Dielectric and piezoelectric properties of (K0.48Na0.52)Nb1−x(Mo3/4Sr1/4)xO3 lead-free ceramics

Lead-free (K0.48Na0.52)Nb1−x(Mo3/4Sr1/4)xO3 (KNN-xMS) ceramics with x = 0–0.016 were prepared by a conventional sintering. The samples were characterized by X-ray analysis and scanning electron microscopy. The electrical properties were investigated with a special emphasis on the influence of the Mo3/4Sr1/4 content. Results show that all samples have the orthorhombic perovskite structure. A discontinuous change in the lattice parameters is found in the vicinity of x = 0.008, which is considered as a behavior of the morphotropic phase boundary (MPB). The ceramics have excellent electrical properties of d33 = 131pC/N and kp = 40 % with the MPB composition. The existence of two orthorhombic phases and the perfect microstructure play key roles in the high piezoelectric response in the KNN-xMS ceramics. The results indicate that the ceramics are promising lead-free piezoelectric materials.