Explanation

It refers to the crystal with piezoelectric effect. Among 32 point group, 21 have no symmetry center. All of them have piezoelectricity (except for point group 432), of which 10 types have piezoelectricity under hydraulic throw, and the other 10 types can only have piezoelectricity effect under unidirectional pressure in proper direction, which are called hydraulic sensitivity and non hydraulic pressure sensitivity piezoelectricity respectively. The crystal with piezoelectric effect is cut to a certain orientation and placed in an alternating external electric field to stretch with the direction of the electric field. If the frequency of the alternating electric field matches the natural frequency of the chip, resonance will occur. It can be used to control the frequency of the electromagnetic wave, or as a frequency standard. It is mainly used to manufacture load measuring elements, resonators, filters, surface acoustic wave energy conversion and propagation substrates. Commonly used are tourmaline crystal, crystal, potassium sodium tartrate, lithium sulfate monohydrate, etc.

Classification