Abstract
M.Sc. (Nanoscience)
Calcium phosphate co-doped with gadolinium and praseodymium Ca3(PO4)2:Gd3+,Pr3+ nanophosphors were prepared by urea combustion and citrate gel combustion methods. These nanophosphors were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Photoluminescence (PL) and Energy Dispersive X-ray spectrometry (EDS). The XRD patterns were consistent with a rhombohedral phase of Ca3(PO4)2 referenced in JCPDS cards number 00-017-0498 (for as prepared sample) and 00-070-2065 (for annealed sample).
The particle morphologies were analysed using SEM. The SEM images showed that the powder was composed of distorted spheres and agglomeration of spherical particle for the as prepared and annealed samples, respectively. The PL spectroscopy was used to measure the luminescence of the material. The PL excitation spectra of Ca3(PO4)2:Gd3+ and Ca3(PO4)2:Pr3+ showed peaks at 274 nm and 455 nm associated with the f-f transitions of Gd3+ and Pr3+, respectively. The PL emission spectra of Ca3(PO4)2:Gd3+ exhibited peak at 313 nm (6P7/2→8S7/2 transition); such type of emission is used in phototherapy treatment. The Pr3+ is used to enhance the UVB emission of Gd3+ in co-activated. The energy transfer was assigned to a phonon-mediated processes.