Crystal structure and charge compensation mechanisms in a barium potassium β-ferrite

Abstract

The structure of a mixed-ion Ba²⁺–K⁺β-ferrite, Ba_0.39K_0.39Fe₁₁O_17.03, has been determined by X-ray diffraction, and refined in the hexagonal space-group P6₃/mmc, R(F)= 3.4%, R_w(F²)= 5.9%. At least two possible charge compensation mechanisms could be identified: (i) a Frenkel defect of Fe³⁺ ions indicating an extra oxygen ion in the conduction plane, and (ii) Fee+ ions and/or vacancies at Fe³⁺ ion sites in the spinel block. The K⁺ ions and most of the Ba²⁺ ions in the conduction plane are found at a 6(h) site near the 2(d)(Beevers-Ross) site; the remainder of the Ba²⁺ ions are at a 6(h) site at x≈ O.88, y=–x.