Broadband-NIR luminescent MgNb2O6:Cr3+ transparent glass ceramics fabricated by co-melting and controlled crystallization

Broadband near-infrared (NIR) light sources are essential for night-vision illumination, biomedical imaging, food testing, and anti-counterfeiting. NIR phosphor-converted LEDs (pc-LEDs) are attractive due to their compact structure, long lifetime, and energy efficiency. However, conventional transmission-type packaging disperses micrometer-sized phosphors in polymer encapsulants, causing severe light scattering from refractive index mismatch and heat accumulation from low thermal conductivity. These issues limit NIR transmittance and output power. Cr³⁺-doped glass-ceramics (GCs) can overcome these limitations by combining high transmittance, thermal conductivity, and chemical durability with low phonon energy and high activator solubility. However, transparent GCs with high thermal quenching resistance remains challenging because of refractive index mismatch, grain coarsening, and multiple crystalline phases during heat treatment. Recently, a team of material scientists led by Libin Xia and Xinyu Ye from Jiangxi University of Science and Technology, China,  reported the fabrication, microstructure, luminescence properties, thermal stability, and NIR LED performance of Cr³⁺-doped MgNb₂O₆ transparent GCs by co-melting and controlled crystallization.

The team published their work in Journal of Advanced Ceramics on September 4, 2026.

In this work, we synthesized Cr³⁺-doped MgNb₂O₆ GCs by co-melting glass-forming and target-phase precursors. “The SiO₂–Na₂O system was used as the glass matrix, while MgO and Nb₂O₅ provided the target MgNb₂O₆ crystalline phase. By precisely tuning the Mg/Nb ratio and employing a two-step heat treatment, we achieved controllable precipitation of single-phase MgNb₂O₆ microcrystals with uniform size distribution.”

“The resultant GCs possess acceptable transmittance and favorable thermal quenching resistance,” said the author. “With nucleation at 730 °C and crystallization at 940 °C, the optimized GC shows a transmittance of approximately 50% and a high absorptivity of 60.5%. Cr³⁺ ions simultaneously occupy Mg²⁺ and Nb⁵⁺ sites in MgNb₂O₆, creating intermediate and weak crystal fields. This leads to broadband NIR emission covering 600–1300 nm with a full width at half maximum of 210 nm.”The optimized GC has an average grain size of 1.69 µm and good elemental uniformity. The thermal quenching activation energy is 0.22 eV, and the Huang–Rhys factor S = 5.43 indicates intermediate electron–phonon coupling. The Debye temperature and Vickers hardness are 566.3 K and 7.78–8.65 GPa, respectively, indicating high structural rigidity. Due to its unique structure, the prepared GC exhibits favorable thermal quenching resistance, retaining 67.5% of its initial luminous intensity at 373 K. The NIR LED device integrated with the MgNb₂O₆:Cr³⁺ GC and a blue LED chip delivers an output power of 240.9 mW and a power conversion efficiency of 6.3%. The external quantum efficiency is 18.3%. This makes it promising for night-vision illumination, food testing, biomedical diagnosis, and anti-counterfeiting.”

However, more delicate research is still needed to explore the long-term reliability, high-power stability, and packaging optimization of the MgNb₂O₆:Cr³⁺ GC as a new NIR light source. In this regard, the team also proposed future work including further improving thermal stability and device efficiency.

Other contributors include Jinliang Huang, Peihong Shi, Junhua Lin, Weijie Yan from the School of Carbon Neutrality; School of Materials Science and Engineering; College of Rare Earths at Jiangxi University of Science and Technology, China.

About Author

Libin Xia is an associate professor and a master’s supervisor at Jiangxi University of Science and Technology, China. His current interests and fields of research are rare-earth doped glass-ceramics/ceramics phosphors. He has led six projects, including the National Natural Science Foundation of China, the Jiangxi Natural Science Foundation, and the Science and Technology Project of the Provincial Department of Education. He has published more than 20 academic papers and applied for two national patents.

Funding

This work was supported by the National Natural Science Foundation of China (52062017) and Jiangxi Provincial Natural Science Foundation (20232BAB204013).

DOI LINK:

https://doi.org/10.26599/JAC.2026.9221371

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2025 IF is 14, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2025 CiteScore is 24.6 (6/133) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508