Abstract:
In the frequency range 10$^{-2}$–10$^8$ Hz at a temperature of 300 K, the dielectric spectra of undoped and doped Ni, Mn, Co, Cu, Fe, Mo high-resistivity ($\rho>$ 10$^{10}$ Ohm $\cdot$ m) sillenite crystals (Bi$_{12}$SiO$_{20}$) were studied. It is shown that the detected features of the spectra are due to the response of an array of free electrons, the dark concentration of which is determined by the presence of donor or acceptor impurities. The results of calculating dielectric spectra within the framework of the Debye theory, as well as within the framework of a complicated theory using the function $G(\tau)$ of the distribution of numbers of relaxers over their relaxation times, are presented. The relaxation times of the response to the action of a probing electric field are estimated and it is shown that they are determined by the Maxwellian relaxation times for electrons. The parameters of the function $G(\tau)$ are determined. It is shown that a significant variation in relaxation times for different impurities is due, in addition to differences in electron concentrations, to the dependence of the electron drift mobility on the parameters of traps in the presence of which charge transfer occurs.
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