The fractal dimensions of the grain boundary region in doped SnO2 ceramics were determined on the basis of a previously derived fractal model. This model considered the fractal dimension to be a measure of the homogeneity of distribution of charge carriers. Application of the derived fractal model permitted the calculation of the fractal dimension by using impedance spectroscopy results. The model was verified by the experimentally determined temperature dependence of the fractal dimension of SnO2 ceramics. The results obtained confirmed that the non-Debye response of the grain boundary region was connected with the distribution of defects, and consequently with the homogeneity of distribution of the charge carriers. It was also found that the C−T−1 function had a maximum at the temperature at which a change in the predominant type of defect took place. This effect could be considered to be a third-order transition.

Temperature Dependence of Fractal Dimension of Grain Boundary Region in SnO2-Based Ceramics. G.Branković, Z.Branković, D.R.Leite, J.A.Varela: Journal of Materials Science, 2006, 41[19], 6193-7