Piezoelectric ceramics applications

Piezoelectric ceramics, which depend on lead compounds, are used to produce transducers and sensors which make possible ultrasound technologies used in wide-ranging medical and commercial applications, guidance and sensing systems used in defense and commerce, and in addition, new "smart materials" research projects. 

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The heart of STM is a piezoelectric scanner, sometimes called piezodrive or simply piezo. In this chapter, we provide a brief summary of the basic physics of piezoelectricity and piezoelectric ceramics relevant to the applications in STM. Three major types of piezodrives, the tripod, the bimorph, and the mbe, are analyzed in detail. 

The first piezoceramic to be developed commercially was BaTi03, the model ferroelectric discussed earlier (see Section 2.7.3). By the 1950s the solid solution system Pb(Ti,Zr)03 (PZT), which also has the perovskite structure, was found to be ferroelectric and PZT compositions are now the most widely exploited of all piezoelectric ceramics. The following outline description of their properties and fabrication introduces important ideas for the following discussion of the tailoring of piezoceramics, including PZT, for specific applications. It is assumed that the reader has studied Sections 2.3 and 2.7.3. 

Electrostrictive materials offer important advantages over piezoelectric ceramics in actuator applications. They do not contain domains (of the usual ferroelectric type), and so return to their original dimensions immediately a field is reduced to zero, and they do not age. Figure 6.24(a) shows the strain-electric field characteristic for a PLZT (7/62/38) piezoelectric and Fig. 6.24(b) the absence of significant hysteresis in a PMN (0.9Pb(Mg1/3Nb2/303-0.1 PbTi03) electrostrictive ceramic. 

The first commercial application of a piezoelectric ceramic (barium... 

Composite piezoelectric transducers made from poled Pb-Ti-Zr (PZT) ceramics and epoxy polymers form an interesting family of materials which highlight the advantages of composite structures in improving coupled properties in soilds for transduction applications A number of different connection patterns have been fabricated with the piezoelectric ceramic in the form of spheres, fibers, layered, or three-dimensional skeletons Adding a polymer phase lowers the density, the dielectric constant, and the mechanical stiffness of the composite, thereby altering electric field and concentrating mechanical stresses on the piezoelectric ceramic phase. 

While PVDF has piezoelectric properties similar to those of piezoelectric ceramic materials, the pyroelectric coefficient is too low to be useful except for specialized applications where the main... 

High flexibility, low drive voltage, and large bending deflection are definite advantages of IPMCs over other rigid piezoelectric ceramic materials. These characteristics make IPMC actuators and sensors very popular in various biomedical applications. 

Piezoelectric ceramics and polymers can play the double role of sensors and actuators these materials can either generate an electric field under an applied load or change dimensions when subjected to a voltage difference. When fabrication problems associated with their embedding are solved, they will find wide application for structure vibration control. 

Applications for piezoelectric ceramics utilize one of the two piezoelectric effects ... 

Actuators are an important and growing market for piezoelectric ceramics. In applications requiring precise... 

Thin sheets of piezoelectric materials are used in sensors, buzzers, and actuators. In addition to the conventional vibrators, pressure and acceleration sensors are now also being manufactured from these materials. Lead zirconate titanate (PZT) is one of the most common materials used for these applications. The trend is to produce thinner and thinner and smaller and smaller parts. Therefore tape casting has become the manufacturing route of choice. One of the basic applications of piezoelectric ceramics is as a gas igniter where a spark is generated by the piezoelectric under an applied mechanical stress. Microphone discs are also prepared from thin... 

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