Tunable luminescence and energy transfer of Dy3+-activated Bi4Si3O12--Bi4Ge3O12 pseudo-system phosphor for warm white-emitting

Abstract

Dy3+-activated Bi4Si3O12-Bi4Ge3O12 pseudo-system phosphors have been synthesized by a solid state reaction method and characterized using XRD, SEM and fluorescence spectrometry. Upon 279 nm excitation, the emission of Dy3+ ions is observed at 486 nm (blue), 574 nm (yellow) and 662 nm (red), corresponding to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 transitions, respectively. The different kinds of excitation for the luminescence intensity behaviors have been discussed through efficient Bi3+ → Dy3+ energy transfer. As Si4+ is substituted by Ge4+, the crystallization and the intensity of emission are improved; however, the value of correlated color temperature (CCT) is also increased. The values of CIE chromaticity coordinates and CCT endorse warm white light emission from the phosphor. The paper shows that phosphor could be a potential single-emitting-component warm white emitting for LED applications.