硅酸盐对Ferrihydrite相转化为α-Fe2O3微粒形貌的调控作用

Modulation Function of Silicate on Morphology of α-Fe_2O_3 Particles from Ferrihydrite Phase Transformation

以Ferrihydrite(又称水合氧化铁hydrous iron oxide)为反应前驱物,Fe(II)为催化剂,在微量Na2SiO3存在下,控制pH=6～9范围内合成出了亚微米级纺锤形和准立方形α-Fe2O3微粒.研究了初始pH,Na2SiO3浓度,Ferrihydrite老化方式对相转化时间和产物形貌的影响,利用XRD,SEM等手段对产物进行了表征.结果表明,Na2SiO3对Ferriihydrite催化相转化有一定的抑制作用,是影响其相转化过程及产物形貌的关键.在弱碱性条件下,[Si]/[Fe3+]为0.01时可直接获得纺锤形(轴比≥2)或准立方形(300～400nm)α-Fe2O3粒子,并对形成机理进行了初步讨论.

Submicron spindle and pseudocube α-Fe2O3 particles were synthesized at pH=6～9 in the presence of trace Na2SiO3. In the current system, ferrihydrite was used as a precursor and FeCl2 as a catalyst. The effect of initial pH, the concentration of Na2SiO3 as well as the forming conditions of the ferrihydrite on the phase transformation process and the morphology of α-Fe2O3 particles was studied, respectively. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were employed to monitor the change in the synthesis process. The results show that Na2SiO3 inhibited the transfomation of ferrihydrite, which leads to the formation of the spindle or pseudocube α-Fe2O3 particles. Under the condition of weak alkalinity and Si/Fe3＋=0.01, the spindle （the axial ratio≥2） or pseudocube （300～400 nm） α-Fe2O3 particles were prepared and the formation mechanism of α-Fe2O3 particles was discussed.