Spinodal Decomposition in Lead-free Piezoelectric
BaTiO<sub>3</sub>–CaTiO<sub>3</sub>–BaZrO<sub>3</sub> Crystals
Gabriel Buse
Cong Xin
Pascal Marchet
Ana Borta-Boyon
Mai Pham-Thi
Hughes Cabane
Emmanuel Veron
Michael Josse
Matias Velazquez
Michel Lahaye
Eric Lebraud
Mario Maglione
Philippe Veber
10.1021/acs.cgd.8b00596.s001
https://acs.figshare.com/articles/journal_contribution/Spinodal_Decomposition_in_Lead-free_Piezoelectric_BaTiO_sub_3_sub_CaTiO_sub_3_sub_BaZrO_sub_3_sub_Crystals/7100663
Polycrystals
and centimeter-sized BaTiO<sub>3</sub>-based single
crystals were grown by top seeded solution growth from the BaTiO<sub>3</sub>–CaTiO<sub>3</sub>–BaZrO<sub>3</sub> system.
High effective partition coefficients of Zr ranging from 15 to 6 with
small Zr content have been calculated from Castaing microprobe measurements,
whereas those of Ca increase slightly from 0.45 to 0.7. A spinodal
decomposition mechanism is emphasized during the growth leading to
the emergence of two phases with close compositions. Chemical analysis
displayed periodical Zr and Ca content fluctuations within the whole
boules, and Rietveld measurements highlighted two phases belonging
to perovskite structures with tetragonal <i>P</i>4<i>mm</i> and orthorhombic <i>Amm</i>2 space groups.
Samples with various calcium and zirconium contents were characterized
by means of dielectric and piezoelectric measurements. Most efficient
samples are indistinctly polycrystals or oriented single crystals
where electromechanical performances are compositional-dependent.
Polycrystalline samples and single crystals oriented along (001)<sub>pc</sub> and (110)<sub>pc</sub> displayed Curie temperatures ranging
from 50 to 111 °C. Electromechanical coupling factor up to 58%
and piezoelectric charge coefficient <i>d</i><sub>33</sub> = 496 pC·N<sup>–1</sup> were obtained at room temperature.
The miscibility gap between the two perovskite solid solutions as
well as Ca and Zr element content variation in single crystals lower
crystal piezoelectric response that remains nonetheless of the
same efficiency compared to that of ceramics of the same composition.
2018-09-06 00:00:00
charge coefficient
solution growth
indistinctly polycrystals
chemical analysis
Zr content
P 4 mm
BaZrO
spinodal decomposition mechanism
perovskite structures
Spinodal Decomposition
partition coefficients
Castaing microprobe measurements
Polycrystalline samples
pc
Zr element content variation
zirconium contents
Curie temperatures
CaTiO
Rietveld measurements
centimeter-sized BaTiO 3
miscibility gap
Amm 2 space groups
phase
periodical Zr
room temperature