Static and dynamic conductivity of amorphous nanogranular composites (CoTaNb)x(MgO)1-x

The paper presents the results of study of amorphous nanogranular composite films CoTaNbxMgO1−x, (21.73≤ x ≤73.27 at%) with a thickness of 311–1040 nm on a lavsan substrate with a thickness of about 20 μm. The results of experimental studies of microstructure, static conductivity (at direct current), dynamic conductivity (50 kHz – 15 MHz), determined from measurements of the total impedance and phase angle, and dynamic microwave conductivity (8–12 GHz), calculated from measurements microwave reflectance, were presented. The spectra of dynamic conductivity as a function of frequency, the dependence of static conductivity and the ratio of dynamic to static conductivity on the content of the metal phase and on the ratio of the sizes of granules to the spaces between granules were obtained. Using the mechanisms of closed and open circuit models of intragranular currents and an algorithm for calculating structural and conductive characteristics from measured values of microwave reflectance, the conductivity of granules was calculated and its contribution to the dynamic microwave conductivity of composites was assessed. •The structure and microwave (MW) conductivity of nanogranular composites have been studied.•The conductivity of individual granules of the amorphous nanocomposite is estimated.•MW conductivity is controlled by currents inside the granules up to the percolation threshold.•MW conductivity is 2–4 orders of magnitude higher than conductivity at direct current.