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This paper presents the results of a study of long-time relaxation (LR) and residual conductivity in n-type gallium phosphide (GaP) crystals irradiated by 50 MeV electrons. A manifold increase in photosensitivity and quenching of residual conductivity was found as a result of irradiation. It is shown that LR in GaP is due to disordered regions (generated by electron irradiation) which have conductivity close to self one. The Fermi level in the disordered regions is determined by which is located deep in the forbidden band (Е е − 1.0 eV). LR effect is mainly explained by a spatial separation of electrons and holes, recombination of which is prevented by potential barriers. The observed increase in conductivity is associated with the increase in the concentration of minority carriers as well as with increase of the Hall mobility at the sample illumination.

The effect of direct transport current (I) and heat treatment on resistive properties of bismuth-based ceramic high-temperature superconducting oxides of various compositions is studied by temperature dependent resistivity (r) measurements at fixed points in the vicinity of liquid nitrogen temperature in the presence of Earth's uncompensated magnetic field. It is shown that the observed results are significantly dependent on the sample preparation and post-processing conditions as well as on the measurement temperature. The results obtained are interpreted within the framework of the theory of Josephson weak links modified under the impact of self magnetic field of the sample’s transport current. An attempt is also done to find an analogy between the dependence of the characteristic parameters on the transport current in the case of heat treatment and on the dose when the samples are irradiated by various types of ionizing radiation.

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