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Self-organization of inorganic nanocrystals

Self-organizations of inorganic nanocrystals in 1D, 2D and 3D superlattices are described. In the latter case, supra-crystals with face-centred-cubic (fcc) structure are demonstrated. Collective properties due to the nanocrystal organization are described. These properties are either intrinsic or due to dipolar interactions.

 

Source: Self-organization of inorganic nanocrystals M.P.Pileni J. Phys.: Condens. Matter,2006, 18, S67–S84.

peer journals

Do Binary Supracrystals Enhance the Crystal Stability?

Z. Yang,T. Altantzis,S.Bals, G. Van Tendeloo, M. P. Pileni J.Phys. Chem.C., 2018, DOI. 10.1021/acs.jpcc.7b12373

We study the oxygen thermal stability of two binary systems. The larger particles are magnetic Co (7.2 nm) or Fe3O4 (7.5 nm)  nanocrystals whereas the smaller ones (3.7 nm) are Au nanocrystals. The nanocrystal ordering, as well as the choice of the magnetic nanoparticles very much influence the stability of the binary system. A perfect crystalline structure is obtained with the  Fe3O4/Au binary supracrystals. For the Co/Au binary system, oxidation of Co results in the chemical transformation from Co to CoO, where the size of the Co nanoparticles increases from 7.2 to 9.8 nm in diameter. During the volume expansion of the Co nanoparticles, Au nanoparticles within the binary assemblies coalescence and are at the origin of the instability of the binary nanoparticle supracrystals. On the other hand, for the Fe3O4/Au binary system, the oxidation of Fe3O4  to g-Fe2Odoes not lead to a size change of the nanoparticles, which maintains the stability of the binary nanoparticle supracrystals.

 

 

 

peer journals

Control of the size and shape of inorganic nanocrystals at various scales from nano to macrodomains.

In this paper, we propose the hypothesis that, in highly pure media, the cluster shape can be retained at various scales. Impurities and/or the additives can control the shape of the developing crystals by adsorption on selective sites. We demonstrate that the shape of clusters is retained at the nanoscale. This is supported by structural studies and both experiment and simulated optical properties of nanocrystal assemblies. We compare the data to those obtained by using a large variety of techniques and observation of crystal growth in nature.

Source : Control of the size and shape of inorganic nanocrystals at various scales from nano to macrodomains. M.P. Pileni J. Phys. Chem. C 111, 2007, 9019-9038

peer journals

Self-assembly of inorganic nanocrystals: Fabrication and collective intrinsic properties. 

In this Account, we demonstrate that the ordering of nanocrystals over long distances in 3D superlattices, called supracrystals, can lead to unexpected results: the emergence of collective intrinsic properties. The shape of the nanocrystal organization at the mesoscopic scale also induces new physical properties. In addition, we show that nanocrystals can be used as masks for lithography.

Source : Self-assembly of inorganic nanocrystals: Fabrication and collective intrinsic properties. M.P. Pileni Acc. of Chem. Res., 2007, 40, 685-693.

 

peer journals

Use of reverse micelles to make either spherical or worm-like palladium nanocrystals: Influence of stabilizing agent on nanocrystal shape.

Depending on thewater content, reversemicelles induce the formation of fccmetallic palladiumworm-like nanocrystals made of spheres. After extraction from the nanoreactor, either spheres or worm-like nanocrystals are obtained, and it was found that the binding energy between the coating agent and the Pd surface is a key parameter in shape control (i.e., in the surface reconstruction).

Source : Use of reverse micelles to make either spherical or worm-like palladium nanocrystals: Influence of stabilizing agent on nanocrystal shape. K. Naoe, C. Petit and M.P. Pileni Langmuir, 2008, 24, 2792-2798.

peer journals

2D self-organization of core/shell COhcp/Co nanocrystals.

In this paper we report the preparation of ordered hexagonal 2D arrays of core/shell Cohcp/CoO nanocrystals. A full structural investigation has been carried out using high-resolution transmission electron microscopy, electron diffraction, and electron energy-loss spectroscopy.

Source : 2D self-organization of core/shell COhcp/Co nanocrystals. I. Lisiecki, M. Walls, D. Parker and M.P. Pileni, Langmuir, 2008, 24, 4295-4299.

peer journals

How do self-ordered silver nanocrystals influence their growth into triangular single crystals ?

Thin triangular silver single crystals are obtained by annealing self-ordered 5 nm silver nanocrystals coated with decanethiol at 50 ° C and deposited on highly oriented pyrolitic graphite (HOPG). With the annealing time, the nanocrystals coalesce progressively in the 2D hexagonal arrays and 3D face-centered cubic (fcc) superlattices. By controlling the ordering degree of the nanocrystal assemblies, we observe that the size of the ordered domains tunes the final size of the triangles.

Source : How do self-ordered silver nanocrystals influence their growth into triangular single crystals ? A.I. Henry, A. Courty, N. Goubet and M.P. Pileni J. Phys. Chem. C , 2008, 112, 48-52.