Structural behavior and superconductivity of YBa2Cu3Ox

The compound YBa2Cu3Ox was given various oxidation treatments over a range of oxygen pressures from 0.02 to 200 MPa and temperatures up to 1223K. A tetragonal to orthorhombic phase transformation was observed, leading to superconducting behavior below 94K. The orthorhombic unit cell parameters (i.e. volume, bond lengths, and axial distortions) were found to correlate with the superconducting transition temperatures. These correlations are rationalized in terms of the interrelationship of oxygen stoichiometry with the lattice parameters of the orthorhombic phase. The nature of superconductivity in YBa2Cu3Ox and La2CuO4 is related to the Cu-O coordination polyhedra and an explanation is proposed for the observed multiple superconducting transitions in YBa2Cu3Ox.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26602/1/0000143.pd