Dysprosium doped di-calcium magnesium di-silicate white light emitting phosphor by solid state reaction method

Abstract

In this paper, we report the dysprosium doped di-calcium magnesium di-silicate namely Ca₂MgSi₂O₇:xDy³⁺ (x = 1.0, 1.5, 2.0, 2.5 and 3.0 mol%) phosphors were prepared by traditional high temperature solid state reaction method. Phosphors with optimum photo-luminescence intensity [Ca₂MgSi₂O₇:Dy³⁺ (2 %)] were characterized by X-ray diffraction (XRD) technique. The crystal structure of sintered phosphors were an akermanite type which belongs to the tetragonal crystallography with space group ${\text{P}}\overline{ 4 2}_{1} {\text{m}}$. The chemical composition of the sintered phosphor Ca₂MgSi₂O₇:Dy³⁺ (2 %) was confirmed by the energy dispersive X-ray spectroscopy (EDS). Under the ultraviolet excitation, the emission spectra of Ca₂MgSi₂O₇:xDy³⁺ (x = 1.0, 1.5, 2.0, 2.5 and 3.0 mol%) phosphors were composed of broad band with the characteristic emission of Dy³⁺ ions are peaking at 475 nm (blue), 577 nm (yellow) and 678 nm (red), originating from the transitions of ⁴F_9/2 → ⁶H_j state (where j = 15/2, 13/2, 11/2). The combination of these three emissions constituted white light as indicated on the Commission Internationale de l’Eclairage chromaticity diagram. The possible mechanism of the prepared white light emitting Ca₂MgSi₂O₇:xDy³⁺ (x = 1.0, 1.5, 2.0, 2.5 and 3.0 mol%) phosphors were also investigated. Investigation on decay property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston, which suggests that this phosphor can be used as sensors to detect the stress of an object. Thus the present investigation indicates that piezo-electricity is responsible to produce ML in prepared phosphors.