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The effect of hydrostatic pressure up to 12 kbar on the electrical resistance in the basal ab-plane of optimally oxygen-doped (δ<0.1) single crystals Y1–xPrxBa2Cu3O7–δ moderately doped with praseodymium (x≈0.23) with a critical temperature Tc≈67 K. Compared to undoped single-crystal YBa2Cu3O7–δ, doping with praseodymium led to a decrease in the critical temperature by ≈24 K with a simultaneous increase in ρab (300 K) by ≈130 μΩcm. In the region of the transition to the superconducting state, several clearly pronounced peaks are observed on the dρ/dT – T curves, which indicates the presence of several phases with different critical temperatures in the sample. The application of high hydrostatic pressure leads to an increase in Tc by about 3 K. This increase slows down with increasing pressure, and the baric derivatives, dTc/dP, decrease from 0.44 K/kbar at atmospheric pressure to 0.14 K/kbar at 11 kbar. The comparatively weak change in the critical temperature under the action of hydrostatic pressure is due to the relatively small value of the orthorhombic distortion, (a–b)/a. The change in the baric derivative dTc/dP upon all-round compression of the sample is due to the fact that, along with an increase in the Debye temperature, the matrix element of the electron-phonon interaction also increases. Possible mechanisms of the effect of high pressure on Tc are discussed taking into account the presence of features in the electronic spectrum of carriers.

The thermal and electrical conductivity of a single-crystal Cd 0.22 Hg 0.78 Te was studied in the temperature range of practical applications (77-300 K). The sample has impurity conductivity, which is limited by the scattering of charge carriers by phonons. Heat in the sample is transferred by phonons and thermal conductivity is limited by phonon-phonon scattering. The electron contribution to the thermal conductivity can be neglected.