Measurement and Analysis of Ionic Conductance in Solids

Abstract

If full use is to be made of the properties which materials possess because of their defect structures and, more importantly, if these properties are to be optomized in the design of materials for specific applications then the nature of the defects and of their distributions, interactions and movements must be fully understood.The occurrence of ionic conductance and of self- and impurity diffusion in classical ionic conductors, such as the alkali and silver halides, first suggested the existence of point defects in these crystals (Schottky; 1935, Frenkel; 1926). Careful measurements of ionic conductance and of diffusion coefficients, when accompanied by thorough analyses of these data, have remained the principal source of accurate information on the thermodynamic parameters which govern point defect behaviour and thus provide the basis of our understanding of ionic migration in these crystals. In this chapter the modern experimental techniques for the measurement and analysis of these kind of ionic conductance data, which, ideally should be measured on single crystal specimens, will be described. In some very well understood cases these analyses have recently been improved by incorporating temperature-dependent defect parameters derived from theoretical calculations into the data fitting procedures.