황산제일철/황산제이철의 몰비와 침전제 종류(NaOH, $NH_4OH$)를 변화시켜 공침법으로 $Fe_3O_4$를 합성하였다. 합성한 분말의 특성을 평가한 결과 모든 실험조건(황산제일철/황산제이철의 몰비와 침전제의 종류)에서 단일상의 나노 크기 $Fe_3O_4$가 생성 되었다. NaOH를 침전제로 사용한 경우에 $NH_4OH$를 침전제로 사용한 경우보다 입자크기가 작고, 좁은 입도분포를 나타내었다. 동일한 침전제를 사용할 경우에는 혼합 황산철(황산제일철/황산제이철)의 몰비가 증가할수록 입자크기와 결정자 크기가 증가하였으며 입도 분포는 넓어졌다. 모든 실험조건에서 합성된 $Fe_3O_4$ 분말은 초상자성을 나타내었으며 침전제로 $NH_4OH$를 사용하고 혼합 황산철의 몰비를 2.5로 하였을 때 가장 높은 포화자화 값 72 emu/g을 갖는 $Fe_3O_4$를 합성할 수 있었다.
The effect of ferrous/ferric molar ratio and precipitants on the formation of nano size magnetite particle was investigated by coprecipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide and ammonium hydroxide was used as a precipitant. Single phase magnetite was synthesized with all of experiment conditions (ferrous/ferric molar ratios and precipitants). Particle size was smaller, and particle size distribution was narrower when NaOH was used than $NH_4OH$ was used. The crystallinity and particle size was increased and narrower particle size distribution with increasing molar ratio ferrous/ferric sulfate with the same precipitant. Super paramagnetism could be obtained at all of experiment conditions. The highest saturation magnetization (72 emu/g) was obtained when the ferrous/ferric molar ratio was 2.5 and precipitant was used $NH_4OH$.
