Express Method for Impedance Spectroscopy of Small Solid-State Samples at Frequencies of 20 kHz–1 GHz

A simple and effective technique for express diagnostics of materials, which allows for the most efficient preparation of samples, the actual measurements, and obtaining data on material parameters, in particular, on the dispersion of the permittivity, is proposed. An express method for impedance spectroscopy of small samples at frequencies from 20 kHz to 1 GHz has been developed on the basis of a vector network analyzer using a conical coaxial measuring cell and adapters for connecting two-pole objects to the coaxial input of the device. The measuring cell is designed for disk samples with a diameter of up to 6 mm with a maximum volume of up to 0.1 cm3 as well as for samples in the form of rectangular plates that can be inscribed in a circle of the same diameter. Adapters also make it possible to connect two-terminal networks in the form of concentrated hinged or surface-mounted elements. In contrast to measurements in a coaxial path, the proposed technique does not require an accurate connecting transverse dimension, which allows for prompt sample preparation. The issues of determining the frequency range in which the measurement error does not exceed the allowable value are considered. A method is proposed for increasing the upper limit of the operating frequency of the measuring cell with the test sample using additional calibration. The developed program for controlling the processes of standard and additional calibration and the process of measurements in a certain frequency range, at which the measurement error does not exceed the permissible value, makes it possible to obtain the values of resistance, capacitance, inductance, and other electrical characteristics of the measuring cell with the sample under study within a few seconds.