Applications of various piezoelectric devices, such as filters, resonators, etc., have continued until the mid-1950s. Subsequently, Japan actively developed ultrasonic transducers, high-frequency transducers, and pressure sensors using BaTiO3 piezoelectric ceramics. In 1947, Roberts of the United States applied high voltage on BaTiO3 ceramics for polarization treatment to obtain the piezoelectricity of piezoelectric ceramics. In 1946, the Institute of Insulation of the Massachusetts Institute of Technology discovered that applying a DC high-voltage electric field to a barium titanate ferroelectric ceramic so that its spontaneous polarization is preferentially oriented in the direction of the electric field and that after the removal of the electric field, it can maintain a certain residual polarization, making it With the piezoelectric effect, piezoelectric ceramics have been born since then. In World War II, BaTiO3 ceramics were discovered, and piezoelectric materials and their applications made epoch-making progress. In World War I, Curie’s successor, Lang Zhiwan, first made use of the piezoelectric effect of quartz to create an underwater ultrasonic probe that was used to probe submarines and opened a chapter in the history of piezoelectric applications. In 1894, Voigt pointed out that the crystals of only twenty point groups without a symmetry center may have a piezoelectric effect, and quartz is a representative of piezoelectric crystals, and it has been applied. In 1881, the Curie Brothers experiment verified the inverse piezoelectric effect, giving quartz the same positive and negative piezoelectric constants. In 1880, the Curie brothers first discovered the piezoelectric effect of tourmaline and began the history of piezoelectric science. 2.Development History of piezoelectric ceramics After the polarization treatment of the piezoelectric ceramics, in the electric field After cancellation, it will retain a certain degree of macroscopic residual polarization, so that the ceramic has a certain piezoelectric properties. After being coated on the end face, it is subjected to a polarization treatment under a strong DC electric field, so that the original polarization orientations of the respective polarization vectors are preferentially oriented in the direction of the electric field. In order for the ceramic to exhibit macroscopic piezoelectric characteristics, it is necessary to burn the piezoelectric ceramic. Since the ceramic is a polycrystalline aggregate in which crystal grains are randomly oriented, the spontaneous polarization vector of each of the ferroelectric crystal grains is also chaotically oriented. The main difference from typical piezoelectric quartz crystals that do not contain ferroelectric components is that the crystal phases that make up the main component are ferroelectric crystal grains. Piezoelectric ceramics is a class of electronic ceramic materials with piezoelectric properties.
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