Temperature stability and electrical properties in La-doped KNN-based ceramics
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Materials Science and Engineering Program
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AbstractTo improve the temperature stability and electrical properties of KNN‐based ceramics, we simultaneously consider the phase boundary and the addition of rare earth element (La), 0.96K0.5Na0.5Nb0.96Sb0.04O3‐0.04(Bi1‐xLax)0.5Na0.5ZrO3 (0 ≤ x ≤ 1.0) ceramics. More specifically, we investigate how the phase boundary and the addition of La3+ affect the phase structure, electrical properties, and temperature stability of the ceramic. We show that increasing the La3+ content leads to a change in phase structure, from a rhombohedral‐tetragonal (R‐T) phase coexistence to a cubic phase. More importantly, we show that the appropriate addition of La3+ (x = 0.2) can simultaneously improve the unipolar strain (from 0.127% to 0.147%) and the temperature stability (i.e., the unipolar strain of 0.147% remains unchanged when T is increased from 25 to 80°C). In addition, we find that the ceramics with x = 0.2 exhibit a large piezoelectric constant (d33) of ~430 pC/N, a high Curie temperature (TC) of ~240°C and a fatigue‐free behavior (after 106 electric cycles). The enhanced electrical properties mostly originate from the easy domain switching, whereas the improved temperature stability can be attributed to the R‐T phase boundary and the appropriate addition of La3+.
CitationLv X, Wu J, Zhu J, Xiao D, Zhang X (2018) Temperature stability and electrical properties in La-doped KNN-based ceramics. Journal of the American Ceramic Society. Available: http://dx.doi.org/10.1111/jace.15695.
SponsorsAuthors gratefully acknowledge the support of the National Natural Science Foundation of China (NSFC Nos. 51722208 and 51332003) and the Fundamental Research Funds for the Central Universities (2012017yjsy111). Authors thank Mrs. Wang Hui (Analytical & Testing Center of Sichuan University) for performing the FE‐SEM measurements.