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Assembly of sol-gel-grown $Li _{(x)} CoO_{2}$ nanocrystals through electromagnetic irradiation

Das, Mahua and Ranjith, R and Bittencourt, C and Krupanidhi, SB and Pireaux, JJ and Shivashankar, SA (2009) Assembly of sol-gel-grown $Li _{(x)} CoO_{2}$ nanocrystals through electromagnetic irradiation. In: Applied Physics A: Materials Science & Processing, 95 (2). pp. 523-536.

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We report the fabrication of assembled nanostructures from the pre-synthesized nanocrystals building blocks through optical means of exciton formation and dissociation. We demonstrate that Li (x) CoO2 nanocrystals assemble to an acicular architecture, upon prolonged exposure to ultraviolet-visible radiation emitted from a 125 W mercury vapor lamp, through intermediate excitation of excitons. The results obtained in the present study clearly show how nanocrystals of various materials with band gaps appropriate for excitations of excitons at given optical wavelengths can be assembled to unusual nanoarchitectures through illumination with incoherent light sources. The disappearance of exciton bands due to Li (x) CoO2 phase in the optical spectrum of the irradiated film comprising acicular structure is consistent with the proposed mechanism of exciton dissociation in the observed light-induced assembly process. The assembly process occurs through attractive Coulomb interactions between charged dots created upon exciton dissociation. Our work presents a new type of nanocrystal assembly process that is driven by light and exciton directed.

Item Type: Journal Article
Publication: Applied Physics A: Materials Science & Processing
Publisher: Springer
Additional Information: Copyright of this article belongs to Springer.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 22 Apr 2009 05:28
Last Modified: 19 Sep 2010 05:29
URI: http://eprints.iisc.ac.in/id/eprint/19656

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