7th International Congress on Ceramics

Piezoelectric and ferroelectric studies of BNT–BT ceramics near the morphotropic-phase-boundary composition

Reference	Presenter	Authors (Institution)	Abstract
08-023	Miriam Castro	Prado, A.(Instituto de Investigaciones en Ciencia y Tecnologia de Materiales); Ramajo, L.(Instituto de Investigaciones en Ciencia y Tecnologia de Materiales); Rubio-Marcos, F.(Instituto de Cerámica y Vidrio); Webber, K.G.(Institute of Glass and Ceramics); Castro, M.(Instituto de Investigaciones en Ciencia y Tecnologia de Materiales);	Bismuth sodium titanate $B i_{0.5} N a_{0.5} T i O_{3}$ (BNT) is a lead-free piezoelectric material which exhibits significant remanent polarization ( $~$ 38 $°$ C/cm2) and a Curie temperature of $~$ 320°C [1]. Due to their properties BNT-based ceramics are considered as excellent candidates to replace conventional piezoelectric materials, in which the toxicity of lead has raised serious environmental problem, such as $P b T i O_{3} - P b Z r O_{3}$ (PZT), $P b (M g_{1 / 3} N b_{2 / 3}) O_{3} - P b T i O_{3}$ (PMN–PT), etc. [2-3]. However, the BNT ceramics present a moderate piezoelectric coefficient ( $d_{33} = 74 p C / N$ ) and a high coercive field ( $~$ 73kV/cm) [4] which difficult the polarization process. As an alternative to improve the dielectric and piezoelectric properties of this material, the formation of solid solutions of BNT as $(1 - x) B i_{0.5} N a_{0.5} T i O_{3} - x B a T i O_{3}$ ,(BNT-BT), has been proposed [5]. The excellent properties of this system are attributed to the existence of a morphotropic phase boundary (MPB), between rhombohedral and tetragonal crystal symmetries. In this work, we present a simple method to prepare $(1 - x) B i_{0.5} N a_{0.5} T i O_{3} - x B a T i O_{3}$ (x= 0.0, 0.04, 0.06, 0.07, 0.08, 0.09) based lead-free piezoelectric ceramics through the solid-state reaction route. Powders were mixed in different compositions near of morphotropic phase boundary and the influence of the BT concentration on ceramics was investigated in order to understand the relations of structural phase stabilization, microstructure, and piezoelectric and ferroelectric properties. References: [1] M. Cernea, L. Trupina, C. Dragoi, B. S. Vasile, R. Trusca, J. Alloys Compd. 515 (2012) 166-170. [2] B. J. Chu, D. R. Chen, G. R. Li, Q. R. Yin, J. Eur. Ceram. Soc. 22 (2002) 2115-2121. [3] D. White, X. Zhao, M. F. Bresser, X. Tan, J. Mater. Sci. 43(15) (2008) 5258–5264. [4] X. Wang, Y. Li, Y. Gao, Z. Wang, L. Chen, Nano Energy. 13 (2015), 687–692. [5] T. Takenaka, K. Maruyama, K. Sakata, J. Appl. Phys. 30 (1991) 2236.
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