Dielectric constant

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Dielectric constant

relative static permittivity (or static relative permittivity) of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux

Flux

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Relative static permittivities of some materials at room temperature
Room temperature

**Room temperature** is a common term to denote a certain temperature within enclosed space at which humans are accustomed.Room temperature is thus often indicated by general human comfort, with the common range of 10celsius to 23?C , though climate may acclimatize people to higher or lower temperatures....
under 1 kHz
Radio Wave

**Radio Wave** may refer to:*Radio frequency*Radio Wave 96.5, a radio station in Blackpool, UK...
Material	Relative static permittivity _r
Aluminium Aluminium Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13.... (1 kHz)	-1300a (-1300+i Imaginary unit In mathematics, physics, and engineering, the imaginary unit is denoted by or the Latin or the Greek iota . It allows the real number system, to be extended to the complex number system, Its precise definition is dependent upon the particular method of extension.... 1.3×10¹⁴)a
Silver Silver Silver is a chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal.... (1 kHz)	-85b (-85+i Imaginary unit In mathematics, physics, and engineering, the imaginary unit is denoted by or the Latin or the Greek iota . It allows the real number system, to be extended to the complex number system, Its precise definition is dependent upon the particular method of extension.... 8×10¹²)b
Vacuum Vacuum A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty," but in reality, no volume of space can ever be perfectly empty....	1 (by definition)
Air AIR Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...	1.00054
Teflon	2.1
Polyethylene Polyethylene Polyethylene or polythene is a thermoplastic commodity heavily used in consumer products . Over 60 million tons of the material are produced worldwide every year....	2.25
Polystyrene Polystyrene Polystyrene , sometimes abbreviated PS, is an Aromaticity polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry....	2.4–2.7
Carbon disulfide Carbon disulfide Carbon disulfide is a colorless, volatile liquid with the chemical formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent....	2.6
Paper Paper Paper is thin material mainly used for writing upon, printing upon or packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....	3.5
Electroactive polymers Electroactive polymers Electroactive Polymers or EAPs are polymers whose shape is modified when a voltage is applied to them.They can be used as actuators or sensors....	2–12
Silicon dioxide Silicon dioxide The chemical compound 'silicon dioxide', also known as 'silica' , is an oxide of silicon with a chemical formula of and has been known for its hardness since antiquity....	4.5
Concrete Concrete Concrete is a construction material composed of cement as well as other cementitious materials such as fly ash and slag cement, construction aggregate , water , and Chemistry admixtures....	4.5
Pyrex Pyrex Pyrex is a brand name for glassware, introduced by Corning Incorporated in 1915. Originally, Pyrex was made from thermal shock resistant borosilicate glass.... (Glass Glass Glass generally refers to a Hardness, brittle, transparency amorphous solid, such as that used for windows, many Glass Bottles, or eyewear, including, but not limited to, soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovite , or aluminium oxynitride.... )	4.7 (3.7–10)
Rubber Rubber Natural rubber is an elastomer?an Elasticity_ hydrocarbon polymer?that was originally derived from a milky colloidal suspension, or latex , found in the sap of some plants....	7
Diamond Diamond In mineralogy, diamond is the Allotropes of carbon where the carbon atoms are arranged in an isometric-hexoctahedral crystal lattice. After graphite, diamond is the second most stable form of carbon....	5.5–10
Salt Salt A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and base . Salts are ionic compounds composed of cations and anions so that the product is electrically electric charge ....	3–15
Graphite Graphite The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Greek language ??afe?? : "to draw/write", for its use in pencils, where it is commonly called lead, as distinguished from the actual metallic element lead....	10–15
Silicon Silicon Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....	11.68
Ammonia Ammonia Ammonia is a chemical compound with the chemical formula nitrogenhydrogen. It is normally encountered as a gas with a characteristic pungent odor....	26–22–20–17 (-80–-40–0–20 °C)
Methanol Methanol Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a chemical compound with chemical formula carbonhydrogen3oxygenhydrogen ....	30
Furfural Furfural The chemical compound furfural is an industrial chemical derived from a variety of agriculture byproducts, including maize, oat and wheat bran, and sawdust....	42.0
Glycerol Glycerol Glycerol is a chemical compound also commonly called glycerin or glycerine. It is a colorless, odorless, Viscosity liquid that is widely used in pharmaceutical formulations....	41.2–47–42.5 (0–20–25 °C)
Water Water Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....	88–80.1–55.3–34.5 (0–20–100–200 °C)
Hydrofluoric acid Hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride in water. While it is extremely corrosive and dangerous to handle, it is technically a weak acid....	83.6 (0 °C)
Formamide Formamide Formamide, also known as methanamide, is an amide derived from formic acid. It is a clear liquid which is miscible with water and has an ammonia-like odor....	84.0 (20 °C)
Sulfuric acid Sulfuric acid Sulfuric acid, hydrogen2sulfuroxygen4, is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry....	84–100 (20–25 °C)
Hydrogen peroxide Hydrogen peroxide Hydrogen peroxide is a very pale blue liquid which appears colorless in a dilute solution, slightly more viscous than water. It is a weak acid....	128 aq–60 (-30–25 °C)
Hydrocyanic acid	158.0–2.3 (0–21 °C)
Titanium dioxide Titanium dioxide Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula titaniumoxygen2....	86–173
Strontium titanate Strontium titanate Strontium titanate is an oxide of strontium and titanium with the chemical formula strontiumtitaniumoxygen3. It is a centrosymmetric paraelectricity material with a perovskite structure....	310
Barium strontium titanate	15 nc Nanocrystal Fahlman, B. D. has described a nanocrystal as any nanomaterial with at least one dimension = 100nm and that is singlecrystalline. More properly, any material with a dimension of less than 1 micrometre, i.e., 1000 nanometers, should be referred to as a nanoparticle, not a nanocrystal.... –500
Barium titanate Barium titanate Barium titanate is an oxide of barium and titanium with the chemical formula BaTiO3. It is a ferroelectric ceramic material, with a photorefractive effect and piezoelectric properties....	90 nc Nanocrystal Fahlman, B. D. has described a nanocrystal as any nanomaterial with at least one dimension = 100nm and that is singlecrystalline. More properly, any material with a dimension of less than 1 micrometre, i.e., 1000 nanometers, should be referred to as a nanoparticle, not a nanocrystal.... –1250–10,000 (20–120 °C)
(La,Nb)PbO₃ Lead zirconate titanate Lead zirconate titanate is a ceramic perovskite material that shows a marked piezoelectricity.It is also known as PZT which is an abbreviation of the chemical formula....	500–6000
Conjugated polymers Conjugated system A conjugated system occurs in an organic compound where atoms covalently Chemical bond with alternating single and multiple bonds and influence each other to produce a region called electron delocalization....	6–100,000
µm Micrometre A micrometre or micron is one Micro- of a metre, or equivalently one thousandth of a millimetre. It is also commonly known as a micron.... –nm Nanometre A nanometre is a Units of measurement of length in the metric system, equal to one billionth of a metre .It is one of the more often used units for very small lengths, and equals ten ?ngstr?m, an internationally recognized non-International System of Units of length.... heterostructures	1000–100,000 (10⁶–10⁸ at 100 Hz)

