High-pressure synthesis and characterization of the Au-1201 phase

A new Au(Ba,La)(2)CuO5+delta (Au-1201) phase was synthesized at 6 GPa and 1250 degreesC. This compound is the first member of the Au-containing cuprate family. It crystallizes in an orthorhombic primitive cell with lattice parameters a = 3.7976(3) Angstrom, b = 3.8509(3) Angstrom, c = 8.5749(9) A. Electron diffraction studies revealed the existence of additional weak reflections indicating a superlattice of a(s) = 5a, b(s) = b, c(s) = 2c. A weak superconducting signal was observed below 7 = 19 K in the magnetic susceptibility, but the diamagnetism was not large enough to assume bulk superconductivity. (C) 2003 Elsevier B.V. All rights reserved.