Density and dc conductivity of Li2O-Bi2O3-B2O3 and Li2O-GeO2-B2O3 glasses

Density and dc conductivity measurements have been carried out for differen t groups of Li2O-Bi2O3-B2O3 and Li2O-GeO2-B2O3 glasses. For Li2O-Bi2O3-B2O3 glasses the density, molar volume, resistivity and the activation energy i ncrease markedly upon increasing Bi2Oe content. There are remarkable change s in these properties at Bi2Oe/Li2O=0.5 regardless of the glass composition . It is assumed that Bi2O3 exists in the structure mainly in the form of Bi O5 polyhedra. A unique dependence, for all glasses, of density on the Bi2O3 /B2O3 ratio suggests that the structural unites of Bi2O3 and B2Oe are linke d together forming a bismo-borate network. The density and activation energ y of Li2O-GeO2-B2O3 glasses change linearly with GeO2 concentration. The re sults indicate that, in these glasses, activation energy and molar volume a re characterised with the ration Li2O/B2O3. The density is controlled with the O/B ratio and this reflects the formation of a germanoborate matrix.