ELECTRON-PARAMAGNETIC-RESONANCE OF V4-CENTER-DOT-B2O3 GLASSES CONTAINING VANADIUM AND COBALT IONS( IONS IN ZNO)

Glasses with composition xCoO(0.3-x)ZnO.0.7B(2)O(3) have been prepared over the range 0 less than or equal to x less than or equal to 0.2 co ntaining 1 mol% V2O5. Electron paramagnetic resonance spectra of VO2of these glasses has been measured at X-band (v 9 . 15 GHz) at room te mperature. Spin Hamiltonian parameters of the VO2+ ions have been calc ulated. For x greater than or equal to 0.08 the hyperfine spectra a of VO2+ could not be observed The EPR spectra show that octahedral symme try around V4+ is improved as diamagnetic modifier ZnO is replaced by paramagnetic modifier CoO. Duffy-Ingram type basicity calculations for these glasses imply that the improvement in octahedral regularity is due to enhancement of pi bonds between V4+ and its ligands by increase of glass basicity (Lewis electron donation ability) of the glass.