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| [[File:Dielectric.png|thumb|A polarized dielectric material]]
| | == Prada Chaussure En plus == |
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| A '''dielectric material''' ('''dielectric''' for short) is an electrical [[Insulator (electrical)|insulator]] that can be [[Dipolar polarization|polarized]] by an applied [[electric field]]. When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in a [[Electrical conductor|conductor]], but only slightly shift from their average equilibrium positions causing '''dielectric polarization'''. Because of dielectric polarization, positive charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field that reduces the overall field within the dielectric itself.<ref name=britannica1/> If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axis aligns to the field.<ref name=britannica1/>
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| The study of dielectric properties concerns storage and dissipation of electric and magnetic energy in materials.<ref>[[Arthur R. von Hippel]], in his seminal work, ''Dielectric Materials and Applications'', stated: "''Dielectrics''... are not a narrow class of so-called insulators, but the broad expanse of ''nonmetals'' considered from the standpoint of their interaction with electric, magnetic, or electromagnetic fields. Thus we are concerned with gases as well as with liquids and solids, and with the storage of electric and magnetic energy as well as its dissipation." (Technology Press of MIT and John Wiley, NY, 1954).</ref> It is important to explain various phenomena in [[electronics]], [[optics]], and [[solid-state physics]].
| | <li>[http://www.52byl.com/news/html/?187284.html http://www.52byl.com/news/html/?187284.html]</li> |
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| ==Terminology==
| | <li>[http://bbs.cdscjd.com/forum.php?mod=viewthread&tid=4515452 http://bbs.cdscjd.com/forum.php?mod=viewthread&tid=4515452]</li> |
| While the term ''insulator'' implies low [[electrical conduction]], ''dielectric'' typically means materials with a high [[polarizability]]. The latter is expressed by a number called the [[relative permittivity]] (also known in older texts as dielectric constant). The term insulator is generally used to indicate electrical obstruction while the term dielectric is used to indicate the energy storing capacity of the material (by means of polarization). A common example of a dielectric is the electrically insulating material between the metallic plates of a [[capacitor]]. The polarization of the dielectric by the applied electric field increases the capacitor's surface charge.<ref name=britannica1>Quote from [[Encyclopædia Britannica]]''':''' "''Dielectric, insulating material or a very poor conductor of electric current. When dielectrics are placed in an electric field, practically no current flows in them because, unlike metals, they have no loosely bound, or free, electrons that may drift through the material''."
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| *{{cite encyclopedia|title = Dielectrics (physics)|encyclopedia = Britannica |pages = 1|publisher =|year = 2009 |url=http://www.britannica.com/EBchecked/topic/162630/dielectric |accessdate = 2009-08-12}}</ref>
| | <li>[http://vote.qdxiaoluohao.com/dzx/forum.php?mod=viewthread&tid=5769059&extra= http://vote.qdxiaoluohao.com/dzx/forum.php?mod=viewthread&tid=5769059&extra=]</li> |
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| The term "[[:wikt:dielectric|dielectric]]" was coined by [[William Whewell]] (from "[[:wikt:dia-|dia]]-electric") in response to a request from [[Michael Faraday]].<ref>{{Cite book|author=J. Daintith|title=Biographical Encyclopedia of Scientists|publisher=CRC Press|year=1994|isbn=0-7503-0287-9|page=943}}</ref><ref>James, Frank A.J.L., editor. The Correspondence of Michael Faraday, Volume 3, 1841–1848, {{cite web|url = http://hermital.org/book/holoprt5-1.htm#F5.8|title =Letter 1798, William Whewell to Faraday, p. 442.}} The Institution of Electrical Engineers, London, United Kingdom, 1996. ISBN 0-86341-250-5</ref> A ''perfect dielectric'' is a material with zero electrical conductivity. ([[cf.]] [[perfect conductor]]),<ref>{{cite web|url=http://books.google.com.br/books?id=ZecSEXlJE0YC&lpg=PA21&dq=pec%20lossy%20dielectric%20lossless%20materials&pg=PA22#v=onepage&q&f=false |title=Microwave Engineering - R. S. Rao (Prof.) - Google Livros |publisher=Books.google.com.br |date= |accessdate=2013-11-08}}</ref> thus exhibiting only a displacement current; therefore it stores and returns electrical energy as if it were an ideal capacitor.
