Nonlinear Optical Constants of Superionic Conductors: A Study from the Bond Orbital Theory

Abstract

According to the bond fluctuation model of superionic conductors, the polarizability of a material that exhibit high ionic conductivity must be large. That is, the model predicts that ion conducting materials must have large values of optical constants. This prediction has been confirmed recently, through a comparative study of the nonlinear optical constants of ion conducting and non-conducting glasses. In the present report, the values of the nonlinear optical constants (3) of R 2 O-B 2 O 3 (R=Rb, Cs, Ag) glasses have been estimated by using the bond orbital theory. For the Rb 2 O-B 2 O 3 and Cs 2 O-B 2 O 3 glasses, a good agreement between the calculated and the measured values has been found. On the other hand, for the Ag 2 O-B 2 O 3 system, a deviation was observed. Such a disagreement has been explained by taking into account the contribution of d-electrons of the Ag ions, which plays also a fundamental role in the ion transport mechanism.

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

“…where χ (1) , χ (2) and χ (3) are the linear, second-order and third-order nonlinear optical susceptibilities.…”

“…Therefore, the model predicts that superionic conductors should have high electronic polarizability [2]. Based on this prediction, we have studied the correlation between the ionic conduction and the nonlinear optical properties in glasses [3], [4].…”

Bond Fluctuation Model of Superionic Conductors: Concepts and Applications

“…The comparison revealed that the nonlinear optical constants of superionic glasses are much larger than those of other glasses. Theoretical analysis based on bond orbital model applied to AgI containing borate glasses revealed that the origin of the enhancement in optical nonlinearity is related to the presence of d-electrons of Ag which plays also an important role in the ion transport processes [63]. The effect of the Ag d-electrons in the calculation of third order susceptibility is illustrated in Fig.…”

Correlation between the nonlinear optical constants and the structural relaxation parameters in chalcogenide glasses

“…In a previous study, we have shown that the ionic conductivity in some oxide glasses such as M 2 O-B 2 O 3 (M = Ag, Rb, Cs) correlates with the third order optical susceptibility [21]. The origin of such a correlation can be understood from the point of view of bond fluctuation model of superionic conductors [10].…”