The Preparation And Properties Of BNT-BT Powders And BNT-BT/PVDF Piezocomposites

A kind of lead-free piezoelectric composite is reported in this paper,which functive is sodium bismuth titanate-barium titanate (NBBT) ceramic and matrix is Polyvinylidene Fluoride (PVDF) .NBBT powders are prepared by solid-reaction and hydrothermal synthesis process. The conclusion shows that pure NBBT powders can be obtained when the powders is calcined at the 850℃ for 3 hours, while a little of impurity occur in NBBT powders at 750℃ and 800℃.Alkaline concentration has a great effect on the phase and shape of powders. Impurity (Bi₂Ti₂O₇) occur when alkaline concentration is lower, and impurity decrease when the alkaline concentration gradually increase. Pure NBBT powders can be obtained at the alkaline concentration of 10mol/L. Particle size distributions become narrow and medial diameters become small when alkaline concentration rises. The reactive temperature is higher than 160℃ in the process of NBBT hydrothermal synthesis. Particles size distribution of NBBT becomes narrow when reactive temperature rise. The medial diameter is 0.5μm when the reactive temperature is 180℃. When the reactive time is lower than 12 hours, Bi₁₂TiO₂₀ occurs. Particles size distribution becomes narrow when the reactive time extends.In this paper, 0-3 NBBT/PVDF piezoelectric composite is prepared by hot-press and solidification process. The conclusion shows hot-press can not only raise the piezoelectric constant and dielectric constant, but also reduce the dielectric loss. The influence of mass percentage of NBBT, temperature and pressure of hot-press on the performance of composites is studied. The conclusion shows that when the mass percentage increase, the piezoelectric constant augment, dielectric loss lessen, dielectric constant augment, then lessen, and reach the peak when the NBBT mass percentage is 80%.With the hot-press temperature rise, piezoelectric constant augment ,and dielectric loss basically steady ,dielectric constant lessen. With the hot-press pressure augment, piezoelectric constant augment, and dielectric loss...