Structure and Electrical Properties of Lead-Free (Na0.5K0.5)NbO3-BaTiO3 Ceramics

概要

論文の詳細を見る
(Na0.5K0.5)NbO3 with 0–20 mol% BaTiO3 has been prepared following the conventional mixed oxide process. High-density samples were obtained through the addition of BaTiO3 into (Na0.5K0.5)NbO3 because of an increase in grain size. X-ray diffraction analysis revealed that, during sintering, all of the BaTiO3 diffuses into the lattice of (Na0.5K0.5)NbO3 to form a solid solution, in which orthorhombic symmetry changes to tetragonal symmetry at $x\approx 0.06$, and tetragonal symmetry changes to cubic symmetry at $x=0.20$ or higher. It was found that the samples with a low content of BaTiO3 exhibit relatively good ferroelectric and piezoelectric properties. For 0.98(Na0.5K0.5)NbO3-0.02 BaTiO3 ceramics, the remanent polarization ($P_{\text{r}}$) is 7.5 μC/cm2 with a coercive field ($E_{\text{c}}$) of 12 kV/cm. The piezoelectric constant $d_{33}$ reaches 104 pC/N. The electromechanical coupling coefficients of the planar mode $k_{\text{p}}$ and the thickness mode $k_{\text{t}}$ reach ${\sim}29$% and ${\sim}38$%, respectively. Our results show that (Na0.5K0.5)NbO3-BaTiO3 is a good lead-free piezoelectric ceramic.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-09-15