DOPED HEXAGONAL BARIUM AND STRONTIUM FERRITE PARTICLE, AND MANUFACTURE OF CO-PRECIPITATED PRECURSOR THEREOF

摘要

PURPOSE: To easily produce the subject particles with high efficiency by suspending doped Fe₃O₄/ACO₃ particles (A is Ba, Sr) into an alkali halide soln. and spray-drying the suspension, then calcining the same. ;CONSTITUTION: The particles are produced by (A) forming the particles of the Fe₃O₄/ACO₃ codeposited matter (A is Ba, Sr) doped from an Fe³⁺ compd., Fe²⁺ compd., compd. of Ba or Sr, compd. of Co, Zn, Ni or their mixture, compds. of Ti, Ru or their mixture and alkaline metal carbonate; (B) suspending the doped Fe₃/ACO₃ particles in a thick aq. alkali halide soln., (C) spray-drying the suspension to form the dry powder, in which the doped Fe₃O₄/ACO₃ particles on the surface of the high-temp. fusible alkali halide crystals, are distributed, (D) calcining the dry powder at a temp. of about 700 to 900°C to change the Fe₃O₄/ACO₃ solid to the particles of the formula (A is described above, M is Co, Zn, Ni; N is Ti, Ru, (r) and (s) are about 0.1 to 1.2) having the average grain size of about 0.01 to 0.3 μ and (E) recovering these particles from the alkali halide.;COPYRIGHT: (C)1990,JPO