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Bi 0.5 K 0.5 TiO 3 –CaTiO 3 ceramics: Appearance of the pseudocubic structure and ferroelectric‐relaxor transition characters
Author(s) -
Wei Yongxing,
Zhang Ning,
Jin Changqing,
Zhu Weitong,
Zeng Yiming,
Xu Gang,
Gao Ling,
Jian Zengyun
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16244
Subject(s) - tetragonal crystal system , ferroelectricity , materials science , dielectric , phase transition , condensed matter physics , raman spectroscopy , solid solution , transition temperature , hysteresis , atmospheric temperature range , mineralogy , crystallography , crystal structure , optics , physics , thermodynamics , chemistry , superconductivity , optoelectronics , metallurgy
In this study, solid solution ceramics of (1− x )Bi 0.5 K 0.5 TiO 3 – x CaTiO 3 (BKT‐CT, x = 0, 0.12, 0.15, 0.18, 0.21, and 0.25) were prepared. A phase transition from the tetragonal symmetry to the pseudocubic symmetry is discovered near x = 0.25. The reasons for the appearance of the pseudocubic phase were discussed. The compositions of x ≤ 0.21 show the ferroelectric ordering at room temperature. The remnant polarization ( P r ) is 22.4 μC/cm 2 for the x = 0.15 composition. The temperature dependence of the relative permittivity suggests two dielectric anomalies for x ≤ 0.18. The dielectric anomaly in the low‐temperature range is related to a spontaneous transition between the ferroelectric and relaxor states. The temperature ( T F‐R ) for the transition decreases with the CT addition, falling from 211°C for x = 0.12‐134°C for x = 0.18. Only one relaxor‐like dielectric anomaly was observed for x ≥ 0.21. The thin double ferroelectric hysteresis loops have been observed during the ferroelectric‐relaxor transition process for x ≥ 0.21. The maximum electrostrain ( S m ) reaches 0.155% at 100°C for x = 0.21. The low‐temperature Raman measurement suggests the intrinsic tetragonal distortions for x = 0.25.