| | <li>[http://recit.cscapitale.qc.ca/~clj/prof/spip.php?article22 http://recit.cscapitale.qc.ca/~clj/prof/spip.php?article22]</li> |
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| ==Electric susceptibility==
| | <li>[http://www.gha-systemprofile.de/index.php?site=gallery&picID=71 http://www.gha-systemprofile.de/index.php?site=gallery&picID=71]</li> |
| {{Main|permittivity}}
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| | | </ul> |
| The '''electric susceptibility''' χ<sub>e</sub> of a dielectric material is a measure of how easily it [[polarization density|polarizes]] in response to an electric field. This, in turn, determines the electric [[permittivity]] of the material and thus influences many other phenomena in that medium, from the capacitance of [[capacitors]] to the [[speed of light]].
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| It is defined as the constant of proportionality (which may be a [[tensor]]) relating an electric field '''E''' to the induced dielectric [[polarization (electrostatics)|polarization density]] '''P''' such that
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| :<math>
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| {\mathbf P}=\varepsilon_0\chi_e{\mathbf E},
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| </math>
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| where <math>\, \varepsilon_0</math> is the [[Vacuum permittivity|electric permittivity of free space]].
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| The susceptibility of a medium is related to its relative permittivity <math>\, \varepsilon_r</math> by
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| :<math>\chi_e\ = \varepsilon_r - 1.</math>
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| So in the case of a vacuum,
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| :<math>\chi_e\ = 0. </math>
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| The [[electric displacement]] '''D''' is related to the polarization density '''P''' by
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| :<math>
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| \mathbf{D} \ = \ \varepsilon_0\mathbf{E} + \mathbf{P} \ = \ \varepsilon_0 (1+\chi_e) \mathbf{E} \ = \ \varepsilon_r \varepsilon_0 \mathbf{E}.
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| </math>
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| ===Dispersion and causality===
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| In general, a material cannot polarize instantaneously in response to an applied field. The more general formulation as a function of time is
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| :<math>\mathbf{P}(t)=\varepsilon_0 \int_{-\infty}^t \chi_e(t-t') \mathbf{E}(t')\, dt'.</math>
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| That is, the polarization is a [[convolution]] of the electric field at previous times with time-dependent susceptibility given by <math>\chi_e(\Delta t)</math>. The upper limit of this integral can be extended to infinity as well if one defines <math>\chi_e(\Delta t) = 0</math> for <math>\Delta t < 0</math>. An instantaneous response corresponds to [[Dirac delta function]] susceptibility <math>\chi_e(\Delta t) = \chi_e \delta(\Delta t)</math>.
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| It is more convenient in a linear system to take the [[continuous Fourier transform|Fourier transform]] and write this relationship as a function of frequency. Due to the [[convolution theorem]], the integral becomes a simple product,
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| :<math>\mathbf{P}(\omega)=\varepsilon_0 \chi_e(\omega) \mathbf{E}(\omega).</math>
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| Note the simple frequency dependence of the susceptibility, or equivalently the permittivity. The shape of the susceptibility with respect to frequency characterizes the [[dispersion (optics)|dispersion]] properties of the material.
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| Moreover, the fact that the polarization can only depend on the electric field at previous times (i.e., <math>\chi_e(\Delta t) = 0</math> for <math>\Delta t < 0</math>), a consequence of [[causality]], imposes [[Kramers–Kronig relation|Kramers–Kronig constraints]] on the susceptibility <math>\chi_e(0)</math>.
