Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

Abstract

A single-host lattice, white light-emitting SrAl₂O₄:Dy³⁺ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl₂O₄:Dy³⁺ phosphor was in a monoclinic phase with space group P2₁. The chemical composition of the sintered SrAl₂O₄:Dy³⁺ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy³⁺ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 →&!nbsp; ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 in the 4f⁹ configuration of Dy³⁺ ions. Commission International de I’Eclairage color coordinates of SrAl₂O₄:Dy³⁺ are suitable for white light-emitting phosphor. 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) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl₂O₄:Dy³⁺ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl₂O₄:Dy³⁺ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl₂O₄:Dy³⁺ phosphor was useful for the white light-emitting diodes and stress sensor respectively.