abstract
The crystal and magnetic structures of layered perovskites TbBaCo2-xFexO5+gamma (0.08 less than or equal to x less than or equal to 0.24) were studied by neutron powder diffraction. Increasing iron concentration up to the v values higher than 0.10 leads to the orthorhombic-->tetragonal phase transition resulting from the transformation of 2 x I x 1-type superstructure, formed due to ordering of extra oxygen incorporated into the vacant sites in [TbOgamma] layers, into 3 x 3 x I superlattice. The concentration ranges, where the orthorhombic and tetragonal lattices exist, are separated with a narrow two-phase domain. For the tetragonal phases with 3 x 3 x I superstructure (space group P4/mmm), the Co/Fe ions are antiferromagnetically coupled, forming G-type spin-ordered configuration. The Co3+ cations located in square-pyramidal sites adopt intermediate spin state, whilst a relatively small magnetic moment of Co3+ I ions in the octahedral sublattice indicates that a minor fraction of cobalt is in the low-spin state. (C) 2004 Elsevier Inc. All rights reserved.
keywords
TRANSPORT-PROPERTIES; MAGNETIC-STRUCTURE; PEROVSKITE; NDBACO2O5+DELTA; TBBACO2O5.5; TRANSITION; PHASES; TB; GD; DY
subject category
Chemistry
authors
Khalyavin, DD; Balagurov, AM; Beskrovnyi, AI; Troyanchuk, IO; Sazonov, AP; Tsipis, EV; Kharton, VV
our authors
Vladislav Kharton
Invited Principal ResearcherGroups