Bulk and Interfacial Ionic Conduction in LiAlSiO_4 Glass Ceramics Containing Nano- and Microcrystallites

摘要

The lithium ion transport in LiAlSiO_4 glass and glass ceramics with different degrees of crystallinity,CHI,is studied by means of conductivity spectroscopy.In glass ceramics with low degrees of crystallinity,CHI < 0.42,the lithium ion conductivity is higher than in the glass and increases with increasing CHI.We ascribe this conductivity enhancement to fast ionic conduction at the interfaces between the crystallites and the glassy phase.The dependence of the conductivity on the degree of crystallinity is fitted by using a three-phase continuum percolation model,the phases being the ion conducting glassy phase,the insulating crystallites and the highly conducting interfaces.In the framework of this model,we have to make the assumption that the width of the interfaces is about 1/3 of the crystallite radii.Possible origins of these anomalous interfacial widths are discussed.