| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 100 === BaFe12O19 powder, a hard magnetic ceramic, was synthesized using a co-precipitation method. In preparation, the following materials were used: an aqueous solution of ferric and barium nitrates, in a stoichiometric ratio to form BaFe12O19, as starting solution, ammonium as precipitating agent and a mixed liquids containing acetone and water as reaction liquid medium. By fixing the total volume of the reaction liquid medium, effects of the acetone fraction R ( = volume of acetone used/total volume of the reaction medium) in the liquid medium on the characteristics of the obtained barium ferrite powder were investigated. After precipitation and centrifugal filtration, the collected solid precipitants were dried at 90℃ and then preheated at 300℃ to form the solid precursors. The solid precursors were then calcined at different temperatures ranging from 600℃ to 1000℃. The calcined powder was characterized using thermal analyzer, x-ray diffractometer, infrared spectrometer, scanning electronic microscope, transmission electronic microscope and superconducting quantum interference device. When R = 0.6, BaFe12O19 crystalline phase was first appeared in the powder calcined at 600℃and BaFe12O19 monophase powder was obtained at 900℃. The BaFe12O19 powder obtained at R = 0.6 and 1000℃ possessed good magnetic properties: saturation magnetization of 67 emu/g, remanence magnetization of 32~33 emu/g and coercive force of 5 kOe.
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