Structural and impedance spectroscopic study of Zn-substituted Ba5CaTi2Nb8O30 tetragonal tungsten bronze ceramics

•The structure and impedance properties were studied in Ba5CaTi2−xZnxNb8O30 ceramics.•The effect of Zn-substitution on the structural and electrical properties was confirmed.•The contribution of grains and grain boundaries was verified by analysis of the Nyquist plots.•The single and doubly ionized...

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Bibliographic Details
Published in:Journal of alloys and compounds 2021-11, Vol.882, p.160716, Article 160716
Main Authors: Bendahhou, Amine, Marchet, Pascal, El Barkany, Soufian, Abou-salama, Mohamed
Format: Article
Language:English
Subjects:
AC conductivity
Ceramics
Chemical Sciences
Crystallites
Current carriers
Densification
Electrical properties
Grain size
Impedance spectroscopy
Material chemistry
Modulus spectrum
Nyquist plots
Oxygen vacancies (OVs)
Photomicrographs
Rietveld method
Tetragonal tungsten bronze
Tungsten bronze
Tungsten compounds
Zinc compounds
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Summary:•The structure and impedance properties were studied in Ba5CaTi2−xZnxNb8O30 ceramics.•The effect of Zn-substitution on the structural and electrical properties was confirmed.•The contribution of grains and grain boundaries was verified by analysis of the Nyquist plots.•The single and doubly ionized oxygen vacancies are responsible for electrical conduction in Ba5CaTi2-xZnxNb8O30 ceramics. [Display omitted] Zn-doped tungsten bronze compounds derived from Ba5CaTi2Nb8O30, with Ba5CaTi2−xZnxNb8O30 composition (x = 0; 0.04 and 0.08) were synthesized by the conventional solid-state reaction route. Both solubility of Zn in Ba5CaTi2Nb8O30 and tungsten bronze formation with the P4bm space group were verified by the Rietveld method using X-ray diffraction data. The average crystallite size was of the order of 0.08 µm according to Scherrer's formula. SEM micrographs of Ba5CaTi2−xZnxNb8O30 ceramics showed high densification, low porosity, thus a homogeneous grain distribution of different sizes over the entire surface. The average grain size was in the range of 1.3–1.6 µm. The frequency-dependent electrical properties were analyzed by complex impedance spectroscopy. Different types of studies such as the Nyquist plot, real and imaginary part of the impedance, conductivity, modulus formalism, and charge carrier activation energy were used to explain the microstructure-electrical properties relationships.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.160716