Tunable Bi Near-Infrared Emission in Aluminosilicate Glass Based on Local Excess Charge Model

Ultra-broadband near-infrared (NIR) luminescence of bismuth ions in glass is widely used, but the stability problem of Bi NIR centers limits its practical application. Therefore, in this work, the original local excess charge model that can effectively regulate the Bi NIR luminescence behavior was expanded and supplemented in bismuth doped yttrium aluminum-silicate glass. The statistical excess charge field around Bi was built up via either introduction of glass modifier (Y³⁺) or substitution of silicon by different glass former ions with a valence state lower than +4 (Al³⁺) in yttrium aluminumsilicate glass. As a result, the behavior of Bi NIR centers (i.e., the valence states of Bi, the intensities and peak positions of absorption and NIR emission) was determined. Also, the distribution characteristics of Bi NIR centers were proposed. Bi⁰ NIR centers are preferentially located in the multimember rings of silicon, while Bi⁺ NIR centers are situated at the interstices of silicon network. This work could solve a problem to stabilize Bi NIR centers in yttrium aluminumsilicate glass, even other alkali metals and alkali metals (Li/Na/K, Mg/Ca/Sr/Ba, etc.) aluminumsilicate glass, thus establishing the experimental and theoretical supports for the design of Bi-doped laser glasses and fabrication of fibers in future. This work also verified the effectiveness and universality of the local excess charge model, providing a strategy for stabilizing the valance state of other multivalent luminescent ions (i.e. Eu, Ce, Cu, Ag, Sn) and their distribution in glass network structure.