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Formation of the core–shell microstructure in lead-free Bi1/2Na1/2TiO3-SrTiO3 piezoceramics and its influence on the electromechanical properties

Koruza, J. and Rojas, V. and Molina-Luna, Leopoldo and Kunz, Ulrike and Duerrschnabel, Michael and Kleebe, Hans-Joachim and Acosta, Matias (2016):
Formation of the core–shell microstructure in lead-free Bi1/2Na1/2TiO3-SrTiO3 piezoceramics and its influence on the electromechanical properties.
36, In: Journal of the European Ceramic Society, (4), Elsevier Science Ltd., pp. 1009-1016, ISSN 09552219, DOI: 10.1016/j.jeurceramsoc.2015.11.046,
[Article]

Abstract

The Bi1/2Na1/2TiO3-based materials exhibit the largest electric-field-induced strains among lead-free piezoceramics and are considered as promising candidates for actuation applications. A typical representative of this group is (1-x)Bi1/2Na1/2TiO3-xSrTiO3, where its excellent electromechanical properties were recently related to the existence of a core–shell microstructure. Although the latter was also reported in other Bi1/2Na1/2TiO3-based ceramics, the formation mechanism remains unknown. In the present work we therefore first investigated the solid-state reaction occurring during calcination using simultaneous thermogravimetric analysis, X-ray diffraction, scanning and transmission electron microscopy. The reaction occurred in two steps, whereby the cores and shells had different formation reaction temperatures, which resulted in a metastable heterogeneous microstructure. Furthermore, a series of sintered samples with different relative densities, grain sizes, and core densities was prepared. Modifications of these microstructural parameters resulted in variation of the maximal strain by 17% and in the electric-field required to trigger the phase transitions by 38%.

Item Type: Article
Erschienen: 2016
Creators: Koruza, J. and Rojas, V. and Molina-Luna, Leopoldo and Kunz, Ulrike and Duerrschnabel, Michael and Kleebe, Hans-Joachim and Acosta, Matias
Title: Formation of the core–shell microstructure in lead-free Bi1/2Na1/2TiO3-SrTiO3 piezoceramics and its influence on the electromechanical properties
Language: English
Abstract:

The Bi1/2Na1/2TiO3-based materials exhibit the largest electric-field-induced strains among lead-free piezoceramics and are considered as promising candidates for actuation applications. A typical representative of this group is (1-x)Bi1/2Na1/2TiO3-xSrTiO3, where its excellent electromechanical properties were recently related to the existence of a core–shell microstructure. Although the latter was also reported in other Bi1/2Na1/2TiO3-based ceramics, the formation mechanism remains unknown. In the present work we therefore first investigated the solid-state reaction occurring during calcination using simultaneous thermogravimetric analysis, X-ray diffraction, scanning and transmission electron microscopy. The reaction occurred in two steps, whereby the cores and shells had different formation reaction temperatures, which resulted in a metastable heterogeneous microstructure. Furthermore, a series of sintered samples with different relative densities, grain sizes, and core densities was prepared. Modifications of these microstructural parameters resulted in variation of the maximal strain by 17% and in the electric-field required to trigger the phase transitions by 38%.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 36
Number: 4
Publisher: Elsevier Science Ltd.
Uncontrolled Keywords: Piezoelectricity, Lead-free, Core–shell, Electromechanical properties, Relaxor
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences > Earth Science > Geo-Material-Science
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Electron Microscopy (aem)
11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
Date Deposited: 10 Dec 2018 09:54
DOI: 10.1016/j.jeurceramsoc.2015.11.046
Funders: This work was supported by the AdRIA Hesse state center for Adaptronics, the German Research Foundation (DFG) Sonderforschungsbereich 595, and Leibniz program under RO954/22-1., The transmission electron microscopes employed for this work were partially funded by the German Research Foundation (DFG/INST163/2951)., Dipl.-Ing. Claudia Fasel is acknowledged for her involvement in the STA-IR measurements.
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