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Structure and Magnetic Properties of Nanocomposite Fe2O3/TiO2 Catalysts Fabricated by Heterogeneous Precipitation

Year: 2012 Volume: 6 Issue: 1 1 - 4 Pages

• Authors:
• Jana P. Vejpravova
• Daniel Niznansky
• Vaclav Vales
• Barbara Bittova
• Vaclav Tyrpekl
• Stanislav Danis
• Vaclav Holy
• Stephen Doyle

Abstract: The aim of our work is to study phase composition, particle size and magnetic response of Fe2O3/TiO2 nanocomposites with respect to the final annealing temperature. Those nanomaterials are considered as smart catalysts, separable from a liquid/gaseous phase by applied magnetic field. The starting product was obtained by an ecologically acceptable route, based on heterogeneous precipitation of the TiO2 on modified g-Fe2O3 nanocrystals dispersed in water. The precursor was subsequently annealed on air at temperatures ranging from 200 oC to 900 oC. The samples were investigated by synchrotron X-ray powder diffraction (S-PXRD), magnetic measurements and Mössbauer spectroscopy. As evidenced by S-PXRD and Mössbauer spectroscopy, increasing the annealing temperature causes evolution of the phase composition from anatase/maghemite to rutile/hematite, finally above 700 oC the pseudobrookite (Fe2TiO5) also forms. The apparent particle size of the various Fe2O3/TiO2 phases has been determined from the highquality S-PXRD data by using two different approaches: the Rietveld refinement and the Debye method. Magnetic response of the samples is discussed in considering the phase composition and the particle size.

• Keywords:
• X-ray diffraction
• profile analysis
• Mössbauer spectroscopy
• magnetic properties
• TiO2
• Fe2O3
• Fe2TiO5

Nanosize Structure Phase States in the Titanium Surface Layers after Electroexplosive Carburizing and Subsequent Electron Beam Treatment

Year: 2011 Volume: 5 Issue: 11 1655 - 1657 Pages

• Authors:
• Victor E. Gromov
• Evgenii A. Budovskikh
• Ludmila P. Bashchenko
• Yurii F. Ivanov
• Anna V. Ionina
• Nina A. Soskova
• Guoyi Tang

Abstract: The peculiarities of the nanoscale structure-phase states formed after electroexplosive carburizing and subsequent electron-beam treatment of technically pure titanium surface in different regimes are established by methods of transmission electron diffraction microscopy and physical mechanisms are discussed. Electroexplosive carburizing leads to surface layer formation (40 m thickness) with increased (in 3.5 times) microhardness. It consists of β-titanium, graphite (monocrystals 100-150 nm, polycrystals 5-10 nm, amorphous particles 3-5nm), TiC (5-10 nm), β-Ti02 (2-20nm). After electron-beam treatment additionally increasing the microhardness the surface layer consists of TiC.

• Keywords:
• nanoscale
• phase
• structure
• titanium