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Title: The role of polymer films on the oxidation of magnetite nanoparticles

Abstract

A detailed investigation about the role of polymer films on the oxidation process of magnetite nanoparticles (∼7 nm diameter), under laser irradiation is performed employing micro Raman spectroscopy. To support this investigation, Fe{sub 3}O{sub 4}-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe{sub 3}O{sub 4}-np/PSS){sub n} with n=2,3,5,7,10 and 25 bilayers are employed as a model system to study the oxidation process under laser irradiation. Raman data are further processed by principal component analysis. Our findings suggest that PSS protects Fe{sub 3}O{sub 4}-np from oxidation when compared to powder samples, even for the sample with the greater number of bilayers. Further, the oxidation of magnetite to maghemite occurs preferably for thinner films up to 7 bilayers, while the onset for the formation of the hematite phase depends on the laser intensity for thicker films. Water takes part on the oxidation processes of magnetite, the oxidation/phase transformation of Fe{sub 3}O{sub 4}-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite. - Graphical abstract:more » Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films avoids the oxidation and phase transformation of nanosized magnetite. - Highlights: • (Fe{sub 3}O{sub 4}-np/PSS){sub n} nanofilms, with n=2 up to 25, where layer-by-layer assembled. • The influence of film architecture on the Fe{sub 3}O{sub 4}-np oxidation was investigated through Raman spectroscopy. • Encapsulation of Fe{sub 3}O{sub 4}-np by PSS showed to be very efficient to avoid the Fe{sub 3}O{sub 4}-np oxidation.« less

Authors:
 [1];  [2];  [3];  [4];  [1];  [1]
  1. Universidade de Brasilia, Instituto de Fisica, 70910-000 Brasilia, DF (Brazil)
  2. Universidade de Brasilia, Instituto de Quimica, 70910-000 Brasilia, DF (Brazil)
  3. Instituto de Fisica de São Carlos, USP, 13560-9700 São Carlos, SP (Brazil)
  4. (Brazil)
Publication Date:
OSTI Identifier:
22658166
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CATALYST SUPPORTS; ENCAPSULATION; EXPERIMENTAL DATA; FILMS; IRON OXIDES; LASER RADIATION; LAYERS; MAGNETITE; NANOPARTICLES; OXIDATION; PHASE TRANSFORMATIONS; POLYMERIZATION; POLYMERS; RAMAN SPECTROSCOPY

Citation Formats

Letti, C.J., Paterno, L.G., Pereira-da-Silva, M.A., Centro Universitario Central Paulista – UNICEP, 13563-470 São Carlos, SP, Morais, P.C., and Soler, M.A.G., E-mail: soler@unb.br. The role of polymer films on the oxidation of magnetite nanoparticles. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.10.027.
Letti, C.J., Paterno, L.G., Pereira-da-Silva, M.A., Centro Universitario Central Paulista – UNICEP, 13563-470 São Carlos, SP, Morais, P.C., & Soler, M.A.G., E-mail: soler@unb.br. The role of polymer films on the oxidation of magnetite nanoparticles. United States. doi:10.1016/J.JSSC.2016.10.027.
Letti, C.J., Paterno, L.G., Pereira-da-Silva, M.A., Centro Universitario Central Paulista – UNICEP, 13563-470 São Carlos, SP, Morais, P.C., and Soler, M.A.G., E-mail: soler@unb.br. Wed . "The role of polymer films on the oxidation of magnetite nanoparticles". United States. doi:10.1016/J.JSSC.2016.10.027.
@article{osti_22658166,
title = {The role of polymer films on the oxidation of magnetite nanoparticles},
author = {Letti, C.J. and Paterno, L.G. and Pereira-da-Silva, M.A. and Centro Universitario Central Paulista – UNICEP, 13563-470 São Carlos, SP and Morais, P.C. and Soler, M.A.G., E-mail: soler@unb.br},
abstractNote = {A detailed investigation about the role of polymer films on the oxidation process of magnetite nanoparticles (∼7 nm diameter), under laser irradiation is performed employing micro Raman spectroscopy. To support this investigation, Fe{sub 3}O{sub 4}-np are synthesized by the co-precipitation method and assembled layer-by-layer with sodium sulfonated polystyrene (PSS). Polymer films (Fe{sub 3}O{sub 4}-np/PSS){sub n} with n=2,3,5,7,10 and 25 bilayers are employed as a model system to study the oxidation process under laser irradiation. Raman data are further processed by principal component analysis. Our findings suggest that PSS protects Fe{sub 3}O{sub 4}-np from oxidation when compared to powder samples, even for the sample with the greater number of bilayers. Further, the oxidation of magnetite to maghemite occurs preferably for thinner films up to 7 bilayers, while the onset for the formation of the hematite phase depends on the laser intensity for thicker films. Water takes part on the oxidation processes of magnetite, the oxidation/phase transformation of Fe{sub 3}O{sub 4}-np is intensified in films with more bilayers, since more water is included in those films. Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films showed to be very efficient to avoid the oxidation process in nanosized magnetite. - Graphical abstract: Encapsulation of Fe{sub 3}O{sub 4}-np by PSS in layer-by-layer films avoids the oxidation and phase transformation of nanosized magnetite. - Highlights: • (Fe{sub 3}O{sub 4}-np/PSS){sub n} nanofilms, with n=2 up to 25, where layer-by-layer assembled. • The influence of film architecture on the Fe{sub 3}O{sub 4}-np oxidation was investigated through Raman spectroscopy. • Encapsulation of Fe{sub 3}O{sub 4}-np by PSS showed to be very efficient to avoid the Fe{sub 3}O{sub 4}-np oxidation.},
doi = {10.1016/J.JSSC.2016.10.027},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behaviormore » attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.« less
  • No abstract prepared.
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  • We report on the observations of coherent random lasers in weakly scattering polymer films embedded with silver nanoparticles. The dominant oscillation cavity calculated from the ensemble-averaged power Fourier transform spectrum of single-shot emission spectra is shorter by more than two orders of magnitude than the scattering mean-free path, indicating that the oscillation cavity is loosely associated with multiple scattering. We suggest that the coherent feedback arises from the cooperative effect of light scattering and field enhancement in the vicinity of silver nanoparticles.