RAMAN-SPECTRA AND VIBRATIONAL ANALYSIS OF BAFE12O19 HEXAGONAL FERRITE

This paper reports on the first Raman spectra of barium hexaferrite, B aFe12O19, as a member of the magnetoplumbite-type structure. The spect ra, recorded from 150 to 1000 cm(-1) at room and liquid nitrogen tempe rature, are analyzed on the basis of D-6h factor group selection rules . The iron atom on the bipyramidal site is discussed with regard to it s particular dynamics. The distribution of normal modes in BaFe12O19 i s examined on the basis of the Raman spectra of beta-alumina and a ser ies of ferrites. Emphasis has been put on the factors influencing the Raman frequencies, namely the value of the coordination number, the de gree of connection of a coordinated group, and the mass effect. (C) 19 98 Academic Press.