Study on the polarization enhancement mechanism and electrical properties of high temperature bismuth layered KxNa0.5-xBi4.46Ce0·04Ti4O15+y ceramics

• Published in: Ceramics international Vol. 47; no. 20; pp. 29023 - 29029
• Main Authors: Chen, Ye, Du, Yike, Fan, Dongming, Niu, Huiyan, Zuo, Yuandong, Hu, Liangwei, Liu, Kanghui, Shen, Meng, Shang, Xunzhong, Chen, Yong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.10.2021
• Subjects: BLSFs; Defect dipole; High curie temperature; Lead free; Na0·5Bi4·5Ti4O15; Defect dipole; BLSFs; Lead free; Na0·5Bi4·5Ti4O15; High curie temperature
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2021.07.064

KxNa0.5-xBi4.46Ce0·04Ti4O15+y (x = 0, 0.04, 0.08, 0.12, 0.16, 0.20) ceramics were synthesized by solid state reaction. The microstructure and electrical properties of the solid solutions were characterized. It is found that the doping of appropriate amount of K improved the degree of lattice distortion of the material, and the characteristic parameter b/a of lattice distortion obtained the maximum value through structural refinement at x = 0.12. A defect dipole pair (KBi″−Vo••) is formed by adjusting the defects of the material. The polarizability of defects is 4.88 × 10-37F·m2. The formation of defect dipole pairs that deflect towards the direction of spontaneous polarization reduces the difficulty of polarization and improves the piezoelectric properties. Finally, the optimal piezoelectric coefficient (d33) of NBCT-xK ceramics is 23 pC/N, and the residual polarizability (2Pr) is 4.14 μC/cm2. The values of residual polarization rate (2Pr), piezoelectric coefficient (d33) and b/a show the same trend, which will gradually decrease when their value increases to a certain extent. The dielectric loss of all samples below 200 °C are lower than 0.01, and the dielectric constant is relatively flat below 400 °C. Moreover, the Curie temperature (Tc) of KxNa0.5-xBi4.46Ce0·04Ti4O15+ybased ceramics is increased to 686.0 °C, which will enable the ceramics to be used in oilfield logging, aerospace and military fields in high temperature environment.