Geometrical characterization of acicular goethite particles in systematically controlled processing

The three-dimensional particle size of synthesized acicular goethite particles was studied by combining electron microscopy and X-ray diffraction. The two-dimensional projected size (i.e. length and width) increased with increasing ferrous content, increasing oxidation temperature and decreasing rate of aeration. The mean value of the crystallite size ratio D010D110 decreased with decreasing surface area when a small amount of excess alkali was present. This D010D110 change might be attributed to the change in the cross-sectional shape of the goethite particles.