Structure and piezoelectric properties of lead-free (Na0.52K0.44− x)(Nb0.95− xSb0.05)O3- xLiTaO3 ceramics.

Lead-free (Na_0.52K_{0.48− x})(Nb_{0.95− x}Sb_0.05)O₃- xLiTaO₃ ( x = 0.025–0.05) piezoelectric ceramics in which the Sb content is kept constant, have been specially designed and successfully fabricated by a conventional solid state reaction method. The (Na_0.52K_0.48)(Nb_0.95Sb_0.05)O₃ ceramics can be well sintered after A-site and B-site cations are replaced by Li⁺ and Ta⁵⁺, respectively. A single-phase perovskite structure remains within the studied substitution concentration. An orthorhombic-tetragonal phase transition occurs with gradually increasing the content of Li⁺ and Ta⁵⁺, and was identified in the composition range of 0.0375 < x < 0.0425 where two kinds of ferroelectric phases may coexist and simultaneously a strong compositional dependence of electrical properties was found out. An appropriate content of Sb effectively enhanced the piezoelectric properties of the materials. The optimum overall properties with a piezoelectric constant d₃₃ of 321 pC/N, a dielectric constant $$ \varepsilon_{33}^{T} $$ of 1,780, a planar electromechanical coupling coefficient k_p of 0.52 and a Curie temperature T_c of 315 °C were obtained in the composition with x = 0.0425, indicating the ceramics studied have potentials for replacing lead-containing ceramics for device applications. [ABSTRACT FROM AUTHOR]