MAGNETIC-BEHAVIOR OF THE 112-TYPE SUBSTITUTED CUPRATE YBACOCU1-XFEXO5

A new solid solution YBaCoCu1-xFexO5+delta has been synthesized for 0.30 less than or equal to x less than or equal to 0.60. The neutron diffraction study of the phase YBaCoCu1-xFexO5 (x = 0.50) confirms that its nuclear structure is centric, i.e., belongs to the space group P4/mmm, which must be now considered as characteristic of the ''112'' structure, built up of double pyramidal layers of transition metal elements M(M = Fe, Co, Cu). The neutron diffraction spectra registered at 1.4 and 300 K show that the magnetic moments are antiferromagnetically coupled, lying in the (a, b) plane; the susceptibility measurements and Mossbauer spectroscopy data show for iron the only presence of Fe(III), a cationic disordering, and allow an intermediate spin configuration for Co(III) to be identified. For x = 0.5 the phase can then be formulated (YBaCo0.5Co0.5Cu0.5Fe0.5O5)-Co-III-Cu-II-O-III. (C) 1995 Academic Press, Inc.