Abstract
The crystal structure and superconducting properties of YBa2(Cu1-xFex)3Oy prepared by various heat treatments were examined by X-ray powder diffraction, electrical resistivity, ac susceptibility and57Fe Mössbauer effect measurements. The orthorhombic phases were obtained up to x=0.02, 0.04 and 0.12 by the heat treatments of (a)slow cooling from 850°C in O2 gas, (b)quenching into liq. N2 from 930°C in air followed by oxidation below 400°C in O2 gas and (c)heating at 800°C in N2 gas followed by oxidation below 400°C in O2 gas, respectively. The differences of the orthorhombic region and Tc among the samples prepared by the heat treatments (a), (b) and (c) were explained by the distribution of Fe ions intra- and inter-(Cu-O)planes.
