تأثير آلاينده خنثاي Ca-La بر روي خواص ترابردي و ابررسانايي تركيب Nd-123

The charge neutral doping effects of Ca-La on the transport and superconductivity properties in Nd-123 superconductors

Polycrystalline samples of Nd1_xCaxBa2-xLaxCu307_§ (with 0.0 < x < 0.15) were prepared by the standard solid state method. The transport and superconducting properties have been studied by the resistivity and thermoelectric power measurements as a function of temperature and doping concentration. With increasing doping concentration, the resistivity was increased and thermoelectric power was constant at high temperature while it was increased slightly at low temperature. The critical temperature Tc was linearly decreased with increasing doping. The density of statets at Fermi energy g(eF) were obtained from the thermoelectric power. They were decreased as x increased. The thermoelectric power as a function of temperature was analyzed in terms of the phenomenological narrow band model. The model well described thermoelectric power data up to near the critical temperature. Severl property results such as the resistivity p(x,T), thermoelectric power S(x,T), critical temperature Tc(x) , and g(ep) variation suggested that the hole localization is the main reason of superconducting suppression in the charge neutral doped cuprates.