Microstructural Changes during the Reduction/Reoxidation Process in Donor-Doped BaTiO3 Ceramics |
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Authors: | Darko Makovec Miha Drofenik |
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Affiliation: | Department of Ceramics, "Jožef Stefan" Institute, Ljubljana, Slovenia |
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Abstract: | Microstructural changes occurring during oxidation of the reduced form of donor-doped BaTiO3 (Ba1− X D X .Ti1− X 4+Ti X 3+O3) and during reduction of the oxidized form of donor-doped BaTiO3 (Ba1− X D X .Ti1− X /44+( V Ti) X /4O3) were studied using TEM. Samples of both types of solid solutions, containing different La concentrations (from 2 to 20 mol% La), were prepared by sintering under reducing conditions and in air, respectively. The reduced form of donor-doped BaTiO3 was oxidized by annealing at high temperatures (1150° and 1350°C) in air, while the oxidized form was reduced by annealing under reducing conditions. Because of oxidation of the reduced phase of donor-doped BaTiO3, the Ti-rich phases Ba6Ti17O40 and BaLa2Ti4O12 were precipitated. Reduction of the oxidized form caused precipitation of the Ba-rich phase Ba2TiO4 preferentially inside the matrix grains. All precipitates had well-defined orientational relationships with the perovskite matrix. |
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Keywords: | microstructure reduction barium titanate |
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