scholarly journals Phonon hydrodynamics and ultrahigh–room-temperature thermal conductivity in thin graphite

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 309-312 ◽  
Author(s):  
Yo Machida ◽  
Nayuta Matsumoto ◽  
Takayuki Isono ◽  
Kamran Behnia
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Phonon Dispersion ◽  
High Conductivity ◽  
Temperature Range ◽  
A Value ◽  
Out Of Plane ◽  
Intimate Link

Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between high conductivity, thickness, and phonon hydrodynamics. The room-temperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was 4300 watts per meter-kelvin—a value well above that for diamond and slightly larger than in isotopically purified graphene. Warming enhances thermal diffusivity across a wide temperature range, supporting partially hydrodynamic phonon flow. The enhancement of thermal conductivity that we observed with decreasing thickness points to a correlation between the out-of-plane momentum of phonons and the fraction of momentum-relaxing collisions. We argue that this is due to the extreme phonon dispersion anisotropy in graphite.

Thermophysical Properties of Germanium for Thermal Analysis of Growth from the Melt

1981 ◽  
Vol 9 ◽  
Author(s):  
Roger K. Crouch ◽  
A. L. Fripp ◽  
W. J. Debnam ◽  
R. E. Taylor ◽  
H. Groot
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Room Temperature ◽  
Bridgman Method ◽  
The Other ◽  
Temperature Range ◽  
Diffusivity Measurements

ABSTRACTThe thermal diffusivity of Ge has been measured over a temperature range from 300° C to 1010° C which includes values for the melt. Specific heat has been measured from room temperature to 727° C. Thermal conductivity has been calculated over the same temperature range as the diffusivity measurements. These data are reported along with the best values from the literature for the other parameters which are required to calculate the temperature and convective fields for the growth of germanium by the Bridgman method. These parameters include the specific heat, the viscosity, the emissivity, and the density as a function of temperature.

Thermal conductivity and thermal diffusivity coefficients of 12Kh18N10T stainless steel in a wide temperature range

2008 ◽  
Vol 46 (5) ◽  
pp. 731-733 ◽  
Author(s):  
S. V. Stankus ◽  
I. V. Savchenko ◽  
A. V. Baginskii ◽  
O. I. Verba ◽  
A. M. Prokop’ev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Temperature Range

Thermal Transport Properties of Multi-Walled Carbon Nanotube Arrays

2007 ◽  
Author(s):  
Huaqing Xie ◽  
An Cai ◽  
Xinwei Wang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Diffusivity ◽  
Room Temperature ◽  
Infrared Detector ◽  
Laser Flash ◽  
Temperature Range ◽  
Nanosecond Pulsed Laser ◽  
Multi Walled Carbon Nanotube ◽  
Individual Cnts

A laser flash technique was applied to measure the thermal diffusivity along a multi-walled carbon nanotube (CNT) array in temperature range of −55∼200 °C. In the measurements, a nanosecond pulsed laser was used to realize noncontact heating and the temperature variations were recorded by an infrared detector. The experimental results show that the thermal diffusivity of the CNT array increases slightly with temperature in the −55∼70 °C temperature range and exhibits no obvious change in the −75∼200 °C temperature range. The CNT array has much larger thermal diffusivity than several known excellent thermal conductors, reaching about 4.6 cm2s−1 at room temperature. The mean thermal conductivity (λ) of individual CNTs was further estimated from the thermal diffusivity, specific heat (Cp), and density (ρ) by using the correlation of λ = αρCp. The thermal conductivity of individual CNTs increases smoothly with the temperature increase, reaching about 750 Wm−1K−1 at room temperature.

scholarly journals Рассеяние фононов на парамагнитных ионах европия и самария в феррите висмута

