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Type: Artigo de periódico
Title: Chemical synthesis and structural characterization of highly disordered ni colloidal nanoplarticles
Author: Winnischofer, H
Rocha, TCR
Nunes, WC
Socolovsky, LM
Knobel, M
Zanchet, D
Abstract: This work focuses on synthetic methods to produce monodisperse Ni colloidal nanoparticles (NPs), in the 4-16 nm size range, and their structural characterization. Narrow size distribution nanoparticles were obtained by high-temperature reduction of a nickel salt and the production of tunable sizes of the Ni NPs was improved compared to other methods previously described. The as-synthesized nanciparticles exhibited spherical shape and highly disordered structure, as it could be assigned by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Annealing at high temperature in organic solvent resulted in an increase of nanoparticle atomic ordering; in this case, the XRD pattern showed an fcc-like structure. Complementary data obtained by X-ray absorption spectroscopy confirmed the complex structure of these nanoparticles. Temperature dependence of the magnetic susceptibility of these highly disordered Ni NPs showed the magnetic behavior cannot be described by the conventional superparamagnetic theory, claiming the importance of the internal structure in the magnetic behavior of such nanomaterials.
Subject: nanoparticle
crystal structure
magnetic properties
Country: EUA
Editor: Amer Chemical Soc
Rights: fechado
Identifier DOI: 10.1021/nn700152w
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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