Dielectric Performance of (1-x)Na0.5Bi0.5TiO3-xBaTiO3 Lead-Free Piezoelectric Ceramics Synthesized by Sol-Gel Combustion Method

Lead-free piezoelectric ceramics (1-x)Na_0.5Bi_0.5TiO₃-xBaTiO₃(x=0.04, 0.06, 0.08) was synthesized via sol–gel combustion method. Structural analysis was performed by using X-ray diffraction (XRD). The structural morphology of the nanoparticles was studied using scanning electron microscopy (SEM). The ceramics show a rhombohedral-tetragonal morphotropic phase boundary (MPB) in the range of x =0.04-0.08, which makes ceramics having superior dielectric and piezoelectric properties. There is a decrease of the grain size with increasing BT concentration, suggesting that dissolving BT into NBT inhibits the grain growth. And the multi-peak fitting result shows lattice constants of NBT have increased with the BT doped into NBT. Belong to the ionic polarization relaxation type, the low temperature dielectric anomalous peak shift towards a high temperature and the high temperature dielectric anomalous peak shift towards a lower temperature showed by the dielectric-temperature spectrum. Dielectric-temperature spectrum further determines that (1-x)NBT-xBT ceramics are relaxation ferroelectrics, and join BT makes the Curie temperature decreasing about 21 to 24°C. High piezoelectric properties with d₃₃=148pC/N are observed in NBT-BT_0.06.