Microstructure and enhanced electrical properties of lead-free Bi1/2Na1/2TiO3–BaTiO3–La2CoMnO6 ternary system ceramics

The structure, field-induced strain, polarization and dielectric response of lead-free La2CoMnO6-modified 0.935Bi1/2Na1/2TiO3–0.065BaTiO3 (BNT–BT6.5–xLCMO, with x=0–0.020) ceramics were investigated. X-ray diffraction (XRD) patterns show that all compositions have a pure perovskite structure and LCMO effectively diffused into the BNT–BT6.5 lattice during sintering to form a solid solution. Around critical composition (x=0.005) at a driving field of 70 kV/cm, large unipolar strain of 0.22% (Smax/Emax=328 pm/V) and high piezoelectric constant of 211 pC/N are obtained at room temperature. The coercive field (Ec=18.6 kV/cm) drop down greatly, whereas the remnant polarization (Pr=28.8 μC/cm2) decreases only a little at this critical composition. These results indicate that BNT–BT6.5–xLCMO ceramics can be considered as promising candidate materials for lead-free piezoelectric practical applications.