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Binary Superlattices from {Mo 132 } Polyoxometalates and Maghemite Nanocrystals: Long‐Range Ordering and Fine‐Tuning of Dipole Interactions
Author(s) -
Breitwieser Romain,
Auvray Thomas,
Volatron Florence,
Salzemann Caroline,
Ngo AnhTu,
Albouy PierreAntoine,
Proust Anna,
Petit Christophe
Publication year - 2016
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201502127
Subject(s) - superlattice , maghemite , materials science , nanocrystal , range (aeronautics) , dipole , nanotechnology , nanoparticle , binary number , chemical physics , optoelectronics , chemistry , organic chemistry , arithmetic , mathematics , composite material
In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ‐Fe 2 O 3 ) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo 132 } is demonstrated. To do so, colloidal solutions of oleic acid‐capped γ‐Fe 2 O 3 and long‐chain alkylammonium‐encapsulated {Mo 132 } dispersed in chloroform are mixed together and supported self‐organized binary superlattices are obtained upon the solvent evaporation on immersed substrates. Both electronic microscopy and small angles X‐ray scattering data reveal an AB‐type structure and an enhanced structuration of the magnetic nanocrystals (MNCs) assembly with POMs in octahedral interstices. Therefore, {Mo 132 } acts as an efficient binder constituent for improving the nanocrystals ordering in 3D films. Interestingly, in the case of didodecyldimethylammonium (C 12 )‐encapsulated POMs, the long‐range ordered binary assemblies are obtained while preserving the nanocrystals magnetic properties due to weak POMs–MNCs interactions. On the other hand, POMs of larger effective diameter can be employed as spacer blocks for MNCs as shown by using {Mo 132 } capped with dioctadecyldimethylammonium (C 18 ) displaying longer chains. In that case, it is shown that POMs can also be used for fine‐tuning the dipolar interactions in γ‐Fe 2 O 3 nanocrystal assemblies.