Über Silberferrite X. Mitteilung γFeOOH aus Ferrocarbonat und die Umwandlung des γFeOOH in αFeOOH

Abstract

Durch Oxydation von gefälltem Ferrocarbonat mit Luftsauerstoff erhält man unter gewissen Vorsichtsmaßregeln γ‐FeOOH. Nähere Untersuchungen, welche sich auf das DEBYE‐SCHERRER‐ Diagramm, die Entwässerung zu γ‐Fe2O3, die Silberferritsynthese, die Alterung bei 20° und die kolloidchemischen Eigenschaften erstreckten, ergaben, daß dieses Hydrat sich von dem Metahydroxyd nach KRAUSE [γ‐FeOOH aus Fe(OH)2] kaum unterscheidet: Beide Hydrate sind als praktisch reine, kristalline eisenige Säuren anzusehen. Durch Peptisation in verd. Säuren entstehen positiv geladene, durch Alkalipeptisation negative Hydrosole.

Preparation of nanocrystalline Ti, Mn, Co, Fe, and Zn Oxides via heat treatment in aqueous solutions

“…XRD data indicate that, during heat treatment in solution, the nonequilibrium phases γ -and δ -FeOOH may undergo phase transformations (to α -FeOOH ) or chemical changes (to α -Fe 2 O 3 ), in accordance with earlier reports [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. XRD data indicate that, during heat treatment in solution, the nonequilibrium phases γ -and δ -FeOOH may undergo phase transformations (to α -FeOOH ) or chemical changes (to α -Fe 2 O 3 ), in accordance with earlier reports [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

“…The average size and habit of α-FeOOH crystallites forming from γand δ-FeOOH also depend on the heattreatment conditions, in accordance with earlier results [9,11,23]. For example, α-FeOOH prepared by heattreating γ-FeOOH in distilled water consists of columnar crystallites.…”

Preparation of nanocrystalline Ti, Mn, Co, Fe, and Zn oxides via heat treatment in aqueous solutions

“…XRD data indicate that, during heat treatment in solution, the nonequilibrium phases γ -and δ -FeOOH may undergo phase transformations (to α -FeOOH ) or chemical changes (to α -Fe 2 O 3 ), in accordance with earlier reports [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Micrographs of intermediate reaction products clearly show etch patterns on the parent crystallites ( Fig.…”

“…The average size and habit of α-FeOOH crystallites forming from γ-and δ-FeOOH also depend on the heattreatment conditions, in accordance with earlier results [9,11,23]. For example, α-FeOOH prepared by heattreating γ-FeOOH in distilled water consists of columnar crystallites.…”

The Transformation of Lepidocrocite to Goethite

“…LEPIDOCROCITE being less stable than its polymorph goethite can easily be converted to goethite in the presence of alkali hydroxide (Krause et al, 1934) or ferrous sulphate solutions (Baudisch and Albrecht, 1932). This transformation was thought by Nitschmann (1938) to be a topotactic reaction.…”