Structures of nanosized Fe–Ti mixed oxide particles produced by freezing method

Abstract

Fe–Ti mixed oxide nanoparticles with different atomic ratios in Ti/(Fe + Ti) from 0 to 1.0 have been prepared by hydrolysis of aqueous solutions containing Fe(III) and Ti(IV) ions and a freezing method with liquid N₂, which inhibits crystallization and particle growth. The particles produced were poorly crystalline according to XRD and the product, in the absence of Ti(IV), was assigned to 2-line ferrihydrite. The products had a high specific surface area of 369–460 m² g⁻¹, corresponding to a mean particle size of 3–4 nm. These nanosized particles were composed of crystallites of about 1 nm size. It was found by Mössbauer spectroscopy that the particles produced were superparamagnetic and their blocking temperature and inner electric field decreased with increasing Ti(IV) content.