Dysprosium-Doped Strontium Magnesium Silicate White Light Emitting Phosphor Prepared by Solid State Reaction Method

Abstract

In this paper, we report the dysprosium-doped strontium magnesium silicate, namely, SrMgSi ₂ O ₆ :xDy ³⁺ (x = 1.0, 1.5, 2.0, 2.5, and 3.0 mol%) phosphors prepared by the traditional high temperature solid state reaction method. The prepared phosphors were characterized by X-ray diffraction, field emission scanning electron microscope coupled with the energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared technique. The crystal structures of sintered phosphors were an akermanite type which belongs to the tetragonal crystallography with space group P4̅2 ₁ m. The chemical composition of the sintered phosphor SrMgSi ₂ O ₆ :Dy ³⁺ (2%) was confirmed by the EDS. Under the ultraviolet excitation, the emission spectra of SrMgSi ₂ O ₆ :xDy ³⁺ (x = 1.0, 1.5, 2.0, 2.5, and 3.0 mol%) phosphors were composed of broadband with the characteristic emission of Dy ³⁺ ions peaking at 475 nm (blue) and 574 nm (yellow), originating from the transitions of ⁴ F _9/2 → ⁶ H _j state (where j = 15/2 and 13/2). The combination of these two emissions constituted white light emission as indicated on the Commission Internationale de l'Eclairage chromaticity diagram. The possible mechanism of the prepared white light emitting SrMgSi ₂ O ₆ :xDy ³⁺ (x = 1.0, 1.5, 2.0, 2.5, and 3.0 mol%) phosphors were also investigated. Investigation on decay property show that the prepared phosphor held fast and slow decay process. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) were calculated. Values of CCT and CRI were found, well within the defined acceptable range.