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Characterization of Bi4Ge3O12 single crystal by impedance spectroscopy

By Zélia Soares Macedo, André Luiz Martinez and Antonio Carlos Hernandes

Abstract

Bi4Ge3O12 (bismuth germanate - BGO) single crystals were produced by the Czochralski technique and their electrical and dielectric properties were investigated by impedance spectroscopy. The isothermal ac measurements were performed for temperatures from room temperature up to 750 °C, but only the data taken above 500 °C presented a complete semicircle in the complex impedance diagrams. Experimental data were fitted to a parallel RC equivalent circuit, and the electrical conductivity was obtained from the resistivity values. Conductivity values from 5.4 × 10(9) to 4.3 × 10-7 S/cm were found in the temperature range of 500 to 750 °C. This electrical conductivity is thermally activated, following the Arrhenius law with an apparent activation energy of (1.41 ± 0.04) eV. The dielectric properties of BGO single crystal were also studied for the same temperature interval. Permittivity values of 20 ± 2 for frequencies higher than 10³ Hz and a low-frequency dispersion were observed. Both electric and dielectric behavior of BGO are typical of systems in which the conduction mechanism dominates the dielectric response

Topics: bismuth germanate, impedance spectroscopy, Materials of engineering and construction. Mechanics of materials, TA401-492, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Technology, T, DOAJ:Materials, DOAJ:Technology and Engineering
Publisher: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
Year: 2003
DOI identifier: 10.1590/S1516-14392003000400026
OAI identifier: oai:doaj.org/article:16fb3baf8cb948a99d39f1f3ffe55d95
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