Papers by Keyword: Electromechanical Coupling Factor

Abstract: 1-3 polymer-based piezoelectric composites were fabricated using epoxy as matrix by the cut-filling method. The influences of shape parameter on properties of the piezoelectric composite, which include the unit cross-sectional area and the aspect ratio w/t were analyzed. The results indicate that with the increasing of the unit cross-sectional area, the quality factor value Q_m increases and the hydrostatic piezoelectric voltage g_h increases and then goes down rapidly while the PMN volume fraction φ(PMN) is kept under the 50%. When the φ(PMN) is 60%, g_h is decreased. The trend of the hydrostatic figures of merit d_h·g_h is similar with g_h as the change of the unit cross-sectional area, but the value is different. In the 60% PMN volume fraction, the optimal value of the d_h·g_h is chosen. With the increasing of the w/t, the hydrostatic pressure sensitivity M_h, the d_h·g_h values and the Q_m values are all decreased rapidly, and the thickness electromechanical coupling factor k_t is increased. In other words, the test results show that the smaller of unit cross-sectional area and thinner of thickness, the more helpful for frequency bandwidth and sensitivity when it is used in transducer.

Abstract: In the poling process of PZT ceramics, the poling temperature is a critical condition. When the poling temperature is too low, no matter how high is the poling field and how long is the poling time, the planar electromechanical coupling factor k_p is lower. When the poling temperature is higher enough, the k_p can reach to a saturated value with a lower poling field and short poling time. The variation of dielectric constant with the poling conditions is the same as that of planar electromechanical coupling factor. When poling with a low temperature, the dielectric constant after poling is lower than 1400. When poling with higher temperature, no matter how high is the poling field and how long is the poling time, the dielectric constant after poling is higher than 1500.

Abstract: In this investigation, we extend our previous works to improve piezoelectric properties of Pb(Zr,Ti)O₃ ceramics. Modified lead zirconate titanate (PZT) piezoceramics with a composition Zr/Ti=53/47 containing a trace of mixing dopants were prepared by conventional ceramic technology sintering powder compacts. Replacement of (Zr, Ti)⁺⁴ by Nb⁺⁵, Pb⁺² by Sb⁺³ and Mn⁺⁴ in PZT perovskite type solid solutions was accomplished by the creation of cation and anion vacancies. Modified ceramics were explored as a function of firing temperature to acquire exceedingly good piezoelectric characterizations. From the analysis results, calcined at 850°C for 2 h, and then sintered at 1280°C for 2 h, PZT piezoceramic showed the larger dielectric constant er 2013, mechanical quality factor Qm 120 and maximum electromechanical coupling factor kp 0.67. Besides, the bulk ceramic grains distribution were found to be uniform. Furthermore, the sample was found to possess piezoelectric properties, the resonance frequency being about 200 KHz suitable for acoustic sensor.