A Study on the Relationship between Nonlinear Optical Constants and the Ionic Conductivity in Glasses

The bond fluctuation model of superionic conductors predicts that the polarizability of solids that exhibit high ionic conduction is large. Based on this background, a study on the nonlinear optical constants in superionic glasses has been started. As a first step, the relationship between the third-order susceptibility χ⁽³⁾ and the linear susceptibility χ⁽¹⁾ of various kinds of glasses has been studied. It is found that the values of χ⁽³⁾ of superionic conducting glasses exceed considerably the values predicted by the usual Miller rule. The deviation arises from the increase of the ionic coordinate dependent electronic polarizability, which plays also an important role in the ion transport processes.