Lee Chung-Hyo
Department of Advanced Materials Science and Engineering, Mokpo National University, Muan-gun, Chonnam, 58554, Republic of Korea.
J Nanosci Nanotechnol. 2021 Jul 1;21(7):3791-3794. doi: 10.1166/jnn.2021.19228.
The effect of mechanical alloying (MA) on the solid state reaction of hematite and graphite system with a positive reaction heat was investigated using a mixture of elemental Fe₂O₃-C powders. The solid state reduction of hematite to Fe₃O₄ has been obviously observed after 3 hours of MA by a vibrating ball mill. A two-phase mixture of Fe₃O₄ and remaining Fe₂O₃ is obtained after 5 hours of MA. Saturation magnetization gradually increases with MA time due to the formation of Fe₃O and then reaches 23 emu/g after 5 hours of MA. In addition, a Fe₃O₄ single phase is obtained by MA after 3 hours and subsequently heat treated up to 700°C. X-ray diffraction result shows that the average grain size of Fe₃O₄ prepared by MA for 5 hours and heat treatment to be in the range of 92 nm. The saturation magnetization of Fe₃O₄ prepared by MA and heat treatment reaches a maximum value of 56 emu/g for 5 hours MA sample. It is also observed that the coercivity of 5 hours MA sample annealed at 700 °C is still high value of 113 Oe, suggesting that the grain growth of magnetite phase during annealing process tends to be suppressed.
使用元素Fe₂O₃-C粉末混合物，研究了机械合金化（MA）对具有正反应热的赤铁矿和石墨体系固态反应的影响。通过振动球磨机进行3小时的机械合金化后，明显观察到赤铁矿固态还原为Fe₃O₄。机械合金化5小时后得到Fe₃O₄和剩余Fe₂O₃的两相混合物。由于Fe₃O的形成，饱和磁化强度随机械合金化时间逐渐增加，机械合金化5小时后达到23 emu/g。此外，通过机械合金化3小时然后在高达700°C下进行热处理可获得Fe₃O₄单相。X射线衍射结果表明，通过机械合金化5小时并热处理制备的Fe₃O₄平均晶粒尺寸在92 nm范围内。通过机械合金化和热处理制备的Fe₃O₄的饱和磁化强度对于机械合金化5小时的样品达到最大值56 emu/g。还观察到在700°C退火的机械合金化5小时样品的矫顽力仍为113 Oe的高值，这表明退火过程中磁铁矿相的晶粒生长趋于受到抑制。
