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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.)

Magnetic ordering contribution on diffusion process forming hollow materials

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Author(s):
de Paula, V. G. [1] ; Diaz Pomar, C. [1] ; Padilha, A. C. M. [2] ; Souza, J. A. [1]
Total Authors: 4
Affiliation:
[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Santo Andre, SP - Brazil
[2] Brazilian Nanotechnol Natl Lab LNNano CNPEM, Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Solid State Ionics; v. 339, OCT 15 2019.
Web of Science Citations: 0
Abstract

We have experimentally observed the influence of a magnetic phase transition on the morphological transformation during a thermal oxidation reaction in air due to ionic diffusion process. A Fe ferromagnetic metallic microwire turns into a semiconducting iron oxide microtube when heat treated above the Curie temperature. Electrical transport behavior of Fe microwires measures changes in ionic transport across magnetic transition. Scanning electron microscopy images and x-ray diffraction measurements revealed that the formed microtubes are comprised of a Fe2O3 outer and Fe3O4 inner shells when the sample is heated above the Fe magnetic ordering temperature. This result is closely related to the higher atomic mobility in the paramagnetic state. We discuss the influence of magnetic spin interaction on Fe vacancy formation and the ionic mass transport. Numerical calculations of the vacancy formation energy in both ferromagnetic and paramagnetic states support our experimental observation that enhanced ionic mobility, leaving vacancies behind, is correlated to the vanishing of magnetic spin interactions above T-c. (AU)

FAPESP's process: 16/09769-3 - Synthesis and Physical Properties Characterization of microtubes
Grantee:José Antonio Souza
Support Opportunities: Regular Research Grants
FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
Grantee:Adalberto Fazzio
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 11/19924-2 - Study and development of advanced novel materials: electronic, magnetic and nanostructured: an interdisciplinary approach
Grantee:Carlos Rettori
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 18/15682-3 - Synthesis and Physical Properties Characterization of Micro/Nanostructured Semiconducting Materials
Grantee:José Antonio Souza
Support Opportunities: Regular Research Grants