Performance test method of piezoelectric ceramic material

Curie temperature

When the temperature is higher than the curie temperature (Tc), the piezoelectric ceramic disc transducer is in the paraelectric phase, and the spontaneous polarization and piezoelectricity also disappear. At the Curie temperature, many physical properties of piezoelectric ceramic materials, such as permittivity, heat capacity, and linear expansion coefficient, will undergo sudden changes. Therefore, the Curie of piezoelectric ceramic materials can be determined only by measuring the temperature corresponding to the sudden change point. temperature.

 

Longitudinal piezoelectric strain constant (static)

In the absence of external electric field, meet the electrical short circuit conditions

 

Strong field dielectric properties

The free relative permittivity and dielectric loss tangent of piezoelectric ceramic transducer are related to temperature, humidity, frequency of alternating electric field, field strength and time of applied voltage. Dielectric properties generally refer to free relative permittivity and dielectric loss tangent.

 

Pyroelectric coefficient

 The pyroelectric coefficient of piezoelectric ceramic materials was measured by charge integration method. This method determines the change in remanent polarization with temperature by measuring the pyroelectric charge accumulated on the capacitor.

 

The stretching vibration mode of the longitudinal length of the cylinder

In the longitudinal length stretching vibration mode, the exciting electric field is parallel to the propagation direction of the elastic wave, and the elastic stiffness (or compliance) constant is related to the electromechanical coupling effect.

 

Wafer Thickness Stretch Vibration Mode

Under the condition of electrical short circuit, the frequency of the stretching vibration mode of the thickness of the free vibration all-electrode piezoelectric transducer components is calculated according to the formula tanx=x/kt2. Kt—thickness stretching vibration electromechanical coupling coefficient, X—value of normalized frequency.

 

Thickness Shear Vibration Mode of Rectangular Plate

The thickness shear vibration is shown in the figure, the sample is polarized along the 1 direction, and the excitation electric field is applied along the 3 direction, then the shear force is generated on the 1 and 3 planes as shown in a, and the 1 and 3 planes are sheared as shown in b, when When the electric field is reversed, the 1 and 3 planes produce reverse shear as shown in c. Under the excitation of the alternating electric field, the sample produces shear vibration in which the particle displacement is along the 1 direction, and the propagation direction of the wave is along the 3 direction, so the shear wave is a transverse wave.

 

Transmission line method test of characteristic frequency and dynamic resistance

 

 Using the transmission line method of piezoceramics crystal to test the characteristic frequency and dynamic resistance under the longitudinal length stretching vibration mode of the cylinder, the stretching vibration mode of the disc thickness and the shear vibration mode of the rectangular slice thickness shall be carried out according to the regulations.