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In this paper, we investigate the temperature dependence of the transverse conductivity in Y_1-zPr_zBa₂Cu₃O_7-δ single crystals with different praseodymium concentrations. It is determined that the increase of the praseodymium concentration in Y_1-zPr_zBa₂Cu₃O_7-δ leads to the enhancement of localization effects. This in turn results to the transition from the pseudo-gap regime to the variable-range-hopping regime.

Temperature dependences of the electrical resistance along the c-axis of ${\mathrm{\text{YBa}}}_2{\mathrm{\text{Cu}}}_3{\mathrm{\text{O}}}_{7-\delta }$ single crystals are investigated before and after irradiation with electrons at 0.5–2.5 MeV energies. The irradiation was done at $T\lesssim 10$ K and the irradiation dose was varied from $1.4\times 10^{18}{\mathrm{\text{cm}}}^{-2}$ to $8.8\times 10^{18}{\mathrm{\text{cm}}}^{-2}$. An enhancement of the charge carriers localization with increase of the irradiation dose has been revealed. A crossover from the pseudogap (PG) regime to the variable-range hopping conductivity has been observed.

The effect of room-temperature annealing on the basal-plane conductivity of YBCO single crystals is investigated after their irradiation with fast electrons. It is revealed that the excess conductivity $\mathrm{\Delta }\sigma (T)$ of the samples obeys an exponential temperature dependence in a broad temperature range $T_f<T<T^{\ast }$. Here, $T_f$ is the crossover temperature from the pseudogap to the fluctuation conductivity regime. The description of the excess conductivity with the expression $\mathrm{\Delta }\sigma \propto T/T^{\ast }exp({\mathrm{\Delta }}^{\ast }/T)$ can be interpreted in terms of the mean-field theory where $T^{\ast }$ corresponds to the mean-field transition temperature to the pseudogap state and the dependence $\mathrm{\Delta }\sigma (T)$ is described within the framework of the BCS-BEC crossover theory.

The frequency dependence of the thallium sulfide (TlS) crystal impedance is analyzed in wide frequency and temperature range for the hopping and superionic conduction mechanisms. It has been established that in weak alternating electric fields, there is a hopping mechanism of charge transfer. The use of impedance spectroscopy methods in TlS crystals, at temperatures of 300, 350 and 400 K in the frequency range of 2*10⁶ Hz and subjected to $\gamma$-irradiation doses 0, 0.25 and 0.75 MGy charge transfer processes, has been investigated. Hodographs constructed from the data of experimental measurements of 400 K, in the low-frequency region ($>10^3$ Hz) and regardless of the absorbed gamma quanta, indicating additional contributions to the conductivity, presumably corresponds to the fact that in the frequency range of the applied signal, carrier diffusion does not reach the diffuse layer. This type of hodographs at low frequencies is characteristic of the Warburg impedance.