Formation of U-type hexaferrites
- 1 August 2004
- journal article
- Published by Springer Science and Business Media LLC in Journal of Materials Research
- Vol. 19 (8), 2462-2470
- https://doi.org/10.1557/jmr.2004.0317
Abstract
The formation of U-type hexaferrites with the composition Ba4B2Fe36O60 (B = Co, Ni, Zn) was studied. Samples were characterized by means of x-ray diffraction, electron microscopy (with energy-dispersive spectroscopy), and thermogravimetric and thermomagnetic analyses. U-hexaferrites are formed from the intermediate phases M-hexaferrite (BaFe12O19) and Y-hexaferrite (Ba2B2Fe12O22), which at the same time represent units in the U-hexaferrites’ crystal structure. The preparation of monophase U-hexaferrites was made possible by combining high-energy milling or chemical coprecipitation with a calcination at 1250–1300 °C. Structural defects, such as stacking faults, were observed in monophase samples with a high-resolution transmission electron microscope. The observed defects can be regarded as seeds for the formation of other hexaferrite phases after prolonged calcination times or higher calcination temperatures.Keywords
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