Pyroelectricity is the ability of certain materials to generate an electrical potential when they are heated or cooled. As a result of this change in temperature, positive and negative charges move to opposite ends through migration (i.e. the material becomes polarized) and hence, an electrical potential is established. Electrical potential is the potential energy per unit charge associated with a static (time-invariant) electric field, also called the electrostatic potential or the electric potential, typically measured in volts. ... mtDNA-based chart of large human migrations. ... In electrostatics, the polarization is the vector field that results from permanent or induced electric dipole moments in a dielectric material. ...

Explanation

Pyroelectricity can be visualized as one side of a triangle, where each corner represents energy states in the crystal: kinetic, electrical and thermal energy. The side between electrical and thermal corners represents the pyroelectric effect and produces no kinetic energy. The side between kinetic and electrical corners represents the piezoelectric effect and produces no heat. The kinetic energy of an object is the extra energy which it possesses due to its motion. ... Electrical energy can refer to several closely related things. ... 1. ... The kinetic energy of an object is the extra energy which it possesses due to its motion. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ... In physics, heat, symbolized by Q, is defined as transfer of thermal energy [1] Generally, heat is a form of energy transfer associated with the different motions of atoms, molecules and other particles that comprise matter when it is hot and when it is cold. ...

Although artificial pyroelectric materials have been engineered, the effect was first discovered in minerals such as quartz and tourmaline and other ionic crystals. The pyroelectric effect is also present in both bone and tendon. The name is derived from the Greek pyr, fire, and electricity. Quartz is one of the most common minerals in the Earths continental crust. ... The tourmaline mineral group is chemically one of the most complicated groups of silicate minerals. ... An ionic crystal is a crystal consisting of ions bound together by their electrostatic attraction. ... Grays Anatomy illustration of a human femur. ... A tendon (or sinew) is a tough band of fibrous connective tissue that connects muscle to bone or muscle to muscle and is built to withstand tension. ... Lightning strikes during a night-time thunderstorm. ...

Pyroelectric charge in minerals develops on the opposite faces of asymmetric crystals. The direction in which the propagation of the charge tends toward is usually constant throughout a pyroelectric material, but in some materials this direction can be changed by a nearby electric field. These materials are said to exhibit ferroelectricity. All pyroelectric materials are also piezoelectric, the two properties being closely related. Minerals are natural compounds formed through geological processes. ... This article or section is in need of attention from an expert on the subject. ... Piezoelectricity is the ability of crystals, certain ceramic materials, (and to some degree, all materials) to generate a voltage in response to applied mechanical stress. ...

Very small changes in temperature can produce an electric potential due to a materials' pyroelectricity. Passive infrared sensors are often designed around pyroelectric materials, as the heat of a human or animal from several feet away is enough to generate a difference in charge. Passive InfraRed sensors (PIRs) are electronic devices which are used in some security alarm systems to detect motion of an infrared emitting source, usually a human body. ...

History

The first reference to the pyroelectric effect is in writings by Theophrastus in 314 BC, who noted that tourmaline becomes charged when heated. Sir David Brewster gave the effect the name it has today in 1824. Both William Thomson in 1878 and Voight in 1897 helped develop a theory for the processes behind pyroelectricity. Pierre Curie and his brother, Jacques Curie, studied pyroelectricity in the 1880s, leading to their discovery of some of the mechanisms behind piezoelectricity. Pyroelectricity is definitely not a new concept, but research and application of the useful property continues to this day. Theophrastus (Greek Θεόφραστος, 370 — about 285 BC), a native of Eressos in Lesbos, was the successor of Aristotle in the Peripatetic school. ... Centuries: 5th century BC - 4th century BC - 3rd century BC Decades: 360s BC 350s BC 340s BC 330s BC 320s BC 310s BC 300s BC 290s BC 280s BC 270s BC 260s BC 319 BC 318 BC 317 BC 316 BC 315 BC 314 BC 313 BC 312 BC 311... The tourmaline mineral group is chemically one of the most complicated groups of silicate minerals. ... David Brewster Sir David Brewster, (December 11, 1781 – February 10, 1868) was a Scottish scientist. ... 1824 was a leap year starting on Thursday (see link for calendar). ... William Thomson, 1st Baron Kelvin, OM, GCVO, PC, PRS, FRSE, (26 June 1824 – 17 December 1907) was a mathematical physicist, engineer, and outstanding leader in the physical sciences of the 19th century. ... 1878 (MDCCCLXXVIII) was a common year starting on Tuesday (see link for calendar). ... 1897 (MDCCCXCVII) was a common year starting on Friday (see link for calendar). ... // Pierre Curie (Paris, France, May 15, 1859 – April 19, 1906, Paris) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity. ... Jacques Curie and his brother, Pierre Curie, studied pyroelectricity in the 1880s, leading to their discovery of some of the mechanisms behind piezoelectricity. ... // Development and commercial production of electric lighting Development and commercial production of gasoline-powered automobile by Karl Benz, Gottlieb Daimler and Maybach First commercial production and sales of phonographs and phonograph recordings. ...

