OPTICAL-ABSORPTION AND ELECTRON-PARAMAGNETIC-RESONANCE STUDY OF CR3-DOPED PHOSPHATE-GLASSES()

We report in this paper optical absorption and electron paramagnetic r esonance (EPR) results obtained on Cr3+-doped phosphate glasses. Optic al absorption allowed us to evaluate the crystal-field parameters D-q, B and C. Electron paramagnetic resonance measurements indicate that C r3+ ions are located in sites with low symmetry and a relatively large zero-field splitting. Both electron paramagnetic resonance and optica l absorption data show that the chemical bonds of Cr3+ ions with the l igands are rather covalent in nature but that the ionic contribution t o those bonds decreases in the order: PBa > PBaK > PBaKMg. Furthermore , it is found from this study that the crystal-field strength increase s in the order: PBa < PBaK < PBaKMg.