25-08-2017, 09:32 PM
Piezo ceramics
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Piezo ceramics characteristics
Piezoelectric ceramics have the property of developing an electric charge when mechanical stress is exerted on them.
In these materials, an applied electric field produces a proportional strain. The electrical response to mechanical stimulation is called the direct piezoelectric effect, and the mechanical response to electrical stimulation is called the converse piezoelectric effect.
Piezoelectric ceramics are usually divided into two groups. The antonyms “hard” and “soft” doped piezoelectric ceramics refer to the ferroelectric properties, i.e. the mobility of the dipoles or domains and hence also to the polarization/depolarization behaviour.
Hard doped piezoceramic materials
Hard doped PZT materials can be exposed to high electrical and mechanical stresses. The stability of their properties makes them ideal for high-power applications.
Piezoceramic materials NCE41 and NCE40 are low loss materials for high power applications. The low dielectric and mechanical losses (tan(δ), Qm) combined with high piezoelectric charge constant (d33) make them suitable for high-performance ultrasonic applications.
Furthermore NCE41 and NCE40 can be exposed to high repetitive quasi-static and dynamic loads for ignition applications. NCE41 and NCE40 differ from each other in permittivity and mechanical quality factor values. This variability enables to fulfil all specific requirements.
Technical piezo ceramics description
Piezoelectricity is the property of nearly all materials that have a non-centrosymmetric crystal structure.
Some naturally occurring crystalline materials that possess these properties are quartz and tourmaline. Some artificially produced piezoelectric crystals are Rochelle salt, ammonium dihydrogen phosphate and lithium sulphate. Another class of materials possessing these properties is polarized piezoelectric ceramic. In contrast to the naturally occurring piezoelectric crystals, piezoelectric ceramics have a polycrystalline structure.