Non-centrosymmetric structures in an M4Ynhexagonal ferrite series

Abstract

Further single-crystal x-ray diffraction studies of flux-grown hexagonal ferrites containing Zn, Zn+Mn, or Co have shown a third series of mixed-layer structures, M4Yn, to supplement the earlier MnS and M2Yn groups. The M4Yn series permits non-centrosymmetry; of the nine phases observed, five are non-centric, R3m (three structures), P3m1 and P[unk]m2. The latter was almost uniquely determined from symmetry considerations. Stacking sequences were confirmed by 00·l structure-factor calculations. A nomenclature system for quasi-polytypic mixed-layer structures is discussed.