Piezoelectric effect is the ability of a material to generate an electric charge in response to an applied mechanical stress or pressure.
- The phenomenon can be observed in some materials – including quartz, topaz, tourmaline, ceramics such as lead zirconate titanate (PZT), and even certain biological substances like bone and the tendons.
- Inverse piezoelectric effect: Some materials also display an inverse piezoelectric effect, where the application of an electric current induces a mechanical strain or deformation.
- Mechanism:
- Normally, the charges in a piezoelectric crystal are exactly balanced. The forces (electric dipole moments) of the charges exactly cancel out, leaving no net charge on the crystal faces.
- When the crystal is stretched or compressed due to mechanical stress, this pushes the charges out of balance.
- Now the dipole moments no longer cancel one another out and net positive and negative charges appear on opposite crystal faces. This gives rise to a small electric current.
- Applications: Used in pressure sensors, accelerometers, acoustic devices, high voltage generators, electronic frequency generators, microbalances, inkjet printers, electronic stethoscopes.