Dysprosium doped and titanium activated calcium silicates for cool white light emitting diode derived from natural resources

Abstract

An environment friendly and cost-effective method is presented to utilize natural resources to synthesize Ca3−xSi2O7:xDy3+,x(%)=0.00, 0.25, 0.50, 0.75, 1.00 cool white light emitting diodes by solid-state synthesis technique. The structural, morphological and luminescent properties of the synthesized phosphors have been studied using various experimental techniques. X-ray diffraction confirms that doping of dysprosium (Dy3+) enhances the volume fraction of Ca2SiO4 phase with respect to Ca3Si2O7 phase, upto x(%)=0.50. As indicated by the scanning electron microscope images all samples show partial liquid phase sintering. Fourier transform infrared spectroscopy shows the presence of bands corresponding to the vibrational modes of Si–O and O–Si–O units present in Ca3Si2O7 and Ca2SiO4 phase. Diffuse reflectance spectra results produce optical band gap values between 3.67- 3.79 eV. Along with the characteristic emission bands of Dy3+, the photoluminescence spectra contains additional bands due to trace titanium ions naturally found in the agriculture and food wastes. Commission International de’Eclairage coordinates (CIE) coordinates are in the white region of the CIE diagram, suggesting that this is an effective method of utilizing agriculture and food wastes for synthesizing cool white light emitting diodes.