scholarly journals Negative‐to‐Positive Thermal Conductivity Temperature Coefficient Transition Induced by Dynamic Fluctuations of the Alkyl Chains in the Layered Complex (C 4 H 9 NH 3 ) 2 CuCl 4

2020 ◽  
Vol 26 (12) ◽  
pp. 2610-2618 ◽  
Author(s):  
Norihisa Hoshino ◽  
Syunsaku Tamura ◽  
Tomoyuki Akutagawa
Keyword(s):  
Thermal Conductivity ◽  
Temperature Coefficient ◽  
Alkyl Chains ◽  
Layered Complex

scholarly journals Study of Thermometry in Two-Dimensional Sb2Te3 from Temperature-Dependent Raman Spectroscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Manavendra P. Singh ◽  
Manab Mandal ◽  
K. Sethupathi ◽  
M. S. Ramachandra Rao ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Heat Dissipation ◽  
Peak Position ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Excellent Candidate ◽  
High Figure

AbstractDiscovery of two-dimensional (2D) topological insulators (TIs) demonstrates tremendous potential in the field of thermoelectric since the last decade. Here, we have synthesized 2D TI, Sb2Te3 of various thicknesses in the range 65–400 nm using mechanical exfoliation and studied temperature coefficient in the range 100–300 K using micro-Raman spectroscopy. The temperature dependence of the peak position and line width of phonon modes have been analyzed to determine the temperature coefficient, which is found to be in the order of 10–2 cm−1/K, and it decreases with a decrease in Sb2Te3 thickness. Such low-temperature coefficient would favor to achieve a high figure of merit (ZT) and pave the way to use this material as an excellent candidate for thermoelectric materials. We have estimated the thermal conductivity of Sb2Te3 flake with the thickness of 115 nm supported on 300-nm SiO2/Si substrate which is found to be ~ 10 W/m–K. The slightly higher thermal conductivity value suggests that the supporting substrate significantly affects the heat dissipation of the Sb2Te3 flake.

Thermal Conductivity of Complex Hydrocarbon Systems at Pressures Up To 1000 MPa

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Vladimir Kutcherov ◽  
Alexey Chernoutsan ◽  
Anton Kolesnikov ◽  
Boris Grigoriev
Keyword(s):  
Thermal Conductivity ◽  
Crude Oil ◽  
Temperature Coefficient ◽  
Atmospheric Pressure ◽  
Pressure Range ◽  
Gas Condensate ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Coefficient Of Thermal Conductivity ◽  
Transient Hot Wire Technique

The thermal conductivity of five samples of crude oil and one sample of gas condensate was measured by the transient hot-wire technique. The measurements were made along isotherms (245, 250, 273, 295, 320, 336, and 373 K) in the pressure range from atmospheric pressure up to 1000 MPa and along isobars (at 0.1, 100, 200, 300, 400, 500, and 1000 MPa) in the temperature range 245–450 K. It was observed that the thermal conductivity of the samples investigated strongly depends on the pressure and rises with increasing pressure for all the temperatures. At a certain pressure, the temperature coefficient of thermal conductivity reverses from negative to positive. The pressure at which this reversal was observed varied in the range of 300–380 MPa.

THE THERMAL CONDUCTIVITY OF NAPALM–GASOLINE GELS

1948 ◽  
Vol 26a (2) ◽  
pp. 50-59 ◽  
Author(s):  
G. O. Langstroth ◽  
F. Zeiler
Keyword(s):  
Thermal Conductivity ◽  
Temperature Coefficient ◽  
Small Diameter ◽  
Temperature Coefficient Of Resistance ◽  
Simple Method ◽  
Viscous Liquids ◽  
Low Viscosity ◽  
Tungsten Filaments ◽  
Better Than

A slightly modified form of the rapid and simple method suggested by Hutchinson for the measurement of the thermal conductivity of liquids has been found to suffer from convection effects with samples of low viscosity, except with conductivity tubes of very small diameter. For more viscous liquids such as glycerol it was found to be adequate under all conditions studied. The method has been applied in the determination of the conductivity of Napalm–gasoline gels. For temperatures T between − 50° and 50 °C., and Napalm concentrations C between 0 and 10%, the conductivity k in cal. sec.−1 cm.−1 per degree C. is described to better than 1% by the relation, k × 105 = 29.7 − 0.068 T + 0.11 C. The temperature coefficient of resistance of the unaged tungsten filaments used in the tubes differed considerably from the value given by the International Critical Tables for aged tungsten filaments. For temperatures T0 between − 50° and 50 °C., the coefficient α0 per degree C. is given to better than 1% by the relation, [Formula: see text].

scholarly journals The thermal conductivities of oxygen and nitrogen

1928 ◽  
Vol 118 (780) ◽  
pp. 594-607 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Coefficient ◽  
Thermal Conduction ◽  
Standard Substance ◽  
The Absolute ◽  
Thermal Conductivities

The interest in the determination of the thermal conductivities of oxygen and nitrogen lies partly in their relation to the thermal conductivity of air. The latter is the medium which practically every experimenter on gaseous thermal conduction has investigated, and has therefore become the standard substance in this field of research. Being a mixture chiefly of the gases oxygen and nitrogen, with the latter in the greater proportion, the value of its conductivity should lie between those of oxygen and nitrogen and should be nearer that of nitrogen than that of oxygen. The authors, in common with Weber and Todd, have verified this experimentally, the only observer finding these con­ductivities in a contrary order being Winkelman, who used a cooling thermometer method. The following is a table of the results hitherto obtained for the absolute thermal conductivities at 0° C. of oxygen and nitrogen, together with their authors’ results for air. The values marked with an asterisk have been deduced by applying the temperature coefficient, 0.0029 per 0° C., to results which were obtained at temperatures above 0° C. Weber has recently published a new result for the thermal conductivity of air, 0.0000574, which is about 1 per cent. higher than his old value. Assuming that, if his results for oxygen and nitrogen were revised, they would be increased in the same proportion, his new values for these gases would be—oxygen 0.0000583, and nitrogen 0.0000572.

scholarly journals Strong Suppression of Thermal Conductivity in the Presence of Long Terminal Alkyl Chains in Low‐Disorder Molecular Semiconductors

2021 ◽  
pp. 2008708
Author(s):  
Ekaterina Selezneva ◽  
Alexandre Vercouter ◽  
Guillaume Schweicher ◽  
Vincent Lemaur ◽  
Katharina Broch ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Strong Suppression ◽  
Alkyl Chains ◽  
Molecular Semiconductors
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