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Unable to Resist
Published in Sharon Ann Holgate, Understanding Solid State Physics, 2021
If just metals and alloys are considered, the thermal conductivity (κ) and electrical conductivity (σ) vary in a similar pattern, so that values of κ/σ at a given T are almost constant over a fairly wide range of temperatures (see Table 6.1). This relationship was first observed by German physicists Gustave Heinrich Wiedemann (1826–1899) and Rudolf Franz (1827–1902) in the middle of the 19th century, and it is known as the Wiedemann–Franz law.
Methods for Calculating the Thermoelectric Characterizations of Nanomaterials
Published in Alexander V. Vakhrushev, Suresh C. Ameta, Heru Susanto, A. K. Haghi, Advances in Nanotechnology and the Environmental Sciences, 2019
A. V. Severyukhin, O. Yu. Severyukhina, A. V. Vakhrushev
The relationship between electrical conductivity and the electronic component of thermal conductivity is determined by the Wiedemann–Franz law law: κe=LTσ,(17) where L is the Lorentz number. It should be noted that in the general case the concentration of carriers influences the value of the Lorentz number, so for materials, with a low carrier concentration, the Lorentz number L decreases.
Heat Treatment by Induction
Published in Valery Rudnev, Don Loveless, Raymond L. Cook, Handbook of Induction Heating, 2017
Valery Rudnev, Don Loveless, Raymond L. Cook
The Wiedemann–Franz law governs the relationship between the thermal conductivity (k) and the electrical resistivity (ρ) for the majority of pure metals and metallic materials. However, some alloys including cast irons are exceptions to this general rule, because in addition to the chemical composition, the morphology of the graphite (e.g., nodules vs. flakes) and the matrix constituents can alter that relationship.
Application of statistical and soft computational techniques in machining of Nickel based supper-alloy using cryogenically treated tools for estimation of surface roughness
Published in Australian Journal of Mechanical Engineering, 2022
Yogesh V. Deshpande, Atul B. Andhare, Pramod M. Padole
For the electrical and thermal conductivity of metals and alloys, the free electrons are responsible. The Wiedemann-Franz law is helpful to link thermal conductivity to electrical resistivity (Reddy et al. 2009). Therefore, the electrical resistivity of the tool material was measured for three samples. The resistivity was used to obtain the value of electrical conductivity for UT and CT inserts. The electrical conductivity was more in the cryogenically treated insert as compared to the untreated one. The percentage improvement in electrical conductivity for CT insert is noted as 25.61% compared to UT insert. The properties of coated tungsten carbide inserts, along with values of hardness and electrical conductivity, are presented in Table 2.
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
Thermal conductivity is the amount of heat that flows from higher temperature region to the lower temperature region within a material. In semiconductor, the heat is transferred through lattice vibrations, while in metals heat is conducted through free electrons. TE materials should have low values of thermal conductivity. Figure 12 represents the plot between the thermal conductivity per relaxation time and chemical potential at various temperatures of RhFeZ (Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) alloys. It is found that the thermal conductivity increases with temperature. As the temperature increases, the energy of electrons also increases. Compared to electrical conductivity, thermal conductivity responds more to the change in temperature. The behaviour of electrical conductivity and thermal conductivity is similar. Maxima of thermal conductivity and electrical conductivity lie on the same chemical potential value. This confirms the Wiedemann–Franz law [39]. According to Wiedemann-Franz law the thermal conductivity is directly proportional to electrical conductivity.
Parameters effect on electrical conductivity of copper fabricated by rapid manufacturing
Published in Materials and Manufacturing Processes, 2020
Gurminder Singh, Sunpreet Singh, Jagtar Singh, Pulak M Pandey
For the validation of the obtained statistical model with Wiedemann-Franz law, the electrical conductivity values were plotted versus thermal conductivity values. Similar kind of mechanism of moving and scattering electrons acted for both electrical and thermal conductivity. Wiedemann-Franz law predicts a linear correlation between the electrical and thermal conductivity based on the solid-state physical definitions. Equation 5 represents the relation of electrical () and thermal () conductivity.