High temperature synthesis and characteristics of Al-substituted iron alkoxide

Abstract

A crystalline solid identified as Al-substituted iron alkoxide is obtained from the reaction at 246° C of glycerol with synthetic Al-bearing goethite, when the latter's composition is: Fe 0.904Al 0.096 OOH. X-ray powder diffractograms (XRD) of this solid show a significant shift of the d spacings in comparison to a previously reported pure iron glycerate complex derived from synthetic α-FeOOH. The composition of the metallic alkoxide, calculated from chemical analysis data is: [(C 3H 5O 3Fe 0.98Al 0.02)] n . When this powder is calcined at 1000°C, well-crystallized Al-substituted hematite is produced, whose XRD patterns indicate a shift of the characteristic hematite lines to lower values. The partial (isomorphic) substitution of Fe by Al may also be ascertained from the hydrolysis of the [(C 3H 5O 3Fe 0.98Al 0.02)] n complex by boiling water; then the XRD and chemical analyses of the resulting product show limited formation of a spinel solid solution. In contrast, hydrolysis of pure iron alkoxide yields high amounts of ferrimagnetic spinel (mainly FeO·Fe 2O 3). Some characteristics of the Al-substituted iron alkoxide and of its hydrolysis and calcination products are briefly examined.