Geng; Chen, Binqi; Liu, Yumei; Zhou, Si et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

The rapid expansion of digital data requires storage with high capacity, long-term stability, and secure encryption. Persistent luminescence (PersL) is promising for optical storage, but flexible multilevel encoding and efficient readout remain challenging. Here, we report gradient deep-trap engineering in LiYF<sub>4</sub>:Tb<sup>3+</sup> nanocrystals for multiplexed encrypted storage. The distorted coordination of scheelite-type LiYF<sub>4</sub> and fluoride displacement under X-ray irradiation promote charge-compensating defects, generating a broad distribution of deep traps (0.8-1.4 eV) that exceeds conventional sodium-based fluorides. Besides long-lasting PersL, LiYF<sub>4</sub>:Tb<sup>3+</sup> exhibits pronounced photostimulated and thermally stimulated luminescence (PSL and TSL). Thermoluminescence (TL) analysis reveals a gradient trap profile enabling temperature-selective carrier release. Utilizing this controllable trap distribution with strong charge retention and thermal cyclability, we demonstrate multilayer optical encryption within a single medium, where distinct information can be selectively decoded. These findings hold great promise for advanced optical data storage, enabling scalable encoding and retrieval for high-density, secure data.