Coherent Interfaces between Crystals in Nanocrystal Composites

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Title Coherent Interfaces between Crystals in Nanocrystal Composites
Author Liu, Hongwei; Zheng, Zhanfeng; Yang, Dongjiang; Ke, Xuebin; Jaatinen, Esa; Zhao, Jin-Cai; Zhu, Huai Yong
Journal Name ACS Nano
Year Published 2010
Place of publication United States
Publisher American Chemical Society
Abstract Numerous materials are polycrystalline or consist with crystals of different phases. However, materials consisting of crystals on the nanometer scale (nanocrystals) are not simply aggregates of randomly oriented crystals as is generally regarded. We found, that in four different materials that consist of nanocrystals of two different phases and were obtained by different approaches, the nanocrystals of different phases are combined coherently forming interfaces with a close crystallographic registry between adjacent crystals (coherent interfaces). The four materials were fabricated by (i) depositing Ag2O nanoparticles on titanate nanofibers, (ii) phase transition from TiO2(B) nanofibers to the nanofibers of mixed TiO2(B) and anatase phases, (iii) dehydration of the single crystal fibril titanate core coated with anatase nanocrystals, and (iv) attaching zeolite Y nanocrystals on the surface of titanate nanofibers. The finding suggests that preferred orientations and coherent interfaces generally exist in nanocrystal systems, and according to our results, they are largely unaffected by the fabrication process that was used. This is because the preferred orientations require that the engaged crystal planes from two connected crystals have the same basal spacing and that the crystals can interlock tightly at the atomic level to form thermodynamically stable interfaces. Hence it is rational that the preferred orientations and coherent interfaces dominant the nanostructures formed between the different nanocrystals and play a key role in assembling the composite nanostructures. The orientation and interfaces between crystals of different phases in mixed-phase materials are extremely difficult to determine. Nonetheless, the thermodynamic stability of the coherent interfaces allows us to apply phase-transformation invariant line strain theory to predict the preferred orientation (and thus the structure of the coherent interfaces). The theoretical predications agree remarkably with the transmission electron microscopy (TEM) analysis. This implies that we may acquire knowledge of the orientation and the interface structures in the mixed-phase materials without TEM measurement, and the knowledge is essential for comprehensively understanding properties of the many materials and processes that depend on the interfaces.
Peer Reviewed Yes
Published Yes
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Copyright Statement Self-archiving of the author-manuscript version is not yet supported by this journal. Please refer to the journal link for access to the definitive, published version or contact the author[s] for more information.
Volume 4
Issue Number 10
Page from 6219
Page to 6227
ISSN 1936-0851
Date Accessioned 2011-07-18
Language en_AU
Research Centre Queensland Micro and Nanotechnology Centre
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Materials Engineering
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1x

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