Piezoelectric Properties

The values listed above pertain to test specimens. They are for reference purposes only and cannot be applied unconditionally to other shapes and dimensions. In practice, piezoelectric materials show varying values depending on their thickness, actual shape, surface finish, shaping process and post-processing.

Note: measurements made 24 hours after polarization.
Maximum voltage:5-7 VAC /mil for 850, 851, 855, Type VI VDC

~2X. 9-11 VAC /mil for 840, 841, 842, 844, 880, 881 VDC ~2X.

*At 1 kHz, low field.
**Maximum operating temperature = Curie point/2.

APC’s piezoelectric ceramics are generally manufactured from PZT (Pb – lead, Zr – zirconium, Ti – titanium). This compound class shows much better piezo-electrical and piezo-mechanical efficiency than naturally occurring piezoelectric materials such as quartz.

The PZT– formulation can be varied with a variety of dopants allowing for a broad spectrum of material properties optimized for different application profiles.

Unfortunately, not all desirable properties can be put into a distinct piezo compound. Piezo-mechanics is to some extent is an “art of compromise”, when selecting a suitable material for a distinct application.

Developing new piezo-materials is a steadily ongoing process in the ceramic industry. PZT is the most widely used smart material for solid-state actuation. Alternative materials with enhanced strain capability are under study, but all these “innovative” materials have drawbacks regarding common driving conditions.

PZT ceramics’ material data are usually defined at low field excitation where nonlinearities are not dominant. In practice, high electrical fields are applied often applied resulting in a nonlinear enhanced response (“ferro-effects”) and altered parameters. Nevertheless, for reasons of comparison with materials from different suppliers, the classical characterizations are used for describing piezoelectric ceramics. The data shown in the tables are valid for room temperature operation.

Piezoelectric ceramics are a ferroelectric compound. This means, that the electro-mechanical conversion process for producing a motion is related a kind of self-enhancement process based on an internal reorganization of the material’s structure. This self-enhancement process results in the higher piezo-electrical efficiency of PZT when compared to natural materials like quartz.

When subjected to a mechanical force certain crystalline minerals become electrically polarized. Tension and compression generate voltages of opposite polarity, in proportion to the applied force. The converse of this relationship also is true: a voltage-generating crystal exposed to an electric field lengthens or shortens according to the polarity of the field, and in proportion to the strength of the field. These behaviors are the piezoelectric effect and the inverse piezoelectric effect, respectively. Piezoelectric materials have been adapted to an im­pressive diversity of sensing and action applications, including generation of sonic and ultrasonic signals. For many of these applications there are no practical alternatives.

Metal oxide-based piezoelectric ceramics and other man-made materials have enabled designers to employ the piezoelectric effect and the inverse piezoelectric effect in applications for which natural materials are unsuitable. The composition, shape, and dimensions of a piezoelectric ceramic element can be tailored to meet demanding requirements. Further, these materials are physically strong and chemically inert, and they are relatively inexpensive to manufacture.

PC International manufactures its custom piezoelectric elements from a selection of proprietary piezoelectric materials. Our lead zirconate titanate (PZT) materials are manufactured from some of the highest purity raw materials available on the market and have been developed and refined through years of extensive research and development.

APC has produced custom piezoelectric ceramics and PZT materials for over twenty-five years and we would like to be the one to manufacture the piezoelectric ceramics that meet your needs. However, if you would like to produce the piezoelectric ceramics on your own, APC offers many of its unprocessed PZT materials for direct sale to customers.

A ceramic element of suitable composition is made piezoelectric by exposing the element to a strong direct current electric field. When the electric field is removed the element is permanently polarized (poled) and elongated in the direction of the field. Subsequently, compression along the direction of polarization, or tension perpendicular to the direction of polarization, generates voltage of the same polarity as the polarizing voltage. Tension along the direction of polarization, or compression perpendic­ular to the direction of polarization, generates voltage with polarity opposite that of the polarizing voltage. This conversion of mechanical energy into electrical energy—generator action—is used in fuel-igniting de­vices, solid state batteries, and other products.