Design of electrical parameter d33 characteristic of piezo ceramics

There are many detection methods for d33. This instrument not only keeps the characteristics of dynamic method, but also avoids the shortage of manual operation and time-consuming. It is a simple and fast tool for d33 test. In recent years, foreign countries have developed numerical control resistance measurement instrument which can be connected with computer, such as HP4192A impedance analyzer. It still uses the quasi-static method to detect the charge under the action of pressure, but due to the factors such as charge attenuation, leakage and strict requirements of charge amplifier, the accuracy of detection is affected to a certain extent, so it is popularized more widely hard. the same sample was measured by the above method. The values are not completely consistent, so the d33 parameters detected are only of reference significance, but the comparability is limited. a method based on sweep frequency is designed for test device. The device adopts the detection method of resonance and anti resonance frequency, which keeps the characteristics of multi parameters and high accuracy of dynamic measurement; at the same time, it can detect and calculate other PZT material parameters, avoid the disadvantages of tedious manual operation and time-consuming calculation, and broaden the application scope of dynamic method.           

Measurement principle of d33 value        

 D33 value reflects the strain force produced when a unit voltage is applied to the piezoelectric crystal pzt piezo ceramics, which is called piezoelectric strain constant.       

The voltage of piezoelectric ceramics C. is the total capacitance (f); F.is the force along the direction of ceramic polarization (n). There are many measuring methods for piezoelectric ceramics d33, such as electrical measurement, acoustic measurement, force measurement and optical measurement, among which electrical measurement is the most common. There are three kinds of electrical measurement: ① static method. The static method is to use the positive piezoelectric effect of piezoelectric ceramic disc, that is, adding a constant force F3 and measuring the d33 of the material by charge q generated . ② Dynamic method. by measuring the characteristic frequency of piezoelectric ceramic plate, and using some parameters to determine the piezo ceramic plate material d33 ③ quasi-static method. The basic principle is the same as that of the static method, except for the force F applied on the sample. It is not constant, but a low frequency alternating vibration force. D33 value test method can directly reflect the piezoelectric effect of the linear relationship between the force and the generated charge of piezoelectric ceramic components; in the test method, there are also on-line computer test devices, but they are based on the piezoelectric ceramic in the test environment.