THERMAL-CONDUCTIVITY AND ELECTRICAL-RESISTIVITY OF THE T' PHASE- AND THE T-PHASE IN 2-1-4 OXIDE SUPERCONDUCTORS

The temperature dependences of the thermal conductivity, kappa(T), and the electrical resistivity, Pr1.85Ce0.15CuO4-y (PCCO) with the T' pha se, and La1.85Sr0.15CuO4-y (LSCO) and La1.935Ca0.065CuO4-y (LCCO) with the T phase, have been measured. The superconducting transition tempe rature T(Con), of NCCO, PCCO, LSCO, and LCCO were 26.4, 23.0, 37.1, an d 8.8 K, respectively. The enhancement of kappa(T) below just T(Con) s uch as seen in 1-2-3 oxide superconductors was not clearly observed. k appa(T) for the samples of NCCO and PCCO showed a pronounced maximum s uch as that of sapphire crystal around 30 and 40 K, respectively. For these samples of NCCO and PCCO, it has been shown that the analysis ba sed on the various phonon scattering mechanisms is in good agreement w ith our experiment.