ELECTRON-PARAMAGNETIC-RESONANCE IN COO.CAO.B2O3 GLASSES CONTAINING VANADIUM IONS

Glasses with composition x CoO.(0.25-x) CaO.0.75 B2O3 have been prepar ed over the range 0 less than or equal to x less than or equal to 0.25 containing 2 mol% of V2O5. Electron paramagnetic Resonance spectra of VO2+ of these glasses has been measured at X-band (upsilon approximat e to 9.15 GHz) at room temperature and at liquid nitrogen temperature. Spin Hamiltonian parameters of the VO2+ ions have been calculated. It is found that for x less than or equal to 0.12 the octahedral symmetr y of the V4+ site is improved. A part of these glasses were annealed a t 473 K for 24 hours and EPR spectra were recorded and analysed.