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Peltier Cooler
Thermoelectric heat pumps use the thermoelectric effect, specifically the Peltier effect, to heat or cool materials by applying an electrical current across them. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling, although in practice the main application is cooling since heating can be achieved with simpler devices (with Joule heating). Thermoelectric temperature control heats or cools materials by applying an electrical current across them. A typical Peltier cell absorbs heat on one side and produces heat on the other.L. E. (2008). Cooling, heating, generating power, and recovering wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoelectric Effect
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, heat is transferred from one side to the other, creating a temperature difference. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is affected by the applied voltage, thermoelectric devices can be used as temperature controllers. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect (temperature differences cause electromotive forces), the Peltier effect (thermocouples create temperature differences), and the Thomson effect (the Seebeck coefficient varies with temperature). The Seebeck and Peltier effects are different manifestations of the same physical proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-type (semiconductor)
N-type, N type or Type N may refer to: * N-type semiconductor is a key material in the manufacture of transistors and integrated circuits * An N-type connector is a threaded RF connector used to join coaxial cables * The MG N-type Magnette was produced by the MG Car company from October 1934 to 1936 * The N-type calcium channel is a type of voltage-dependent calcium channel * A Type (model theory) with n free variables * The Dennis N-Type vehicle chassis was used to build fire engines and trucks * The N type carriage is an intercity passenger carriage used on the railways of Victoria, Australia * The REP Type N The REP Type N was a military reconnaissance monoplane produced in France in 1914.Taylor 1989, p.758 Design and development It was a wire-braced, mid-wing monoplane of conventional design with fixed, tailskid undercarriage.Davilla & Soltan 2002 ... was a military reconnaissance aircraft produced in France in 1914 * N type battery, see: N battery * Type N power plugs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth
Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs naturally, and its sulfide and oxide forms are important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery-white color when freshly produced. Surface oxidation generally gives samples of the metal a somewhat rosy cast. Further oxidation under heat can give bismuth a vividly iridescent appearance due to thin-film interference. Bismuth is both the most diamagnetic element and one of the least thermally conductive metals known. Bismuth was formerly understood to be the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was found to be very slightly radioactive. The metal's only primordial isotope, bismuth-209, undergoes alpha decay with a half-l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Antimonide
Bismuth antimonides, Bismuth-antimonys, or Bismuth-antimony alloys, (Bi1−''x''Sb''x'') are binary alloys of bismuth and antimony in various ratios. Some, in particular Bi0.9Sb0.1, were the first experimentally-observed three-dimensional topological insulators, materials that have conducting surface states but have an insulating interior. Various BiSb alloys also superconduct at low temperatures, are semiconductors, and are used in thermoelectric devices. Bismuth antimonide itself (see box to right) is sometimes described as Bi2Sb2. Synthesis Crystals of bismuth antimonides are synthesized by melting bismuth and antimony together under inert gas or vacuum. Zone melting is used to decrease the concentration of impurities. When synthesizing single crystals of bismuth antimonides, it is important that impurities are removed from the samples, as oxidation occurring at the impurities leads to polycrystalline growth. Properties Topological insulator Pure bismuth is a semim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon–germanium
SiGe ( or ), or silicon–germanium, is an alloy with any molar ratio of silicon and germanium, i.e. with a molecular formula of the form Si1−''x''Ge''x''. It is commonly used as a semiconductor material in integrated circuits (ICs) for heterojunction bipolar transistors or as a strain-inducing layer for CMOS transistors. IBM introduced the technology into mainstream manufacturing in 1989. This relatively new technology offers opportunities in mixed-signal circuit and analog circuit IC design and manufacture. SiGe is also used as a thermoelectric material for high-temperature applications (>700 K). History The first paper on SiGe was published in 1955 on the magnetoresistance of silicon germanium alloys . The first mention of SiGe devices was actually in the original patent for the bipolar transistor where the idea of a SiGe base in a heterojunction bipolar transistor (HBT) was discussed with a description of the physics in the 1957. The first epitaxial growth of SiGe he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Telluride
Lead telluride is a compound of lead (element), lead and tellurium (PbTe). It crystallizes in the NaCl crystal structure with Pb atoms occupying the cation and Te forming the anionic lattice. It is a narrow gap semiconductor with a band gap of 0.32 eV. It occurs naturally as the mineral altaite. Properties * Dielectric constant ~1000. * Electron Effective mass (solid-state physics), Effective mass ~ 0.01Electron rest mass, ''m''e * Hole mobility, μp = 600 cm2 V−1 s−1 (0 K); 4000 cm2 V−1 s−1 (300 K) * Seebeck coefficient: ~326 μV/K (undoped, at 300K), ~200 μV/K (Ag-doped) Applications PbTe has proven to be a very important intermediate Thermoelectric materials, thermoelectric material. The performance of thermoelectric materials can be evaluated by the figure of merit, ZT=S^2\sigma T/\kappa, in which S is the Seebeck coefficient, \sigma is the Electrical resistivity and conductivity, electrical conducti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Telluride
