Co-Pt-B particles prepared by chemical reduction

The magnetic and structural properties of ultrafine Co-Pt-B particles are studied in samples near the equiatomic CoPt composition. The particles are prepared by the chemical reduction of CoCl/sub 2/:6H/sub 2/O and PtCl/sub 4/ with NaBH/sub 4/. The as-made powders have an fcc structure, and they are magnetically soft. An fcc to fct phase transformation is observed after annealing at 700 degrees C, resulting in coercivities up to 17.8 kOe at room temperature. The variation of coercivity with particle morphology and structure is investigated. >