Enhanced ferroelectric, piezoelectric, and dielectric properties in potassium sodium niobate lead-free piezoelectric ceramics by constructing of multiple phase boundaries

In this work, we report excellent ferroelectric, piezoelectric, and dielectric properties in 0.95(K0.5−x/2Na0.5−x/2Lix)NbO3-0.04BaZrO3-0.01BiFeO3, ((KN)1−xLxN-BZ-BF) lead-free piezoelectric ceramics system by constructing a coexistence of orthorhombic-tetragonal phase boundary near the room temperature, and increasing of grain size as well through the conventional sintering process. The addition of Li+ ions, in ((KN)1−xLxN-BZ-BF) composition, increased the grain size, and shifted the orthorhombic-tetragonal phase transition to near room temperature, and shifted the tetragonal-cubic phase transition toward higher temperatures, since both large electrical properties, and moderate Curie temperature was achieved simultaneously. The sample with x = 0.03 showed large average grain size of (9 µm), and possess coexisting of orthorhombic-tetragonal phases, since the sample showed excellent physical properties, such as d33 = 330 pC/N, kp = 0.5, Pr = 25 µC/cm2, and εr = 1740. The origin of these decent combinations of physical properties owes to the coexistence of orthorhombic-tetragonal phase transition to near room temperature, large grain size, and hybridization between Bi 6p, and O 2p as well.