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The magnetic properties of fine Fe-B particles with different boron concentrations and particle sizes were studied. The powders were prepared by reducing Fe-salts with NaBH/sub 4/ as a reducing agent in aqueous solution. The particle size ranged from 300 to 600 AA. X-ray diffraction patterns show that the particles are crystalline for boron concentrations less than 20 at.% and amorphous for greater concentrations. The maximum coercivity and saturation magnetization obtained for these particles are approximately 1200 Oe and 160 emu/g at room temperature. The coercivities are about two orders of magnitude higher than the values reported for Fe-B metallic glasses and alpha -Fe. >

Barium ferrite fine particles have been synthesized from ferric nitrate and barium nitrate aqueous solution by an aerosol technique. The as-received particles showed a spin-glass behavior with a history-dependent low-field magnetization below 180 K. An exothermic peak with an initial crystallization temperature of 687 degrees C was found by DSC (differential scanning calorimetry) analysis. Heat treatments above this temperature greatly changed the magnetic properties and morphologies without changing the Ba/Fe atomic ratio, which was 1/12. Heat-treated samples had coercivities and saturation magnetizations as high as 5360 Oe and 70.6 emu/g, respectively. >