Ferroelectric vs Piezoelectric-difference between ferroelectric and piezoelectric
This page on Ferroelectric vs Piezoelectric mentions difference between ferroelectric and piezoelectric materials.
Ferroelectric and piezoelectric materials derive their properties from a combination of structural and electrical properties. As the name implies, both types of materials have electric attributes.
Piezoelectric material
The piezoelectric material is the one which possesses property to convert mechanical energy into electric energy and vice versa. The piezoelectric materials are divided into two major groups viz. crystals and ceramics.
Direct Piezoelectric Effect
The piezoelectric materials will generate electrical potential when they are subjected to some kind of mechanical stress. This direct piezoelectric effect is found in strain sensor, gas lighters, microphones, ultrasonic detectors etc.
The direct piezoelectric effects due to compression and tension are shown in the figure-1 above.
Compression Effect: When volume is decreased, it shows voltage with same polarity as
of material.
Tension Effect: When volume is increased, it shows voltage with opposite polarity as
of material.
Inverse Piezoelectric Effect
When the Piezoelectric material is subjected to electric field (i.e. voltage), as a result it consequently lengthens or shortens which is proportional to the voltage. This inverse piezoelectric effect is found in crystal speakers, crystal oscillators, actuators, record player pic ups etc.
➤As shown in the figure-2(A), if applied voltage has the same polarity then the material gets
expanded.
➤As shown in the figure-2(B), if applied voltage has opposite polarity then the
material gets contracted.
Ferroelectric material
• All the ferroelectric materials exhibit piezoelectric effect due to lack of symmetry.
• Special class of piezoelectric materials exhibit certain other
characteristics also.
• It exhibits spontaneous polarization i.e. polarization in absence of electric field.
• Ferroelectrics are electric analog of ferromagnets.
This may display permanent magnetic behaviour. The first ferromagnetic material named
Rochelle Salt has been discovered by Valasek.
• In ferroelectic, the polarization can be changed and reversed by external
electric field. This is shown in the figure-3.
Ferroelectric vs Piezoelectric
A large number of materials which are ferroelectric are also piezoelectric. However, the converse is not true.
Following table summarizes comparison between piezoelectric and ferroelectric material types.
| Features | Piezoelectric | Ferroelectric |
|---|---|---|
| Characteristics | Generates electric potential when subjected to mechanical energy (viz. compression or tension) is applied. | Polarization can be changed and reversed with the applied external electric field. |
| Material classes | Organic, Ceramic, single crystal | Organic, Ceramic |
| Examples of materials | PVF2, PZT, PLZT, Quartz, LiNbO3 | PVF2, Liquid Crystals, PZT (Lead [Pb], Zirconate, Titanate) thin film |
| Applications | actuator, transducer, optical, frequency control, SAW devices, ultrasonic receiver | non-volatile memory, displays |
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