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1999 (1)
1Author    Carla Cannas, Giorgio Concas, Anna Musinu, Giorgio Piccaluga, Giorgio SpanoRequires cookie*
 Title    Mössbauer Spectroscopic Study of Fe 2 0 3 Nanoparticles Dispersed over a Silica Matrix  
 Abstract    A series of Fe 2 0 3 -Si02 nanocomposites (9 -33 wt% of Fe 2 0 3) has been prepared by a sol-gel method and submitted to thermal treatments at 300 -900 °C. The samples were characterized by X-ray diffraction and Mössbauer Spectroscopy measurements. Superparamagnetic behavior is exhibited by all the samples, indicating that the size of iron oxide grains is in the nanometer range (4-6 nm). Increase of iron content and temperature treatment give rise to a small particle growth, while the spread of sizes around the average value increases with the iron concentration. The Mössbauer spectra, at all the explored compositions, show a very steep increase of the peak width by treatment temperature at 900 °C, indicating the formation of the ferrimagnetic 7-Fe 2 0 3 phase from the antiferromagnetic amorphous Fe 2 0 3 phase, which dominates in the samples treated at lower temperatures. The samples at 28.5% and 33.2%, treated at 900 °C, also show a component of 7-Fe 2 0 3 in the blocked state at room temperature. Moreover, the growth of the particles favours the formation of other oxide phases (a and £ phase) along with the 7 phase. 
  Reference    Z. Naturforsch. 54a, 513—518 (1999); received June 28 1999 
  Published    1999 
  Keywords    Nanocomposite, Ferric Oxide, Mössbauer Spectroscopy, X-ray Diffraction 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0513.pdf 
 Identifier    ZNA-1999-54a-0513 
 Volume    54