Mechanical dehydration of γ-FeOOH by wet grinding procedures

Abstract

The decomposition of y-FeOOH induced mechanically in cyclohexane leads t o y-Fe203 which is more stable than the sample obtained by the thermal dehydration of unground y-FeOOH.

Prereactional transformations in the topotactic conversion γ-FeOOH → γ-Fe2O3

“…The confirmation of our presumption about the indispensability of dehydroxylation resulting in cation excess in the y-FeOOH lattice as necessary for the y-Fe,03 spinel phase formation may be the distinct decrease of temperature of that phase transition when lepidocrocite is heated with organic bases 1171, as well as the increase of the a-Fe,O,/y-Fe,O, ratio with the increase of water vapour partial pressure during heating of y -FeOOH [18]. The mechanical transformation a t ambient temperature during dry grinding in an automatic mortar yields a-Fe,O, [ 5 ] , but an information published very recently about y-Fe,O, obtained during mechanical decomposition of y-FeOOH in cyclohexane [7] implies that in these conditions the process of dehydroxylatiori of lepidocrocite proceeds faster than the destruction of its layer structure. spinel structure.…”