STRUCTURE OF NICKEL-DOPED ALPHA-FEOOH

Colloidal particles of nickel-doped alpha-FeOOH prepared under varied conditions were characterized using transmission electron microscopy, X-ray diffraction, thermogravimetry-differential thermal analysis, Fourier transform infrared analysis, inductively coupled plasma spectroscopy and nitrogen adsorption. The unit cell dimensions of the resulting alpha-FeOOH slightly changed on doping with nickel. Both the total and surface hydroxyl ions decreased with increasing amounts of nickel. The nickel content in the surface layer determined by X-ray photoelectron spectroscopy was larger than the total nickel content determined by inductively coupled plasma spectroscopy. The results obtained indicate that the substitution of iron with nickel took place in the surface layer more than in the internal phase.