本研究以改良後的共沉澱法合成出高磁性之六角鐵酸鋇粉體。將鋇、鐵硝酸鹽類依BaFe12O19化學計量比混合溶於100毫升的水溶液，再滴入溫度為30℃、400毫升的氨水和丙酮溶液中進行沉澱反應3小時。溶液中，氨水和丙酮的相對量藉由R值(R值定義為氨水使用的體積量/丙酮和氨水的總體積量)來調整，R值範圍為0到1。經離心程序後將所收集的粒子於300℃乾燥且之後於600到900℃間進行煆燒。煆燒後的粉體會經X-光繞射儀、紅外線光譜儀、掃描式電子顯微鏡、穿透式電子顯微鏡、振動樣品磁性量測儀等的測試來瞭解其特性。實驗結果指出鐵酸鋇的結晶能於650℃生成但是其樣品仍然含有部分的BaCO3和α-Fe2O3。要得到純鐵酸鋇粉體須將沉澱物煆燒溫度提高到800℃。當R值為0.6且煆燒溫度為800℃時，所得到鐵酸鋇粉體之飽和磁化強度為67.7 emu/g和矯頑磁力為4.84 kOe。 Hexagonal barium ferrite (BaFe12O19) powders with superior magnetic properties were synthesized using a modified co-precipitation method. One hundred milliliters of the aqueous solution, containing the stoichiometric amounts of barium and iron nitrates to form BaFe12O19, were added into the 400-mL solution of acetone and ammonia, which was controlled at 30 C, to undergo precipitation reaction for 3 h. The relative amounts of acetone and ammonia in the solution were varied according to R (define : volume of ammonia used/the total volume of the solution of acetone and ammonia) and R ranged from 0 to 1. After being centrifugally separated, the collected particles were dried at 300 C, followed by calcining at temperatures (T) between 600 ~ 900 C. The calcined particles were then characterized using x-ray diffractometer, infrared spectrometer, scanning electron microscope, transmittance electron microscope, and vibrating sample magnetometer. The experimental results indicated that crystalline BaFe12O19 was able to be formed at 650 C but the specimen still contained some BaCO3 and a-Fe2O3. To obtain pure BaFe12O19 powder, calcining the precipitates at 800 oC were required. When R = 0.6 and T = 800 oC, the obtained BaFe12O19 powder exhibited saturated magnetization of 67.7 emu/g and coercive force of 4.84 kOe.
