Characterization of Cr3+ doped mixed alkali ions effect in zinc borate glasses – Physical and spectroscopic investigations

Abstract The physical and structural properties of Cr 3+ doped 19.9 ZnO + x Li 2 O + (30 − x ) Na 2 O + 50B 2 O 3 (5 ⩽ x ⩽ 25) (ZLNB) glasses have been studied. Powder X-ray diffraction patterns indicated the amorphous nature of the glass samples. The physical parameters of all the glasses were also evaluated with respect to the composition. They exhibit the non-linearity providing the evidence for mixed alkali ions effect. The infrared spectra of the glasses in the range 400–4000 cm −1 showed the presence of BO 3 and BO 4 local structures in all the glass systems. No boroxol ring formation was observed in the structure of these glasses. Optical absorption and electron paramagnetic resonance studies were carried out at room temperature. From the optical absorption data various optical parameters such as optical band gap, Urbach energy were evaluated. Crystal field and Racah parameters are evaluated from optical absorption spectra. The EPR spectra of Cr 3+ doped ZLNB glasses exhibited resonance signals at g = 4.066 and g = 1.9779 characteristic of Cr 3+ ions. The evaluated bonding parameters suggest the covalent nature.