Ferroelektrik

Ferroelektrik is a material that exhibits a spontaneous electric polarization that can be reversed by applying an external electric field. This property is analogous to ferromagnetism, where a spontaneous magnetic moment can be reversed by a magnetic field. The spontaneous polarization in ferroelectric materials arises from the alignment of electric dipoles within the crystal lattice. These dipoles can be formed by the displacement of positive and negative ions within the unit cell. Above a certain temperature, known as the Curie temperature, the thermal energy overcomes the forces aligning the dipoles, and the material loses its ferroelectric properties, becoming paraelectric.

The key characteristic of ferroelectric materials is their hysteresis loop, which plots the electric polarization as a function of the applied electric field. This loop demonstrates that the polarization does not vanish when the electric field is removed, indicating spontaneous polarization. The coercive field is the electric field strength required to reverse the polarization. Ferroelectric materials are typically ceramics, such as barium titanate (BaTiO3) and lead zirconate titanate (PZT), but some organic compounds can also exhibit ferroelectricity.

The ability to switch polarization with an electric field makes ferroelectrics useful in a variety of applications. These include non-volatile memory devices (FeRAM), sensors, actuators, and high-frequency electronic components. The reversible nature of their polarization allows for the storage of binary data (0s and 1s) by representing the two polarization states. Their electromechanical coupling also enables them to convert electrical energy into mechanical strain and vice-versa.