Structural characterization and optical properties of dysprosium doped strontium calcium magnesium di-silicate phosphor by solid state reaction method

摘要

Dysprosium doped strontium calcium magnesium di-silicate phosphor namely: SrCaMgSi_2O_7:Dy~(3+) was prepared by the solid state reaction method. The crystal structure of the prepared phosphor was an akermanite type structure, which belongs to the tetragonal crystallography with space group P42_1m. From field emission scanning electron microscopy (FESEM), agglomerations of particles were observed due to the high temperature synthesis process. The chemical composition of the sintered SrCaMgSi_2O:Dy~(3+) phosphor was confirmed by energy dispersive X-ray spectroscopy (EDX). Under the ultra-violet (UV) excitation, the characteristic emission of Dy~(3+) ions peaking at 478, 580 and 674 nm, originating from the transitions of ~4F_(9/2) → ~6H_(15/2),~4F_(9/2) → ~6H_(13/2) and ~4F_(9/2) → ~6H_(11/2) in the 4f~9 configuration of Dy~(3+). Commission International de I'Eclairage (CIE) color coordinates of SrCaMgSi_2O_7:Dy~(3+) are suitable as white light emitting phosphor. Decay graph indicate that this phosphor contains fast decay and slow decay process. The mechanoluminescence (ML) intensity of SrCaMgSi_2O_7:Dy~(3+) phosphor 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 the piezo-electrically induced de-trapping model is responsible to produce ML in SrCaMgSi_2O_7:Dy~(3+) phosphor. The possible mechanism of white light emitting long lasting phosphor is also investigated.