| Popis: |
In this chapter, the authors review the advances in piezoelectric ceramics (materials and applications) that have occurred in the past 10-15 years. The reasons for the acceptance of the piezoelectric ceramics are (1) the high piezoelectric activity and high permittivity and (2) the ease of fabricating the material into a very wide variety of sizes and shapes. Present understanding of the fracture processes in piezoelectric ceramics depends on developments in fractography. These developments now permit us to identify and measure the flaw at which a fracture originates. In addition to piezoelectricity, another electromechanical effect, known as electrostriction, is exhibited by all nonconducting materials, including glasses and liquids. In summary, the electrostrictive elements offer interesting new possibilities for actuator and motor structures, adding a new step to the continuum of "soft" piezoelectric ceramics. |
