Paraelectricity

Paraelectricity

Paraelectricity is the ability of many materials (specifically ceramic crystals) to become polarized under an applied electric field. Unlike Ferroelectricity; this can happen even if there is no permanent electric dipole that exists in the material, and removal of the fields results in the polarization in the material returning to zero [Chiang, Y. et al: Physical Ceramics, "John Wiley & Sons" 1997, New York] . The mechanisms which give rise to paraelectric behaviour are the distortion of individual ions (displacement of the electron cloud from the nucleus) and the polarization of molecules or combinations of ions or defects.

Paraelectricity occurs in crystal phases in which electric dipoles are unaligned (i.e. unordered domains that are electrically charged) and thus have the potential to align in an external electric field and strengthen it. In comparison to the ferroelectric phase, the domains are unordered and the internal field is weak.

The LiNbO3 crystal is ferroelectric below 1430 K, and above this temperature it turns to paraelectric phase. Other perovskites similarly exhibit paraelectricity at high temperatures.

Paraelectricity may provide an alternative to the traditional heat pump. A current applied to a paraelectric material will cause it to cool down - which could be useful for refrigeration or for cooling computer chips.

ee also


*paramagnetism
*ferroelectricity

Navbox
name = Polarization states
title=Polarization states
list1=dielectric – paraelectricity – ferroelectricity – antiferroelectricity


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • paraelectricity — noun The temporary polarization of a material in the presence of an electric field …   Wiktionary

  • Dielectric — A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their …   Wikipedia

  • Ferroelectricity — is a property of certain materials which possess a spontaneous electric polarization that can be reversed by the application of an external electric field.[1][2] The term is used in analogy to ferromagnetism, in which a material exhibits a… …   Wikipedia

  • Antiferroelectricity — is a physical property of certain materials. It is closely related to ferroelectricity; the relation between antiferroelectricity and ferroelectricity is analogous to the relation between antiferromagnetism and ferromagnetism.An antiferroelectric …   Wikipedia

  • paraelectric — adjective Of, pertaining to, or exhibiting paraelectricity …   Wiktionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”