What is piezoelectric ceramic ?

Piezlelectric ceramics are a kind of functional material which can convert  mechanical energy and electric energy into each other. Piezoelectric effect is a property  that some of crystal and piezoelectric ceramics have. When load on the load in some dielectric, so that it will produce polarization, and on its surface, the separation of positive and negative charge will occur. When the external force is removed, if the polarizationdoes not disappear, it is called the positive piezoelectric effect; On the contrary, when the dielectric polarization direction of the application of electric field, the dielectric will be deformed, but when the electric field removed, the dielectric deformation also disappear, this phenomenon is called inverse piezoelectric effect, or  called electrostrictive phenomenon.
Lead Zirconate Titanate (PZT) piezoelectric ceramics is the most widely used, can effectively achieve the conversion of mechanical energy and electrical energy, so in the modern industry, it has a wide range of applications, and occupying 70%of total output of piezoelectric ceramics.
In addition, because PZT piezoelectric ceramicscontain a large amount of Pb, it has negative impact on the ecological environment. Therefore, it is the key point  of piezoelectric ceramics research to find the suitable lead-free materials to replace PZT piezoelectric ceramics.