Nanoscale domains in K0.48Na0.52Nb0.96Sb0.04O3 – Bi0.5Na0.5ZrO3 ceramics enhance piezoelectric properties

(1-x) K 0.48 Na 0.52 Nb 0.96 Sb 0.04 O 3 - x Bi 0.5 Na 0.5 ZrO 3 [(1-x) KNNS - x BNZ] lead-free piezoelectric ceramics with R(rhombohedral)-T(tetragonal) phase boundary have been successfully synthesized. The influences of Bi 0.5 Na 0.5 ZrO 3 (BNZ) doping on the phase structure, microstructure as well as dielectric properties, piezoelectric properties of the ceramics were systematically studied. It was observed by XRD and ε r - T curve that the R and T phases coexisted in the ceramic samples in the range of 0.03 ≤ x ≤ 0.04. The introduction of BNZ can obviously refine the ceramic grains and improve the density of the ceramics through the observation of the SEM images. In addition, some small nanostructured domains were found in the (1-x) KNNS - x BNZ ceramic when x = 0.03, which can be attributed to the fact that the domain wall energy of the ceramics is in a low state in the R-T phase boundary region, and the optimal values of ε r = 5609, tan δ = 0.035, and d 33 = 278 pC/N were obtained simultaneously. Therefore, we believe that the (1-x) KNNS - x BNZ ceramics can provide a better solution for the application of lead-free piezoelectric ceramics. • The Bi 0.5 Na 0.5 ZrO 3 promoted the construction of R-T phase boundary in ceramics. • Nano-domains were found in the ceramics with R-T phase boundaries. • The decrease of domain wall energy promotes the formation of nano-domain. • The optimization of ceramics benefits from the R-T phase boundary.