A glass of composition (20−x)Li2O–xLiCl–65B2O3–10SiO2–5Al2O3 where 0 ≤ x ≤

12.5wt% was prepared using the normal melt-quenching technique. The optical

constants and electrical conductivity and their correlation were investigated,

furnished and discussed with the substitution of Li2O for LiCl. The mechanism of

the optical absorption and the calculated Urbach energy follow the rule of phononassisted

transitions. The ionic conduction mechanism was determined by activation

energy process. Substitution up to 10wt% LiCl provides high ionic conductivity

(1.9 x 10−2S/m) due to the high average electronegativity of LiCl which increases

the polarizability of lithium ions. The small cation–anion distance approach

confirmed the enhancement in ionic conductivity of LiCl containing glass

compared to that of Li2O. Due to the large size of Cl− ions, there was an expansion of the lattice which in turn broadens the available path windows. For 12.5wt%

LiCl, anomalous density behavior was observed and a reduction in conductivity

occurred to 5.4 x 10−3S/m. Owing to the model of bond fluctuation, the reduction

was attributed to the increase in the alkali halide concentration which creates

bottlenecks that hinder the motion of Li+ ions. The ionic conductivity character was

strongly supported by the behavior of the glass ionicity factor, density, molar

volume, refractive index, average boron–boron separation, molar refraction,

metallization criterion and non-bridging oxygen concentration of the studied glass.

Bond Character, Optical Properties and Ionic Conductivity of

Li2O/B2O3/SiO2/Al2O3 Glass: Effect of Structural Substitution of Li2O for LiCl.

M.Abdel-Baki, A.M.Salem, F.A.Abdel-Wahab, F.El-Diasty: Journal of Non-

Crystalline Solids, 2008, 354[40-41], 4527-33