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| ==Dielectric polarization==<!--Dielectric polarization redirects here-->
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| ===Basic atomic model===
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| [[Image:dielectric model.svg|right|thumb|400px|Electric field interaction with an atom under the classical dielectric model.]]
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| In the classical approach to the dielectric model, a material is made up of atoms. Each atom consists of a cloud of negative charge (Electrons) bound to and surrounding a positive point charge at its center. In the presence of an electric field the charge cloud is distorted, as shown in the top right of the figure.
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| This can be reduced to a simple [[dipole]] using the [[superposition principle]]. A dipole is characterized by its [[electrical dipole moment|dipole moment]], a vector quantity shown in the figure as the blue arrow labeled ''M''. It is the relationship between the electric field and the dipole moment that gives rise to the behavior of the dielectric. (Note that the dipole moment points in the same direction as the electric field. This isn't always correct, and is a major simplification, but is suitable for many materials.)
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| When the electric field is removed the atom returns to its original state. The time required to do so is the so-called [[Relaxation (physics)|relaxation]] time; an exponential decay.
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| This is the essence of the model in physics. The behavior of the dielectric now depends on the situation. The more complicated the situation, the richer the model must be to accurately describe the behavior. Important questions are:
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| *Is the electric field constant or does it vary with time?
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| **If the electric field does vary, at what rate?
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| *What are the characteristics of the material?
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| **Is the direction of the field important ([[isotropy]])?
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| **Is the material the same all the way through ([[Homogeneity (physics)|homogeneous]])?
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| **Do any boundaries/interfaces have to be taken into account?
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| *Is the system [[Linear system|linear]], or do [[Nonlinear system|nonlinearities]] have to be taken into account?
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| The relationship between the electric field '''E''' and the dipole moment '''M''' gives rise to the behavior of the dielectric, which, for a given material, can be characterized by the function '''F''' defined by the equation:
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| :<math>\mathbf{M} = \mathbf{F}(\mathbf{E})</math>.
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| When both the type of electric field and the type of material have been defined, one then chooses the simplest function ''F'' that correctly predicts the phenomena of interest. Examples of phenomena that can be so modeled include:
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| *[[Refractive index]]
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| *[[Group velocity dispersion]]
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| *[[Birefringence]]
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| *[[Self-focusing]]
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| *[[Harmonic generation]]
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| ===Dipolar polarization=== <!--Dipolar polarization redirects here-->
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| Dipolar polarization is a polarization that is either inherent to [[polar molecule]]s ('''orientation polarization'''), or can be induced in any molecule in which the asymmetric distortion of the nuclei is possible ('''distortion polarization'''). Orientation polarization results from a permanent dipole, e.g., that arising from the 104.45° angle between the asymmetric bonds between oxygen and hydrogen atoms in the water molecule, which retains polarization in the absence of an external electric field. The assembly of these dipoles forms a macroscopic polarization.
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| When an external electric field is applied, the distance between charges, which is related to [[chemical bond]]ing, remains constant in orientation polarization; however, the polarization itself rotates. This rotation occurs on a timescale that depends on the [[torque]] and surrounding local [[viscosity]] of the molecules. Because the rotation is not instantaneous, dipolar polarizations lose the response to electric fields at the lowest frequency in polarizations. A molecule rotates about 1ps per radian in a fluid, thus this loss occurs at about 10<sup>11</sup> Hz (in the microwave region). The delay of the response to the change of the electric field causes [[friction]] and heat.
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| When an external electric field is applied in the [[infrared]], a molecule is bent and stretched by the field and the molecular moment changes in response. The molecular vibration frequency is approximately the inverse of the time taken for the molecule to bend, and the '''distortion polarization''' disappears above the infrared.
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| ===Ionic polarization=== <!--Ionic polarization redirects here-->
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| Ionic polarization is polarization caused by relative displacements between positive and negative [[ion]]s in [[ionic crystal]]s (for example, [[Sodium chloride|NaCl]]).
