Enhancement of orthorhombicity and superconductivity in argon preheated EuSrBaCu 3O 6+ z

Abstract

We have studied the structural and superconducting properties of the superconductor EuSrBaCu 3O 6+ z . This compound when annealed in oxygen at 450°C showed and orthorhombic structure in contradiction to the earlier published data. When the same sample was heated in argon followed by oxygen annealing, the orthorhombicity ( b− a)/( b+ a) increased from 2.86X10 −3 to 6.96X10 −3 and T c from 80 to 87 K. Further, there was an enhancement in the shielding and the intergranular critical current. A combination of several factors such as changes in the Cul-apical oxygen distance, chain oxygen ordering and hole density may qualitatively account for the observed data.