HIGH-TEMPERATURE 3-D THERMOLUMINESCENCE SPECTRA OF EU3-YPO4 POWDER SYSTEMS REACTED BY HYDROLYZED COLLOID REACTION (HCR) TECHNIQUE( ACTIVATED YVO4)

Three-dimensional (3-D) thermoluminescence (TL) spectra of Eu3+:YVO4, Eu3+:YV0.4P0.6O4 and Eu3+:Ce:YPO4 powders irradiated by X-rays were st udied in the temperature range 30-350 degrees C. The powders were reac ted by a special hydrolyzed colloid reaction (HCR) technique at simila r to 80 degrees C and were subsequently fired at 800 degrees C. The gl ow curves possess two major peaks indicating different defect structur es. The first TL peak was observed at similar to 85 degrees C and repr esents defects in the anion sublattice. It was increased by extended f iring and colloidization processes and by substituting PO43- for the V O43- anion. The second TL peak was found at 135 degrees C and is gener ated by impurity defects in the cation site of an yttrium orthovanadat e-phosphate system. It was identified by the assistance of the Ce dopa nt. In Eu3+:Ce:YPO4 the predominance of one of above-mentioned defect structures can be changed by a suitable selection of HCR parameters, t hus obtaining high emission intensities caused by two orders of magnit ude lower X-ray radiation levels than those used for the orthovanadate s.