Ion dynamics in Ba-, Sr-, and Ca-doped La(2)Mo(2)O(9) from analysis of ac impedance

Conductivity measurement on alkaline earth-doped La(2)Mo(2)O(9) is well documented, but the ion dynamic study of this material is scarcely reported. Alternating current impedance measurement of Ba-, Sr-, and Ca-doped La(2)Mo(2)O(9) in the light of ion dynamics has been discussed. The low-temperature regime, 250 A degrees C to 500 A degrees C, has been selected for study on the basis of frequency dispersion of conductivity as well as in terms of modulus formalism. The values of exponential parameter, s, of universal dielectric response and the stretching exponent, beta, of Kohlrausch-Williams-Watts relation are evaluated from curve fitting. Scaling behavior of the doped materials has also been investigated. Temperature dependence of such parameters is checked and is interpreted for the plausible mechanism of ionic motion in the material at low temperature