Polymer encapsulation effects on the magnetism of EuS nanocrystals

authors	Pereira, AS; Rauwel, P; Reis, MS; Silva, NJO; Barros-Timmons, A; Trindade, T
nationality	International
journal	JOURNAL OF MATERIALS CHEMISTRY
keywords	SINGLE-MOLECULE PRECURSORS; RADICAL POLYMERIZATION; MINIEMULSION POLYMERIZATION; CARBON NANOTUBES; LATEX-PARTICLES; QUANTUM DOTS; CDE E; NANOPARTICLES; ROUTE; NANOMATERIALS
abstract	Surface mediated phenomena are important in controlling the magnetism of nanocrystals. Here, we provide a versatile chemical method which allows the formation of EuS nanocrystals encapsulated in poly(styrene) (PS). These materials are the first example of a polymer based EuS nanocomposite prepared in situ. Besides their practical interest, these materials are of general relevance because they allow fundamental knowledge on the magnetism of EuS, which is commonly used as a model of an insulating ferromagnet, to be acquired. Comparatively to the starting powders of EuS nanocrystals (8 nm), in the final nanocomposites there is a decrease of the blocking temperature TB and a change in the shape of the field-cooled susceptibility curve, indicating that the intensity of dipolar interactions decreases when the nanoparticles are incorporated into PS. Differences in the magnetic properties of the EuS nanocrystals and the EuS/PS nanocomposites are also due to the appearance of a peak in the susceptibility at 60 K, in the latter sample, ascribed to surface phenomena occurring in EuS nanocrystals dispersed in the polymer matrix.
publisher	ROYAL SOC CHEMISTRY
issn	0959-9428
year published	2008
volume	18
issue	38
beginning page	4572
ending page	4578
digital object identifier (doi)	10.1039/b806499g
web of science category	Chemistry, Physical; Materials Science, Multidisciplinary
subject category	Chemistry; Materials Science
unique article identifier	WOS:000259411300010