نتایج جستجو برای: thermal conductivity coefficient

تعداد نتایج: 412572  

Journal: :Faraday discussions 2014
Shane P Ashby Jason A Thomas Jorge García-Cañadas Gao Min Jack Corps Anthony V Powell Hualong Xu Wei Shen Yimin Chao

Silicon is a promising alternative to current thermoelectric materials (Bi(2)Te(3)). Silicon nanoparticle based materials show especially low thermal conductivities due to their high number of interfaces, which increases the observed phonon scattering. The major obstacle with these materials is maintaining high electrical conductivity. Surface functionalization with phenylacetylene shows an ele...

2017
Rafal BROCIEK Damian SLOTA

In this paper an inverse problem for the space fractional heat conduction equation is investigated. Firstly, we describe the approximate solution of the direct problem. Secondly, for the inverse problem part, we define the functional illustrating the error of approximate solution. To recover the thermal conductivity coefficient we need to minimize this functional. In order to minimize this func...

2008
Ramesh Narayan Mikhail V. Medvedev

We estimate the thermal conductivity of a weakly collisional magnetized plasma with chaotic magnetic field fluctuations. When the fluctuation spectrum extends over two or more decades in wave-vector, we find that thermal conduction is very efficient; the conduction coefficient is only a factor ∼ 5 below the classical Spitzer estimate. We suggest that conduction could play a significant role in ...

2018
Degang Zhao Lin Wang Lin Bo Di Wu

The Ni-doped ZrCo1−xNixSb half-Heusler compounds were prepared by arc-melting and spark plasma sintering technology. X-ray diffraction analysis results showed that all samples were crystallized in a half-Heusler phase. Thermoelectric properties of ZrCo1−xNixSb compounds were measured from room temperature to 850 K. The electrical conductivity and the absolute value of Seebeck coefficient increa...

Journal: :Nano letters 2014
S Yiğen A R Champagne

We extract experimentally the electronic thermal conductivity, Ke, in suspended graphene that we dope using a back-gate electrode. We make use of two-point dc electron transport at low bias voltages and intermediate temperatures (50-160 K), where the electron and lattice temperatures are decoupled. The thermal conductivity is proportional to the charge conductivity times the temperature, confir...

2014
N. Neophytou H. Kosina

The thermoelectric (TE) performance of materials is determined by the figure of merit ZT=σS/κ, where σ denotes the electrical conductivity, S the Seebeck coefficient and κ the thermal conductivity. Large improvements in ZT have recently been reported in nanoscale materials due to drastic reduction in κ. Despite this improvement, however, ZT still remains too low for allowing large scale TE depl...

2014
Jung J Kim Kwang-Soo Youm Mahmoud M Reda Taha

A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in...

2014
Sivasankaran Harish Mitsuru Tabara Yoshifumi Ikoma Zenji Horita Yasuyuki Takata David G Cahill Masamichi Kohno

We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples ...

Journal: :Nano letters 2015
Yanming Sun Haiyu Fang Lujun Pan Meng Han Shen Xu Xinwei Wang Biao Xu Yue Wu

Small molecules with functional groups can show different electron affinity and binding behavior on nanocrystal surface, which in principle could be used to alternate the electrical transport in self-assembled nanocrystal thin films. These small molecules can also serve for scattering the phonons to reduce the thermal conductivity. Here, we present our research on the thermoelectric characteris...

Journal: :The journal of physical chemistry letters 2014
Andrea Pisoni Jaćim Jaćimović Osor S Barišić Massimo Spina Richard Gaál László Forró Endre Horváth

We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples' morphologies indicate the minor role of the grain boundaries on the heat transport. Theoretical modeling demonstrates the importance of the resonant scattering in both specime...

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