Properties of PZT-Based Piezoelectric Ceramics Between-150 and 250°C

Abstract The properties of three PZT-based piezoelectric ceramics and one PLZT electrostrictive ceramic weremeasured as a function of temperature. In this work, the dielectric, ferroelectric polarization versuselectric field, and piezoelectric properties of PZT-4, PZT-5A, PZT-5H, and PLZT-9/65/35 were measuredover a temperature range of-150 to 250°C. In addition to these measurements, the relative thermalexpansion of each composition was measured from 25 to 600°C, and the modulus of rupture of eachmaterial was measured at room temperature. This report describes the experimental results andcompares and contrasts the properties of these materials with respect to their applicability to intelligentaerospace systems.Keywords: piezoelectric, PZT, PLZT, temperature InWoducfion The term piezoelectricity refers to the relationship between pressure and electricity that exists within aunique family of materials. Piezoelectrics are materials that either output a voltage when subjected to amechanical stress or exhibit a dimensional change when an electric field is applied. These two behaviorsare referred to as the direct and indirect modes of operation respectively [1-2]. Both modes ofpiezoelectric operation are currently being utilized in modem aerospace systems in such diverseapplications as vibration cancellation and optical positioning [3-5]. Because these materials have theability to sense and respond to changes in their environment, they are often referred to as "smart" or"intelligent" materials [6]. The primary applications of piezoelectric technologies in fixed-wing aircraft include the active controlof boundary layers along leading edges [7], the suppression of internal cabin noise [8], and theelimination of panel flutter [9] and tail buffeting [10]. This technology is also being applied inhelicopters to eliminate the vibrations present in rotor blades [ 11-13]. In addition to the aeronautical applications of intelligent structures, piezoelectric technologies are alsobeing developed for use in spacecraft systems. In recent years, satellite systems have become smaller andlighter to reduce the cost of launching the payloads into orbit. As spacecraft masses have been reduced,however, the elimination of vibrational disturbances has become a critical design issue. Since many ofthe scientific instruments aboard these spacecraft require precision pointing to perform their intendedfunctions, the spacecraft must be mechanically stable for the payloads to function as designed. As such,methods of incorporating intelligent structures to minimize jitter in spacecraft structures has become acritical area of research and development in the aerospace community [14-15]. Piezoelectric materials are typically incorporated into aerospace structures by either applying a patch-style device to the surface of the structure [16-17] or by embedding the device into a graphite-epoxycomposite structure [18-20]. In each instance, distributed networks of sensors and actuators are used tosense and nullify vibrational disturbances. Similarly-controlled systems are also being developed for usein space-based instruments to actively position optical components [21]. These control systems typicallyinclude a position sensor that locates the optical component and a piezoelectric drive mechanism whichpositions the optic based on real-time feedback from the position sensor.Because of the wide range of operating conditions for the systems under development, carefulconsideration must be given to the selection of piezoelectric materials. This is particularly important