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Issue 39, 2010
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Tailoring the nanoscale boundary cavities in rutile TiO2 hierarchical microspheres for giant dielectric performance

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Abstract

Rutile TiO2 hierarchical microspheres were prepared by a facile solution chemistry method with an aim to achieve nanoscale boundary cavities (NBCs) that can be tailored for optimum giant dielectric performance. The formation of these microspheres proceeded via a supersaturated spontaneous nucleation and a subsequent radial growth to develop into well-defined 3D hierarchical structures. All microspheres showed a diameter of about 8–10 μm and were constructed by small bundles that consisted of smaller nanowires with a diameter of 8–10 nm. These nanowires are characterized by a preferential growth along the [001] direction which eventually led to the externally exposed (110) planes for hierarchical microspheres. Strikingly, in between these constituent nanowires, there existed plenty of NBCs that created a great number of surface defect dipoles. The NBCs were further tailored by subsequent annealing of the microspheres, as clearly indicated by lattice contraction, linear increase of axis ratio, and red-shift of band-gap energy. As a consequence, rutile TiO2 hierarchical microspheres showed an optimum giant permittivity of approximately 104 level till 500 Hz at room temperature, compatible to the known giant-dielectric multicomponent materials such as CaCu3Ti4O12. These findings were rationalized in terms of NBCs and the resulting surface defect dipoles. As a reproductive prototype, tailoring of the NBCs in rutile hierarchical microspheres as reported in this work can be applied to a broad class of assembled nanostructures and probably film systems to modulate the dielectric performances for advanced electronic device aspects.

Graphical abstract: Tailoring the nanoscale boundary cavities in rutile TiO2 hierarchical microspheres for giant dielectric performance

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Publication details

The article was received on 28 Apr 2010, accepted on 14 Jul 2010 and first published on 08 Sep 2010


Article type: Paper
DOI: 10.1039/C0JM01232G
Citation: J. Mater. Chem., 2010,20, 8659-8667
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    Tailoring the nanoscale boundary cavities in rutile TiO2 hierarchical microspheres for giant dielectric performance

    W. Hu, L. Li, W. Tong, G. Li and T. Yan, J. Mater. Chem., 2010, 20, 8659
    DOI: 10.1039/C0JM01232G

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