Enhanced piezoelectric properties of Fe2O3–2TiO2 codoped Li0.05(Na0.5K0.5)0.95(Nb0.975Sb0.025)O3 lead-free ceramics with uniform microstructure

In this study, Fe2O3 and TiO2 codoped Li0.05(Na0.5K0.5)0.95(Nb0.975Sb0.025)O3[(1 − x) Li0.05(Na0.5K0.5)0.95(Nb0.975Sb0.025)O3–x(Fe2O3–2TiO2) (x = 0–0.008)] ceramics were prepared by conventional solid state reaction method, and the microstructure and electrical properties of these samples were investigated. The X-ray diffraction and Raman scattering results show the phase structure of the ceramics undergoes with the increase of Fe2O3–2TiO2 content. The grain size distribution of non-doped Li0.05(Na0.5K0.5)0.95(Nb0.975Sb0.025)O3 ceramics was relatively wide. The microstructure was composed of grains ranging 0.2–3.0 μm in size. However, with increasing Fe2O3–2TiO2 content, the grain size distribution became relatively narrow. Meanwhile, the piezoelectric coefficient (d33) and electromechanical coupling coefficient (kp) showed peak values of 252 pC/N, and 0.424, respectively, which were achieved in the sample with x = 0.002 sintered at 1020 °C.