Preparation Of Nanogenerator Based On Piezoelectric Fibers And The Study Of Its Piezoelectric Potential Introduction And Transfer

Piezoelectric materials can transform mechanical energy into electrical energy,and have been widely used in transducers,actuators and sensors.When the scale of piezoelectric materials is reduced to the nanometer scale,their performance will be greatly changed.Such as the elastic coefficient of piezoelectric fiber will decrease,elastic limit will increase,and piezoelectric constant will also along with the increased fiber diameter,and become very sensitive to weak,low frequency,irregular mechanical vibration,and can produce piezoelectric response.This kind of mechanical vibration is a kind of green,renewable energy in the environment,such as air flow,water flow,noise,vibration,biological motion and so on.Therefore piezoelectric nanomaterials can collect abandoned vibration energy from the surrounding environment and convert it into electrical energy,applying in nanogenerator,catalytic degradation of organic pollutants,and other fields,with promising application prospect.However,in the existing studies,studies on the preparation,microstructure and piezoelectric and ferroelectric properties of piezoelectric fibers are still not thorough enough,and their piezoelectric properties are still worse than those of piezoelectric ceramics.Moreover,the mechanism of how piezoelectric fibers deform and generate piezoelectric potential under external stress/strain,and how the piezoelectric potential is transferred to the outside and used is not well studied.Its output performance in nano-generator and catalytic degradation performance need to be further improved.Therefore,this thesis takes piezoelectric nanofibers as the research object,and focus on the followings:(1)Firstly,based on the new type of high performance of lead-free piezoelectric ceramics(1-x)(K1-yNay)(Nb1-z Sbz)O3-x Bi0.5(Na1-w Kw)0.5Zr O3 composition design,through the electrostatic spinning method KNNS-BNKZ nanofibers were prepared for the first time,the structure,piezoelectric and ferroelectric properties of the fibers were characterized through a variety of analysis testing methods.(2)Then based on the KNNS-BNKZ nanofibers,piezoelectric generator with different structure were prepared,the output of the NGs were tested and the influence of substrate,electrodes,fiber space configuration,deformation mode,load resistance and so on the output were investigated.Through the optimization of structural design,energy harvesting and storage were realized.(3)We have demonstrated a new design for curved piezoelectric structures and geometries created by the application of an uneven patterned substrate and electrospun ferroelectric microfibers.These fibers exhibit stable upward self-poling induced by a strain gradient originating from the flexoelectric effect without any type of external stimulus,and can be fabricated into high performance flexible nanogenerators with output comparable to those of poled ones.Such a self-poling effect due to the strain gradient in the ferroelectric piezoelectric fibers can resistan external electric field and temperature.(4)Piezoelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3(BZT-BCT)fibers have been synthesized and used as piezoelectric catalyst for decomposing organic dye in aqueous solution through scavenging energy from the surrounding environment for the first time.These studies have greatly contributed to the research of one dimensional piezoelectric/ ferroelectric material’s preparation,structure and properties,promoting its application on the collection of green renewable vibrational energy,are of great significance.