Lead zirconate titanate, piezoelectric effect

The sensor is illustrated schematically in Fig. 1. The piezoelectric-excited millimeter-sized cantilever (PEMC) sensor is a macro-cantilever that comprises piezoelectric layer (lead zirconate titanate PZT) layer bonded to a nonpiezoelectric layer of a few millimeters in length and 1 mm in width (9,21). We use the direct piezoelectric effect to excite the cantilever, and the same PZT film senses the resulting response. PZT film is bonded to a base glass... 

Electric energy is converted into mechanical vibrations in modem machinery using the piezoelectric effect. It concerivs the reversible property of special ceramic materials to deliver an electric voltage when affected by external forces. This characteristic is used for the generation of ultrasonic vibrations in such a way that the applied voltage is converted into mechanical vibrations. Modern sonic converters usually contain several piezoceramic disks of lead zirconate titanate restricted by two final masses that are mechanically prestressed by a centric screwing. 

Wing, J., Schierholz, R., Schonau, K.A., Fuess, H., Knapp, M., Kungl, H., Hoffmann, M.J. (2007) Nanodomains in morphotropic lead zirconate titanate ceramics On the origin of the strong piezoelectric effect, J. Appl. Phys., 102 024111. 

The type of sensors used in AET almost exclusively are sensors that exploit the piezoelectric effect of lead zirconate titanate (PZT). While piezoelectric sensors and their design are described in numerous books and papers (e.g. Krautkramer and Krautkramer 1986 Kino 1987 Hykes et al. 1992), some characteristics play an influential role in AE measurements and need to be highlighted. These features are important for the sensitive recording of acoustic emissions (sensitivity) and the broadband analysis of the signals with reference to fracture mechanics (frequency). 

Tu Y.L., CalzadaM.L., Phillips N.J., Milne S.J. Synthesis and electrical characterization of thin films of PT and PZT made from a diol-based sol-gel ronte. J. Am. Ceram. Soc. 1996 79 441 148 Tu Y.L., Milne S.J. A study of the effects of process variables on the properties of PZT films produced by a single-layer sol-gel techniqne. J. Mater. Sci. 1995a 30 2507-2516 Tu Y.L., Milne S.J. Characterization of single-layer PZT (53/47) films prepared from an air-stable sol-gel route. J. Mater. Res. 1995b 10 3222-3231 Tuchiya T., Itoh T., Sasaki G., Suga T. Preparation and properties of piezoelectric lead zirconate titanate thin films for microsensors and microactnators by sol-gel processing. J. Ceram. Soc. Jpn 1996 104 159-163... 

Thin film ceramic materials with important magnetic, optical, electronic, and mechanical properties are often highly anisotropic. Thus, the ability to control orientation is critically important in thin film applications. For many of the oxide materials, as well as Ae ionic materials, aqueous solution or sol-gel routes are the most convenient or the only method of preparation. Examples of these include barium titanate (BaTiOs) used in multilayer capacitors, lead-zirconate-titanate (Pb(Zr,Ti)03, "PZT") used as a piezoelectric material, and zinc oxide (ZnO) used in varistors. Thus, the use of substrates to control orientation can eliminate major problems in deposition of thin films. In some cases, e.g., the many magnetic and non-magnetic phases of iron oxide, the ability to control the phase formed is critical to production of the desired properties. While this can be controlled by solution conditions, the proper surface can add an additional and very effective mechanism of control. 

Since discovering and making use of the piezoelectric effect in naturally occurring crystals such as quartz and Rochelle salts, scientists have produced a wide range of piezoelectric materials in the laboratoi y. An early example is barium titanate, used in an electrical component called a capacitor. Currently, most piezoelectric materials are oxide materials based on lead oxide, zirconate oxide, and titanium. These very hard piezoelectric materials are termed piezoceramics. 

In some sense the actuators, which generate action on command (i.e. information) form the counterpart to sensors which collect information about the surroundings. Actuators which change the composition have been implicitly addressed by the text (cf. e.g. electrochemical piunps). Actuators in a narrower sense cause mechanical effects (e.g. transfer of electrical into mechanical energy) and rely especially on the phenomenon of electrostriction (cf. piezoelectricity). For details the reader is referred to Ref. [573]. Also in this context perovskites play a dominant role (in particular perovskites based on lead titanate zirconates), and defect chemistry, even though not decisive, is of considerable importance (cf. Section 2.2.7). 

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