Structural Evolution of the R-T Phase Boundary in KNN-Based Ceramics
Type
ArticleKAUST Department
Material Science and Engineering ProgramPhysical Science and Engineering (PSE) Division
Date
2017-10-20Online Publication Date
2017-10-20Print Publication Date
2018-03Permanent link to this record
http://hdl.handle.net/10754/626030
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Although a rhombohedral-tetragonal (R-T) phase boundary is known to substantially enhance the piezoelectric properties of potassium-sodium niobate ceramics, the structural evolution of the R-T phase boundary itself is still unclear. In this work, the structural evolution of R-T phase boundary from -150 °C to 200 °C is investigated in (0.99-x)K0.5Na0.5Nb1-ySbyO3-0.01CaSnO3-xBi0.5K0.5HfO3 (where x=0~0.05 with y=0.035, and y=0~0.07 with x=0.03) ceramics. Through temperature-dependent powder X-ray diffraction (XRD) patterns and Raman spectra, the structural evolution was determined to be Rhombohedral (R, <-125 °C) → Rhombohedral+Orthorhombic (R+O, -125 °C to 0 °C) → Rhombohedral+Tetragonal (R+T, 0 °C to 150 °C) → dominating Tetragonal (T, 200 °C to Curie temperature (TC)) → Cubic (C, >TC). In addition, the enhanced electrical properties (e.g., a direct piezoelectric coefficient (d33) of ~450±5 pC/N, a conversion piezoelectric coefficient (d33*) of ~580±5 pm/V, an electromechanical coupling factor (kp) of ~0.50±0.02, and TC~250 °C), fatigue-free behavior, and good thermal stability were exhibited by the ceramics possessing the R-T phase boundary. This work improves understanding of the physical mechanism behind the R-T phase boundary in KNN-based ceramics and is an important step towards their adoption in practical applications. This article is protected by copyright. All rights reserved.Citation
Lv X, Wu J, Xiao D, Zhu J, Zhang X (2017) Structural evolution of the R-T phase boundary in KNN-based ceramics. Journal of the American Ceramic Society 101: 1191–1200. Available: http://dx.doi.org/10.1111/jace.15266.Sponsors
National Science Foundation of China, Grant/Award Number: 51722208, 51332003, 51272164; King Abdullah University of Science and Technology (KAUST)Publisher
WileyAdditional Links
http://onlinelibrary.wiley.com/doi/10.1111/jace.15266/abstractae974a485f413a2113503eed53cd6c53
10.1111/jace.15266