Dynamics of lithium ions in bismuthate glasses

The dynamics of lithium ions in lithium bismuthate glasses have been studie d in the frequency range from 10 Hz to 2 MHz and in the temperature range f rom 323 to 543 K. The composition dependence of the dc (direct current) con ductivity has been explained in terms of the structure of bismuthate glasse s. The activation energy has been analyzed in the framework of the Anderson -Stuart model. An additional energy term arising from the Madelung constant of glasses and the polarizability of the bismuth ions has been suggested t o explain the discrepancy between the calculated and experimentally obtaine d values. The relaxation mechanism of these glasses has been explored by em ploying the modulus and conductivity formalisms and the microscopic paramet ers obtained from the analysis have been compared. Furthermore, the stretch ed exponential relaxation parameter and the dc conductivity have been corre lated with the decoupling index. (C) 2000 American Institute of Physics. [S 0021-9606(00)71102-0].