Abstract
The room temperature crystal structure of BaFe 12O 19 hexagonal ferrite has been refined from X-ray single crystal data. This compound is hexagonal, space group P6 3 mmc , with two formula units per cell and cell parameters a = 5.8920(1) Å and c = 23.183(1) Å. The crystal structure has been refined to a final R value of 1.6% for 380 independent reflections. Three different models are considered for the structural and dynamic characteristics of the bipyramidal Fe ions: (1) a nondisordered configuration, (2) a static disorder between two adjacent pseudotetrahedral sites, and (3) a dynamical disorder between these sites. The X-ray results show that the bipyramidal Fe ions have a disordered configuration and previous Mössbauer spectroscopy studies prove that, at room temperature, the disorder is a dynamical one. The observed oxygen thermal relaxation, Fourier-difference peaks, and interatomic distances are consistent with a fast diffusional motion of the bipyramidal Fe ions within a quasiharmonic double-well potential.
Published Version
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