HEBREW UNIV JERUSALEM (ISRAEL) DEPT OF INORGANIC AND ANALYTICAL CHEMISTRY
Transparent galss ceramics with CrIII were obtained by different thermal treatment of glass with composition mol 73.6 SiO2, 11.8 Al2O3, 4.2. Li2O, 7.0 ZnO, 1.6 TiO2, 1.5 ZrO2, 0.3 As2O3, 0.024 Cr2O3, melted under various conditions. Parallel measurements of X-ray diffraction, optical and EPR spectra reveal the different formation of gahnite from precursor glass or petalite-like phase. Laser excited emission spectra and decay curves of Cr3 in gahnite-type glass-ceramics are compared with those in gahnite crystals. The nature of the Cr3 sites is determined from the positions of the emission and excitation peaks and from measurements of the decay times.