Akademik Veri Yönetim Sistemi
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, cilt.28, sa.9, ss.2641-2647, 2015 (SCI-Expanded)
In the present study, thermal conductivity (kappa - T), thermoelectric power (S - T), and figure of merit (ZT) measurements from room temperature down to 20 K of polycrystalline Bi2Sr2Ca1-x Na (x) Cu2O8+y and Bi2Sr2Ca1-x K (x) Cu2O8+y superconductors prepared by a polymer solution technique using polyethyleneimine, PEI, have been carried out. The thermoelectric power, S(T), of samples have both negative (at high T) and positive values (at low T), and are found to increase with decreasing temperature, reaching their maximum values (peaks) around their T (c) values and dropping rapidly to zero below T (c). Na and K substitutions also have a considerable effect on the thermal conductivity, kappa. Namely, with increasing Na concentration the magnitude of kappa is decreased, but for the K substitution, the magnitude of kappa is drastically increased for x = 0.75.