Structures of Ti(IV)-doped α-FeOOH particles

The influence of Ti(iv) on the formation and structure of alpha-FeOOH particles was investigated by characterizing the coprecipitation products of Fe(iii) with Ti(iv) at different atomic ratios (Ti/Fe) in the range 0-0.1. The particle width of the products increased as Ti/Fe was increased. At Ti/Fe greater than or equal to 0.05 the crystallite size of alpha-FeOOH increased with increase of Ti/Fe while the XRD peaks decreased in intensity. Thermal analysis and Mossbauer spectroscopy showed that the alpha-FeOOH phase diminishes upon doping with Ti(iv) and that less crystalline regions composed of agglomerates of fine particles develop. EXAFS revealed that the doped Ti(iv) disturbs the nearest coordination structure surrounding Fe(iii). According to N-2 adsorption, micropores are formed in the particles upon addition of Ti(iv). It is deduced from the obtained results that the addition of Ti(iv) produces double domain particles consisting of an alpha-FeOOH core and a porous poorly crystalline shell.