Magnetic and structural properties of La-substituted ferrites

Production methods for obtaining the metastable LaFe/sub 12/O/sub 19/ are described. The magnetic properties of La-substituted Sr hexaferrite and pure LaFe/sub 12/O/sub 19/ are summarized. The uniaxial anisotropy of LaFe/sub 12/O/sub 19/ increases dramatically with decreasing temperature. This is attributed to a change of the Fe/sup 3+/ to an Fe/sup 2+/ on the 2a site which is confirmed by Mo/spl uml/ssbauer spectroscopy. This leads to a semiconductor behavior visible in the temperature dependence of the electrical resistivity.