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Conversion of Valence State and Coordination State of Fe in Transparent Glass-Ceramics Containing Li2ZnSiO4 Nanocrystals



Transparent glass-ceramics containing Li2ZnSiO4:Fe nanocrystals were prepared by melt-quenching method followed by post-heat-treatment process. The as-prepared glasses and glass-ceramics showed red to near-infrared photoluminescence centered at 730 nm, ascribed to Fe3+ ions in tetrahedral coordination. The intensity of the photoluminescence was enhanced by two technologically simple techniques—the valence state of irons was controlled from Fe2+ to Fe3+ ions using oxidizing agents, whereas the coordination state was compulsorily converted from octahedral to tetrahedral symmetry by performing a ceramization process. The presence of Fe2+ ions was considered a major origin for Fe3+ photoluminescence quenching. Oxidation of Fe2+ and conversion of Fe2+ ions into tetrahedral symmetry contribute to suppression of energy transfer from Fe3+ emitters to Fe2+ quenching centers.