[P2-44] Characterization of KxNa1-xNbO3 powders and ceramics prepared by hydrothermal synthesis
There is an increasing demand to replace Pb(Zr,Ti)O3-based piezoelectric materials with lead-free alternatives, because of the toxicity of lead oxide which is largely used during the production process. KxNa1-xNbO3 (KNN) is considered as one of the most promising candidates for lead free piezoelectric ceramics due to its high Curie temperature and good electrical properties.
KxNa1-xNbO3 ceramics can be used for several applications such as high frequency transducers, ultra-sonic diagnostics and tunable micro-wave components. However, it is well known that dense and well-sintered K0.5Na0.5NbO3 ceramics are very difficult to obtain by the ordinary sintering process owing to the high volatility of alkali elements at high temperatures. The major strategy to overcome this problem is simply to synthetized KNN powders at low temperature. One method of making dense (KxNa1−x)NbO3 ceramics is to use refined powder with improved sintering activity, prepared in the molten salt process, sol-gel routine or hydrothermal process. In this work, (KxNa1−x)NbO3 powders and ceramics were prepared by hydrothermal synthesis. X-ray diffraction and scanning electron microscope were performed to investigate the structure and surface morphology of the (KxNa1−x)NbO3 powders and ceramics. The results showed that all the KNN powders possessed the pervoskite structure and a handful of second phases. The K0.7Na0.3NbO3 ceramic prepared by the powders exhibits relatively good properties (relative dielectric constant ε= 416 and piezoelectric coefficient d33=40 pC/N).
KxNa1-xNbO3 ceramics can be used for several applications such as high frequency transducers, ultra-sonic diagnostics and tunable micro-wave components. However, it is well known that dense and well-sintered K0.5Na0.5NbO3 ceramics are very difficult to obtain by the ordinary sintering process owing to the high volatility of alkali elements at high temperatures. The major strategy to overcome this problem is simply to synthetized KNN powders at low temperature. One method of making dense (KxNa1−x)NbO3 ceramics is to use refined powder with improved sintering activity, prepared in the molten salt process, sol-gel routine or hydrothermal process. In this work, (KxNa1−x)NbO3 powders and ceramics were prepared by hydrothermal synthesis. X-ray diffraction and scanning electron microscope were performed to investigate the structure and surface morphology of the (KxNa1−x)NbO3 powders and ceramics. The results showed that all the KNN powders possessed the pervoskite structure and a handful of second phases. The K0.7Na0.3NbO3 ceramic prepared by the powders exhibits relatively good properties (relative dielectric constant ε= 416 and piezoelectric coefficient d33=40 pC/N).