Magnetic Properties of Milled and Thermal Relaxed YBa₂(Cu_1-xFe_x)₃O_y

Abstract

The influence of the mechanical milling and subsequent thermal relaxation on magnetic and superconducting behaviour of YBa2(Cu1_ y F e x ) 3 O y system has been studied.Two methods of heat treatment were used: Set I -slow cooling from 980 °C in flowing O2 and Set H -reducing at 770°C in flowing Are followed by reoxidation in flowing O2 below 400°C.The transition to superconductivity, diamagnetic response, critical current density and the effective magnetic moment in the normal state have been estimated.Our measurements indicate that the reducing atmosphere preparation is less detrimental on superconducting properties.The results are discussed in terms of occupancy Cu sites by Fe and redistribution of oxygen atoms.