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| If crystals or molecules do not consist of only atoms of the same kind, the distribution of charges around an atom in the crystals or molecules leans to positive or negative. As a result, when lattice vibrations or molecular vibrations induce relative displacements of the atoms, the centers of positive and negative charges might be in different locations. These center positions are affected by the symmetry of the displacements. When the centers don't correspond, polarizations arise in molecules or crystals. This polarization is called '''ionic polarization'''.
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| Ionic polarization causes [[ferroelectric effect|ferroelectric transition]] as well as [[dipolar polarization]]. The transition, which is caused by the order of the directional orientations of permanent dipoles along a particular direction, is called '''order-disorder phase transition'''. Transition caused by ionic polarizations in crystals is called '''displacive phase transition'''.
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| ==Dielectric dispersion==
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| In physics, '''dielectric dispersion''' is the dependence of the permittivity of a dielectric material on the frequency of an applied electric field. Because there is always a lag between changes in polarization and changes in an electric field, the permittivity of the dielectric is a complicated, [[complex number|complex-valued]] function of frequency of the electric field. It is very important for the application of dielectric materials and the analysis of polarization systems.
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| This is one instance of a general phenomenon known as [[material dispersion]]: a frequency-dependent response of a medium for wave propagation.
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| When the frequency becomes higher:
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| # it becomes impossible for dipolar polarization to follow the electric field in the [[microwave]] region around 10<sup>10</sup> [[Hertz|Hz]];
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| # in the [[infrared]] or far-infrared region around 10<sup>13</sup> Hz, ionic polarization and molecular distortion polarization lose the response to the electric field;
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| # electronic polarization loses its response in the ultraviolet region around 10<sup>15</sup> Hz.
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| In the frequency region above ultraviolet, permittivity approaches the constant ''ε''<sub>0</sub> in every substance, where ''ε''<sub>0</sub> is the permittivity of the free space. Because permittivity indicates the strength of the relation between an electric field and polarization, if a polarization process loses its response, permittivity decreases.
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| ==Dielectric relaxation==
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| '''Dielectric relaxation''' is the momentary delay (or lag) in the [[dielectric constant]] of a material. This is usually caused by the delay in molecular polarization{{Disambiguation needed|date=June 2011}} with respect to a changing electric field in a dielectric medium (e.g., inside capacitors or between two large [[Electrical conductor|conducting]] surfaces). Dielectric relaxation in changing electric fields could be considered analogous to [[hysteresis]] in changing [[magnetic field]]s (for [[inductor]]s or [[transformer]]s). Relaxation in general is a delay or lag in the response of a [[linear system]], and therefore dielectric relaxation is measured relative to the expected linear steady state (equilibrium) dielectric values. The time lag between electrical field and polarization implies an irreversible degradation of [[Gibbs free energy|free energy]](G).
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| In [[physics]], '''dielectric relaxation''' refers to the relaxation response of a dielectric medium to an external electric field of microwave frequencies. This relaxation is often described in terms of permittivity as a function of [[frequency]], which can, for ideal systems, be described by the Debye equation. On the other hand, the distortion related to ionic and electronic polarization shows behavior of the [[resonance]] or [[oscillator]] type. The character of the distortion process depends on the structure, composition, and surroundings of the sample.
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| The number of possible wavelengths of emitted radiation due to dielectric relaxation can be equated using Hemmings' first law (named after Mark Hemmings)
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| :<math>n = \frac{l^2-l}{2} </math>
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| where
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| :''n'' is the number of different possible wavelengths of emitted radiation
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| :<math>l</math> is the number of energy levels (including ground level).
