Abstract
M.Sc. (Nanoscience)
Alkaline sodium phosphate (NaMPO4, M=Mg, Ca, Sr and Ba) phosphors doped with Ce3+ were prepared using combustion method. The effects of Ce3+ concentration on the optical and photoluminescence properties were investigated. The structure and particle morphologies of the phosphors were analysed using X-ray diffractometer (XRD) and field emission scanning electron microscopy (FE-SEM) respectively while the elemental composition of the phosphor were analysed using energy dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) was used to analyse the elemental composition, chemical and electronic states of the phosphors. The optical and luminescence properties were analysed by UV-Vis spectroscopy and photoluminescence spectroscopy respectively.
The XRD results confirmed that the samples consisted of the expected crystalline phases found in the standard powder diffraction files. Energy band gaps were estimated from the diffuse reflectance data and were found to vary with the dopant content. SEM images indicated that the particles have irregular shape. FT-IR spectrum confirmed water impurities and symmetric, asymmetric and bending vibrations of the (PO4)3- ions in the prepared materials. The photoluminescence spectra recorded when the samples were excited using different wavelengths consisted of a broad and strong band ascribed to electronic transitions in Ce3+.