X-Ray Diffraction Study on the Crystal Structure of Nd_1+xBa_2-xCu₃O_7-δ

Abstract

Crystal structures in the Nd 1+ x Ba 2- x Cu 3 O 7-δ system have been investigated by X-ray powder diffraction combined with Rietveld analysis. The compound NdBa 2 Cu 3 O 7-δ is isomorphic with orthorhombic YBa 2 Cu 3 O 7-δ . With the increase of x the orthorhombic distortion decreases, and the compound becomes tetragonal at x =0.2. The tetragonal structure is isomorphic with the tetragonal form of YBa 2 Cu 3 O 7-δ . T c of the compounds with x =0 and 0.05 is above 90 K, which decreases monotonically with x and the compound becomes semiconducting at x =0.4.