Dielectric and piezoelectric properties of (K_0.48Na_0.52)Nb_1−<i>x</i>(Mo_3/4Sr_1/4)_<i>x</i>O₃ lead-free ceramics

Lead-free (K 0.48 Na 0.52 )Nb 1− x (Mo 3/4 Sr 1/4 ) x O 3 (KNN- x MS) 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 Mo 3/4 Sr 1/4 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 d 33 = 131pC/N and k p = 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- x MS ceramics. The results indicate that the ceramics are promising lead-free piezoelectric materials.