From Composite Materials for Aircraft Structures, Second Edition

A.1 Piezoelectric Materials

Piezoelectric materials have the ability to generate charge when subjected to mechanical stress, and conversely can elongate or contract when subjected to an electrical field. [1] Typical piezoelectric materials are: quartz, barium titanate, cadmium sulphide, lead zirconium titanate (PZT) and piezoelectric polymers polyvinyldene fluoride (PVDF), polymer films, and polyvinyl chloride (PVC).

A.1.1 Ceramics

Piezoelectric ceramic materials such as lead zirconate titanate [Pb(ZrTi)O 3], known as PZT, exhibit the piezoelectric effect where the size of the deformation or voltage depends on crystal orientation. Properties of PZT are stable in the range ?22 C to = 155 C. PZT can be manufactured in thin plates, strips, or fibers suitable for embedding or surface bonding.

Piezoelectric properties are established by applying at elevated temperature a high electrical field in a direction known as the polling direction to align all the ferroelectric domains within the ceramic (i.e., to achieve constant polarization direction). Conventional PZT wafers or plates are generally polarized normal to the plane of the sheet. When a voltage is applied to the conducting layers on the surface of the sheet, the sheet deforms or develops in-plane forces.

Conventional PZT sheets are quite brittle (low strain to failure), limiting in actuation capability, and are intrusive if embedded in composite laminates. A new concept for the actuation and sensing of structures using PZT fibers and interdigitated electrodes has been developed (Fig. A.1). This material incorporates unidirectional PZT fibers (typically about 130 ?m in diameter) into a matrix, producing a...

Copyright American Institute of Aeronautics and Astronautics, Inc. 2004 under license agreement with Books24x7

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Piezoelectric Ceramics
Piezoelectric ceramics produce an electrical charge when a load is applied and deformation occurs. Piezoelectric ceramics can also produce force or deformation when an electrical charge is applied.
Electroceramics are ceramic materials that have been specially formulated for specific electrical, electro-magnetic, or optical properties. They include dielectric ceramics, electrostrictive ceramics, ferrite ceramics, garnets (ferromagnets), and piezoelectric ceramics.
Dielectric Ceramics and Substrates
Dielectric ceramics and substrates are electrical insulators with dielectric strength, dielectric constant and loss tangent values tailored for specific device applications.
Piezoelectric Sensors
Piezoelectric sensors measure the electrical potential caused by applying mechanical force to a piezoelectric material. They are used in a variety of pressure-sensing applications.
Ceramic Powders and Precursors
Ceramic powders and precursors contain oxides, carbides, nitrides, carbon, and other non-metals. They are usually micron or mesh-size in distribution. Ceramic powders, sol-gel solutions and precursors are fabricated through atomization, crushing, milling, precipitation, and other chemical processes.

Topics of Interest

Voltage and ferroelectric characteristics are important factors in determining the performance of piezoelectric MEMS. ROHM is focusing on developing a thinner lead zirconate titanate (PZT) material...

Four of the more important types of piezoceramic materials are introduced below. Lead Zirconate-Titanate - Because of their high coupling factors and wide range of possible variations, most of the...

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5.11 Piezoelectric Wave-Propagation Transducers Piezoelectricity derives its name from the Greek word piezein, to press. When a piezoelectric crystal is strained by an applied stress, an electric...