News Excerpt:
In the future, piezoelectricity might be used for energy harvesting.
About Piezoelectricity:
- Jacques and Pierre Curie, two brothers who were French physicists, discovered piezoelectricity in 1880.
- The process of utilizing crystals to transform mechanical energy into electrical energy or vice versa is known as piezoelectricity.
- When mechanical stress is applied to some materials, those materials have a tendency to accumulate electric charges.
- The fact that a piezoelectric material will produce a voltage when pressure is applied to it is known as the piezoelectric effect.
- The inverse piezoelectric effect is used in many transducers to produce ultrasonic sound waves.
How does piezoelectricity appear under pressure in ceramic or crystal materials?
- When the material is in a free state (without any pressure), those molecules will be arranged in a certain way which corresponds to an equilibrium of the material and in which the charges of the molecules cancel themselves if we look at the whole.
- When pressure is applied, however, those molecules change position and align into a dipolar state in which the global charge isn’t null anymore and 2 sides of the materials become polarized.
Piezoelectric materials:
- The piezoelectric materials are usually grouped into three categories:
- Naturally occurring (single) crystal substrates
- Ceramics with perovskite structure
- Polymer films
- For example, some materials which show a more pronounced piezoelectric effect are:
- Crystals (Quartz, Potassium Nibonate)
- Certain Ceramics (Lead Zirconate Titanate or PZT, Barium Titanate)
- Biological material (Bone)
- DNA and various proteins
- The most used piezoelectric materials, the lead zirconate titanate (or PZT) crystals generate measurable piezoelectricity when their static structure is deformed by about 0.1% of the original dimension.
Applications of piezoelectricity:
- Piezoelectricity is being used in electronic applications these days:
- Speakers & buzzers
- Actuators
- Drivers
- Sensors
- Motors
- Quartz watches
