What Is A Piezoelectric Ceramic Wafer And What Is The Piezoelectric Effect?

Piezoelectric ceramic wafer: scientific name: lead zirconate titanate, English abbreviation PZT - where, P is the abbreviation of the lead element Pb, Z is the abbreviation of the zirconium element Zr, and T is the abbreviation of the titanium element Ti. PZT piezoelectric ceramics are polycrystalline crystals made by sintering lead dioxide, lead zirconate, and lead titanate at a high temperature of 1200 degrees. It has a positive piezoelectric effect and a negative piezoelectric effect.
Piezoceramic buzzers are mainly composed of piezoelectric ceramics and metal substrate pastes. The substrate material generally includes iron sheet, copper sheet, steel sheet, nickel alloy sheet, according to the acceptable price and performance required by customers to choose different substrates. Piezoelectric ceramic sheet belongs to the ferroelectric substance, is an artificially manufactured polycrystalline piezoelectric material, which has an electric domain structure similar to the magnetic domain structure of ferromagnetic materials.
Manufacturing process of piezoelectric ceramic wafers: batching→ abrasives→ burning→ stirring abrasives→ forming (rolling, extrusion, casting), → discharge→ sintering→ silver → baking→ burning silver→ polarization → measurement→ bonding piezoelectric ceramic buzzer→ audiometric detection (full inspection).
Piezoceramic wafers have a certain polarization direction, so there is a certain electric field. In the absence of an external electric field, the various electric domains are randomly distributed on the crystal, and their polarization effects are canceled out by each other, so the internal polarization intensity of the original piezoelectric ceramic is zero, but when the voltmeter is connected to the two electrodes of the ceramic plate for measurement, the polarization intensity existing inside the ceramic plate cannot be measured.
This is because the polarization strength in the piezoceramic sheet is always expressed in the form of an electric dipole moment, i.e. a positive bound charge appears at one end of the piezoceramic and a negative bound charge at the other end. Due to the binding charge, a layer of free charge from the outside world is adsorbed on the electrode face of the piezoelectric ceramic plate. These free charges are equal in number to the binding charge symbol in the piezoelectric ceramic sheet, which acts to shield and counteract the polarization strength inside the ceramic sheet to the outside world. Therefore, the voltmeter cannot measure the degree of polarization in the piezoelectric ceramic sheet.
Piezoelectric ceramic sheets have a piezoelectric effect due to spontaneous polarization inside the ceramic. After these spontaneous polarizations are forced to be oriented through the polarization process, there is a residual polarization strength in the ceramic.
If external forces (such as pressure or electric fields) can change this polarization strength, piezoelectric ceramics have a piezoelectric effect.