Published online by Cambridge University Press: 10 February 2011
Immittance spectroscopy [IS] involves the measurement of the small-signal frequency response of dielectrics, semiconductors, electrolytes, biological cells, and polycrystalline, amorphous, and single-crystal electrically conducting materials. Analysis of such data to provide insight into the detailed, microscopic, physicochemical processes present in the full electrode and bulk material system is a crucial part of IS. Background information on IS and a discussion of its strengths and weaknesses are presented. The use of weighted, complex, nonlinear-least-squares for direct data fitting and for the solution of the ill-posed inversion problem of estimating continuous distributions of activation energies for important response models and for experimental data is illustrated. Replacements for the widely used, but incorrect, complexelectric- modulus data-analysis relations proposed long ago by C. T. Moynihan and associates for disordered ionic conductors, are presented and discussed. Recent proposals for various kinds of universal response behavior are examined and found to be unjustified. The present analysis methods are illustrated by applying them to 24°C data on a lithium aluminosilicate glass and to data over a wide temperature range on single-crystal CaTiO3:30%Al3+