AVS 61st International Symposium & Exhibition
    2D Materials Focus Topic Thursday Sessions
       Session 2D-ThP

Paper 2D-ThP7
Investigation of Luminescent Properties of Ca5(PO4)3OH:Gd3+,Pr3+ Phosphor for Application in Displays, Phototherapy Lamps and Thermoluminescence Dosimetry

Thursday, November 13, 2014, 6:00 pm, Room Hall D

Session: 2D Materials Poster Session
Presenter: Puseletso Mokoena, University of the Free State, South Africa
Authors: P. Mokoena, University of the Free State, South Africa
L. Chithambo, Rhodes University, South Africa
H.C. Swart, University of the Free State, South Africa
O.M. Ntwaeaborwa, University of the Free State, South Africa
Correspondent: Click to Email
Luminescent properties of calcium phosphate phosphors are being investigated today for many applications in different types of light emitting devices. We have investigated the photoluminescent (PL), cathodoluminescent (CL) and thermoluminescent (TL) properties of hydroxyapatite or Ca5(PO4)3OH:Gd3+,Pr3+ phosphor for application in phototherapy lamps, information displays and TL dosimetry, respectively.. This phosphor was prepared by co-precipitation method and the concentrations of Gd3+ and Pr3+ in the Ca5(PO4)3OH host were varied. The PL data were recorded in air under excitation by a monochromotaized xenon lamp, the CL was measured in vacuum with a Gatan MonoCL4 attached to Jeol JSM-7800F field emission scanning microscope and the TL glow curves were recorded using a Riso TL/OSL reader (model TL/OSL-DA-20) system. In addition, the structure, particle morphology, and chemical states and composition of the phosphor were analyzed by x-ray diffraction, scanning electron microscopy and x-ray photoelectron spectroscopy respectively. The phosphor exhibited a narrowband ultraviolet B (UVB) emission located at 313 nm when excited with the xenon lamp or high energy electrons. This emission was attributed to the 6P7/2→8S7/2 transition of Gd3+ and was shown to improve considerably by incorporation of Pr3+ suggesting that there was energy transfer from Pr3+ to Gd3+. The TL glow curves were measured in order to investigate the nature of the electron trapping centers and to determine the related activation energy. A single prominent peak was observed at 347 K at a constant heating rate of 5 K.s-1. The TL kinetic parameter (activation energy) was deduced by the initial rise method, peak shape method and variable heating rates method.