Theoretical Prediction and Experimental Validation of Enhancing the Piezoelectric Properties of (K, Na)NbO3 Modified by Li, Ta, and Sb According to the Linear Combination Rule

Lead-free piezoelectric ceramics of (K, Na)NbO3 modified by Li, Ta, and Sb (KNN-LTS) have been widely investigated recently. In this research, this optimized composition of KNN-LTS ceramics near polymorphic phase transition is explored according to the linear combination rule (LCR) for the first time. Changing with the compositions monotonically, remanent polarization (Pr) decreased monotonically, whereas permittivity (e33Te0) increased similarly. The increase in either e33T/e0 or Pr initially enhances piezoelectric coefficient d33 before reducing it because d33 can be improved by e33T/e0 and Pr. The optimal composition of (Na0.52K0.4415Li0.0385)(Nb0.8735Ta0.064Sb0.0625)O3, predicted by LCR, exhibits the excellent electric properties of d33 = 359 pC/N, kp = 42%, thus suggesting that the LCR effectively predicts the electric properties of the KNN-LTS ceramics.