Grain size control of lead-free Li0.06(Na0.5K0.5)0.94NbO3 piezoelectric ceramics by Ba and Ti doping

High unipolar strain in samarium-doped potassium–sodium niobate lead-free ceramics

“…8, the average grain sizes of the ceramics slightly increase in the beginning and then signicantly reduce as x further increases. A maximum value of average grain size was observed in the KNNST-B 0.80 S 0.20 NKZ ceramics, which is one of the reasons why the ceramics with x ¼ 0.20 have good electrical properties (S max /E max ), [25][26][27][28] as will be discussed later.…”

“…It is generally accepted that the 3 r value of KNN-based ceramics is closely related to its grain size, and the 3 r value decreases with a decreasing grain size. [25][26][27][28] As shown in Fig. 7 and 8, the average grain size of the ceramics with different x values gradually decreases with an increasing x, which makes an important impact on the declining 3 r .…”

“…It was reported that the decreased grain sizes can enhance the coupling effect between crystalline grain and grain boundary, which can inhibit the polarization rotation and domain wall motion. [25][26][27][28] As shown in Fig. 7(a-d) and 8(a and b), the average grain sizes of the ceramics became smaller and smaller as a whole, resulting in a deterioration of piezoelectric properties.…”

“…7,15,16,18,19,21 Generally, the grain sizes of the ceramics play an important role in electrical properties. 8,[25][26][27][28] Here, we characterized the FE-SEM patterns and the corresponding Sm element mappings of the ceramics with x ¼ 0.05, 0.20, 0.40, and 0.60, as shown in Fig. 7(a-d).…”

Phase transition and piezoelectric properties of K0.48Na0.52NbO3–LiTa0.5Nb0.5O3–NaNbO3 lead-free ceramics

“…Nevertheless, pure KNN ceramics are known to be difficult to process to full density by natural sintering, and the highest piezoelectric coefficient (d 33 ) was not more than 100 pC/N. In order to improve the densification and piezoelectric properties of KNN ceramics, the different additions were added into KNN to form new KNN-based ceramic systems, such as KNN-LiSbO 3 [3], KNN-LiTaO 3 [4,5], KNN-LiSbO 3 -LiTaO 3 [6,7], KNN-AgTaO 3 [8], KNN-BiScO 3 [9], KNN-BaTiO 3 [10], and KNN-(Bi 0. 5 Li 0.5 )TiO 3 [11].…”