Ferroelektrisch

Ferroelektrisch describes a property of certain crystalline materials that exhibit a spontaneous electric polarization which can be reversed by an external electric field. This phenomenon is analogous to ferromagnetism, where materials have a spontaneous magnetic moment that can be reoriented by an external magnetic field. The spontaneous polarization in ferroelectric materials arises from the arrangement of ions within their crystal lattice. In the absence of an external field, the positive and negative charge centers within the unit cell do not coincide, leading to a net electric dipole moment.

When an external electric field is applied, these dipoles align themselves with the field. If the field is strong enough, it can overcome the internal forces holding the dipoles in place and reverse their orientation. This reversibility is a key characteristic of ferroelectricity. The direction of spontaneous polarization can be switched back and forth by applying electric fields of opposite polarity. The temperature at which a material loses its ferroelectric property and becomes paraelectric is called the Curie temperature. Above this temperature, the thermal vibrations disrupt the ordered alignment of the dipoles.

Ferroelectric materials have important applications in various technologies. They are used in non-volatile random-access memory (NVRAM) devices, where the polarization state can be used to store information. Other applications include piezoelectric transducers, which convert electrical energy into mechanical energy and vice versa, and pyroelectric sensors, which detect changes in temperature. The study of ferroelectric materials is an active area of research, with ongoing efforts to discover new materials with enhanced properties and to develop novel applications.