本實驗利用共沉澱法來製備BaFe12O19硬磁性粉體。實驗程序中，起始水溶液為含有生成BaFe12O19所需化學劑量比的硝酸鐵與硝酸鋇，沉澱劑為氨水，而反應液態介質為水和丙酮的混合溶液。固定反應液態介質的總體積並探討改變反應液態介質中水和丙酮比例（R值:丙酮使用體積量/水和丙酮總體積量）對製得的鐵酸鋇粉體性質影響。離心收集到的沉澱物經過90℃乾燥後先做300℃5小時的預熱處理以形成所需的前驅物粉體，接著再進行600℃到1000℃5小時的煆燒處理。前驅物粉體與煆燒後所得粉體藉由熱分析儀、X-光繞射分析儀、紅外線光譜儀、掃描式電子顯微鏡、穿透式電子顯微鏡和超導量子干涉磁量儀對其特性分析。實驗結果顯示當R值為0.6時所得前驅物經600℃煆燒處理後就可出現鐵酸鋇的結晶相態，且900℃煆燒則可得到單一相態鐵酸鋇。而煆燒達1000℃時得到的鐵酸鋇粉體有67 emu/g高飽和磁化強度、33 emu/g的殘留磁場強度和5 kOe矯頑磁力。 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.