Strong Piezoelectricity in (1 - X)(K_0.4Na_0.6)(Nb_0.96Sb_0.04)O₃-xBi_0.5K_0.5Zr_1-ySn_yO₃ Lead-Free Binary System: Identification and Role of Multiphase Coexistence

Here we report a strong piezoelectric activity in (1 - x)(K_0.4Na_0.6)(Nb_0.96Sb_0.04)O₃-xBi_0.5K_0.5Zr_1-ySn_yO₃ lead-free ceramics by designing different phase boundaries. The phase boundaries concerning rhombohedral-orthorhombic-tetragonal (R-O-T) and rhombohedral-tetragonal (R-T) multiphase coexistence were attained by changing BKZS and Sn contents and then were identified by the X-ray diffraction patterns as well as temperature-dependent permittivity and ν1 Raman modes associated with BO₆ perovskite octahedron. A high strain (strain = 0.21-0.28% and d₃₃∗ = 707-880 pm/V) and a strong piezoelectric coefficient (d₃₃ = 415-460 pC/N) were shown in the ceramics located at the multiphase coexistence region. The reported results of this work are superior to that (d₃₃∗ ∼ 570 pm/V and d₃₃ ∼ 416 pC/N) of the textured (K,Na,Li)(Nb,Ta,Sb)O₃ ceramics [Nature 2004, 432, 84]. We believe that the material system of this work will become one of the most promising candidates for piezoelectric actuators. (Graph Presented).