|} The relative static permittivity (or static relative permittivity) of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux

Flux

In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.*In the study of transport phenomena , flux is defined as the amount that flows through a unit area per unit time....
. It is the ratio of the amount of stored electrical energy when a potential is applied, relative to the permittivity of a vacuum. The relative static permittivity is the same as the relative permittivity evaluated for a frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
of zero.

The relative static permittivity is represented as e_r or sometimes or K or Dk. It is defined as

where e_s is the static permittivity of the material, and e₀ is the electric constant

Electric constant

Vacuum permittivity, referred to by international standards organizations as the electric constant, and denoted by the symbol e0, is a fundamental physical constant relating the mechanical quantities to the units for electrical charge, for example, in Coulomb's law....
. (The relative permittivity is the complex

Complex number

In mathematics, the complex numbers are an extension of the real numbers obtained by adjoining an imaginary unit, denoted i, which satisfies:...
frequency-dependent , which gives the static relative permittivity for .)

Other terms for the relative static permittivity are the dielectric constant, or relative dielectric constant, or static dielectric constant. These terms, while they remain very common, are ambiguous and have been deprecated by some standards organizations. The reason for the potential ambiguity is twofold. First, some older authors used "dielectric constant" or "absolute dielectric constant" for the absolute permittivity rather than the relative permittivity. Second, while in most modern usage "dielectric constant" refers to a relative permittivity, it may be either the static or the frequency-dependent relative permittivity depending on context.

By definition, the linear relative permittivity of vacuum, where , is equal to 1, although there are theoretical nonlinear quantum

Quantum electrodynamics

Quantum electrodynamics is a relativity theory quantum field theory of electrodynamics. QED was developed by a number of physicists, beginning in the late 1920s....
effects in vacuum that have been predicted at high field strengths (but not yet observed).

