Piezoelectric Ceramics And Their Applications

I. Overview
Piezoelectric ceramics are a kind of polycrystalline with piezoelectric effect, because its production process is similar to that of ceramics (raw material crushing, molding, high-temperature sintering), hence the name.
Some anisotropic crystals, under the action of mechanical force, deform, so that the charged particles are relatively displaced, resulting in positive and negative binding charges on the crystal surface, this phenomenon is called the piezoelectric effect. This property of crystals is called piezoelectricity. Piezoelectric properties were discovered by brothers J. Curie and P. Curie in 1880. A few months later, they experimentally demonstrated the inverse piezoelectric effect, which is geometrically deformed when a voltage is applied to the crystal.
Before 1940, only two types of ferroelectrics were known (crystals that not only have spontaneous polarization in a certain temperature range, but also the direction of spontaneous polarization strength can be reoriented due to the strong action of the external field): one is polypoly and some closely related tartarinates; One class is potassium dihydrogen phosphate and its sibling. The former has piezoelectric properties at room temperature and has technical use value, but has the disadvantage of easy dissolution; The latter has piezoelectric properties at low temperatures (lower than -14 picture keyword C), and the engineering use value is not large.
Between 1942 and 1945, it was discovered that barium titanate (BaTiO picture keywords) has an abnormally high dielectric constant, and soon it was found that it has piezoelectricity, BaTiO picture keywords The discovery of piezoelectric ceramics is a leap forward in piezoelectric materials. Previously, there were only piezoelectric single crystal materials, and since then piezoelectric polycrystalline materials - piezoelectric ceramics have appeared, and have been widely used. In 1947, the United States used BaTiO picture keywords ceramics to manufacture pickup for gramophones, and Japan used it two years later than the United States. BaTiO image keywords There are disadvantages that piezoelectricity is weaker than that of polypoly and piezoelectric properties vary more with temperature than quartz crystals.
In 1954, B. Jaffe et al. in the United States discovered the piezoelectric PbZrO picture keyword - PbTiO picture keyword (PZT) solid solution system, which was an epoch-making event that made it possible to make devices that could not be made in the era of BaTiO picture keywords. Since then, PLZT transparent piezoelectric ceramics have been developed, so that the application of piezoelectric ceramics has been extended to the field of optics.
So far, the application of piezoelectric ceramics has been extremely extensive, from space development to family life.
China's research on piezoelectric ceramics began in the late fifties, about 10 years later than foreign countries, and has a fairly strong force in the trial production and industrial production of piezoelectric ceramics, and many materials have reached or approached the international level.