| 摘要 |
A process for preparing doped barium and strontium hexaferrite compounds having the formula (I): Afe12-r-sMrNsO19 (I) wherein A is barium or strontium; M is cobalt, zinc, nickel; N is titanium or ruthenium and r and s are individually in the range from about 0.1 to about 1.2, said process comprising: (a) forming particles of a doped Fe3O4/ACO3 co-precipitate wherein A is defined above from (i) a ferric compound, (ii) a ferrous compound, (iii) a barium or strontium compound, (iv) a cobalt, zinc or nickel compound, (v) a titanium or ruthenium compound and (vi) alkali metal carbonate; (b) suspending the doped Fe3O4/ACO3 particles in a concentrated aqueous solution of an alkali halide; (c) spray drying said suspension to form a dried powder comprising said doped Fe3O4/ACO3 particles distributed onto the surfaces of the high temperature-melting alkali halide crystals; (d) calcining said dried powder at a temperature from about 700 DEG C. to about 900 DEG C. to convert said Fe3O4/ACO3 solids into doped barium hexaferrite particles having formula (I) and an average particle size from about 0.01 to about 0.3 microns; and (e) recovering said doped hexaferrite particles from said alkali halide.
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