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.