Spectral studies on Cr3+ ions doped in sodium–lead borophosphate glasses

Electron paramagnetic resonance (EPR), optical absorption and emission spectra of Cr3+ ions doped in (30−x) (NaPO3)6+30PbO+40B2O3+xCr2O3 (x=0.5, 2.0, 3.0, 4.0 and 5.0 mol%) glasses have been studied. The EPR spectra exhibit resonance signals with effective g values at g≈4.55 and g≈1.97. The EPR spectra of x=3.0 mol% of Cr2O3 in sodium–lead borophosphate glass sample were studied at various temperatures (295–123 K). The intensity of the resonance signals increases with decrease in temperature. The optical absorption spectrum exhibits four bands characteristic of Cr3+ ions in octahedral symmetry. From the analysis of the bands, the crystal-field parameter Dq and the Racah interelectronic repulsion parameters B and C have been evaluated. The emission spectrum exhibit one broad band characteristic of Cr3+ ions in octahedral symmetry. This band has been assigned to the transition 4T2g (F)→4A2g (F). Correlating EPR and optical data, the molecular bonding coefficient (α) has been evaluated.