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Structure and properties of nanoglasses

Horst Hahn 1Herbert D. Gleiter 2

1. Karlsruhe Institute of Technology (KIT), Karlsruhe 76131, Germany
2. Forschungszentrum Karlsruhe, Institute of Nanotechnology, P.O.B. 3640, Karlsruhe D-76021, Germany

Abstract

Interface or grain boundary effects in materials have been widely investigated since the discovery of nanocrystalline materials. Another interesting class of materials are nanoglasses or na¬nostructured amorphous solids. These materials can be produced by synthesis of amor¬phous nanoparticles in an inert-gas-condensation (IGC) process and subsequent compaction in UHV. The resulting solid material is characterised by its increased density of structural defects and free atomic volume in the interfaces between the former particles. Nanoglasses have been reported in a variety of binary alloys [1, 2]. Recent molecular dynamics simulations showed that the short-range order in the interface of Cu64Zr36 nanoglasses is significantly different from that found in the starting amorphous nanoparticles [3]. A combined study of small-angle X-ray scattering and positron annihilation lifetime spectroscopy on Sc75Fe25 nanoglasses has yielded evidence of a relative reduction of the atomic density in the interface by more than 10% [4].
These important structural modifications may give rise to new mechanical, transport or mag¬ne¬tic properties. Indeed we have evidence that in Fe90Sc10 nanoglasses, the magnetic state of the system is strongly affected. Mössbauer spectroscopy and magnetometric characterization reveal an increase of the Curie temperature by more than 200 K and an enhancement of the magnetic hyperfine field compared to the regular amorphous system, unexplainable by any compositional changes alone [5].

References:
[1]    Jing J. et al, Journal of Non-Crystalline Solids 113(2-3), 167170 (1989)
[2]    Weissmüller J. et al, Key Engineering Materials (Volumes 77 - 78), 161–170(1992)
[3]    Ritter Y. et al, accepted at Acta materialia (2011)
[4]    Fang J. X. et al, submitted (2011)
[5]    Witte R. et al, to be published

 

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Related papers

Presentation: Invited oral at Warsaw and Karlsruhe Nanotechnology Day, by Horst Hahn
See On-line Journal of Warsaw and Karlsruhe Nanotechnology Day

Submitted: 2011-08-26 17:28
Revised:   2011-08-29 15:17