Full control on the valence of the active ions in solids to improve properties is the central topic of chemistry and materials. Cr³⁺ and Cr⁴⁺ ions generally emit wavelength-different near-infrared (NIR) light. Here, we have developed a chromium valence-controllable single-phase phosphor, Mg₂GeO₄:Cr³⁺,Cr⁴⁺ to achieve super-broad NIR luminescence. High Li ⁺ content charge compensators can stabilize Cr³⁺, whereas high-temperature sintering tends to facilitate the formation of Cr⁴⁺. Through fine adjusting the synthesis conditions, pure Cr³⁺ or Cr⁴⁺ luminescence can be obtained with peak emission locating at 935 nm and 1190 nm, respectively. Super broad band dual emission spanning from 650 nm to 1600 nm is realized via fully controlling the concentration ratio of Cr³⁺ to Cr⁴⁺ in a single host. By measuring the transmission spectra of several foodstuff illuminated by our phosphors, non-destructive analysis in food safety areas can be realized. This study provides a new strategy for exploiting super broad band NIR luminescent materials.

完全控制固体中活性离子的化合价以改善性能是化学和材料的核心主题。Cr ³⁺和Cr ⁴⁺离子通常发射波长不同的近红外（NIR）光。在这里，我们开发了一种铬价可控的单相荧光粉，Mg ₂ GeO ₄ :Cr ³⁺ ,Cr ⁴⁺以实现超宽的近红外发光。高Li  ⁺ 含量的电荷补偿剂可以稳定Cr ³⁺，而高温烧结倾向于促进Cr ⁴⁺的形成。通过微调合成条件，纯Cr ³⁺或Cr ⁴⁺发光峰值分别位于 935 nm 和 1190 nm。通过完全控制单个主体中Cr ³⁺与Cr ⁴⁺的浓度比，实现了跨越650 nm至1600 nm的超宽带双发射。通过测量我们的荧光粉照射的几种食品的透射光谱，可以实现食品安全领域的无损分析。该研究为开发超宽带近红外发光材料提供了一种新策略。