Effects of Sb content on electrical properties of lead-free piezoelectric (K0.4425Na0.52Li0.0375) (Nb0.9625−xSbxTa0.0375)O3 ceramics

Abstract Lead-free (K 0.4425 Na 0.52 Li 0.0375 ) (Nb 0.9625− x Sb x Ta 0.0375 )O 3 piezoelectric ceramics were prepared by the conventional sintering method. The effects of the Sb content on the phase structure, microstructure, dielectric, piezoelectric, and ferroelectric properties of the (K 0.4425 Na 0.52 Li 0.0375 ) (Nb 0.9625− x Sb x Ta 0.0375 )O 3 ceramics were investigated. The much higher Pauling electronegativity of Sb compared with Nb makes the ceramics more covalent. By increasing x from 0.05 to 0.09, all samples exhibit a single perovskite structure with an orthorhombic phase over the whole compositional range, and the bands in the Raman scattering spectra shifted to lower frequency numbers. The grain growth of the ceramics was improved by substituting Sb 5+ for Nb 5+ . Significantly, the (K 0.4425 Na 0.52 Li 0.0375 ) (Nb 0.8925 Sb 0.07 Ta 0.0375 )O 3 ceramics show the peak values of the piezoelectric coefficient ( d 33 ), electromechanical coupling coefficient ( k p ), and dielectric constant ( ɛ ), which are 304 pC/N, 48% and 1909, respectively, owing to the densest microstructure of typical bimodal grain size distributions. Besides, the underlying mechanism for variations of the electrical properties due to Sb 5+ substitution was explained in this work.