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| ===Debye relaxation===
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| '''Debye relaxation''' is the dielectric relaxation response of an ideal, noninteracting population of dipoles to an alternating external electric field. It is usually expressed in the complex permittivity <math>\varepsilon\,\!</math> of a medium as a function of the field's [[frequency]] <math>\omega</math>:
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| :<math> | |
| \hat{\varepsilon}(\omega) = \varepsilon_{\infty} + \frac{\Delta\varepsilon}{1+i\omega\tau},
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| </math>
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| where <math>\varepsilon_{\infty}</math> is the permittivity at the high frequency limit, <math>\Delta\varepsilon = \varepsilon_{s}-\varepsilon_{\infty}</math> where <math>\varepsilon_{s}</math> is the static, low frequency permittivity, and <math>\tau</math> is the characteristic [[relaxation time]] of the medium.
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| This relaxation model was introduced by and named after the physicist [[Peter Debye]] (1913).<ref>
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| P. Debye (1913), Ver. Deut. Phys. Gesell. 15, 777; reprinted 1954 in collected papers of Peter J.W. Debye Interscience, New York</ref>
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| ===Variants of the Debye equation===
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| *[[Cole–Cole equation]]
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| *[[Cole–Davidson equation]]
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| *[[Havriliak–Negami relaxation]]
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| *Kohlrausch–Williams–Watts function (Fourier transform of [[stretched exponential function]])
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| == Paraelectricity ==
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| Paraelectricity is the ability of many materials (specifically ceramic [[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 [[Dipolar polarization|polarization]] in the material returning to zero.<ref>[[Chiang, Y. et al.]]: Physical Ceramics, ''[[John Wiley & Sons]]'' 1997, New York</ref> The mechanisms that cause '''paraelectric''' behaviour are the distortion of individual [[ions]] (displacement of the electron cloud from the nucleus) and polarization of molecules or combinations of ions or defects.
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| Paraelectricity occurs in [[crystal]] phases where [[electricity|electric]] [[dipole]]s 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 effect|ferroelectric]] phase, the domains are unordered and the internal field is weak.
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| The [[lithium niobate|LiNbO<SUB>3</SUB>]] crystal is [[ferroelectric]] below 1430 [[Kelvin|K]], and above this temperature it transforms into a disordered paraelectric phase. Similarly, other [[perovskite]]s also exhibit paraelectricity at high temperatures.
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| Paraelectricity has been explored as a possible refrigeration mechanism; polarizing a paraelectric by applying an electric field under [[adiabatic|adiabatic process]] conditions raises the temperature, while removing the field lowers the temperature.<ref>{{cite doi|10.1016/0038-1098(65)90060-8}}</ref> A heat pump that polarizes the paraelectric, allows it to return to ambient temperature, then brings it into contact with the object to be cooled, and depolarizes it, would result in refrigeration.
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| == Tunability ==
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| ''Tunable dielectrics'' are insulators whose ability to store electrical charge changes when a voltage is applied.<ref name=k>{{cite web|url=http://www.kurzweilai.net/self-correcting-crystal-may-lead-to-the-next-generation-of-advanced-communications-2 |title=Self-correcting crystal may lead to the next generation of advanced communications |doi=10.1038/nature12582 |publisher=KurzweilAI |date= |accessdate=2013-11-08}}</ref><ref>{{cite doi|10.1038/nature12582}}</ref>
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| Generally, [[strontium titanate]] ({{chem|Sr|Ti|O|3}}) is used for devices operating at low temperatures, while [[barium strontium titanate]] ({{chem|Ba|1−x|Sr|x|Ti|O|3}}) substitutes for room temperature devices. Other potential materials include microwave dielectrics and carbon nanotube (CNT) composites.<ref name=k/><ref>{{cite web|url=http://www.sciencedirect.com/science/article/pii/S0079642510000290 |title=Electrically tunable dielectric materials and strategies to improve their performances |publisher=Sciencedirect.com |date=2010-11-30 |accessdate=2013-11-08}}</ref><ref>{{cite doi|10.1109/ISAF.2008.4693753}}</ref>
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| In 2013 multi-sheet layers of strontium titanate interleaved with single layers of [[strontium oxide]] produced a dielectric capable of operating at up to 125GHz. The material was created via [[molecular beam epitaxy]]. The two have mismatched crystal spacing that produces strain within the strontium titanate layer that makes it less stable and tunable.<ref name=k/>
