Ferroelectric materials are a type of dielectric materials that exhibit spontaneous electric polarization, meaning they possess a permanent electric dipole moment even in the absence of an external electric field. This polarization arises from the alignment of electric dipoles within the material, which can be spontaneously oriented in a particular direction, typically along one of the crystallographic axes.
Key characteristics of ferroelectric materials include:
Spontaneous polarization: Ferroelectric materials have a net electric dipole moment per unit volume, even in the absence of an external electric field.
Hysteresis behavior: Ferroelectric materials exhibit hysteresis loops in their polarization-electric field curves, similar to ferromagnetic materials. This hysteresis behavior arises due to the existence of multiple energetically equivalent polarization states.
Switchable polarization: The direction of the spontaneous polarization in ferroelectric materials can be reversed by applying an external electric field, making them useful for applications in non-volatile memory devices, actuators, and sensors.
Curie temperature: Above a certain temperature known as the Curie temperature (Tc), ferroelectric materials lose their ferroelectric properties due to thermal agitation disrupting the alignment of the electric dipoles.
Ferroelectric materials find applications in various fields such as electronics (e.g., ferroelectric random-access memory - FeRAM), electromechanical devices, piezoelectric actuators, sensors, and capacitors, among others, due to their unique electrical and electromechanical properties. Examples of ferroelectric materials include lead zirconate titanate (PZT), barium titanate (BaTiO3), and lithium niobate (LiNbO3).