Relaxor ferroelectrics are
ferroelectric
Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoelectric and pyroelectric, with the ad ...
materials that exhibit high
electrostriction Electrostriction (cf. magnetostriction) is a property of all electrical non-conductors, or dielectrics, that causes them to change their shape under the application of an electric field.
Explanation
Electrostriction is a property of all dielectri ...
. , although they have been studied for over fifty years, the mechanism for this effect is still not completely understood, and is the subject of continuing research.
Examples of relaxor ferroelectrics include:
*
lead magnesium niobate
Lead magnesium niobate is a relaxor ferroelectric. It has been used to make piezoelectric microcantilever sensors.
References
Niobates
Magnesium compounds
Lead compounds
Piezoelectric materials
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(PMN)
*
lead magnesium niobate-lead titanate (PMN-PT)
*
lead lanthanum zirconate titanate (PLZT)
*
lead scandium niobate (PSN)
*Barium Titanium-Bismuth Zinc Niobium Tantalum (BT-BZNT)
*Barium Titanium-Barium Strontium Titanium (BT-BST)
Applications
Relaxor Ferroelectric materials find application in high efficiency
energy storage
Energy storage is the capture of energy produced at one time for use at a later time to reduce imbalances between energy demand and energy production.
A device that stores energy is generally called an accumulator or battery.
Energy comes in ...
and conversion as they have high dielectric constants, orders-of-magnitude higher than those of conventional ferroelectric materials. Like conventional ferroelectrics, Relaxor Ferroelectrics show permanent dipole moment in domains. However, these domains are on the nano-length scale, unlike conventional ferroelectrics domains that are generally on the micro-length scale, and take less energy to align. Consequently, Relaxor Ferrolelectrics have very high specific capacitance and have thus generated interest in the fields of energy storage.
Furthermore, due to their slim hysteresis curve with high saturated polarization and low remnant polarization, Relaxor ferroelectrics have high discharge energy density and high discharge rates. BT-BZNT Multilayer Energy Storage Ceramic Capacitors (MLESCC) were experimentally determined to have very high efficiency(>80%) and stable thermal properties over a wide temperature range.
References
Electric and magnetic fields in matter
Ferroelectric materials
Electrical phenomena
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