2005

StructureD 2000 Synthesis and Structural Analysis of ε-Fe2O3. — ε-Fe2O3 is obtained from the

mineral nontronite (Na0.3Fe2Si3AlO10(OH)2·nH2O) by thermal decomposition (alumina boat, 900→970 °C, 30 h) and subsequent leaching of the silicate phases (5 M aq. NaOH, 70 °C, 5 d). Rietveld refinement of powder XRD data combined with electron diffraction results shows that ε-Fe2O3 crystallizes in the orthorhombic space group Pna21 (Z = 8) and is isotypic with κ-Al2O3, AlFeO3, and GaFeO3. The presence of some strongly distorted FeO6 octahedra with one large Fe—O distance, which may be con-sidered as a 5+1 coordination, appears to be characteristic for ε-Fe2O3. — (KELM, K.; MADER*, W.; Z. Anorg. Allg. Chem. 631 (2005) 12, 2383-2389; Inst. Anorg. Chem., Rhein. Friedrich-Wilhelms-Univ., D-53121 Bonn, Germany; Eng.) — Schramke

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