Effect thermoelectrical

The metallic nature of concentrated metal-ammonia solutions is usually called "well known." However, few detailed studies of this system have been aimed at correlating the properties of the solution with theories of the liquid metallic state. The role of the solvated electron in the metallic conduction processes is not yet established. Recent measurements of optical reflectivity and Hall coefficient provide direct determinations of electron density and mobility. Electronic properties of the solution, including electrical and thermal conductivities, Hall effect, thermoelectric power, and magnetic susceptibility, can be compared with recent models of the metallic state. 

Because the dark current properties of SPD and MCP-SPD arrays are low and much of the dark current has thermal origins, the dark current can be substantially reduced by detector cooling. Most devices are equipped with Peltier-effect thermoelectric cooling systems coupled to cold liquid coolant systems to achieve temperatures as low as -40 to -80°C in some designs. 

There is a huge amount energy in our environment. And the nature has its own laws of the transformation between the solar, thermal and vibration energy, and electricity, the most universal energy form used in daily life. Currently, only a part of the photovoltaic effect, thermoelectric effect, piezoelectric effect, and triboelectric effect has been investigated, and more efforts are required to carefully understand these effects to further optimize the device structure and enhance the device performance. 

The matrix of Onsager s coefficients L, is generally nondiagonal. Therefore, the flux is determined not only by means of one thermodynamic force, but also by taking into account the other forces. A classical example in this respect is the thermoelectric effect. Thermoelectric effects wiU be discussed in greater detail later, for the example of multicomponent diffusion. Onsager also proved that the... 

The presence of temperature gradients is a cracial problem for the accuracy of measurements leading to errors due to the thermoelectric effect. Thermoelectric sensors have been made on this principle. In this case, the cell can schematically be represented by... 

In 1857, Thomson (Lord Kelvin) placed the whole field on firmer footing by using the newly developing field of thermodynamics (qv) to clarify the relationship between the Seebeck and the Peltier effects. He also discovered what is subsequently known as the Thomson effect, a much weaker thermoelectric phenomenon that causes the generation or absorption of heat, other than Joule heat, along a current-carrying conductor in a temperature gradient. 

The primary thermoelectric phenomena considered in practical devices are the reversible Seebeck, Peltier, and, to a lesser extent, Thomson effects, and the irreversible Eourier conduction and Joule heating. The Seebeck effect causes a voltage to appear between the ends of a conductor in a temperature gradient. The Seebeck coefficient, L, is given by... 

The other primary thermoelectric phenomenon is the Peltier effect, which is the generation or absorption of heat at the junction of two different conductors when a current flows in the circuit. Whether the heat is evolved or absorbed is determined by the direction of the current flow. The amount of heat involved is determined by the magnitude of the current, I, and the Peltier coefficients, 7T, of the materials ... 

T. C. Harmon and J. M. Honig, Thermoelectric andThermomagnetic Effects and Applications, McGraw-HiU Book Co., Inc., New York, 1967. 

Y. Y. Khine, J. S. Walker. Thermoelectric magnetohydrodynamic effects during Bridgman semiconductor crystal growth with a uniform axial magnetic field. J Cryst Growth 7 5 150, 1998. 

Some heat pumps, called thermoelectric heat pumps, employ the Peltier effect, using thermocouples. The Peltier effect refers to the evolution or absorption of heat produced by an electric current passing across junctions of two suitable, dissimilar metals, alloys, or semiconductors. Presently, thermoelectric heat pumps are used only in some specialized applications. They have not been developed to a point to make them practical for general heating and cooling of buildings. 

Seebeck s outstanding scientific achievement was the discovei"y of one of the three classical thermoelectric effects, which are the Seebeck, the Peltier, and the Thomson effects. Seebeck s discovery was the first, dating from 1822—1823, followed by that of Jean-Charles-Athanase Peltier in 1832 and that of William Thomson in 1854. Seebeck obseiwed that an electric current in a closed circuit comprised different metallic components if he heated the junctions of the components to different temperatures. He noted that the effect increases linearly with the applied temperature difference and that it crucially depends on the choice of materials. Seebeck tested most of the available metallic materials for thermoelectricity. His studies were further systematized by the French physicist... 

The Entropy Principle gives, on the assumptions as to reversibility of thermoelectric effects ... 

Kohlrausch s theory leaves quite unexplained the fact that no thermoelectric current is set up in a homogeneous wire along which a current of heat is flowing, whilst the theory of Lord Kelvin is difficult to reconcile with the fact that thermoelectric currents cannot be set up in a circuit of liquid metals, although these show the Thomson effect. The latter seems, therefore, to be to a certain extent independent of the Peltier effect. Theories intended to escape these difficulties have been proposed by Planck (1889), and Duhem, in which the conception of the entropy of electricity is introduced. 

Katsuyama S, Tanaka Y, Hashimoto H, Majima K, Nagai H (1997) Effect of substitution of La by alkaline earth metal on the thermoelectric properties and the phase stability of y-La3S4.1 Appl Phys 82 5513-5519... 

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