Seebeck elements

The temperature dependence of Seebeck coefficient and electrical resistivity of the sintered Mn-Si element were measured simultaneously by the power factor measurement device 5. The temperature difference was kept at constant lOK in the temperature range up to HOOK. HaU coefficient and electrical resistivity were measured with van der Pauw method up to 500K. The each sample is spot-welded a 50 yU m platinum wire as the electrode. The current and magnetic field were 0.1 A and 0.356T respectively in the HaU measurement. In the measurement of electrical resistivity the current was 3mA... 

By the usage of two staged graded FGM element the FGM effect on thermoelectric performance such as Seebeck coefficient and power factor was investigated. Moreover, the thermoelectromotive force for overaU temperature difference was also evaluated. 

Figure 2 shows the temperature dependence of the Seebeck coefficient for the p-type sintered Mn-Si elements with two Ge-dopant concentraions (0.25 and 1.0 atm%) measured fi om 350K to 1 lOOK. Each value of Seebeck coefficient has maximum and positioned in the near-intrinsic temperature range. 

The temperature dependence of thermoelectric properties such as the Seebeck coefl dent, electrical resistivity and power factor for two kinds of Ge dopant levels were clarified to shift the temperature ofthemaximmn power factor due to the dopant levels and sintered condition. The power factor at the maximmn for the sinteredMn-Si element was obtained 1.05-l.lxlft (W/mK2) as the promising thermoelectric element for hi and middle temperature range. 

The second, more general, treatment is based on nonequilibrium thermodynamics. Fluxes and forces are connected by a matrix. The diagonal elements (the main effects) of this matrix are well-known - for example, the diffusion coefficient (which is the connection between a particle flux under a concentration gradient) or the thermal conductivity (which relates the temperature gradient with the heat flux). One of the non-diagonal elements is the Seebeck coefficient (= thermopower, ]), which relates a temperature gradient with a particle flux. Based on this, general equations are obtained that describe the heat and particle flow in a thermal and concentration profile ... 

Thermoelectric ects occur whenever more than one type of metal is used in the measurement circuit, which includes the sensing element, the leads, and the readout instrumentatimi. The typical Seebeck coefficient between different metals is around 10 pV/K or more, and it is not unusual for temperature to vary by 5—10 °C between different parts of an apparatus even for room-temperature measurements. Thus, thermoelectric effects can be expected to contribute voltages of 100 pV or more if no precautions are taken, which may lead to errors of 1 °C when measuring the RTD temperature around 300 K, and potentially much worse away from 300 K. The first... 

The basic element in a thermopile is a junction between two dissimilar conductors having a large Seebeck coefficient 0. To perform efficiently a large electrical conductivity a is required to minimize Joulean heat loss and a small thermal conductivity K to minimize heat conduction loss between the hot and cold junctions of the thermopile. These requirements are incompatible and we find that in common with other thermoelectric devices (Goldsmid [3.12]) the best choice of thermoelectric material is that for which a0 K is a maximum and that this occurs for certain heavily doped semiconductors, for example BijTcj and related compounds. To make an efficient thermal infrared detector the device must also be an efficient absorber o f the incident radiation and must have a small thermal mass to give as short a response time as possible. 

The rare earth metals display a rich variety of transport phenomena, which we shall discuss in the remaining sections. Transport properties were last reviewed by Legvold (1972), who presented data for the resistivity, thermal conductivity and Seebeck coefficient of almost all the rare earth metals together with Hall effect results for the elements Gd-Er. Since 1972 little attention has been given to the thermal conductivity and Seebeck coefficient and, accordingly, we shall concentrate on the resistivity, magnetoresistivity and Hall effect measurements, with particular attentiM to recent studies. 

Wang, T.P. 1992. Absolute Seebeck coefficients of metalhc elements. Temperature, Its Measurement and Control in Science and Industry, American Institute of Physics, 6(2) 509—514. 

Trapezoid Module. Fig. 2 shows the distribution of temperature, potential, current density and voltage after the iterations. As expected, the temperature monotonically decreases from the hot copper electrode (0.8 mm wide, 1.0 mm thick and 0.2 mm high) at 700 K to the cold copper electrode with the same dimension at 300 K. The temperature profile is flat at the high temperature region, while the isotherm bends roundly at the lower temperature region. Because both the potential (electromotive force, EMF) generated due to Seebeck effect and the electrical conductivity relates with the local temperature at the TE element, the potential and current density in the TE element (Fig. 2(b) and (c))... 

Here, the three terms represent the heat conduction, the Joule heat generated by the current along the finite element volume, and the heating or cooling generated by the Thomson effect, respectively. T is temperature. A, p, and S denote the thermal conductivity, specific electric resistivity, and relative Seebeck coefficient, respectively, and / is the current density determined by the electric potential and temperature using Eq. 2. Ohm s law is expressed as... 

Type E Thermocouples. The ASTM designation type E indicates a thermocouple pair consisting of a Ni-Cr alloy and a Cu-Ni alloy. This type of thermocouple has the highest Seebeck coefficient, 5, of the three ASTM standard thermocouple types commonly used at low temperatures, types E, K, and T. Also, both elements of this thermocouple have low thermal conductivity, reasonable homogeneity, and corrosion resistance in moist atmospheres. This type is the best thermocouple to use for temperatures down to about 40 K. 

Fig. 6.6 a Temperature-dependent of the Seebeck coefficient b The calculated density of states for CuzXSnSa X = Mn, Fe, or Co) nanocrystals. c Temperature-dependence of the electrical conductivity for the Cu2XSnS4 (X = Mn, Fe, or Co) nanocrystals d Pauling electronegativity for the constituent elements In the Cu2XSnS4... 

Ued] Ueda, M., Hayakawa, H., Mukaida, M., Imai, Y, Seebeck Coef eients of Iron Group Elements Borides , Intermetallics, 12(1), 155-58 (2004) (Electr. Prop., Experimental, 8) [2006Now] Nowacki, J., Polyphase Sintering and Properties of Metal Matrix Composites , J. Mat. 

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