High Qm Research Articles

Relations between Piezoelectric Properties and Microstructure in Poled Piezoelectric Ceramics by Applied Uniaxial Compressive Stress

Relations among kp, fr·d, Qm and domain configurations in some piezoelectric ceramics with various Qm values were investigated under a polarization process (poling treatment) and depolarization process (applied stress treatment). In those materials, kp values in Pb(Zr0.17)(Ti0.33)(Ni1/3Nb2/3)0.5O3 ceramics (low Qm) decreased markedly with applied uniaxial compressive stress increase, and became 0.402 from 0.702 (initial kp value) by 49 MPa, while 90° and 180° domain patterns revealed by chemical etching were not changed, even by either poling or applied stress treatments. However, kp values in (Pb0.625Ca0.375)TiO3 ceramics (high Qm) decreased slightly by 49 MPa, and a clear difference in the 90° domain pattern arrangement was observed before and after both poling and applied stress treatments.

Preparation and Piezoelectric Properties of Ceramics-Plastic Composite Materials

Ceramics-plastic composite materials composed of piezoelectric hard materials with properties of high k33, high QM and low s33E for the ceramics and epoxy resin for the plastic were prepared. Dielectric and piezoelectric properties for thickness expansion were studied and new piezoelectric ceramics-plastic composite materials with properties of about 1/3 times lower densities (2.61 g/cm3), about 1/10 times lower relative dielectric constant (130), about 10 times higher elastic compliance constant (138.6×10-12 m2/N) and 4.4 times higher piezoelectric voltage constant (101×10-3 V·m/N) than usual ceramics were obtained.

Piezoelectric properties in soft-hard pseudobinary system

Abstract Pb(Zr, Ti)O3 Ceramics added with Pb(Sb1/2Nb1/2)O3 (PSN) or Pb(Mn1/3Nb2/3)O3 (PMN) ceramics behave like soft and hard piezoelectric materials, respectively. Variety in piezoelectric properties is obtained in the pseudobinary system constituted by PZT-PSN and PZT-PMN ceramics. Compositions having both high Kp and Qm values are prepared. An enhancement in piezoelectric activity is found when the composition is rich in hard material (PZT-PMN). On the contrary, compositions rich in soft material (PZT-PSN) show deterioration in piezoelectric characteristics. Both phenomena are changed slightly with the sintering temperature. With appropriate sintering temperature, composition having Kp higher than 55% and Qm ranging from 70 to 1300 are obtainable in the soft-hard pseudobinary system.

On the measurement of the mechanical losses of low Qmpiezoelectric materials

Abstract IRE and IEEE Standards on Piezoelectricity describe the characterization of relatively high mechanical Q (Qm) materials. The mechanical dissipation is the most important limitation on the validity of some analytical expressions derived for ideal piezoelectric materials. In this paper we propose an alternative expression for the mechanical quality factor (Qm) of the fundamental resonance of a thickness mode resonator which applies for high and low Qm materials.

Temperature Stability of Piezoelectric Ceramics

This paper reports an investigation into the fundamental temperature stability of piezoelectric ceramics through thermal aging and thermal shock tests. The dependence of piezoelectricity on thermal aging and thermal shock of low Qm and high Qm materials was clarified. The surface charges generated by the thermal shock caused depolarization of the ceramic elements. In particular, it was found that space charges promoted depolarization in the high Qm materials. A resistor inserted in parallel with the element for the thermal shock test improved piezoelectricity by causing quick relaxation of the induced charges.

Anomalous absorption of sound near the Curie point in uniaxial ferroelectrics: Levanyuk, A.P., Minaeva, K.A., Stukov, B.A. Fiziki Tverdogo Tela, Vol 10, No 8 (August 1968) pp 2443–2448 (In Russian, English translation in Soviet Physics—Solid State) (1064)

Piezoelectric materials with excellent electromechanical performance are widely used as core components in high-power applications such as ultrasonic transducers, piezoelectric transformers, ceramic filters and sonar systems. A comprehensive review of the fundamental, progress, and perspective of the various types of piezoelectric materials with high-electromechanical performance based on high mechanical quality factor Qm is presented herein, and in particular, the regulation and optimization of electromechanical performance are systematically introduced and summarized. Based on the investigation and summary, two main key issues faced for high-power applications are elaborated: one is the mutually restrictive relationship between Qm and other parameters (d33, kp and ɛ), and the other one is the temperature stability of electromechanical parameters. Next, the factors and internal mechanisms that affect Qm regulation and optimization are discussed in detail, and the effective strategies for improving Qm and weakening the mutually restrictive relationship are proposed to obtain high-electromechanical performance. Subsequently, some discussions and perspectives are put forward in detail as suggestions for the development and design of high-Qm piezoelectric materials with excellent comprehensive performance. It is hoped that this review would be helpful for researchers and engineers to understand the origins of high-Qm and related mechanisms, and to design new high-electromechanical performance piezoelectric materials meeting high-power applications.