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Servo Feedback Devices and Motor Sensors
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
The Seebeck coefficient, also known as thermoelectric sensitivity, of a material is a measurement of the magnitude of the induced electrical potential in response to the thermal gradient. It depends on the specific thermocouple type, more particularly, metal-lead materials. In practice, the Seebeck coefficient can be determined from the slope of a graph of the Seebeck voltage versus temperature difference, i.e., S=dVdt≈ΔVΔt
Detector Fabrication
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
Specifically, the Seebeck coefficient is a measure of the magnitude of an induced thermoelectric voltage in a material in response to a temperature difference across that material and the entropy per charge carrier in the material. α has units of V/K, though μV/K is more common. Values in the hundreds of μV/K, regardless of sign, are typical of good thermoelectric materials.
Interface Electrical Phenomena in Ionic Solids
Published in P.J. Gellings, H.J.M. Bouwmeester, Electrochemistry, 2019
The experimental determination of the thermopower performed by using two different approaches is illustrated in Figures 4.15 and 4.16. The first (Figure 4.15) involves the determination of the Seebeck coefficient across a sample for several temperature gradients imposed by microheaters located on both sides of the sample. The second approach is based on the temperature gradient in the experimental chamber. The gradient can be changed by changing the position of the specimen in the chamber. The Seebeck coefficient is determined from several Seebeck voltages imposed across the specimen by different temperature gradients. The measurement of thermopower of ionic solids at elevated temperatures is described in References 26, 27, and 29.
First-principles research on the thermoelectric properties of NbCoGe based on the scattering mechanisms
Published in Philosophical Magazine, 2023
Yunji Shi, Rundong Wan, Zhengfu Zhang, Ying Lei, Guocai Tian
At the same temperature, the conductivity of the NbCoGe compound increases with increasing carrier concentration and decreases with increasing temperature for a given carrier concentration, as shown in Figure 6. The effect of the IMP scattering mechanism on the conductivity is significant because the conductivity of NbCoGe compounds without the IMP scattering mechanism is much higher than the conductivity with the effect of the IMP scattering mechanism. With only the ADP scattering mechanism considered, the conductivities of p- and n-type semiconductors are overestimated, with a maximum value of more than 10×107 s/m, which is related to the highest high mobilities. The conductivities of the semiconductors decrease with the addition of more types of scattering mechanisms, indicating that the POP scattering mechanism also affects the. In addition, the conductivity of the n-type semiconductor is significantly larger than that of the p-type semiconductor under the same combinations of scattering mechanisms, combined with the electronic structure energy band diagram, indicating that the degree of electron delocalisation of the p-type NbCoGe compound is larger than that of the n-type NbCoGe compound near the Fermi energy level [42]. As in thermoelectric materials, the corresponding Seebeck coefficient decreases when the conductivity increases.
Electronic structure, magnetic, optical and transport properties of half-Heusler alloys RhFeZ(Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) – a DFT study
Published in Phase Transitions, 2021
R. Meenakshi, R. Aram Senthil Srinivasan, A. Amudhavalli, R. Rajeswarapalanichamy, K. Iyakutti
The Seebeck coefficient is the voltage produced by a material due to the difference in temperature. The transport properties of the majority and minority spin channel are investigated for RhFeZ (Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) half-Heusler alloys. The Seebeck coefficient of RhFeZ (Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) is represented as a function of chemical potential (μ) corresponding to the shifting of the Fermi energy, from 200K to 500 K in Figure 10. Depending on the chemical potential, the temperature dependence of Seebeck coefficient differs. It is clear from the plots that for the compounds RhFeSn and RhFeGe, Seebeck coefficients are positive when µ < EF but negative when µ > EF, and the peak values fall exponentially with the rise in temperature. The absolute values of maximum Seebeck coefficients for RhFeSn and RhFeGe compounds in p-type regions are higher than those in n-type regions at a given temperature. The alloys RhFeSn and RhFeGe are found to have narrow band-gap, small conductivity and high potential difference, hence the value of Seebeck coefficient is high.
Novel Deep Space Nuclear Electric Propulsion Spacecraft
Published in Nuclear Technology, 2021
Troy Howe, Steve Howe, Jack Miller
The figure of merit, which directly influences the efficiency, is dependent on the thermoelectric material properties. Metals, with high electrical and thermal conductivities, typically have low Seebeck coefficients resulting in poor figures of merit.5 Insulators on the other hand have high Seebeck coefficients, albeit with low electrical conductivities reducing their utility in TEGs (Ref. 5). Semiconductors have long been used in TEGs because of their unique combination of electrical and thermal conductivity as well as Seebeck coefficient.5 Manipulating these material properties is key to change the figure of merit, and based on Eqs. (1) and (2), one can see that decreases in electrical resistivity and thermal conductivity as well as increases in the Seebeck coefficient will favorably alter the figure of merit to produce higher efficiencies. Increasing the temperature will increase the efficiency as well but will mostly be hindered by the geometry and material limits of the power conversion systems; changing the figure of merit via material properties is a far more practical method to increase TEG efficiencies.