Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/243187
Type: Artigo
Title: The role of oxygen vacancies and their location in the magnetic properties of Ce1-xCuxO2-delta nanorods
Author: Bernardi, M. I. B.
Mesquita, A.
Béron, F.
Pirota, K. R.
Zevallos, A. O. de
Doriguetto, A. C.
Carvalho, H. B. de
Abstract: Ceria (CeO2) is a promising dilute magnetic semiconductor. Several studies report that the intrinsic and extrinsic structural defects are responsible for room temperature ferromagnetism in undoped and transition metal doped CeO2 nanostructures; however, the nature of the kind of defect necessary to promote and stabilize the ferromagnetism in such a system is still a matter of debate. In the work presented here, nanorods from the system Ce1-xCuxO2-delta with x = 0, 0.01, 0.03, 0.05 and 0.10, with the more stable {111} surface exposed were synthesized by a microwave-assisted hydrothermal method. A very careful structure characterization confirms that the Cu in the samples assumes a majority 2+ oxidation state, occupying the Ce (Ce4+ and Ce3+) sites with no secondary phases up to x = 0.05. The inclusion of the Cu2+ in the CeO2 structure leads to the introduction of oxygen vacancies in a density proportional to the Cu2+ content. It is supposed that the spatial distribution of the oxygen vacancies follows the Cu2+ distribution by means of the formation of a defect complex consisting of Cu2+ ion and an oxygen vacancy. Superconducting quantum interference device magnetometry demonstrated a diamagnetic behavior for the undoped sample and a typical paramagnetic Curie-Weiss behavior with antiferromagnetic interactions between the Cu2+ ions for the single phase doped samples. We suggest that the presence of oxygen vacancies is not a sufficient condition to mediate ferromagnetism in the CeO2 system, and only oxygen vacancies in the surface of nanostructures would lead to such a long range magnetic order.
Ceria (CeO2) is a promising dilute magnetic semiconductor. Several studies report that the intrinsic and extrinsic structural defects are responsible for room temperature ferromagnetism in undoped and transition metal doped CeO2 nanostructures, however, the nature of the kind of defect necessary to promote and stabilize the ferromagnetism in such a system is still a matter of debate. In the work presented here, nanorods from the system Ce1-xCuxO2-delta with x = 0, 0.01, 0.03, 0.05 and 0.10, with the more stable {111} surface exposed were synthesized by a microwave-assisted hydrothermal method. A very careful structure characterization confirms that the Cu in the samples assumes a majority 2+ oxidation state, occupying the Ce (Ce4+ and Ce3+) sites with no secondary phases up to x = 0.05. The inclusion of the Cu2+ in the CeO2 structure leads to the introduction of oxygen vacancies in a density proportional to the Cu2+ content. It is supposed that the spatial distribution of the oxygen vacancies follows the Cu2+ distribution by means of the formation of a defect complex consisting of Cu2+ ion and an oxygen vacancy. Superconducting quantum interference device magnetometry demonstrated a diamagnetic behavior for the undoped sample and a typical paramagnetic Curie-Weiss behavior with antiferromagnetic interactions between the Cu2+ ions for the single phase doped samples. We suggest that the presence of oxygen vacancies is not a sufficient condition to mediate ferromagnetism in the CeO2 system, and only oxygen vacancies in the surface of nanostructures would lead to such a long range magnetic order.
Subject: Óxidos de cério, Ferromagnetismo, Nanopartículas
Country: Reino Unido
Editor: Royal Society of Chemistry
Citation: The Role Of Oxygen Vacancies And Their Location In The Magnetic Properties Of Ce1-xcuxo2-delta Nanorods. Royal Soc Chemistry, v. 17, p. 3072-3080 2015.
Rights: fechado
Identifier DOI: 10.1039/c4cp04879b
Address: https://pubs.rsc.org/en/content/articlelanding/2015/CP/C4CP04879B
Date Issue: 2015
Appears in Collections:IFGW - Artigos e Outros Documentos

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