Thermoelectric power and resistivity of Nd1-xCaxBa2Cu3Oy and Nd1-xLaxBa2Cu3Oy

The structural and transport properties of Nd1-xCaxBa2Cu3Oy (x = 0.0, 0.03, 0.06, and 0.10) and Nd1-xLax- Ba2Cu3Oy. (x nominally 0.0, 0.05, 0.10, and 0.15) have been studied by X-ray powder diffraction, electrical resistivity , and thermoelectric power measurements. In both series, the a- and b-axis lattice parameters decrease with increasing doping while the c-axis lattice parameter increases. The transport properties suggest improved metallic be haviour with increasing Ca doping in contrast to La doping. An anomalous sh arp peak in the thermoelectric power close to T-c was observed, which depen ded on the doping content. We analysed the thermoelectric power as a functi on of temperature with a two-band model with an additional linear T term. A n excellent agreement between model and data was obtained. (C) 2000 Elsevie r Science B.V. All rights reserved.