Enhanced piezoelectric properties of Fe₂O₃-2TiO ₂ codoped Li_0.05(Na_0.5K_0.5)0. 95(Nb_0.975Sb_0.025)O₃ lead-free ceramics with uniform microstructure

In this study, Fe₂O₃ and TiO₂ codoped Li_0.05(Na_0.5K_0.5)0.95(Nb_0.975Sb _0.025)O₃[(1-x) Li_0.05(Na_0.5K _0.5)0.95 (Nb_0.975Sb_0.025)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 Li_0.05(Na_0.5K _0.5)0.95(Nb_0.975Sb_0.025)O₃ ceramics was relatively wide. The microstructure was composed of grains ranging 0.2-3.0λm in size. However, with increasing Fe₂O ₃-2TiO₂ 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.