Luminescence characterization of Ce and Gd doped MgB4O7 phosphors

This paper presents the results of the structural and luminescence characterization of Ce3+ and Gd3+ doped MgB4O7 powders produced by the solid-state synthesis technique. The phase composition of the samples was confirmed by X-ray Diffraction (XRD) method. Morphological characterization using a Scanning Electron Microscope (SEM) revealed a regular surface morphology with spherical/cylindrical grains. The luminescent properties were examined by measuring the RL emission spectra, Optically Stimulated Luminescence (OSL) decay signal, and Thermoluminescence (TL) glow curve. The correlation between luminescence intensity and concentration quenching of the prepared phosphor was investigated. The results show a maximum luminescence efficiency when the synthesis of MgB4O7:Ce,Gd was carried out using contents of 0.1 wt% Ce3+ and 3 wt% Gd-3(+) . The data shows that at the heating rate of 5 degrees C/s, MgB4O7:Ce-0.1%,Gd-3% exhibits five TL peaks: two rapidly decaying peaks at about 80 degrees C and 110 degrees C, a shoulder peak at 180 degrees C, a high sensitivity peak at 235 degrees C TL and another shoulder peak at 320 degrees C (temperatures are approximate). The step annealing patterns suggest that the origin of the OSL signal is associated with the TL traps located between 180 and 235 degrees C. The kinetic parameters using various heating rate (VHR) technique, T-m-T-stop assisted extended initial rise method (IRM) and computerized glow curve deconvolution (CGCD) method were obtained and compared. The phosphor showed the dose linearity up to 10 Gy beta dose with a slight supralinearity for higher doses and the minimum detectable dose value of 743.1 +/- 11 mu Gy. Fading and reusability studies of MgB4O7:Ce-0.1%,Gd-3% further confirmed the phosphor suitability for radiation dosimetry.