YBaMn2O5: Crystal and magnetic structure reinvestigation

The ordered oxygen-deficient perovskite YBaMn2O5 has been synthesized as a monophasic sample. A variable temperature neutron diffraction study of this phase has been carried out. The crystal structure of this manganite was so lved in the space group P4/nmm (a = 5.547 Angstrom and c = 7.649 Angstrom). This oxide, which is closely related to the YBaCuFeO5 structure, forms an alternate stacking of yttrium and barium layers along the c axis. It differ s from the latter, however, by the existence of two distinct sites for mang anese, corresponding to an ordering of the Mn3+ and Mn2+ cations, respectiv ely. Elucidation of the magnetic structure of YBaMn2O5, from low temperatur e PND (powder neutron diffraction) data, leads to a G-type antiferromagneti c model; the superimposed Mn2+/Mn3+ charge order results in ferrimagnetic b ehavior for this phase and explains its magnetic properties, as obtained fr om susceptibility measurements, (C) 1999 Elsevier Science Ltd.