Sol-Gel Derived Li2O Doped BNT-BKT-BT Ceramics: Microstructure and Piezoelectric Properties

The introduction of lithium ion into BNT-BKT-BT ceramics with sol-gel method allows the development of high-performance lead-free piezoelectric ceramics. Nanoscale precursor powders were synthesized through calcination of amorphous gels, and densified ceramics with single perovskite structure were prepared at a relatively low sintering temperature 1110 °C. Crystal grain growth was fully developed with the Li+ addition through scanning electron microscope observation. Enhanced electrical properties, piezoelectric constant d33~184 pC/N and planar electromechanical coupling factor kp~0.30, were obtained for the ceramics.

Influence of Poling Conditions on the Characteristics of PZT Ceramics

In the poling process of PZT ceramics, the poling temperature is a critical condition. When the poling temperature is too low, no matter how high is the poling field and how long is the poling time, the planar electromechanical coupling factor kpis lower. When the poling temperature is higher enough, the kpcan reach to a saturated value with a lower poling field and short poling time. The variation of dielectric constant with the poling conditions is the same as that of planar electromechanical coupling factor. When poling with a low temperature, the dielectric constant after poling is lower than 1400. When poling with higher temperature, no matter how high is the poling field and how long is the poling time, the dielectric constant after poling is higher than 1500.

Effects of AgSbO3 on the Piezoelectric/Dielectric Properties and Phase Transition of Li2O Doped NKN Lead-Free Piezoelectric Ceramics

The effect of AgSbO3on the piezoelectric properties of (K0.5Na0.5)0.95Li0.05NbO3was examined. The AgSbO3doped KNLN samples sintered at 1050°C showed the maximum values of the sintering density of 4.56 g/cm3compared to un-doped KNLN samples sintered at same temperature with 4.25 g/cm3. Moreover, the addition of AgSbO3enhanced the piezoelectric and dielectric properties. Piezoelectric constant (d33), the planar electromechanical coupling factor (kp) and the relative dielectric permittivity (K33T) increased up to 230pC/N, 43.5%, 1080, respectively, with addition of AgSbO3.

Fabrication and Properties of 1-3-2 Piezoelectric Composites

In this paper, the 1-3-2 piezoelectric composites were fabricated by the cut-filling technique using P(MN)ZT piezoelectric ceramic as functional materials and polymer as matrix. The effects of ceramic volume fraction on the electrical properties of the composites were studied. The results indicate that as the ceramic volume fraction increases, the piezoelectric stain factor d33 increases evidently, while the piezoelectric voltage factor g33 decreases. Besides, the planar electromechanical coupling factor Kp and mechanical quality factor Qm of the composite are also less than those of the pure ceramic, while the thickness electromechanical coupling factor Kt is larger than that of the ceramic.