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45. Core–rim structure evolution and electric properties of Ca–Mg–Dy-co-doped BaTiO3 ceramics.

Author

Huang, Jiayan, Chen, Ran, Xing, Juanjuan, Zhang, Faqiang, Jiang, Ying, Gu, Yan, and Gu, Hui

Abstract

The core–rim structure is the micro-basis of BaTiO3-based MLCC dielectric materials. Its formation and evolution mechanism and the effect on electric properties deserve a closer and more detailed study. Herein, a series of core–rim structured 95BaTiO3–2CaO–2MgO–1Dy2O3 ceramics were prepared by controlling their sintering time from 3 min to 20 min to record the microstructure evolution process. The EDS line scanning showed a sharp dopant composition gradient between the core and rim, demonstrating the epitaxial formation mechanism of core–rim structured grain. Based on it, systematic microstructure evolution analyses of the morphology, composition, and defects during the sintering were applied and a multi-scale evolution mechanism was put forward. The sintering process was divided into three major stages involving reaction and nucleation, rapid densification, and rapid grain growth. The core–rim structured grains emerged from the first stage and were destroyed in the third stage. Dense ceramics (∼96.5%) with core–rim structured grains were obtained in the second stage by limiting the holding times to 5 min. The ε′–T spectra and electric strength showed coherent changes and revealed the significant effect of the microstructure feature on the electric properties. [ABSTRACT FROM AUTHOR]

Published
2023
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50. Phase Evolution and Local Piezoelectric Response of Sn‐Doped BaTiO3 Ceramics.

Author

Jiang, Zuojian, Huang, Jiayan, Yuan, Renchen, Xu, Ning'an, Jiang, Ying, Zhang, Jiye, Zhang, Faqiang, Xing, Juanjuan, Gu, Hui, and Fu, Desheng

Subjects
PHASE transitions, CERAMICS, CHARGE transfer, ELECTRON diffraction, CATHODOLUMINESCENCE, REDSHIFT, ANESTHETICS
Abstract

Multiphase coexistence is the key to rendering samples with superior piezoelectric properties for BaTiO3 ceramics. Ba(Ti1−xSnx)O3 (BTS, x = 0.0–0.30) ceramics are prepared by the traditional solid‐state method. Orthorhombic (O) and tetragonal (T) phases are visually observed to coexist only in the ceramics with the low‐doping of Sn (x = 0.025–0.075) by electron backscattered diffraction (EBSD). The O phase percentage increases from 13.90% to 75.10%, therefore enhancing their piezoelectric response over the decreasing T phase. Further increase of x turns the BTS to rhombohedral (R) and cubic (C) phases, while cathodoluminescence (CL) analysis detects significant redshifts of the defect peak, which is mainly due to the change of phase structure. The phase transition can lead to the change of Ti–O6 octahedron, thereby affecting the charge transfer between TiTi′ and OO⋅. High piezoelectric responses can be achieved by the coexistence of O and T phases, which facilitates the rotation of ferroelectric domains. These results are beneficial to understanding the relationship between the microstructure and piezoelectric properties of BTS ceramics, and also indicate that CL can be a useful tool for phase identification. [ABSTRACT FROM AUTHOR]

Published
2022
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