Date: 23 Apr 2009

Structure and piezoelectric properties of lead-free (Na0.52K0.44−x )(Nb0.95−x Sb0.05)O3-xLiTaO3 ceramics

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Abstract

Lead-free (Na0.52K0.48−x )(Nb0.95−x Sb0.05)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 (Na0.52K0.48)(Nb0.95Sb0.05)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 d 33 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.