The Piezoelectric crystal is used in a broad variety of common consumer, commercial, and industrial products. These crystals are used in watches, ultrasound equipment, microphones, cigarette lighters, inkjet printers, speakers, and a wide variety of sensors and motors, among many other applications.
What is a Piezoelectric Crystal?
Piezoelectric crystals are capable of the piezoelectric effect, which is the ability of a material to generate an electric charge when subjected to pressure. There are both natural and synthetic materials with this potential.
This effect was discovered in 1880 by Pierre and Jacques Curie, although it didn’t have any practical applications outside of the laboratory for many years. By World War I, it was used in the creation of sonar, which sparked interest in the potential for further technological advances using the piezoelectric effect.
How Do Piezoelectric Crystals Work?
The potential to conduct electricity is a result of the material’s structure. Piezoelectric crystals have a balanced charge with an asymmetric atomic structure. When mechanical pressure is applied, the structure is deformed, pushing the negative charge to one side and the positive charge to the other. This is known as the direct piezoelectric effect. Crystals with symmetric structure aren’t impacted by pressure in this way and are not piezoelectric.
This effect works in reverse as well—passing electricity from an external source through piezoelectric crystals will convert the electrical energy into sound waves. This is what was used to create sonar, and it is called the inverse piezoelectric effect.
How to Generate Electricity from Piezoelectric Crystals
The process is simple for generating electricity from a piezoelectric crystal that is fairly simple. To turn mechanical energy into electrical energy (the direct piezoelectric effect), metal plates are used to squeeze the crystal. The pressure disturbs the atomic structure and creates an electrical charge which is collected by the plates. More pressure means more electrical power.
The inverse piezoelectric effect is created when the balanced crystal, again placed between two metal plates, is charged with electricity. This essentially forces the crystal to squeeze itself, deforming its structure, which releases a sound wave.
Which Type of Crystals/Materials Exhibit Piezoelectricity?
Quartz is probably the most well-known piezoelectric crystal, perhaps because of its use in quartz clocks and watches. However, there are other materials (crystals and others) with this quality found in nature:
- Rochelle salt
Synthetic piezoelectric materials are typically more cost-effective than naturally occurring ones, so manufactured materials like langasite, lithium niobate, barium titanate, potassium niobate, sodium tungstate, lead zirconate titanate (PZT), and others are often used instead of natural crystals. These synthetic options also tend to have stronger piezoelectric potential.
Piezoelectric Materials at Kadco Ceramics
At Kadco Ceramics, we have a great deal of experience machining a wide variety of piezoelectric materials for everything from sonar to medical equipment, and we can help you choose the piezoelectric material that would best suit your application. In some cases, quartz or topaz may be ideal, or it may be better to use synthetic ferroelectric ceramics for their stronger piezoelectric effect and cost-effectiveness. We’re happy to discuss your project and help you determine the best option.