Laser spectroscopy and electron paramagnetic resonance of Cr3+ doped silicate glasses

Abstract Gels and glasses in the SiO 2 –Al 2 O 3 –ZnO–Cr 2 O 3 and SiO 2 –Al 2 O 3 –MgO–Cr 2 O 3 systems were synthesized by the sol–gel method. A description of the change of the Cr 3+ environment during the xerogel–glass–glass ceramic transformation is presented using optical properties of Cr 3+ ions. Absorption and emission spectra, electron paramagnetic resonance measurements, and site-selective laser spectroscopy were performed to characterize the Cr 3+ fluorescent centers. Absorption and fluorescence are interpreted by structural considerations showing the variation of Cr 3+ environment during heat treatment. By heating glasses, the glass-ceramics containing chromium-doped ZnAl 2 O 4 (gahnite) are formed. The results indicate the presence of chromium ions in a gahnite crystalline phase and emission from the 2 E level is observed. Also a Cr 3+ fluorescence centered at 770 nm results from 4 T 2 level of Cr 3+ sites at low ligand field in glassy phase.