Autor(es)

Barbosa, Vitor F. ; Carvalho, Rodrigo A. R. ; Alkathy, Mahmoud S. ; Bonin, Ricardo Pereira ; Zabotto, Fabio L.

• Tipo de documento: Artigo Científico
• Fonte: CERAMICS INTERNATIONAL; v. 51, n. 22, p. 9-pg., 2025-09-01.

Resumo

Materials that exhibit the magnetoelectric effect have attracted increasing scientific and technological interest. The four-layer Aurivillius system Bi5Ti3FeO15 (BFT4) is a promising candidate for technological applications within this framework. In this work, we investigate the origin and evolution of the relaxation processes and the defect structure of the BFT4 system as a function of the sintering temperature. The samples were sintered via solid-state reaction at 950 degrees C-1050 degrees C. The analysis of the electrical permittivity, electrical modulus, impedance, and AC conductivity functions revealed the presence of two relaxation processes in all samples associated with the microstructure of the system, especially the grain and grain boundaries. The relaxation processes at grain boundaries and DC conductivity are compatible with conduction by doubly ionized oxygen vacancies (Vo ''), with activation energy close to 1 eV. For temperatures below 260 degrees C, the conduction process occurs intra-grains via electronic hopping between localized states, with activation energies close to 0.1 eV. For temperatures above 260 degrees C, a suppression of ionic conduction was observed, induced by the increase in the sintering temperature and the consequent increase in the concentration of oxygen vacancies. This behavior agrees with the structural data, which revealed an increase in the concentration of oxygen vacancies was observed with rising sintering temperature. This trend is also reflected in the DC conductivity and grain relaxation processes, which were attributed to the formation of complex defects of the type [Fe+3-Vo '-Fe+3.e] or [Ti+4.e-Vo ''-Ti+4.e]. Accordingly, the sintering temperature of 975 degrees C was identified as the optimal condition for aligning the structural and micro-structural properties with the suppression of ionic conductivity. (AU)

• Processo FAPESP: 17/13769-1 - Materiais multiferróicos e ferroelétricos para conversores de energia: síntese, propriedades, fenomenologia e aplicações
• Beneficiário: José Antonio Eiras
• Modalidade de apoio: Auxílio à Pesquisa - Temático