Effect of (Co_1/3Sb_2/3) complex doping on the structure and electrical properties of 0.96(K_0.49Na_0.51)(Nb_0.97Ta_0.03)O₃–0.04Bi_0.5Na_0.5ZrO₃ lead-free piezoelectric ceramics

0.96(K_0.49Na_0.51)(Nb_0.97−x (Co_1/3Sb_2/3) _x Ta_0.03)O₃–0.04Bi_0.5Na_0.5ZrO₃ (abbreviated as 0.96KNNT-CS _x –0.04BNZ, x = 0.000, 0.002, 0.004, 0.006, 0.008, 0.010) lead-free piezoelectric ceramics were prepared via a solid state reaction method. The effect of (Co_1/3Sb_2/3) doping amount x on the structure and electrical properties of the ceramics was investigated. The XRD patterns showed the formation of a pure perovskite structure with the coexistence of orthorhombic and tetragonal phases over the whole compositions. However, the vibrational modes slightly shift towards lower frequencies with the increase of x value in the Raman scattering spectra, indicating that the (Co_1/3Sb_2/3) should be incorporated into the perovskite lattice. The optimal electrical properties obtained in the ceramics with x = 0.008 were as follows: piezoelectric coefficient d ₃₃ = 347 pC/N, planar electromechanical coupling coefficient k _p = 42.9 %, mechanical quality factor Q _m = 47, dielectric permittivity \( \varepsilon_{33}^{T} /\varepsilon_{0} \) = 1435, dielectric loss tanδ = 2.7 %, and Curie temperature T _c = 303 °C.