Magnetically Modified TiO2 Powders – Microstructure and Magnetic Properties

Abstract The anatase (TiO 2 ) particles magnetically modified by iron oxides and prepared by an innovating technological procedure are studied from the viewpoint of microstructure and a complex analysis of magnetic behaviour at room and elevated temperatures. Scanning electron microscopy observations have yielded variable shapes of particles in the composite powder whereas the iron oxide particles of diameter bellow 1 μm were detected on the surface of the TiO 2 . The dominant magnetite (Fe 3 O 4 ) accompanied by a small amount of maghemite (γ-Fe 2 O 3 ) and/or hematite (α- Fe 2 O 3 ) were analysed by X-ray powder diffraction. A relatively high saturation magnetization (3.38 Am 2 /kg), negative dipolar interactions, and the low values of reversible and irreversible part of magnetic susceptibility were found out from magnetic measurements at room temperature. During a thermomagnetic treatment the composite sample has been going through a few magnetic phase transitions and transforms into a fully paramagnetic state around 850 K. After its cooling to the room temperature an undesirable magnetic hardening of the sample has occurred.