Fablicaion of Lamellar- and Cell-Structured α-Fe/Fe_3O_4 Complex Particles and Their Application to Magnetic Material and Catalysis

本文研究了层状结构的α-Fe/Fe_3O_4复合粒子和胞状结构的Fe_3O_4粒子对磁性材料和催化作用的影响。(1)用机械合金化α-Fe粉和工业Fe_3O_4粉经退火、冷却可制得Wustite粉。采用X射线衍射、热分析、穆斯堡尔谱和磁性测量等方法研究了它们的晶体结构、热稳定性和磁性。(2)层状结构α-Fe/Fe_3O_4复合粒子的制备将上述方铁矿粉进行热分解，可以得到层状结构的α-Fe/Fe_3O_4复合粒子。颗粒大小为几十微米，由20纳米α-铁和60纳米的磁铁矿组成。样品具有铁磁性，饱和磁化强度为96 emu/g，但未观察到超顺磁性。(3)胞状结构Fe_3O_4粒子的制备用硝酸腐蚀去除α-Fe/Fe_3O_4复合粒子中的α-Fe组分，得到胞状结构Fe_3O_4粒子。(4)Ni-和Co-浮氏体体系的研究由于Ni-和Co-浮氏体在高温下是稳定的，不能得到Ni/Ni_3O_4和Co/Co_3O_4等复杂的、胞状结构的粒子。建议采用Fe（Co）O或Fe（Ni）O方铁矿制备α-Fe/CoFe_2O_4和α-Fe/NiFe_2O_4复合粒子。

The authors studied the shnthsis of lamellar-structured α-Fe/Fe_3O_4 complex particle and cell structured Fe_3O_4 particle to magnetic material and catalysis.(1) Fabrication and cahacterization of wustite ; Wustite powder could be fablicated by anneling and cooling of mechanically alloyed α-Fe powder and Fe_3O_4 commercial powder. Their crystal structure and thermal stability and magnetic property were studied using by X-ray diffraction, thermal analysis, Mossbauer spectroscopy and magnetic measurement.(2) Fablication of lamellar-structured α-Fe/Fe_3O_4 complex particle ; Lamellar-stuctured α-Fe/Fe_3O_4 complex particle could be obtained by thermal decomposition of wustite powder mentioned above. The size of particle was several tens of micron meter, and it was constructed of 20 nanometer α-iron and 60 nanometer magnetite components like lod. It showed ferromagnetic with saturation magnetization of 96 emu/g, but the siperparamagnetism was not observed.(3) Fabrication of cell structured Fe_3O_4 particle ; Cell-structed Fe_3O_4 particle could be obtained by etching out of α-Fe component from α-Fe/Fe_3O_4 complex particle using nitric acid.(4) investigation to Ni-and Co-wustite system ; It was not able to obtain complex and cell-structured particle as Ni/Ni_3O_4 and Co/Co_3O_4, because Ni- and Co-wustite were stable up to high temperature. It was suggested that Fe (Co) O or Fe (Ni) O wustite was recommended to obtain α-Fe/CoFe_2O_4 and α-Fe/NiFe_2O_4 complex particle.