Search

For green development concern, lead-free piezoelectric ceramics 0.96(K0.48Na0.52)Nb0.96Sb0.04O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3-xmol%Tm2O3 fabricated via conventional solid state method are studied. The analyses of X-ray diffraction and Raman dates show the coexistence phase of orthorhombic-tetragonal. Meanwhile, the tetragonal fraction increases with increasing Tm contents. Both the Cure temperature and the responding maximum permittivity decline with increasing x. At the same time, there are diffuse phase transition and relaxation-like phenomena after doping Tm. The activation energy, obtained from Arrhenius equation, suggests that there is a mixed conduction mechanism by both single-ionized and doubly oxygen vacancy diffusion. The temperature stabilities of remnant polarization and unipolar strain are significantly improved in the temperature range of 30-150 °C. Rare earth element Tm is useful for improving the temperature stability of the KNN-based piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Rare earth (RE) elements (Tb, Tm) doped K0.5Na0.5NbO3 (KNN) lead-free ceramics were fabricated using conventional solid-state reaction method. All samples with dominating orthorhombic phase are well developed. The effects of Tb and Tm on impedance, dielectric and ferroelectric properties are systematically studied. There are relaxation-like features of the ceramics after the doping of RE elements. Conduction processes were affected by defect, especially in KNN-Tb ceramics, in the higher temperature region. The doping of Tb and Tm increases density, remnant polarization and the piezoelectric constant of the KNN ceramics due to the effect of donor doping. The overall analysis has confirmed the significance of RE elements (Tb, Tm) doping in KNN and shows that it is a promising candidate as lead-free piezoelectric ceramics. [ABSTRACT FROM AUTHOR]