Raman spectra and vibrational analysis of BaFe12O19 hexagonal ferrite

This paper reports on the first Raman spectra of barium hexaferrite, BaFe12O19, as a member of the magnetoplumbite-type structure. The spectra, recorded from 150 to 1000 cm(-1) at room and liquid nitrogen temperature, are analyzed on the basis of D-6h factor group selection rules. The iron atom on the bipyramidal site is discussed with regard to its particular dynamics. The distribution of normal modes in BaFe12O19 is examined on the basis of the Raman spectra of beta-alumina and a series of ferrites. Emphasis has been put on the factors influencing the Raman frequencies, namely the value of the coordination number, the degree of connection of a coordinated group, and the mass effect. (C) 1998 Academic Press.