Study of the Structure of Vanadium in Soda—Boric Oxide Glasses

The EPR and optical spectra of vanadium in the Na2O–B2O3 glass system have been analyzed. It is found that the data can best be interpreted in terms of a vanadyl-type structure in a ligand field of fourfold symmetry. Good correlation of the optical and EPR data is achieved through molecular orbital calculations, which provide a qualitative description of the behavior of the coordination sphere as the Na2O content of the glass is varied. The model proposed is one in which there is a dilation of the ligand shell corresponding to the boric oxide anomaly superposed on an over-all tendency of the ligand—metal distance to decrease as [Na2O] increases. The hyperfine coupling terms as well as the g tensor and optical data support this model.