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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Oxygen diffusion and vacancy migration thermally-activated govern high-temperature magnetism in ceria

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Author(s):
Varalda, J. [1] ; Dartora, C. A. [2] ; de Camargo, P. C. [3] ; de Oliveira, A. J. A. [3] ; Mosca, D. H. [1]
Total Authors: 5
Affiliation:
[1] Univ Fed Parana, Ctr Politecn, Dept Fis, Caixa Postal 19044, BR-81531980 Curitiba, Parana - Brazil
[2] Univ Fed Parana, Ctr Politecn, Dept Engn Eletr, BR-81531980 Curitiba, Parana - Brazil
[3] Univ Fed Sao Carlos, Dept Fis, Rod Washington Luis, Km 235 SP 310, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: SCIENTIFIC REPORTS; v. 9, MAR 18 2019.
Web of Science Citations: 0
Abstract

Several experimental works currently demonstrate that metallic nano-oxides and carbon nanomaterials expected to be diamagnets, in fact, behave as ferromagnets at room temperature. More than scientifically intriguing, this unconventional and unexpected ferromagnetism pave the way for innovation products and novel nanotechnological applications, gathering the magnetism to interesting functionalities of these nanomaterials. Here, we investigate the non-conventional ferromagnetism observed at high temperatures in nanocrystalline cerium dioxide (CeO2 or nanoceria) thin films that are optically transparent to visible light. Nanoceria exhibits several concrete applications in catalytic processes, photovoltaic cells, solid-state fuel cells, among others, which are mostly due to natural presence of oxygen vacancies and easy migration of the oxygen through the structure. The ferromagnetism in non-stoichiometric nanocrystaline ceria can be consistently described by ab initio electronic structure calculations, which support that oxygen vacancies cause the formation of magnetic moments and can provide a robust interconnectivity within magnetic polarons theoretical framework. Additionally, we present a conceptual model to account the oxygen transport to the non-conventional ferromagnetism at temperatures well above room temperature. The approach is complementary to the thermally-activated effective transfers of charge and spin around oxygen vacancy centers. (AU)

FAPESP's process: 17/24995-2 - Magnetism in multifunctional materials
Grantee:Adilson Jesus Aparecido de Oliveira
Support type: Regular Research Grants
FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
Grantee:Elson Longo da Silva
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC