COMPOSITION AND STRUCTURE OF SOME [BA1-PSRP]ZNFE6O11 Y-TYPE HEXAGONAL FERRITES

Single crystals of the [Ba1-pSrp]ZnFe6O11 series (p varying from 0 to 0.7) were synthesized and studied by means of scanning electron microscope and X-ray diffraction. As soon as Sr is present in the structure, the single crystals are poly-phased, and the chemical formulae show a difference with the starting chemical composition. Only the T-block is affected by the presence of the Sr cation: i) the Zn population on the Mel tetrahedron of the T-block decreases without increasing on the Me2 tetrahedron of the S-block; ii) we are in presence of a displacement of some cations inducing very small changes in the cation-oxygen distances and cation-oxygen-cation angles of the superexchange interaction paths. Therefore, the helimagnetism noted in the [Ba1-pSrp]ZnFe6O11 compounds could be due to the poly-phased crystals, each showing different magnetic behavior.