6533b855fe1ef96bd12b1235
RESEARCH PRODUCT
XPS and EELS investigations of chemical homogeneity in nanometer scaled Ti-ferrites obtained by soft chemistry
Bruno DomenichiniE. FriesNadine MillotPascal Perriatsubject
Materials sciencePrecipitation (chemistry)SpinelOxidechemistry.chemical_elementGeneral Chemistryengineering.materialCondensed Matter PhysicsNanocrystalline materialSoft chemistrychemistry.chemical_compoundCrystallographyX-ray photoelectron spectroscopychemistryChemical engineeringOxidizing agentengineeringGeneral Materials ScienceTitaniumdescription
Abstract Nanocrystalline Ti-ferrites with composition Fe 3− x Ti x O 4 with 0≤ x ≤1 are synthesized using the soft chemistry route. Heterogeneities in precipitate and annealed powders are investigated by a combination of XPS and EELS techniques. As-prepared powder consists in particles with spinel structure and grain size of about 15 nm. Due to high reactivity towards oxygen of nanoparticules, a significant amount of Fe 2+ cations oxidize during precipitation, so that precipitated powders present large deviation from oxygen-metal stoichiometry. Moreover precipitated particles are evidenced to exhibit a strong surface titanium enrichment and an iron richer core. Observation of such cation segregation proves that, during oxide formation process, kinetics of Ti precipitation is slower than that of Fe one. Conditions for tailoring nanocrystalline samples with satisfying composition homogeneity are finally obtained by determination of an appropriate annealing under oxidizing conditions which enables to eliminate Fe–Ti segregation.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1999-02-01 |