Facile synthesis of Eu2+ activated dual light emitting barium silicate phosphors for warm-white light emitting diodes

Eu- (2+)-ion-activated barium magnesium silicate phosphors were synthesized via a solid-state route with SiO2 and Si3N4 as silicon sources. The molar ratio of Si3N4 to SiO2 was varied from 0:1 to 3:1 for controlling the phase and luminescence emission of the synthesized materials. When Si3N4: SiO2 ratio was 0:1, efficient green emission around 513 nm was observed owing to the substitution of Eu2+ ions in Ba2MgSi2O7 lattice. With the increase of Si3N4: SiO2 molar ratio, a trigonal Ba3MgSi2O8 Os phase with blue emission was observed to coexist with monoclinic Ba2MgSi2O7 phase with green emission. Suitable dual emission was obtained for the phosphors synthesized with a Si3N4:SiO2 molar ratio of 0.8:1. White light emitting diodes (WLEDs) were fabricated by coating the optimized phosphors, and commercial red phosphors on InGaN ultraviolet (UV) LED chips. The electroluminescence spectra of the fabricated WLEDs exhibited near white chromaticity (0.34, 0.37) with high CRI of 94 and low CCT of 5213 K. The spectral characteristic results indicated a promising alkali silicate phosphor for UV LED application. (C) 2019 Published by Elsevier B.V.