Synthetic, structural, and spectroscopic studies on Cr 2 O 3 –Na 2 O–CaO–GeO 2 glass and glass ceramic NIR phosphors

作者：Yasushi Nanai, Yutaro Satake, Toyokazu Tanabe, Seiya Shimono, Y. Niwa, Moe Suzukawa, 北沢信章 · 发表于：Japanese Journal of Applied Physics · 年份：2026 · DOI：10.35848/1347-4065/ae8a29 · 研究领域：Luminescence Properties of Advanced Materials、Glass properties and applications、Microwave Dielectric Ceramics Synthesis

Abstract Herein, Cr 2 O 3 –Na 2 O–CaO–GeO 2 glasses and glass ceramics were synthesized and characterized as broadband NIR phosphors. X-ray diffraction and transmission electron microscopy revealed that annealing at 700 °C–800 °C induced the formation of Ca 2 Ge 7 O 16 crystals within the glass matrix. Changes in the oxidation state of Cr ions were analyzed using UV–Vis–NIR diffuse reflectance spectroscopy and X-ray absorption spectroscopy. The as-made glass exhibited broadband 4 T 2 → 4 A 2 emission of Cr 3+ spanning 700–1300 nm. Upon annealing, crystallization caused a blue shift and the appearance of sharp 2 E → 4 A 2 emission of Cr 3+ (R-line), whereas higher temperatures led to a red shift and N-line emission associated with Cr 3+ –Cr 3+ interactions. The PL decay time increased with annealing temperature, reaching a maximum at 775 °C. The PL quantum yield peaked at 0.23 at 725 °C and decreased at higher temperatures due to optical absorption by Cr 4+ ions.