Thermal conductivity and Lorentz number of the “Golden” phase of the Sm1−x GdxS system with homogeneous variable valence of samarium

2000 ◽  
Vol 42 (6) ◽  
pp. 1017-1022
Author(s):  
A. V. Golubkov ◽  
A. V. Gol’tsev ◽  
L. S. Parfen’eva ◽  
I. A. Smirnov ◽  
H. Miserek ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Variable Valence ◽  
Lorentz Number

The Measurement of Thermal Conductivity of Ag/Al Multilayered Films

1991 ◽  
Vol 229 ◽  
Author(s):  
Takeshi Kaizuka ◽  
We-Hyo Soe ◽  
Ryoichi Yamamoto ◽  
Masanori Ohyama
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Free Electron ◽  
Room Temperature ◽  
Electron Theory ◽  
Multilayered Films ◽  
Phonon Contribution ◽  
Ac Calorimetric Method ◽  
Lorentz Number ◽  
Modulation Wavelength

AbstractThe in-plane thermal conductivity of Ag/Al multilayered films was measured at room temperature by ac calorimetric method as a function of the modulation wavelength and was compared with the electrical conductivity. The electrical conductivity increases with wavelength, Λ, like other metallic multilayered films. The thermal conductivity also tends to increase with Λ, but the Λ dependence is not similar to that of electrical conductivity. Obtained Lorentz number value of the multilayers are almost 10–30% larger than that given by the free electron theory. The Wiedemann-Franz law did not hold in the Ag/Al films and the phonon contribution is not negligible.

Atomic Ordering, Electronic Structure, and Transport Properties of LAST-m Systems

2007 ◽  
Vol 1044 ◽  
Author(s):  
S. D. Mahanti ◽  
Khang Hoang ◽  
Salameh Ahmad
Keyword(s):  
Thermal Conductivity ◽  
Electronic Structure ◽  
High Performance ◽  
Chemical Potential ◽  
Phonon Scattering ◽  
Constant Current ◽  
Constant Field ◽  
Atomic Ordering ◽  
Lattice Contribution ◽  
Lorentz Number

AbstractIn recent years, LAST-m (AgPbmSbTem+2) and related materials have emerged as potential high performance high temperature thermoelectrics. These compounds are obtained by starting from PbTe, and replacing pairs of Pb2+ ions by (Ag1+, Sb3+) pairs. One example is LAST-18. When optimally doped, this compound has thermoelectric figure of merit ZT=1.7 at 700K. This large ZT is most likely due to very low lattice thermal conductivity, caused by phonon scattering from nanostructures. These nanostructures involve clustering and ordering of Ag, Sb, and Pb ions. Possible origins of this atomic ordering and how the presence of nanostructures affects the electronic structure near the band gap region are discussed. The temperature (T) dependence of electrical conductivity σ (∼T2.2 in the range 300K <T< 900K) in n-type PbTe is analyzed in terms of the T-dependence of different physical quantities contributing to transport. We find that the dominant contribution comes from the explicit T-dependence of relaxation time rather than its energy dependence. The T-dependence of chemical potential is also significant in the concentration range of interest. Electronic thermal conductivity for constant field (κel,E) and for constant current (κel,J) are found to differ considerably at high temperatures and the Weidemann-Franz (WF) law κel,J = LoσT, where Lo =2x10−8WΩ/K is the Lorentz number, overstimates κel,J by nearly 60% at 800K for carrier concentration n=5x1019/cm3. As a result, one tends to underestimate the lattice contribution κlatt = κexp - κel,J. We give theoretical values of effective Lorentz number L = κel.J/σT for different n and T.

HARDNESS AND THERMAL CONDUCTIVITY OF As-Se-Te CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-931-C4-934 ◽  
Author(s):  
M. F. Kotkata ◽  
M.B. El-den
Keyword(s):  
Thermal Conductivity ◽  
Chalcogenide Glasses

A STUDY OF THE Pb PRECIPITATION IN NaCl FROM THERMAL CONDUCTIVITY EXPERIMENTS

1981 ◽  
Vol 42 (C6) ◽  
pp. C6-893-C6-895
Author(s):  
M. Locatelli ◽  
R. Suchail ◽  
E. Zecchi
Keyword(s):  
Thermal Conductivity
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