Related Experiment Video
Updated: May 8, 2026
Phase-Dependent Control of Trap Depth and Persistent Luminescence in Strontium Aluminate Phosphors
Published on: December 5, 2025
Cr3+-Activated Spinel Phosphors with Inhibited Cr(VI) Formation for Multiapplication via a Lattice Occupation
Yiqing Zhou1, Man Yang1, Jie Chen1
1Key Laboratory of Light Energy Conversion Materials of Hunan Province College, Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
This study introduces a novel strategy to prevent chromium-6 (Cr6+) contamination in chromium-3 (Cr3+)-activated phosphors by strategically occupying specific crystal sites. This method enhances luminescence properties and thermal stability for advanced applications.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Luminescence
Background:
- Chromium-activated phosphors are crucial for red to near-infrared (NIR) applications.
- A significant challenge is the co-existence and contamination of undesirable chromium-6 (Cr6+) species.
- Preventing Cr6+ formation is essential for stable and efficient phosphor performance.
Purpose of the Study:
- To develop a competitive site occupation strategy to prevent Cr3+ oxidation to Cr6+ in spinel phosphors.
- To enhance the photoluminescence properties and introduce new functionalities in Cr3+-doped MAl2O4 (M = Zn, Mg) phosphors.
- To explore the potential applications of the modified phosphors.
Main Methods:
- Incorporation of tetrahedral structural units ([BO4] and [SiO4]) into spinel-type MAl2O4:Cr3+ phosphors.
- Utilizing a competitive site occupation strategy to block Cr3+ from entering and oxidizing at tetrahedral sites.
- Characterization of structural, photoluminescence, and thermal properties of the synthesized phosphors.
Main Results:
- The strategy effectively prevented Cr6+ formation, demonstrating universality in the spinel system.
- ZnAl1.78B0.2O4:Cr3+ (ZABO:Cr) exhibited over five times the emission intensity compared to ZnAl2O4:Cr3+ (ZAO:Cr).
- Internal quantum efficiency (IQE) and external quantum efficiency (EQE) significantly increased from 10.03% and 5.62% (ZAO:Cr) to 81.31% and 35.87% (ZABO:Cr), respectively.
- The phosphors showed enhanced thermal quenching resistance and X-ray-responsive photochromism due to increased electron-trapping defects.
- Multipeak far-red to NIR emission and multistimuli response were observed.
Conclusions:
- A general and effective method was proposed to stabilize the Cr3+ valence state in Cr3+-doped materials.
- The introduced tetrahedral units significantly enhance luminescence efficiency and introduce novel functionalities like thermal stability and photochromism.
- The modified phosphors hold promise for diverse applications including plant cultivation, biological imaging, and anticounterfeiting.