The static relative permittivity of a medium is related to its static electric susceptibility

Electric susceptibility

The electric susceptibility ?e of a dielectric material is a measure of how easily it polarization density in response to an electric field....
, by

in SI

Si, si, or SI may refer to :...
units.

Measurement

The relative static permittivity, e_r, can be measured for static electric field

Electric field

In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field ....
s as follows: first the capacitance

Capacitance

In electromagnetism and electronics, capacitance is the ability of a body to hold an electrical charge.Capacitance is also a measure of the amount of electric charge stored for a given electric potential....
of a test capacitor, C₀, is measured with vacuum between its plates. Then, using the same capacitor and distance between its plates the capacitance C_x with a dielectric

Dielectric

A dielectric is a nonconducting substance, i.e. an Insulator . The term was coined by William Whewell in response to a request from Michael Faraday....
between the plates is measured. The relative dielectric constant can be then calculated as

For time-variant electromagnetic field

Electromagnetic field

The electromagnetic field is a physical field produced by electric charge. It affects the behavior of charged objects in the vicinity of the field....
s, this quantity becomes frequency

Frequency

Practical relevance

The dielectric constant is an essential piece of information when designing capacitor

Capacitor

A capacitor or condenser is a Passive component electronic component consisting of a pair of electrical conductor separated by a dielectric....
s, and in other circumstances where a material might be expected to introduce capacitance

Capacitance

In electromagnetism and electronics, capacitance is the ability of a body to hold an electrical charge.Capacitance is also a measure of the amount of electric charge stored for a given electric potential....
into a circuit. If a material with a high dielectric constant is placed in an electric field

Electric field

In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field ....
, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is commonly used to increase the capacitance of a particular capacitor design. The layers beneath etched conductors in Printed Circuit Boards (PCB

Printed circuit board

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using Conductor pathways, or signal traces, industrial etchinged from copper sheets laminated onto a non-conductive substrate....
s) also act as dielectrics.

Dielectrics are used in RF

Rf or RF is an abbreviation for:* ** Radiative forcing, is an IPCC unit that nominates the global, annual average of radiative imbalance in net heating of the Earth's lower atmosphere as a result of human activities since the beginning of the industrial era....
transmission lines. In a coaxial

Coaxial

In geometry, coaxial means that two or more forms share a common Coordinate axis; it is the three-dimensional linear analog of "concentric".Coaxial cable, as a common example, has a wire Conductor in the center a circumferential outer conductor and an insulating medium called the dielectric separating these two conductors....
cable, polyethylene

Polyethylene

Polyethylene or polythene is a thermoplastic commodity heavily used in consumer products . Over 60 million tons of the material are produced worldwide every year....
can be used between the center conductor and outside shield. It can also be placed inside waveguides to form filters. Optical fibers are examples of dielectric waveguide
Waveguide

A waveguide is a structure which guides waves, such as electromagnetic waves or sound waves. There are different types of waveguide for each type of wave....
s. They consist of dielectric materials that are purposely doped with impurities so as to control the precise value of e_r within the cross-section. This controls the refractive index of the material and therefore also the optical modes of transmission. However, in these cases it is technically the relative permittivity that matters, as they are not operated in the electrostatic limit.

Chemical applications

The relative static permittivity of a solvent is a relative measure of its polarity

Polarity

In physics, polarity is a description of an attribute, typically a binary attribute , or a vector . For example:* An electric charge has a polarity of either positive or negative....
. For example, water

Water (molecule)

File:Blue-water-pool.jpgWater is the most abundant molecule on Earth's surface, constituting about 70% of the Earth's surface in liquid, solid, and gaseous states....
(very polar) has a dielectric constant of 80.10 at 20 °C while n-hexane

Hexane

Hexane is an alkane hydrocarbon with the chemical formula CH34CH3 or C6H14. The "hex" prefix refers to its six carbons, while the "ane" ending indicates that its carbons are connected by single bonds....
(very non-polar) has a dielectric constant of 1.89 at 20 °C. This information is of great value when designing separation, sample preparation and chromatography

Chromatography

Chromatography is the collective term for a family of laboratory techniques for the separation of mixtures. It involves passing a mixture dissolved in a "mobile phase" through a stationary phase, which separates the analyte to be measured from other molecules in the mixture and allows it to be isolated....
techniques in analytical chemistry

Analytical chemistry

Analytical chemistry is the study of the chemical composition of natural and artificial materials. Unlike other major sub disciplines of chemistry such as inorganic chemistry and organic chemistry, analytical chemistry is not restricted to any particular type of chemical compound or chemical reaction....
.

Dielectric constant

Measurement

Practical relevance

Chemical applications

See also