Chromium-modified goethite in an external magnetic field

The behaviour of the different liquid crystalline phases observed in colloidal dispersions of goethite has been studied by small angle x-ray scattering. The particles align parallel to a small magnetic field and perpendicular to a large magnetic field, which was observed in the isotropic and nematic phase. The smectic phase also aligned parallel to a small magnetic field but it formed an aligned columnar phase with a distorted hexagonal structure in higher magnetic fields. The columnar phase mainly aligned in higher magnetic fields. Goethite particles were successfully modified with chromium. The Cr-modified goethite particles show similar phase behaviour as normal goethite particles but with different magnetic properties. The relative importance of the permanent and induced magnetic moment was found to have changed.