Morphology control and texture of hematite particles by dimethylformamide in forced hydrolysis reaction

概要

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The effects of dimethylformamide (DMF) on morphology and texture of hematite particles produced from a forced hydrolysis reaction of FeCl_3-HCI solution wereinvestigated by transmission electron microscopy (TEM), x-ray diffraction (XRD),Fourier transform infrared spectrometry (FTIR), thermogravimetry and differentialthermal analysis (TG-DTA), N_2 and H_2O adsorption, and zeta potential measurements.The morphology of synthetic hematite particles was concentration dependent; theychanged from large sphere with a diameter of ca. 600 nm to diamond-like shape withincreasing DMF concentration in the aging solution accompanying a reduction of theirsize to 80 nm without incorporation of DMF in the particles. This fact was explained byan acceleration of phase transformation from beta-FeOOH to hematite with an elevation of the solution pH owing to dimethylamine produced from a hydrolysis of DMF at an elevated temperature. TEM and XRD suggested that the diamond-like hematite particles formed above 6-10 vol % DMF possess a single-crystal nature. Gas adsorption technique revealed that the particles produced above 10 vol % DMF possess a high thermal stability.TG and FTIR indicated that the hematite particles produced with DMF contained smallamounts of OH^- ions in the lattice though they provided a single-crystal nature.
Materials Research Societyの論文
1998-06-00