This standard specifies the use of the admittance circle to determine the electromechanical coupling coefficient kt and quality factor Qm of the thickness vibration mode of low quality factor piezoelectric ceramic vibrators. This standard is applicable to low quality durable piezoelectric ceramic materials with k2tQm not less than 0.2. GB/T 11320-1989 Test methods for piezoelectric ceramic materials with low mechanical quality factor piezoelectric ceramic materials performance test GB/T11320-1989 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for the properties af piezoelectric ceramicsmaterial witsh the low mechamical quality factor1 Subject content and scope of application
G# 11320-89
This standard specifies the determination of the electromechanical coupling coefficient and quality factor Qm of the thickness vibration mode of the piezoelectric ceramic vibrator with low quality factor by the admittance circle method.
This standard is applicable to piezoelectric ceramic materials with low quality factor Q not less than 0.2. 2 Terms and symbols
The definitions of terms and symbols used in this standard comply with the provisions of GB3389.1 "Common Terms and Terms for Test Methods of Piezoelectric Ceramic Materials".
3 Test principle
The performance parameters of the thickness mode vibrator of the piezoelectric ceramic material with low mechanical quality factor are measured by the admittance circle method. 3.1 Equivalent circuit
The equivalent circuit of a low-quality piezoelectric ceramic vibrator near the harmonic frequency is shown in Figure 1, and the trajectory of the total admittance Y changing with frequency is shown in Figure 2.
Figure 1 Equivalent circuit of a single-mode lossy piezoelectric vibrator Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on November 5, 1988 and implemented on March 1, 1990
3.2 Admittance characteristics
The total admittance of a piezoelectric vibrator can be expressed by the following formula: GB 1132D—89
Figure 2 Admittance diagram
Y = Y+ Y = G + jB = (Ga+ G) + (B+ Ba),tgo, +
Where Y--total admittance, S;
Y. ——Total static admittance, S;
Y.----Total dynamic admittance, S;
G.-Total conductance, S;
B-.—Total susceptance, S;
G.-Leakage conductance (equivalent conductance of electrical loss), S;
G-——Dynamic conductance St
B-Static susceptance, S:
Ba— Dynamic susceptance, S;
a-Angular frequency, rad/s,
C,--Parallel capacitance, F,
tgde—Dielectric loss tangent;
R,——Dynamic resistance, Q;
Dynamic inductance, H,
Dynamic capacitance, F.
4 Test conditions
4.1 Environmental conditions
Normal test atmospheric conditions
Temperature: 25+1C, relative humidity: 48%~52%, atmospheric pressure: 86~106kP84.2 Sample size and requirements
(1)
, the sample is a thin disc, the parallelism of the two main planes is not greater than half of the thickness tolerance, and the metal layer is fully coated on the two soil planes as the electrode, and polarization treatment is performed along the thickness direction. The ratio of the sample diameter d to the thickness should be able to meet the requirements of the excitation simple thickness vibration mode. Generally, the ratio of diameter d to thickness t is about 10. Recommended sample size: 20×2mm.
4.3 Preparation of samples before testing
The samples should be kept clean and dry. According to the requirements of different porcelain materials, they should be stored for a certain period of time after polarization, and placed in the environment specified in Article 4.1 for 2 hours before testing.
4.4 Requirements for testing the electric field E at both ends of the sample
5 Test method
5.1 Test equipment and requirements
Automatic admittance bridge or a complete set of equipment that can measure admittance, such as a low-frequency impedance analyzer. The frequency range can meet the vibration admittance characteristics of the thickness of the star, and the general frequency is within the range of 5 MHz or less. Signal resolution; 1 Hz.
Conductance G and susceptance B measurement range:
0~100 ms. Maximum resolution 10 us, display digits, 4 points. 5.2 Sample holder and clamping methodWww.bzxZ.net
The sample is directly clamped on the sample fixture of the bridge for measurement. The holding force should be small, and the clamp should maintain good electrical contact with the sample. The diameter of the contact point is 0.3-1mm. The clamping point is located three-quarters of the radius from the center of the sample. 5.3 Test steps
During the test, the influence of the stray parameters of the sample fixture must be eliminated first, and an excitation level of less than 1V is applied to the sample. Then the fundamental vibration admittance characteristics are measured, and the frequency values ​​of the two half-power points f-1/2 and F1+12, the series resonant frequency f, and the corresponding dynamic conductance Ga and static susceptance Bo are determined.
6 Calculation of material parameters
6.1 Maximum electrical conductivity fc
Icmar = f.
6. 2 Mechanical quality factor of thickness stretching vibration Qf
Qm = F+1/2 ~- -12
6.3 Electromechanical coupling coefficient of thickness stretching vibration
Wu Zhong, Ci-
Qmm, Dai
6.4 Longitudinal sound velocity
6.5 Open circuit elastic stiffness constant CB
C number = pu, 2
（6）
6.6 Piezoelectric stress constant e
GB 11320-89
ess -- k, Vcess eo
Wherein%: It can be measured at high frequency (such as the seventh harmonic or above), or it can be obtained by the following formula (when, ≤0.1): Ea - el(1 - h2)
6.7Thickness stretching vibration frequency constant N.
In formula (2) to (9);
-fundamental wave parallel resonance frequency, Hz;
Upper half power point frequency, Hz;
f-12-lower half power point frequency, Hz:
Ga---dynamic conductance, S;
Ba——static susceptance, S,
C,--dynamic capacitance, F;
Co-.-parallel capacitance, F ;
R, dynamic resistance, 0;
Sample thickness, m;
Sample density, kg/m;
Longitudinal sound velocity, m/s;
Piezoelectric stress constant, N/V·m or C/m2
-Open circuit elastic stiffness constant, N/m;
—-Clamped relative dielectric constant;
Vacuum dielectric constant, eg=8.85×10-12F/m; f,--Fundamental parallel resonant frequency, Hz. 7
Test report
The performance test report of low mechanical quality factor piezoelectric ceramic materials shall include: a.
The entrusting unit,
The name, number and polarization date of the sample;
Test results;
The name and model of the test instrument;
The temperature and relative viscosity of the test room;
The test date and the name of the tester;
References.
Additional remarks:
GB11320—B9
This standard is proposed by the National Ferroelectric Piezoelectric Ceramics Testing Professional Standardization Working Group. This standard is drafted by the Shanghai Institute of Silicates, Chinese Academy of Sciences. The main drafters of this standard are Dian Xiaodong and Feng Baokang.
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