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针对机械品质因数特别低的压电陶瓷材料,提出了一种测量机电耦合系数和机械品质因数的方法,并用来测定了PbNb_2O_6陶瓷的材料参数。在这个方法中,利用低频阻抗分析仪(HP—4192A型)测量压电振子的阻抗随频率的变化,画出导纳圆图,由导纳圆图得出所需的振子参数,然后计算出径向伸缩振动的机电合系数k_p和机电械品质因数Q_m。对于厚度伸缩振动模式,由与上述径向仲缩振动模式相同的步骤得出机械品质因数,并由泛音比法计算机电耦合系数k_s,所需的泛音及基音频率仍然由低频阻抗分析仪测定。
Aiming at the piezoelectric ceramic materials with very low mechanical quality factor, a method of measuring electromechanical coupling coefficient and mechanical quality factor was proposed and used to determine the material parameters of PbNb_2O_6 ceramics. In this method, the change of the impedance of the piezoelectric vibrator with frequency is measured by a low-frequency impedance analyzer (Model HP-4192A), the admittance circle diagram is drawn, the desired vibration parameter is obtained from the admittance circle diagram, and then the Radial telescopic vibration electromechanical coefficient k_p and mechanical and electrical quality factor Q_m. For the thickness stretching vibration mode, the mechanical quality factor is obtained from the same steps as the above radial contracting vibration mode, and the electronic coupling coefficient k_s is calculated by the overtone ratio method. The required overtone and pitch frequencies are still measured by the low frequency impedance analyzer.