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Electron Tomography Analysis of Reaction Path during Formation of Nanoporous NiO by Solid State Decomposition
journal contribution
posted on 2014-05-07, 00:00 authored by A. K. Shukla, P. Ercius, A. R.
S. Gautam, J. Cabana, U. DahmenUsing transmission electron microscopy,
we have analyzed the structure
of nanoporous NiO formed by thermal decomposition of Ni(OH)2. It was found that a tabular single crystal of Ni(OH)2 transforms pseudomorphically to an array of topotaxially aligned
NiO nanocubes separated by nanoscale pores at a volume fraction of
about 50%. High-resolution electron tomography on NiO produced by
ex situ heating combined with direct in situ observation of the transformation
under the electron beam revealed a dramatic redirection of the reaction
front when pores are closed by consolidation of NiO nanocubes around
the perimeter of the tabular crystals. This causes local changes in
the density, structure, and connectivity of the pores. Insights from
this study are of broader interest for the class of decomposition
reactions that result in nanocrystalline materials with highly tailored
porosity and are significant for the development of devices with impact
in fields as varied as energy storage, catalysis, and sensing.