نتایج جستجو برای: variable thermal conductivity

تعداد نتایج: 505932  

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2013
John W Biddle Vincent Holten Jan V Sengers Mikhail A Anisimov

The heat capacity of supercooled water, measured down to -37°C, shows an anomalous increase as temperature decreases. The thermal diffusivity, i.e., the ratio of the thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothesized liquid-liquid critical point in supercooled water below the line of homogeneous nucleation. However...

Journal: :Physical review letters 2008
Quan Yin Sergey Y Savrasov

Using a novel many-body approach, we report lattice dynamical properties of UO2 and PuO2 and uncover various contributions to their thermal conductivities. Via calculated Grüneisen constants, we show that only longitudinal acoustic modes having large phonon group velocities are efficient heat carriers. Despite the fact that some optical modes also show their velocities which are extremely large...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2003
J M Deutsch Onuttom Narayan

We obtain numerically the thermal conductivity of a quasi-one-dimensional classical chain of hard sphere particles as a function of the length of the chain, introducing a fresh model for this problem. The conductivity scales as a power law of the length over two decades, with an exponent very close to the analytical prediction of 1/3.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2016
Ran He Daniel Kraemer Jun Mao Lingping Zeng Qing Jie Yucheng Lan Chunhua Li Jing Shuai Hee Seok Kim Yuan Liu David Broido Ching-Wu Chu Gang Chen Zhifeng Ren

Improvements in thermoelectric material performance over the past two decades have largely been based on decreasing the phonon thermal conductivity. Enhancing the power factor has been less successful in comparison. In this work, a peak power factor of ∼106 μW⋅cm-1⋅K-2 is achieved by increasing the hot pressing temperature up to 1,373 K in the p-type half-Heusler Nb0.95Ti0.05FeSb. The high powe...

Journal: :The Journal of chemical physics 2007
S Viscardy J Servantie P Gaspard

The thermal conductivity is calculated with the Helfand-moment method in the Lennard-Jones fluid near the triple point. The Helfand moment of thermal conductivity is here derived for molecular dynamics with periodic boundary conditions. Thermal conductivity is given by a generalized Einstein relation with this Helfand moment. The authors compute thermal conductivity by this new method and compa...

Journal: :The Journal of chemical physics 2005
Phil Attard

A statistical mechanical theory for heat flow is developed based upon the second entropy for dynamical transitions between energy moment macrostates. The thermal conductivity, as obtained from a Green-Kubo integral of a time correlation function, is derived as an approximation from these more fundamental theories, and its short-time dependence is explored. A new expression for the thermal condu...

2016
Pablo I. Hurtado Pedro L. Garrido

Since the discovery of long-time tails, it has been clear that Fourier's law in low dimensions is typically anomalous, with a size-dependent heat conductivity, though the nature of the anomaly remains puzzling. The conventional wisdom, supported by renormalization-group arguments and mode-coupling approximations within fluctuating hydrodynamics, is that the anomaly is universal in 1d momentum-c...

Journal: :Physical review letters 2008
Brian M Andersen P J Hirschfeld

The prediction and observation of low-temperature universal thermal conductivity in cuprates has served as a keystone of theoretical approaches to the superconducting state, but recent measurements on underdoped samples show strong violations of this apparently fundamental property of d-wave nodal quasiparticles. Here, we show that the breakdown of universality may be understood as the conseque...

Journal: :Physical review letters 2015
M Taupin G Knebel T D Matsuda G Lapertot Y Machida K Izawa J-P Brison J Flouquet

The thermal conductivity of YbRh_{2}Si_{2} has been measured down to very low temperatures under field in the basal plane. An additional channel for heat transport appears below 30 mK, both in the antiferromagnetic and paramagnetic states, respectively, below and above the critical field suppressing the magnetic order. This excludes antiferromagnetic magnons as the origin of this additional con...

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