High temperature 3-D thermoluminescence spectra of Eu3+ activated YVO4-YPO4 powder systems reacted by hydrolyzed colloid reaction (HCR) technique

Three-dimensional (3-D) thermoluminescence (TL) spectra of Eu3+:YVO4, Eu3+:YV0.4P0.6O4 and Eu3+:Ce:YPO4 powders irradiated by X-rays were studied in the temperature range 30-350 degrees C. The powders were reacted by a special hydrolyzed colloid reaction (HCR) technique at similar to 80 degrees C and were subsequently fired at 800 degrees C. The glow curves possess two major peaks indicating different defect structures. The first TL peak was observed at similar to 85 degrees C and represents defects in the anion sublattice. It was increased by extended firing and colloidization processes and by substituting PO43- for the VO43- anion. The second TL peak was found at 135 degrees C and is generated by impurity defects in the cation site of an yttrium orthovanadate-phosphate system. It was identified by the assistance of the Ce dopant. In Eu3+:Ce:YPO4 the predominance of one of above-mentioned defect structures can be changed by a suitable selection of HCR parameters, thus obtaining high emission intensities caused by two orders of magnitude lower X-ray radiation levels than those used for the orthovanadates.