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| Systems such as {{chem|Ba|1−x|Sr|x|Ti|O|3}} have a paraelectric–ferroelectric transition just below ambient temperature, providing high tunability. Such films suffer significant losses arising from defects.Here we report the experimental realization of a highly tunable ground state arising from the emergence of a local ferroelectric instability in biaxially strained Srn+1TinO3n+1 phases with n ≥ 3 at frequencies up to 125 GHz. In contrast to traditional methods of modifying ferroelectrics — doping or strain — in this unique system an increase in the separation between the (SrO)2 planes, which can be achieved by changing n, bolsters the local ferroelectric instability. This new control parameter, n, can be exploited to achieve a figure of merit at room temperature that rivals all known tunable microwave dielectrics.<ref name=k/>
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| ==Applications==
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| ===Capacitors===
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| {{Main|Capacitor}}
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| [[Image:Capacitor schematic with dielectric.svg|thumb|upright|Charge separation in a parallel-plate capacitor causes an internal electric field. A dielectric (orange) reduces the field and increases the capacitance.]] | |
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| Commercially manufactured capacitors typically use a [[solid]] dielectric material with high permittivity as the intervening medium between the stored positive and negative charges. This material is often referred to in technical contexts as the ''capacitor dielectric''.<ref>Mussig & Hans-Joachim, ''Semiconductor capacitor with praseodymium oxide as dielectric'', {{US Patent|7113388}} published 2003-11-06, issued 2004-10-18, assigned to IHP GmbH- Innovations for High Performance Microelectronics/Institute Fur Innovative Mikroelektronik</ref>
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| The most obvious advantage to using such a dielectric material is that it prevents the conducting plates the charges are stored on from coming into direct electrical contact. More significantly, however, a high permittivity allows a greater stored charge at a given voltage. This can be seen by treating the case of a linear dielectric with permittivity ε and thickness d between two conducting plates with uniform charge density σ<sub>ε</sub>. In this case the charge density is given by
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| :<math>\sigma_{\varepsilon}=\varepsilon\frac{V}{d}</math>
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| and the [[capacitance]] per unit area by
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| :<math>c=\frac{\sigma_{\varepsilon}}{V}=\frac{\varepsilon}{d}</math>
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| From this, it can easily be seen that a larger ε leads to greater charge stored and thus greater capacitance.
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| Dielectric materials used for capacitors are also chosen such that they are resistant to [[ionization]]. This allows the capacitor to operate at higher voltages before the insulating dielectric ionizes and begins to allow undesirable current.
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| ===Dielectric resonator=== | |
| {{Main|dielectric resonator}}
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| A ''dielectric resonator oscillator'' (DRO) is an electronic component that exhibits [[resonance]] for a narrow range of frequencies, generally in the microwave band. It consists of a "puck" of ceramic that has a large dielectric constant and a low [[dissipation factor]]. Such resonators are often used to provide a frequency reference in an oscillator circuit. An unshielded dielectric resonator can be used as a [[Dielectric Resonator Antenna]] (DRA).
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| ==Some practical dielectrics==
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| Dielectric materials can be solids, liquids, or gases. In addition, a [[high vacuum]] can also be a useful, nearly lossless dielectric even though its relative [[dielectric constant]] is only unity.
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| Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators. Some examples include [[porcelain]], [[glass]], and most [[plastic]]s. Air, [[nitrogen]] and [[sulfur hexafluoride]] are the three most commonly used [[gaseous dielectric]]s.
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| *[[Industrial coating]]s such as [[parylene]] provide a dielectric barrier between the substrate and its environment.
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| *[[Mineral oil]] is used extensively inside electrical [[transformer]]s as a fluid dielectric and to assist in cooling. Dielectric fluids with higher dielectric constants, such as electrical grade [[castor oil]], are often used in [[high voltage]] capacitors to help prevent [[corona discharge]] and increase capacitance.
