Structure of highly divided nonstoichiometric iron manganese oxide powders Fe{sub 3{minus}x}Mn{sub x{open_square}{sub 3{delta}/4}}O{sub 4+{delta}}
- Univ. Paul Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganiques et Enginetiques
Highly divided iron manganese oxide powders, Fe{sub 3{minus}x}Mn{sub x{open_square}{sub 3{delta}/4}}O{sub 4+{delta}}, were prepared at low temperature (T {le} 560 C) by the thermal decomposition of mixed oxalate precursors Fe{sub 1{minus}{alpha}}Mn{sub {alpha}}C{sub 2}O{sub 4}, 2H{sub 2}O ({alpha} = x/3). The manganese-rich compounds (x {ge} 1.5) have a complex structure that can be cubic, tetragonal, or a mixture of both tetragonal and cubic spinel phases that indicates a lack of miscibility existing in the Fe{sub 3}O{sub 4}-Mn{sub 3}O{sub 4} phase diagram at low temperature. The structure strongly depends on the chemical composition but also on the nonstoichiometric coefficient ({delta}). It has been identified as one of the mineral vredenburgite and has never been reported before for powders prepared by chimie douce. The oxygen excess, determined by thermogravimetric analyses, is the highest ({delta} = 0.4) when the oxide is prepared at 410 C. These oxides are defect spinel phases containing cationic vacancies.
- OSTI ID:
- 679265
- Journal Information:
- Journal of Solid State Chemistry, Vol. 146, Issue 1; Other Information: PBD: Aug 1999
- Country of Publication:
- United States
- Language:
- English
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