Dielectric and piezoelectric properties of (K<sub>0.48</sub>Na<sub>0.52</sub>)Nb<sub>1−<i>x</i></sub>(Mo<sub>3/4</sub>Sr<sub>1/4</sub>)<sub><i>x</i></sub>O<sub>3</sub> 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.