Complex impedance plots of Bi 2 Te 2 O 7 at 600 C for ceramic pellets. The frequency and capacitance values in the insets correspond to the grain, grain boundary, and electrode responses. The assignment of bulk and grain boundary (gb) and electrode responses were made based on the capacitance scales. Selected frequencies of different response parts are shown. R b and R gb denote bulk and grain boundary resistivities, respectively. Open black squares denote experimental data and red line stands for the fit to the data.
