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Ionic conductivity of acceptor doped sodium bismuth titanate: influence of dopants, phase transitions and defect associates

Koch, Leonie and Steiner, Sebastian and Meyer, Kai-Christian and Seo, In-Tae and Albe, Karsten and Frömling, Till (2017):
Ionic conductivity of acceptor doped sodium bismuth titanate: influence of dopants, phase transitions and defect associates.
In: Journal of Materials Chemistry C, pp. 8958-8965, 5, (35), ISSN 2050-7526, DOI: 10.1039/C7TC03031B, [Online-Edition: https://doi.org/10.1039/C7TC03031B],
[Article]

Abstract

We investigate both, experimentally and theoretically, the electrical conductivity of Mg- and Fe-doped polycrystalline Na_0.5Bi_0.5Ti_O3. Samples with up to 4% of acceptor dopants are studied by means of impedance spectroscopy, scanning electron microscopy, and X-ray diffraction, while an analytical defect chemical model is developed for describing the measured conductivities. Within the framework of defect chemistry, we demonstrate that the experimentally measured conductivities can only be reproduced, if the formation of dopant–vacancy defect complexes is considered and the phase transition from a rhombohedral to a tetragonal symmetry is taken into account, affecting the dissociation of the dopant–vacancy complex. By using migration energies from density functional theory calculations,we obtain a good agreement between the data obtained from the analytical model and the experimental results, if we assume that the association energy is strongly affected by the dopant concentration.

Item Type: Article
Erschienen: 2017
Creators: Koch, Leonie and Steiner, Sebastian and Meyer, Kai-Christian and Seo, In-Tae and Albe, Karsten and Frömling, Till
Title: Ionic conductivity of acceptor doped sodium bismuth titanate: influence of dopants, phase transitions and defect associates
Language: English
Abstract:

We investigate both, experimentally and theoretically, the electrical conductivity of Mg- and Fe-doped polycrystalline Na_0.5Bi_0.5Ti_O3. Samples with up to 4% of acceptor dopants are studied by means of impedance spectroscopy, scanning electron microscopy, and X-ray diffraction, while an analytical defect chemical model is developed for describing the measured conductivities. Within the framework of defect chemistry, we demonstrate that the experimentally measured conductivities can only be reproduced, if the formation of dopant–vacancy defect complexes is considered and the phase transition from a rhombohedral to a tetragonal symmetry is taken into account, affecting the dissociation of the dopant–vacancy complex. By using migration energies from density functional theory calculations,we obtain a good agreement between the data obtained from the analytical model and the experimental results, if we assume that the association energy is strongly affected by the dopant concentration.

Journal or Publication Title: Journal of Materials Chemistry C
Volume: 5
Number: 35
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ) > Hochleistungsrechner
11 Department of Materials and Earth Sciences > Material Science
Zentrale Einrichtungen > University IT-Service and Computing Centre (HRZ)
11 Department of Materials and Earth Sciences
Zentrale Einrichtungen
Date Deposited: 02 Feb 2018 13:17
DOI: 10.1039/C7TC03031B
Official URL: https://doi.org/10.1039/C7TC03031B
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