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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, Jurij and Rojas, Virginia 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.
In: Journal of the European Ceramic Society, Elsevier, pp. 1009-1016, (36), ISSN 09552219, [Online-Edition: http://www.sciencedirect.com/science/article/pii/S0955221915...],
[Article]

Abstract

The Bi 1/2Na1/2TiO3-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 Bi 1/2Na1/2TiO3-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, Jurij and Rojas, Virginia 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 Bi 1/2Na1/2TiO3-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 Bi 1/2Na1/2TiO3-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
Number: 36
Publisher: Elsevier
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 > Material Science
11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
Date Deposited: 04 Jan 2016 16:31
Official URL: http://www.sciencedirect.com/science/article/pii/S0955221915...
Identification Number: doi:10.1016/j.jeurceramsoc.2015.11.046
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