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Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension

Here we report on the impact of reducing the crystalline size on the structural and magnetic properties of γ-Fe(2)O(3) maghemite nanoparticles. A set of polycrystalline specimens with crystallite size ranging from ~2 to ~50 nm was obtained combining microwave plasma synthesis and commercial samples....

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Autores principales: Coduri, Mauro, Masala, Paolo, Del Bianco, Lucia, Spizzo, Federico, Ceresoli, Davide, Castellano, Carlo, Cappelli, Serena, Oliva, Cesare, Checchia, Stefano, Allieta, Mattia, Szabo, Dorothee-Vinga, Schlabach, Sabine, Hagelstein, Michael, Ferrero, Claudio, Scavini, Marco
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279456/
https://www.ncbi.nlm.nih.gov/pubmed/32365930
http://dx.doi.org/10.3390/nano10050867
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author Coduri, Mauro
Masala, Paolo
Del Bianco, Lucia
Spizzo, Federico
Ceresoli, Davide
Castellano, Carlo
Cappelli, Serena
Oliva, Cesare
Checchia, Stefano
Allieta, Mattia
Szabo, Dorothee-Vinga
Schlabach, Sabine
Hagelstein, Michael
Ferrero, Claudio
Scavini, Marco
author_facet Coduri, Mauro
Masala, Paolo
Del Bianco, Lucia
Spizzo, Federico
Ceresoli, Davide
Castellano, Carlo
Cappelli, Serena
Oliva, Cesare
Checchia, Stefano
Allieta, Mattia
Szabo, Dorothee-Vinga
Schlabach, Sabine
Hagelstein, Michael
Ferrero, Claudio
Scavini, Marco
author_sort Coduri, Mauro
collection PubMed
description Here we report on the impact of reducing the crystalline size on the structural and magnetic properties of γ-Fe(2)O(3) maghemite nanoparticles. A set of polycrystalline specimens with crystallite size ranging from ~2 to ~50 nm was obtained combining microwave plasma synthesis and commercial samples. Crystallite size was derived by electron microscopy and synchrotron powder diffraction, which was used also to investigate the crystallographic structure. The local atomic structure was inquired combining pair distribution function (PDF) and X-ray absorption spectroscopy (XAS). PDF revealed that reducing the crystal dimension induces the depletion of the amount of Fe tetrahedral sites. XAS confirmed significant bond distance expansion and a loose Fe-Fe connectivity between octahedral and tetrahedral sites. Molecular dynamics revealed important surface effects, whose implementation in PDF reproduces the first shells of experimental curves. The structural disorder affects the magnetic properties more and more with decreasing the nanoparticle size. In particular, the saturation magnetization reduces, revealing a spin canting effect. Moreover, a large effective magnetic anisotropy is measured at low temperature together with an exchange bias effect, a behavior that we related to the existence of a highly disordered glassy magnetic phase.
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spelling pubmed-72794562020-06-17 Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension Coduri, Mauro Masala, Paolo Del Bianco, Lucia Spizzo, Federico Ceresoli, Davide Castellano, Carlo Cappelli, Serena Oliva, Cesare Checchia, Stefano Allieta, Mattia Szabo, Dorothee-Vinga Schlabach, Sabine Hagelstein, Michael Ferrero, Claudio Scavini, Marco Nanomaterials (Basel) Article Here we report on the impact of reducing the crystalline size on the structural and magnetic properties of γ-Fe(2)O(3) maghemite nanoparticles. A set of polycrystalline specimens with crystallite size ranging from ~2 to ~50 nm was obtained combining microwave plasma synthesis and commercial samples. Crystallite size was derived by electron microscopy and synchrotron powder diffraction, which was used also to investigate the crystallographic structure. The local atomic structure was inquired combining pair distribution function (PDF) and X-ray absorption spectroscopy (XAS). PDF revealed that reducing the crystal dimension induces the depletion of the amount of Fe tetrahedral sites. XAS confirmed significant bond distance expansion and a loose Fe-Fe connectivity between octahedral and tetrahedral sites. Molecular dynamics revealed important surface effects, whose implementation in PDF reproduces the first shells of experimental curves. The structural disorder affects the magnetic properties more and more with decreasing the nanoparticle size. In particular, the saturation magnetization reduces, revealing a spin canting effect. Moreover, a large effective magnetic anisotropy is measured at low temperature together with an exchange bias effect, a behavior that we related to the existence of a highly disordered glassy magnetic phase. MDPI 2020-04-30 /pmc/articles/PMC7279456/ /pubmed/32365930 http://dx.doi.org/10.3390/nano10050867 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Coduri, Mauro
Masala, Paolo
Del Bianco, Lucia
Spizzo, Federico
Ceresoli, Davide
Castellano, Carlo
Cappelli, Serena
Oliva, Cesare
Checchia, Stefano
Allieta, Mattia
Szabo, Dorothee-Vinga
Schlabach, Sabine
Hagelstein, Michael
Ferrero, Claudio
Scavini, Marco
Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title_full Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title_fullStr Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title_full_unstemmed Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title_short Local Structure and Magnetism of Fe(2)O(3) Maghemite Nanocrystals: The Role of Crystal Dimension
title_sort local structure and magnetism of fe(2)o(3) maghemite nanocrystals: the role of crystal dimension
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279456/
https://www.ncbi.nlm.nih.gov/pubmed/32365930
http://dx.doi.org/10.3390/nano10050867
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