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- Superparamagnetic Ni:SiO2-C nanocomposites films synthesized by a polymeric precursor method
- Inst Pesquisas Energeticas & Nucl
- Universidade de São Paulo (USP)
- Universidade Federal do ABC (UFABC)
- Universidade Federal de São Carlos (UFSCar)
- Universidade Estadual Paulista (UNESP)
- Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
- Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
- Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
- In this work, we report on the magnetic properties of nickel nanoparticles (NP) in a SiO2-C thin film matrix, prepared by a polymeric precursor method, with Ni content x in the 0-10 wt% range. Microstructural analyses of the films showed that the Ni NP are homogenously distributed in the SiO2-C matrix and have spherical shape with average diameter of similar to 10 nm. The magnetic properties reveal features of superparamagnetism with blocking temperatures T (B) similar to 10 K. The average diameter of the Ni NP, estimated from magnetization measurements, was found to be similar to 4 nm for the x = 3 wt% Ni sample, in excellent agreement with X-ray diffraction data. M versus H hysteresis loops indicated that the Ni NP are free from a surrounding oxide layer. We have also observed that coercivity (H (C)) develops appreciably below T (B), and follows the H (C) ae [1 - (T/T (B))(0.5)] relationship, a feature expected for randomly oriented and non-interacting nanoparticles. The extrapolation of H (C) to 0 K indicates that coercivity decreases with increasing x, suggesting that dipolar interactions may be relevant in films with x > 3 wt% Ni.
- Journal of Nanoparticle Research. Dordrecht: Springer, v. 13, n. 2, p. 703-710, 2011.
- Polymeric precursor method
- Spin coating
- Nickel nanoparticles
- Acesso restrito
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