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An oxyfluoride glass-ceramic containing Eu2+-doped nepheline and LaF 3 crystals was synthesized with varying compositions to modify its color conversion and quantum efficiency under ultra-violet light emitting diode (UV-LED) excitation. Glass composing elements such as SiO 2 , Na 2 O and Al 2 O 3 were exchanged with LaF 3 to influence the formation of nepheline crystals within the glass matrix. Among the various combinations, when Al 2 O 3 was replaced by LaF 3 there was improvement in the observed emission intensity and photo-luminescence quantum yield (PL-QY). The optimum composition of Al 2 O 3 and LaF 3 content was investigated to improve PL-QY. X-ray diffractometer (XRD) was used to monitor structural changes in the crystals within the glass-ceramic. A white LED, with a high color rendering index (CRI) comparable to commercial white LEDs, was successfully demonstrated using the modified glass-ceramic as a color converter in structures of phosphor in silicone and phosphor in glass. • Oxyfluoride glass ceramic containing Eu2+-doped nepheline was fabricated. • PL-QY was improved by the modification of glass ceramic composition. • Phosphor in glass and phosphor in silicone were composed with the glass ceramic. • White LED with high CRI up to 85 was successfully achieved. [ABSTRACT FROM AUTHOR]

BaF 2 –Al 2 O 3 –B 2 O 3 –SiO 2 glasses and glass-ceramics doped with Eu3+-Tb3+ were fabricated as an inorganic color converter for white LEDs. The BaF 2 –Al 2 O 3 –B 2 O 3 glass composition was modified by adding SiO 2 , and thermal and mechanical stability improved with increasing SiO 2 content while maintaining a quantum yield (QY) as high as 91%. To realize white color coordinates, Tm3+ was additionally introduced at varying contents, and Eu3+ content was also controlled. Excellent chromatic properties, such as a pure white color coordinates (x = 0.33, y = 0.33) with a co-related color temperature of 5772K, and a color rendering index (CRI) of 91 under 370 nm excitation, were successfully achieved. After the glass was heat-treated at 600 °C to fabricate a glass ceramic, the glass-ceramics were mounted on top of a 370 nm UV-LED, successfully demonstrating a white LED with nearly pure white color coordinates and a high CRI of 86. The increased emission intensity in the glass-ceramic was attributed to the formation of BaF 2 crystals which were investigated by X-ray diffractometer (XRD) and a transmission electron microscope with energy dispersive spectroscopy (TEM-EDS). • Glass composition was modified to improve mechanical and thermal properties. • Tm3+ ions were additionally doped for blue emission under UV light. • Tb-Eu-Tm contents were adjusted to make a white color coordinate. • Emission intensity was improved with heat treatment at 600 °C for 10hrs due to form the BaF 2 crystal. • White color coordinate (0.36, 0.36) was successfully achieved with high CRI of 85 under 370 nm UV LED chip. [ABSTRACT FROM AUTHOR]