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| *Because dielectrics resist the flow of electricity, the surface of a dielectric may retain ''stranded'' excess electrical charges. This may occur accidentally when the dielectric is rubbed (the [[triboelectric effect]]). This can be useful, as in a [[Van de Graaff generator]] or [[electrophorus]], or it can be potentially destructive as in the case of [[electrostatic discharge]].
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| *Specially processed dielectrics, called [[electret]]s (which should not be confused with [[ferroelectric]]s), may retain excess internal charge or "frozen in" polarization. Electrets have a semipermanent external electric field, and are the electrostatic equivalent to magnets. Electrets have numerous practical applications in the home and industry.
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| *Some dielectrics can generate a potential difference when subjected to mechanical [[Stress (physics)|stress]], or change physical shape if an external voltage is applied across the material. This property is called [[piezoelectricity]]. Piezoelectric materials are another class of very useful dielectrics.
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| *Some ionic [[crystal]]s and [[polymer]] dielectrics exhibit a spontaneous dipole moment, which can be reversed by an externally applied electric field. This behavior is called the [[ferroelectric]] effect. These materials are analogous to the way [[ferromagnetic]] materials behave within an externally applied magnetic field. Ferroelectric materials often have very high dielectric constants, making them quite useful for capacitors.
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| ==See also==
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| {{colbegin|3}}
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| *[[Paramagnetism]]
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| *[[Ferroelectricity]]
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| *[[Clausius-Mossotti relation]]
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| *[[Dielectric loss]]
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| *[[Dielectric strength]]
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| *[[Dielectric spectroscopy]]
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| *[[EIA Class 1 dielectric]]
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| *[[EIA Class 2 dielectric]]
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| *[[High-k dielectric]]
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| *[[Low-k dielectric]]
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| *[[leakage (electronics)|leakage]]
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| *[[Linear response function]]
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| *[[Metamaterial]]
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| *[[RC delay]]
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| *[[Rotational Brownian motion]]
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| {{colend}}
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| ==References==
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| {{Reflist}}
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| ==Further reading==
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| *{{Cite book
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| | last =Jackson
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| | first =John David
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| | authorlink =John David Jackson (physicist)
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| | title =Classical Electrodynamics
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| | publisher =[[John Wiley & Sons]]
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| | edition =3 rd
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| | date =August 10, 1998
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| | url =http://books.google.com/books?id=U3LBQgAACAAJ&dq=Classical+Electrodynamics
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| | isbn =978-0-471-30932-1 }} 808 or 832 pages.
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| *{{Cite book
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| | last =Scaife
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| | first =Brendan
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| | authorlink =Brendan Scaife
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| | title =Principles of Dielectrics (Monographs on the Physics & Chemistry of Materials)
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| | publisher =[[Oxford University Press]]
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| | edition =2 nd | |
| | date =September 3, 1998
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| | url =http://books.google.co.uk/books?id=9GBP9uBwpScC&dq=Principles+of+Dielectrics&hl=en&sa=X&ei=eWmQT_DTGYne8QPUqsG4BA&redir_esc=y
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| | ISBN =978-0198565574 }}
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| ==External links==
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| *[http://www.lightandmatter.com/html_books/0sn/ch11/ch11.html Electromagnetism] – A chapter from an online textbook
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| *[http://wiki.4hv.org/index.php/Dielectric_Sphere_in_Electric_Field Dielectric Sphere in an Electric Field]
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| *[http://www.doitpoms.ac.uk/tlplib/dielectrics/index.php DoITPoMS Teaching and Learning Package "Dielectric Materials"]
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| *{{Wikisource-inline|list=
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| **{{Cite Americana|short=1|wstitle=Dielectric|noicon=x}}
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| **{{Cite EB1911|short=1|wstitle=Dielectric|noicon=x}}
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| }}
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| {{Polarization states}}
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| [[Category:Dielectrics| ]]
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| [[Category:Electric and magnetic fields in matter]]
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