Relative Seebeck coefficient

The effectiveness of devices using thermoelectric effects depends on the magnitude of the relative Peltier coefficient, II, or its equivalent, the relative Seebeck coefficient, S. However, these are not the only material parameters of importance. As an example, consider the operation of a heat pump. The amount of heat produced or absorbed is... 

Here, the three terms shows the heat conduction, the Joule heat generated by the current, and the heating or cooling generated by Thomson effect, respectively. L, A, p, and S denote the temperature, thermal conductivity, specific electric resistivity, and relative Seebeck coefficient, respectively, and J is the current density determined by the electric potential and temperature in Eq. 2. 

Type J thermocouples (Table 11.58) are one of the most common types of industrial thermocouples because of the relatively high Seebeck coefficient and low cost. They are recommended for use in the temperature range from 0 to 760°C (but never above 760°C due to an abrupt magnetic transformation that can cause decalibration even when returned to lower temperatures). Use is permitted in vacuum and in oxidizing, reducing, or inert atmospheres, with the exception of sulfurous atmospheres above 500°C. For extended use above 500°C, heavy-gauge wires are recommended. They are not recommended for subzero temperatures. These thermocouples are subject to poor conformance characteristics because of impurities in the iron. 

In order to co-polymerize the IC unit, Suzuki and Stille polymerizations have been used. First, Blouin et al. [94] were able to obtain polyindolo[3,2-fr]-carbazole derivatives with bithiophene or biEDOT as co-monomers. Unfortunately, these studies demonstrated a relatively low oxidation potential for these polymers (especially for P35 and P37), limiting their applications in OFETs and PCs. However, for doped state applications, these polymers may exhibit interesting properties [35]. For instance, when copolymerized with bithiophene, the resulting copolymer shows a good electrical conductivity (as high as 0.7 Scm 1) but a low Seebeck coefficient of 4.3 iV K 1 [35]. Finally, the UV-Vis absorption maxima are similar for poly(2,8-indolocarbazole-a/f-bithiophene) and poly(2,8-indolocarbazole-a/f-bis(3,4-ethylenedioxythiophene)). A broad absorption band is centered at 430 nm whereas, for the 3- and 9-substituted copolymers, the broad band is centered around 490-500 nm [94],... 

Some environmental limitations of the standard thermocouple materials compiled by ASTM [36] are reproduced in Table 16.11. The thermal EMF of standard thermoelements relative to platinum is shown in Fig. 16.20 [36]. Seebeck coefficients (first derivative of thermal EMF with respect to temperature) for each of the standard thermocouples as a function of temperature are tabulated in Table 16.12. 

Figure 26-15. Relative potentials of a Zr02 electrode with 1 bar oxygen partial pressure in glass-forming melts with temperature-independent (A, B) and temperature-dependent (C, D) standard Seebeck coefficients. Reference potential 9, = 0. (a) Fiolax klar (b) (Na20)oo7 (K20)o 78(CaO)o, (Si02)o.737 (c) (Na20)o,s6(CaO)ojB7(Si02) .737 (d) BK7 (e) phos-phate-ba optical glass.

Figure 26-20. Practical signincance of thermoelectric potentials. The relative potentials, tRpt< of a platinum electrode in melts satisfying Equation (26-33) were obtained from standiud thermoelectric potentials, of a zirconia electrode and temperature-dependent emfs, E, of cell (VI) according to Equation (26-37). The temperature dependence of Pp, is determined by the standard Seebeck coefficients of the melts and is positive (a), negative (b), and, depending on the temperature, both negative and positive (c).

Compared with the relatively simple resistance measurement, DTEGs require a more sophisticated set-up. The measurand thermopower (Seebeck coefficient) is defined by ... 

PEDOT PSS/CNT is another important type of CP-based composite TE materials. In 2008, Kim et al. foxmd that the segregated-network polymer/ CNT composites dramatically increased with rising CNT concentration in the composite, while their thermal conductivity and Seebeck coefficient remained relatively insensitive to the filler concentration (Figure 6.31) [24]. 

Choi et at studied the TE properties of CNT/Nafion composites containing different kinds of CNTs [27]. It was foimd that the electrical properties of the CNT/Nafion nanocomposites were primarily affected by the CNTs since the Nation acts as an electrically insulating matrix, while the thermal conductivity of the nanocomposites was dominated by the Nation mainly due to weak van der Waals interaction. In this way, electrical and thermal transport can be controlled in an independent way. Although the electrical conductivity depends on the type of CNT, the behavior of the Seebeck coefficient was relatively insensitive to the CNT type at high CNT loading in Nafion/CNT system. 

The thermoelectric performance of colloidal PbSe films and nanoparticles was studied/ There was ligand exchange by an electrically-conducting SbaTcg metal chalcogenide complex (MCC) to inter-quantum dot electrical conductivity. It was shown that these quantum dots had relatively high electrical conductivities, Seebeck coefficient magnitudes, and thermoelectric performance. 

In the classical language, which does not rely on the pole-dipole distinction, the Seebeck coefficients defined at this level are called absolute coefficients. This logically leads to attributing the adjective relative to the dipolar Seebeck coefficient. The link between these coupling factors is, as one may read in the expanded Formal Graph (Graph 12.21),... 

Boron carbide is characterized by a relatively wide gap in its forbidden band, a low thermal conductivity, and a high thermoelectric power. These properties make it a potentially useful material for high-temperature thermoelectric energy conversion. Electrical conductivity and Seebeck coefficient as a function of temperature and composition are shown in Figs. 8.5 and 8.6. 

The Seebeck coefficient S of ThN was first stated to be a few V/K at room temperature [15]. Values relative to Cu from 4 to 375 K measured by the differential technique have been reported graphically by Auskern, Aronson [16]. From an extrapolation of the thermoelectric power data with the slope -0.81 x10 (V/K) to 0 K they estimate the Fermi energy level from the equation S 2n V JZe-HE as Ep = 6 eV and the electron effective mass as 0.7 mg, where mg is the electron rest mass. 

It is well known that Ag2Se is a narrow band-gap semiconductor and a promising candidate for the potential application of thermoelectric devices thanks to their high electrical conductivity and relatively high Seebeck coefficient. For the... 

Akin et al. (1998) An integrated thermopile structure with high responsivity using any standard CMOS process by T. Akin, Z. Olgun, O. Akar, and H. Kulah. Sensors Actual A66, 218-224. This describes a relatively modern application using a CMOS process they report a net Seebeck coefficient of 150 35 pW/K, responsivity of 49.8 V/W, andD = 5.15 x 10 cm Hz / W for their two-arm bridge structure. Their article references other CMOS processes. 

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