A. J. Zaleski

Thermal conductivity and electrical resistivity of the high-Tc superconductor YBa2Cu3O9−Δ

Abstract Thermal conductivity and electrical resistivity of single-phase YBa 2 Cu 2 O 9−Δ compound were measured in the superconducting ( T c =89.5 K) and normal states, in the temperature range 5–320 K. The electronic component of the total thermal conductivity was estimated to be 20%. The electrical resistivity changed linearly in the normal state up to highest measured temperature.

Thermal conductivity anomalies in GdBa2Cu3O7−x

Abstract The measurements of the thermal and electric conductivity of three GdBa 2 Cu 3 O 7−x samples with different orthorhombic distortions are presented. The electronic component of the total conductivity in the normal state is evaluated. Its value is connected with the magnitude of the change of the slope of the total conductivity λ for the critical temperature T c .

Vibrational properties of the R:Ba:Cu =1:2:3 superconductors Part II. The phonon properties of the GdBa2Cu3O6.8–7.0 superconductor at temperatures above and below Tc

Abstract Infrared and Raman spectra of GdBa 2 Cu 3 O 6.8–7.0 ternary oxides have been measured at several temperatures between 10 and 300 K for the single crystal and ceramic state. Lines observed in both spectra are identified and assigned to the respective vibrational modes. The temperature dependence of band frequencies is analyzed. Phonon anomalies are discussed in terms of electron— phonon mechanism and valence fluctuations induced by the polarization change during the vibration.