Manufacture, behaviour and modelling of BaTiO3 nonlinear ceramic disc capacitors for high-voltage applications

The manufacturing and characterization of undoped, nonlinear barium titanate ceramic disc capacitors are discussed. The characterization of the capacitors includes the measurements of capacitance-voltage (C-V) response by means of a novel 1500-V quasi-DC charge/discharge circuit at room temperature and also as a function of temperature. Studies were made on the microstructure of the barium titanate ceramic material by means of scanning electron microscopy (SEM) analysis. The influence of oxygen flow during preparation on the density, capacitance, and nonlinearity of the ceramic material is reported. A model is proposed in which the high dielectric constant and nonlinearity of the ceramic material can be quantitatively explained by considering the material as containing an ensemble of randomly orientated domains. It is shown that temperature dependence of capacitance may also be explained with this model