2020 ◽  
Vol 62 (7) ◽  
pp. 1137
Author(s):  
Р.Г. Митаров ◽  
С.Н. Каллаев ◽  
А.М. Бакмаев ◽  
С.А. Резниченко ◽  
А.Т. Темиров
Keyword(s):  
Thermal Conductivity ◽  
Rare Earth ◽  
Thermal Diffusivity ◽  
Temperature Dependence ◽  
Wide Temperature Range ◽  
Bismuth Ferrite ◽  
Resonance Scattering ◽  
Phonon Thermal Conductivity ◽  
Temperature Range ◽  
The Rare Earth

The temperature dependence of the thermal diffusivity and thermal conductivity of the multiferroics BiFeO3, Bi0.90Sm0.10FeO3 and Bi0.90Еu0.10FeO3 is studied. It was found that the substitution of bismuth ions by the rare-earth europium and samarium ions in bismuth ferrite leads to a decrease in phonon thermal conductivity in a wide temperature range. It was established that the decrease in the thermal conductivity of bismuth ferrite is due to resonance scattering of phonons at paramagnetic levels of europium and samarium ions.

scholarly journals Application of the laser pulse method of measuring thermal diffusivity to thin alumina and silicon samples in a wide temperature range

2010 ◽  
Vol 14 (2) ◽  
pp. 417-423 ◽  
Author(s):  
Nenad Milosevic
Keyword(s):  
Thermal Diffusivity ◽  
Laser Pulse ◽  
Experimental Technique ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Pulse Method ◽  
Laser Pulse Method ◽  
Temperature Range ◽  
Standard Laser

Paper presents results of measuring thermal diffusivity of translucent or partially transparent thin discs of non-metals such as alumina and silicon using most widely spread experimental technique, the standard laser pulse method. Difficulties in its application to such materials are discussed. The thermal diffusivity has been measured from room temperature up to 900?C for alumina, and to 1200?C for silicon. Obtained results are analyzed and compared with available literature data and existing recommended functions.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

Thermal Diffusivity and Conductivity of La0.7Ca0.3-xSrxMnO3 (x=0 to 0.10)

2012 ◽  
Vol 501 ◽  
pp. 319-323
Author(s):  
Hasan A. Alwi ◽  
Lay S. Ewe ◽  
Zahari Ibrahim ◽  
Noor B. Ibrahim ◽  
Roslan Abd-Shukor
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Transition Temperature ◽  
Thermal Diffusivity ◽  
Electrical Properties ◽  
Room Temperature ◽  
Electronic Contribution ◽  
Insulator Metal Transition ◽  
Thermal And Electrical Properties

We report the room temperature thermal conductivity κ and thermal diffusivity α of polycrystalline La0.7Ca0.3-xSrxMnO3 for x = 0 to 0.1. The samples were prepared by heating at 1220 and 1320oC. The insulator-metal transition temperature, TIM and thermal diffusivity increased with Sr content. Phonon was the dominant contributor to thermal conductivity and the electronic contribution was less than 1%. Enhancement of electrical conductivity σ and thermal diffusivity for x ≥ 0.08 was observed in both series of samples. The grain size of the samples (28 to 46 µm) does not show any affect on the thermal and electrical properties.

Highly thermal conductive resins formed from wide-temperature-range eutectic mixtures of liquid crystalline epoxies bearing diglycidyl moieties at the side positions

2017 ◽  
Vol 8 (18) ◽  
pp. 2806-2814 ◽  
Author(s):  
Youngsu Kim ◽  
Hyeonuk Yeo ◽  
Nam-Ho You ◽  
Se Gyu Jang ◽  
Seokhoon Ahn ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Wide Temperature Range ◽  
Epoxy Resins ◽  
Liquid Crystalline ◽  
High Thermal Conductivity ◽  
Temperature Range ◽  
Eutectic Mixtures ◽  
Liquid Crystalline Epoxy ◽  
Conductive Resins

Liquid crystalline epoxy resins with a wide temperature range exhibit a high thermal conductivity of 0.4 W m−1 K−1.

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