Experimental and theoretical investigations on the EPR parameters and molecular orbital bonding coefficients of VO²⁺ ions in BTTB glasses

Abstract

The effect of the spin probe VO²⁺ in 15BaO–15TeO₂–10TiO₂-(60-x) B₂O₃–xV₂O₅ (x = 0.2, 0.4, 0.6, 0.8 mol %) glasses has been studied by employing Electron Paramagnetic Resonance (EPR) and optical absorption spectroscopic techniques. The observed EPR spectra of VO²⁺ ions were attributed on the basis of well-known spin-Hamiltonian of C_4V symmetry. The simulated EPR spectra for VO²⁺ ions in the present glass system were drawn using Easy spin software. Both the experimental and simulated spectra were found to be in good agreement with each other. The optical absorption spectra exhibited three d–d transition bands due to crystal and tetragonal fields of VO²⁺ ions. These bands were assigned to ²B_2g→ ²E_g, ²B_2g→ ²B_1g and ²B_2g→ ²A_1g transitions. The crystal field parameters Dq, Ds and Dt values are calculated. From the EPR and optical data, the molecular bonding coefficients were evaluated. Employing the higher order perturbation formulae of the g factors for 3d¹ ion under tetragonally compressed octahedral fields, theoretical studies were carried out. The spin-Hamiltonian parameters and obtained from both the experimental and theoretical methods were in good agreement with each other.

Keywords:

• BTTBV glasses
• XRD
• Electron paramagnetic resonance (EPR)
• EasySpin
• spin-Hamiltonian parameters (SHPs)
• optical spectroscopy
• crystal field parameters

Acknowledgements

The authors would like to thank The Head, Department of Physics, Osmania University for providing the laboratory facilities. One of the author, B. Srinivas would like to thank the UGC, New Delhi, for providing financial assistance (BSR-RFSMS).