Microstructural and optical features of a Eu-monazite

The obtention of europium-phosphate nanoparticles by the precipitation method and its thermal evolution to become ceramics materials is presented. The monazite structure was obtained from the rabdophane phase after firing at 1000 °C during several hours. The powder characteristics made easy the pressing and sintering processes and it was possible to obtain high density bodies (relative density > 97%) at only 1200 °C. The fluorescence spectra and the lifetimes were investigated as a function of the heating temperature, as well, the microstructure and the residual glassy phase. It was found that higher sintering temperatures (>1500 °C) resulted in lower fluorescence emission than lower temperatures (maximum at 1200 °C) as consequence of the microstructure detrimental. The gamma irradiation up to the dose of 18 kGys did not produce any appreciable effect in the optical properties; however, the sintering temperature modified the optical absorption in the UV range.