New Hexagonal Ferrite, Establishing a Second Structural Series

Abstract

The hexagonal ferrites, of current interest because of their high-frequency properties, are being studied by single-crystal x-ray methods. A new rhombohedral member of the group, ideally Ba4Zn2Fe52O84, has been identified. The centrosymmetric space group is R3̄m; referred to hexagonal axes, c=153.85 Å, a=5.88 Å, and there are 66 anion layers in the c-axis repeat period. The stacking sequence was established by (00.l) structure factor and one-dimensional electron density calculations. The new structure forms a series of mixed-layer compounds with three of the original phases. All of the hexagonal ferrites are thus characterized by two series, each of which features the c-axis interlayering of two discrete structural units. Stacking relations within and between the two series are discussed, along with implications for new structures and series.