FENG  Ziyi, JIANG Xiangping ,TU  Na, CHEN  Chao, CHEN  Yan, YU Zudeng

(Department of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001)

Abstract: Lead-free piezoelectric ceramics Na_0.5Bi_0.5TiO₃+xmol%Co³⁺（abbreviated as: NBT-xC）are prepared by the solid state reaction method. Effects of the amount of Co³⁺ on the phase structure and electrical properties are studied. X-ray diffraction (XRD) indicates that each composition forms a pure rhombohedral perovskite phase. Scanning electron microscope (SEM) photographs show a remarkable growth of grains and compact structures are obtained with  Co³⁺ doped. The doping with  Co³⁺ enhances the mechanical quality factor Qm significantly, whereas the dissipation factor tgδ has a minimum value at x =3.Meanwhile, addition of  Co³⁺ leads to small decreases of piezoelectric constant d33 and planar electromechanical coupling kp.The composition of NBT-3C ceramics exhibit maximum mechanical mechanical quality factor Qm of 934, dissipation factor tgδ of 0.02 at 1kHz. These results demonstrate that the doping of  Co³⁺makes a "hard doping" effect.

Keywords: Na_0.5Bi_0.5TiO₃, Co₂O₃, piezoelectric, ferro-electricity