Maxwell–Wagner relaxation in the CaMn7O12 perovskite

In this work we have measured the complex dielectric permittivity of a polycrystalline material using samples of different thickness (frequency range 20–1 MHz). The results reveal that the CaMn 7 O 12 material is electrically heterogeneous as it consists of regions of different conductivities. In this kind of electrically heterogeneous materials the variation of the dielectric permittivity as a function of temperature can be fitted to a Maxwell–Wagner model. In the case of the CaMn 7 O 12 sample this model fits only partially the experimental data and we need to include three regions of different conductivities to explain the obtained dielectric response.