The pyroelectric crystal classes

Crystal structures can be divided into 32 classes, or point groups, according to the number of rotational axes and reflection planes they exhibit that leave the crystal structure unchanged. Of the thirty-two crystal classes, twenty-one are non-centrosymmetric (not having a centre of symmetry), and of these, twenty exhibit direct piezoelectricity the remaining one being the cubic class 432. Ten of these are polar (i.e. spontaneously polarise), having a dipole in their unit cell, and exhibit pyroelectricity. If this dipole can be reversed by the application of an electric field, the material is said to be ferroelectric. Twenty of the 32 crystal classes are piezoelectric. All 20 piezoelectric classes lack a center of symmetry. Any material develops a dielectric polarization when an electric field is applied, but a substance which has such a natural charge separation even in the absence of a field is called a polar material. Whether or not a material is polar is determined solely by its crystal structure. Only 10 of the 32 point groups are polar. All polar crystals are pyroelectric, so the 10 polar crystal classes are sometimes referred to as the pyroelectric classes. CRYSTAL SYMMETRY: Crystal structures can be divided into 32 classes, or point groups, according to the number of rotational axes and reflection planes they exhibit that leave the crystal structure unchanged. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In mathematics, a reflection (also spelt reflexion) is a map that transforms an object into its mirror image. ... A fixed point of an isometry group is a point that is a fixed point for every isometry in the group. ... In physics, the ferroelectric effect is an electrical phenomenon whereby certain ionic crystals may exhibit a spontaneous dipole moment. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ...

Piezoelectric Crystal Classes: 1, 2, m, 222, mm2, 4, -4, 422, 4mm, -42m, 3, 32, 3m, 6, -6, 622, 6mm, -62m, 23, -43m

Pyroelectric: 1, 2, m, mm2, 3, 3m, 4, 4mm, 6, 6mm

The property of pyroelectricity is the measured change in net polarization (a vector) proportional to a change in temperature. The total pyroelectric coefficient measured at constant stress is the sum of the pyroelectric coefficients at constant strain (primary pyroelectric effect) and the piezoelectric contribution from thermal expansion (secondary pyroelectric effect). Under normal circumstances, even polar materials do not display a net dipole moment. As a consequence there are no electric dipole equivalents of bar magnets because the intrinsic dipole moment is neutralized by "free" electric charge that builds up on the surface by internal conduction or from the ambient atmosphere. Polar crystals only reveal their nature when perturbed in some fashion that momentarily upsets the balance with the compensating surface charge.

Recent developments

Progress has been made in creating artificial pyroelectric materials, usually in the form of a thin film, out of gallium nitride (GaN), caesium nitrate (CsNO₃), polyvinyl fluorides, derivatives of phenylpyrazine, and cobalt phthalocyanine. (See pyroelectric crystals.) Lithium tantalate (LiTaO₃) is a crystal exhibiting both piezoelectric and pyroelectric properties, which has been used to create small-scale nuclear fusion ("pyroelectric fusion"). [1] Gallium nitride (GaN) is a wide bandgap semiconductor material used in optoelectronic, high-power and high-frequency devices. ... General Name, Symbol, Number gallium, Ga, 31 Chemical series poor metals Group, Period, Block 13, 4, p Appearance silvery white   Atomic mass 69. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number caesium, Cs, 55 Chemical series alkali metals Group, Period, Block 1, 6, s Appearance silvery gold Atomic mass 132. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Polyvinyl fluoride (PVF) or -(CH2CHF)n- can be found in things like raincoats, solar panels, metal sheeting, and flammability-lowering coating of airplane interiors. ... wikipedia sucks big balls For other uses, see Cobalt (disambiguation). ... This article needs to be cleaned up to conform to a higher standard of quality. ... CRYSTAL SYMMETRY: Crystal structures can be divided into 32 classes, or point groups, according to the number of rotational axes and reflection planes they exhibit that leave the crystal structure unchanged. ... Wikinews has news related to: Tabletop fusion may lead to neutron source Lithium tantalate (LiTaO3), is a crystalline solid which possesses unique optical, piezoelectric and pyroelectric properties which make it valuable for infrared motion detectors, terahertz generation and detection, surface acoustic wave applications, cell phones and possibly pyroelectric nuclear fusion. ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/grey Atomic mass 6. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Atomic mass 180. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Pyroelectric fusion is a technique for achieving nuclear fusion by using an electric field generated by pyroelectric crystals to accelerate ions of deuterium (tritium might also be used someday) into a metal hydride target also containing detuerium (or tritium) with sufficient kinetic energy to cause these ions to fuse together. ...

See also

• Pyroelectric crystal
• Pyroelectric fusion
• The opposite effect is called electrocaloric effect