Becker, Klaus-Dieter

Da Silva, Klebson L.

Fabián, Martin

Feldhoff, Armin

Menzel, Dirk

Myndyk, Maxym

Šepelák, Vladimir

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diffusion-fundamentals   The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application www.diffusion-fundamentals.org, ISSN 1862-4138; © 2005-2010   Diffusion Fundamentals 12 (2010) 84  © M. Fabián Structural Properties of Nanocrystalline Olivine  Prepared by Ball Milling  M. Fabián,*,1 M. Myndyk,2 K. L. da Silva,3 A. Feldhoff, 3 D. Menzel,4  K.-D. Becker,2 V. Šepelák 2  1 Institute of Geotechnics, Slovak Academy of Sciences,  Watsonova 45, 04353 Košice, Slovakia 2 Institute of Physical and Theoretical Chemistry, Braunschweig University of Technology, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany 3 Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover,  Callinstr. 3a, 30167 Hannover, Germany 4 Institute of Condensed Matter Physics, Braunschweig University of Technology,  Mendelssohnstr. 3, 38106 Braunschweig, Germany  E-Mail: fabianm@saske.sk  Presented at the Bunsen Colloquium: Spectroscopic Methods in Solid State Diffusion and Reactions September 24th − 25th, 2009, Leibniz University Hannover, Germany   One goal of modern materials research and development has been to identify simpler process-ing schemes that do not require high-temperature treatment to induce solid-state reactions. Among the many types of preparation techniques, the nonconventional mechanochemical synthesis has been recognized as a powerful route to novel, high-performance and low-cost nanomaterials [1]. In the present work, a synthesis of nanocrystalline olivine (FexMg1−x)2SiO4 (x = 0,  0.5,  1) prepared via mechanochemical processing of the α-Fe2O3/Fe/MgO/SiO2 mixture in argon atmosphere at room temperature is reported. The mechanically induced phase evolution of the mixture is followed by XRD. Due to the ability of 57Fe Mössbauer spectroscopy to discrimi-nate between probe nuclei on the two nonequivalent crystallographic sites provided by the olivine structure (octahedrally coordinated M1 and M2 sites), valuable insight into the local cation disorder in mechanosynthesized (FexMg1−x)2SiO4 is obtained. However, it was found that Fe2+ has a slight preference for the M1 site at temperatures below approximately 500 °C, with a tendency of disordering around this temperature [2,3], the cation distribution in nanosized materials is still not clear. Quantitative information on the short-range structure, provided by the nuclear spectroscopic technique, is complemented by the investigation of the magnetic behavior (SQUID measurements) of mechanochemically prepared olivine on a mac-roscopic scale. High-resolution TEM studies revealed a non-uniform structure of mechano-Fabián et al., Structural properties of nanocrystalline olivine  diffusion-fundamentals    www.diffusion-online.org  Diffusion Fundamentals 12 (2010) 85  © M. Fabián synthesized (FexMg1−x)2SiO4 nanoparticles consisting of an ordered core surrounded by a dis-ordered surface shell region. References [1]  V. Šepelák, I. Bergmann, A. Feldhoff, P. Heitjans, F. Krumeich, D. Menzel, F. J. Litterst, S. J. Campbell, K. D. Becker,  J. Phys. Chem. C 111 (2007) 5026. [2]  M. Morozov, Ch. Brinkmann, M. Grodzicki, W. Lottermoser, G.Tipplet, G. Amthauer, H. Kroll, Hyperfine Interactions 166 (2005) 573. [3]  Y. A. Abdu, H. Annersten, T. Ericsson, E.C. Hawthorne, Hyperfine Interactions 186 (2008) 981. 

Structural properties of nanocrystalline olivine prepared by ball milling

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Structural properties of nanocrystalline olivine prepared by ball milling

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