Piezoelectric and Dielectric Properties of Nonstoichiometric (Na0.5K0.5)0.97(Nb0.90Ta0.1)O3 Ceramics Doped with MnO2

摘要

MnO2-added nonstoichiometric (K0.5Na0.5)0.97(Nb0.90Ta0.1)O3 lead-free piezoelectric ceramics were prepared by conventional sintering processes. X-ray diffraction data show that MnO2 diffuses into the lattice of (K0.5Na0.5)0.97 (Nb0.90Ta0.1)O3 ceramics and forms a pure perovskite structure with orthorhombic symmetry. The microstructure of the samples showed that a certain amount of MnO2 addition could improve the crystalline grain growth. The addition of a small amount of MnO2 increased the mechanical quality factor (Q m), piezoelectric constant (d 33), and electromechanical coupling factor (k p). At room temperature, (K0.5Na0.5)0.97(Nb0.90Ta0.1)O3 ceramics doped with 0.4 mol% MnO2 showed piezoelectric properties suitable for low-loss piezoelectric actuator applications: k p = 0.43, Q m = 1212, d 33 = 112 pC/N, and tan δ = 0.023.