Bismuth telluride () is a gray powder that is a compound of bismuth and tellurium also known as bismuth(III) telluride. It is a semiconductor, which, when alloyed with antimony or selenium, is an efficient thermoelectric material for refrigeration or portable power generation. is a topological insulator, and thus exhibits thickness-dependent physical properties. Properties as a thermoelectric material Bismuth telluride is a narrow-gap layered semiconductor with a trigonal unit cell. The valence and conduction band structure can be described as a many-ellipsoidal model with 6 constant-energy ellipsoids that are centered on the reflection planes. cleaves easily along the trigonal axis due to Van der Waals bonding between neighboring tellurium atoms. Due to this, bismuth-telluride-based materials used for power generation or cooling applications must be polycrystalline. Furthermore, the Seebeck coefficient of bulk becomes compensated around room temperature, forcing the material ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoelectric Materials
Thermoelectric materials show the thermoelectric effect in a strong or convenient form. The ''thermoelectric effect'' refers to phenomena by which either a temperature difference creates an electric potential or an electric current creates a temperature difference. These phenomena are known more specifically as the Seebeck effect (creating a voltage from temperature difference), Peltier effect (driving heat flow with an electric current), and Thomson effect (reversible heating or cooling within a conductor when there is both an electric current and a temperature gradient). While all materials have a nonzero thermoelectric effect, in most materials it is too small to be useful. However, low-cost materials that have a sufficiently strong thermoelectric effect (and other required properties) are also considered for applications including power generation and refrigeration. The most commonly used thermoelectric material is based on bismuth telluride (). Thermoelectric materials are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seebeck Coefficient
The Seebeck coefficient (also known as thermopower, thermoelectric power, and thermoelectric sensitivity) of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material, as induced by the Seebeck effect. The SI unit of the Seebeck coefficient is volts per kelvin (V/K), although it is more often given in microvolts per kelvin (μV/K). The use of materials with a high Seebeck coefficient is one of many important factors for the efficient behaviour of thermoelectric generators and thermoelectric coolers. More information about high-performance thermoelectric materials can be found in the Thermoelectric materials article. In thermocouples the Seebeck effect is used to measure temperatures, and for accuracy it is desirable to use materials with a Seebeck coefficient that is stable over time. Physically, the magnitude and sign of the Seebeck coefficient can be approximately understood as being given by the en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoelectric Materials
Thermoelectric materials show the thermoelectric effect in a strong or convenient form. The ''thermoelectric effect'' refers to phenomena by which either a temperature difference creates an electric potential or an electric current creates a temperature difference. These phenomena are known more specifically as the Seebeck effect (creating a voltage from temperature difference), Peltier effect (driving heat flow with an electric current), and Thomson effect (reversible heating or cooling within a conductor when there is both an electric current and a temperature gradient). While all materials have a nonzero thermoelectric effect, in most materials it is too small to be useful. However, low-cost materials that have a sufficiently strong thermoelectric effect (and other required properties) are also considered for applications including power generation and refrigeration. The most commonly used thermoelectric material is based on bismuth telluride (). Thermoelectric materials are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Figure Of Merit
A figure of merit (FOM) is a performance metric that characterizes the performance of a device, system, or method, relative to its alternatives. Examples *Absolute alcohol content per currency unit in an alcoholic beverage *accurizing, Accuracy of a rifle *Audio amplifier figures of merit such as gain or efficiency *Battery life of a laptop computer New York Times, June 25, 2009 *Calories per serving *Clock rate of a CPU is often given as a figure of merit, but is of limited use in comparing between different architectures. FLOPS may be a better figure, though these too are not completely representative of the performance of a CPU. *Contrast ratio of an LCD *Frequency response of a Loudspeaker, speaker *Fill factor (solar cell), Fill factor of a solar cell *Image resolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Conductivity
The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity. For instance, metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials such as mineral wool or Styrofoam. Metals have this high thermal conductivity due to free electrons facilitating heat transfer. Correspondingly, materials of high thermal conductivity are widely used in heat sink applications, and materials of low thermal conductivity are used as thermal insulation. The reciprocal of thermal conductivity is called thermal resistivity. The defining equation for thermal conductivity is \mathbf = - k \nabla T, where \mathbf is the heat flux, k is the thermal conductivity, and \nabla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
