Dielectric response of ferroelectric films

The parameters of the electrical equivalent circuit for crystalline ferroelectric films may be derived from measurements of the dielectric response as a function of frequency and of temperature. Careful corrections must be made to minimise complications due to electrode resistance and probe inductance. In general simple R-C circuit models representing features such as low permittivity surface layers are insufficient to describe the data, and a distribution of relaxation times must be introduced. A major contribution to dielectric loss at low temperatures results from electronic hopping conduction. This is evinced by a frequency dependent ac conductivity of the form /spl sigma/(/spl omega/)=A/spl omega//sup s/.