Synthesis And Characterizations Of Piezoelectric Ceramics And Their Composite Materials For Energy Harvesting Applications

Since discovered piezoelectric effect, piezoelectric materials and their applications have been rapidly developed, such as developed from original piezoelectric crystal and ceramic to piezoelectric nano-composite and nanofiber. With the rapid development of wireless sensor networks, much attention is focused on providing the energy source of wireless sensor networks. In all the method providing powder for wireless sensor networks, piezoelectric energy harvesting is a method with the largest potential. As environmental protection is attracted more and more attention, significant progress has been made in the development of lead-free piezoelectric material in the last a few years.In this dissertation, PZT piezoelectric discs was used as energy harvesting components, the output voltage and power was measured using a standard energy harvesting circuit and oscilloscope, when the vibration from the excitation system passing through the piezoelectric materials and circuit transferred to the load resistor. The experiment results show that the voltage increase first then decrease with the increased frequency. The maximum output voltage and power are 2.75 V and the 0.64μW at the frequency of 68 Hz and 80 Hz, respectively.BZT-BCT piezoelectric ceramics were prepared by the traditional solid state sintering, XRD and SEM were used to characterization the phase structure and surface topography, and their piezoelectric, ferroelectric and dielectric property were measured. The effect of sintering temperature on the BZT-BCT piezoelectric ceramics performance was studied. The result show that BZT-BCT ceramic sintered at 1350°C can achieve the maximum piezoelectric coefficient d33 is 230 pC/N, which is close to the value of a traditional material PZT-8 with lead. At the same time with better dielectric and ferroelectric performance.Piezoelectric composite materials PZT/PVDF and lead-free BZT-BCT/PVDF were prepared and the relationship between the fraction of component and the piezoelectric coefficient of the composites were studied. The results showed that piezoelectric constant d33 increase with increased volume fraction of ceramic. Comparing BZT-BCT/PVDF composite material with PZT/PVDF, it is observed that the piezoelectric coefficient of the two composites is similar when the fraction of ceramic is around 60%, which indicate that piezoelectric ceramic with lead can be substituted by lead-free。...