Study on low temperature solution combustion synthesized Sr2SiO4:Dy3+ nano phosphor for white LED

Abstract

A series of Dy3+ (1–5mol.%) activated Sr2SiO4 nanophosphors were prepared by low temperature solution combustion method using oxalyl dihydrazide (ODH) as a fuel. The obtained phosphor was well characterized by powder X-ray diffraction, scanning electron microscopy, and UV–visible spectroscopy. The average crystallite sizes were estimated by Debye–Scherrer formula and Williamson–Hall plots and found to be in the range 20–32nm. Energy band gap was found to be widened with increase of Dy3+ ion dopant. Photoluminescence spectra consist of three main groups of peaks in 460–500nm (blue), 555–610nm (yellow) and 677nm (red) respectively. These peaks were assigned to transition of 4F9/2→6H15/2,13/2,11/2. The critical distance between Dy3+ ions and quenching site was found to be ∼16.71Ǻ. The chromaticity co-ordinates of all the prepared phosphors were located in white light; as a result Dy3+ activated Sr2SiO4 is a promising single phased phosphor for white light emitting diodes. Thermoluminescence (TL) of Dy3+ doped Sr2SiO4 nanophosphors were investigated using γ-irradiation in the dose range 1–6kGy at a warming rate of 2.5°Cs−1. The phosphors show a well resolved single glow peak at ∼145°C. The kinetic parameters were estimated by different methods and the results discussed. The TL intensity increases linearly with γ-dose at room temperature. The effect of fading with storage time was found to be ∼66% which is highly useful in radiation dosimetry.