Title :
Nanocrystalline M-type hexaferrite powders: preparation, geometric and magnetic properties
Author :
Gornert, P. ; Pfeiffer, Helge ; Sinn, E. ; Muller, R. ; Schüppel, W. ; Rösler, M. ; Batlle, X. Garcia ; Garcia del Mure, M. ; Tejada, J. ; Gali, S.
Author_Institution :
Inst. fur Phys. Hochtechnol., Jena, Germany
fDate :
3/1/1994 12:00:00 AM
Abstract :
Co-Ti-Sn-Ge substituted M-type bariumhexaferrite powders with mean grain sizes between about 10 nm and about 1 μm and a narrow size distribution were prepared reproducibly by means of a modified glass crystallization method. At annealing temperatures between 560 and 580°C of the amorphous flakes nanocrystalline particles grow. They behave superparamagnetically at room temperature and change into stable magnetic single domains at lower temperatures. The magnetic volume of the powders is considerably less than the geometric one. However, the effective anisotropy fields are larger by a Factor of two to three
Keywords :
annealing; barium compounds; ferrites; magnetic anisotropy; magnetic properties of amorphous substances; magnetic properties of fine particles; nanostructured materials; powders; superparamagnetism; 560 to 580 C; BaFe12-2xCoxTix-y-zSny GezO19; BaFe12CoTiSnGeO19; amorphous flakes; anisotropy fields; annealing temperatures; glass crystallization method; magnetic domains; magnetic volume; mean grain size; nanocrystalline hexaferrite powders; superparamagnetic; Amorphous magnetic materials; Annealing; Crystallization; Glass; Grain size; Magnetic anisotropy; Magnetic domains; Perpendicular magnetic anisotropy; Powders; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
