Hard and Soft Materials
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 esponse 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(?), 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.
Piezoceramic material NCE80 is intended for power transducers with highest electric drive. Its low dielectric and mechanical losses at extremely high electric drive and high coupling factors make it suitable for high-power applications.
Soft doped piezoceramic materials
Soft doped piezoelectric ceramics are distinguished by a comparatively high domain mobility and thus “ferroelectrically soft” behaviour, i.e. relatively easy polarization. These materials are characterized by high relative permittivity, large electromechanical coupling factors, large piezoelectric constants and low mechanical quality factors. They are particularly suitable for sensing applications, receivers, actuators and low power transducers.
Piezoceramic materials NCE51 and NCE57 are standard soft materials, particularly suitable for actuators and low power non-resonant applications in which high coupling factor and /or high charge sensitivity are requested.
Piezoceramic material NCE53 has slightly lower electro-mechanical coupling factor, but has the advantage of higher temperature stability, and it is suitable especially for shear mode vibration sensors.
Piezoceramic materials NCE55 and NCE59 are very high sensitivity materials featuring extremely high permittivity, large coupling factor and piezoelectric constant. They have a relatively low Curie temperature. These materials are suitable for a wide range of high sensitivity applications with limited temperature range of operation.