Physical properties of akaganeite obtained by hydrolisis of Fe3+ in the presence of Al3+, Cr3+, and Cu2+

Abstract

ABSTRACT: This paper deals with the influence of Al, Cr, and Cu ions on the formation of akaganeite. Powder samples were prepared by thermal hydrolysis of several mixtures of iron and the other cations solutions at 70ºC during 48 hours. X-ray diffraction and Mössbauer spectrometry at 77 K and 300 K demonstrate that akaganeite is the only iron phase being formed. The X-ray patterns for all samples were adequately adjusted through Rietveld method with the monoclinic space group (C2/m:b3). This symmetry requires the existence of two distinct iron octahedral sites which is also confirmed by the Mössbauer spectrum in the paramagnetic state. No appreciable difference in the crystallographic parameters for all the samples were observed. The Mössbauer parameters both in the paramagnetic and in the magnetic states did not change appreciably. These results suggest that the metallic cations did not enter into the akaganeite`s crystallographic structure in a detectable amount.