EPR and optical absorption studies of Cu < sup > 2+ < /sup > ion doped in xLi < inf > 2 < /inf > O-(40-x)Bi < inf > 2 < /inf > O < inf > 3 < /inf > -20CdO- 40B < inf > 2 < /inf > O < inf > 3 < /inf > glasses

Abstract

CuO doped xLi2O-(40-x)Bi2O3-20CdO-40B2O3 glasses where x=0, 10, 20, 30, 40 were prepared by melt quenching The structural changes in the above glass systems were investigated by optical absorption and EPR spectroscopic techniques. From EPR and optical absorption measurements it was confirmed that Cu2+ ions are present in all of the glasses investigated in tetragonally distorted octahedral sites elongated along the z-Axis with dx2-y2 orbital (2B1g) ground state. By correlating the EPR and optical absorption data the bonding parameters α2, β2 and β1 2 have been evaluated. The molecular orbital bond parameter values of xLi2O-(40-x)Bi2O3-20CdO-40B2O3 glasses show that in-plane σ-bonding is moderately covalent in all of the glass samples except for the x=20 glass sample which is ionic in nature. Similarly the out of plane π-bond is ionic for all the glass samples except for x=20 which is covalent in nature.