Wideband impedance spectroscopy from 1Â mHz to 10Â MHz by combination of four- and two-electrode methods

Impedance Spectroscopy (IS) measurements allow to study a wide range of polarization mechanisms associated with different frequency ranges. Experimental devices usually cover limited frequency ranges with sufficient accuracy. We propose (a) a combination of four-electrode and two-electrode devices and (b) a data combination and mutual verification procedure using the actual sample under test. Hereby, we cover a frequency range from 1 mHz to 10 MHz. The data combination relies on the precondition that any dispersive disturbance decayed at some mutual point within an overlapping frequency range between 1 Hz and 45 kHz. We validate our data combination procedure by IS measurements on simple reference systems and comparison with widely accepted model functions, e.g. the complex refractive index model (CRIM) for high frequency behavior and Kramers-Kronig relations in terms of data consistency. In this respect, our suggested processing approach is superior to two selected alternative approaches. We successfully adapt typical empirical model functions, e.g. multi-Cole-Cole, to the resulting wideband data to show that they are fully applicable for further data analysis.