Spherical nanoparticles of europium-doped silica-calcia glass and glass-ceramic: Spectroscopic characterization

The modified Stöber method was used to synthesize silica-calcia powders doped with Eu3+ ions. Two-steps acid-base hydrolysis resulted in spherical particles, with average diameter of around 200 nm, that were annealed in the temperature range of 600-1100 °C. Energy dispersive X-ray spectrometry analysis indicated the matrix composition of 88 wt% SiO2 - 12 wt% CaO. Amorphous material was transferred to glass-ceramic system when it was calcined at temperatures above 800 °C as was shown by X-ray diffraction patterns. Raman and FT-IR spectra analyses confirmed changes in the structure under different thermal treatment. Photoluminescence of Eu3+ ions, used as sensing probe, clearly shown various local structure of the lanthanide ion as demonstrated both in the emission spectra and the luminescence decay profiles. Finally, measurements performed with microRaman instrument were indicated as a sensitive technique to monitor structural changes in bioactive glass through crystallization.