STRUCTURAL, OPTICAL AND LUMINESCENT PROPERTIES OF RARE EARTH ION ACTIVATED PHOSPHOR MATIVATED PHOSPHOR MATERIALS FOR PHOTONIC APPLICATIONS

Abstract

Dysprosium (Dy3+) activated potassium calcium silicate (K4CaSi3O9) phosphor was prepared by a solid state synthesis route. The phosphor has a cubic structure with the space group Pa3̅ as confirmed by X ray diffraction (XRD) measurements. Details of surface morphology and elemental composition of as synthesized un-doped KCS phosphors were obtained by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Chemical structure as well as the vibrational modes present in the as-prepared KCS phosphors was analyzed using Fourier transform infrared spectroscopy (FT-IR). The diffuse reflectance spectra (DRS) were used to determine the optical bandgap of the phosphors and were found to be in the optical range 3.52-3.71eV. Photoluminescence (PL) spectra show intense yellow emission corresponding to the 4F9/2→6H13/2 transition under 350 nm excitation. CIE color chromaticity coordinates evaluated using the PL spectral data lie within the white region. Dexter Theory and Inokuti-Hirayama (I-H) model were applied to study the nature of energy transfer mechanism in the phosphor. Relatively high activation energy (ΔE) of the phosphors evaluated using temperature dependent PL (TD-PL) data confirms the high thermal stability of the phosphor. The above mentioned results indicate that the as-prepared KCS:Dy3+ phosphor is a promising candidate for n-UV based white light emitting diodes (w-LEDs).