Abstract
A qualitative description is presented for the behaviour of the hysteresis loss and the dielectric constant in ceramic barium titanate in terms of the properties of single-crystal barium titanate. When the effects of imperfections and interaction between crystallites are introduced, this description explains the similarity between the dielectric constants of single crystal and ceramic when the hysteresis losses differ by orders of magnitude. Measurements of the dependence of loss and dielectric constant on grain size, as a function of temperature, are described, and the results interpreted. A new explanation of the anomalously high dielectric constant of very fine-grain ceramic barium titanate is given.