황산제일철/황산제이철의 몰비와 침전제 종류(NaOH, NH<sub>4</sub>OH)를 변화시켜 공침법으로 Fe<sub>3</sub>O<sub>4</sub>를 합성하였다. 합성한 분말의 특성을 평가한 결과 모든 실험조건(황산제일철/황산제이철의 몰비와 침전제의 종류)에서 단일상의 나노 크기 Fe<sub>3</sub>O<sub>4</sub>가 생성 되었다. NaOH를 침전제로 사용한 경우에 NH<sub>4</sub>OH를 침전제로 사용한 경우보다 입자크기가 작고, 좁은 입도분포를 나타내었다. 동일한 침전제를 사용할 경우에는 혼합 황산철(황산제일철/황산제이철)의 몰비가 증가할수록 입자크기와 결정자 크기가 증가하였으며 입도분포는 넓어졌다. 모든 실험조건에서 합성된 Fe<sub>3</sub>O<sub>4</sub> 분말은 초상자성을 나타내었으며 침전제로 NH<sub>4</sub>OH를 사용하고 혼합 황산철의 몰비를 2.5로 하였을 때 가장 높은 포화자화 값 72 emu/g을 갖는 Fe<sub>3</sub>O<sub>4</sub>를 합성할 수 있었다.
The effect of ferrous/ferric molar ratio and precipitants on the formation of nano size magnetite particle was investigated by co-precipitation 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<sub>4</sub>OH 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<sub>4</sub>OH.