high thermal conduction material
36299170
Borophene hydride: a stiff 2D material with high thermal conductivity and attractive optical and electronic properties.
Two dimensional (2D) structures of boron atoms, so called borophene, have recently attracted remarkable attention. In a recent exciting experimental study, a hydrogenated borophene structure was realized. Motivated by this success, we conducted extensive first principles calculations to explore the mechanical, thermal conduction, electronic and optical responses of borophene hydride. The mechanical response of borophene hydride was found to be anisotropic, with an elastic modulus of 131 N m 1 and a high tensile strength of 19.9 N m 1 along the armchair direction. Notably, it was shown that by applying mechanical loading the metallic electronic character of borophene hydride can be altered to direct band gap semiconducting, very appealing for application in nanoelectronics. The absorption edge of the imaginary part of the dielectric function was found to occur in the visible range of light for parallel polarization. Finally, it was estimated that this novel 2D structure at room temperature can exhibit high thermal conductivities of 335 W mK 1 and 293 W mK 1 along the zigzag and armchair directions, respectively. Our study confirms that borophene hydride shows an outstanding combination of interesting mechanical, electronic, optical and thermal conduction properties, which are promising for the design of novel nanodevices.
Nanoscale
Bohayra Mortazavi Meysam Makaremi Masoud Shahrokhi Mostafa Raeisi Chandra Veer Singh Timon Rabczuk Luiz Felipe C Pereira
229303554
Borophene hydride: a stiff 2D material with high thermal conductivity and attractive optical and electronic properties
Two dimensional (2D) structures of boron atoms so called borophene, have recently attracted remarkable attention. In a latest exciting experimental study, a hydrogenated borophene structure was realized. Motivated by this success, we conducted extensive first principles calculations to explore the mechanical, thermal conduction, electronic and optical responses of borophene hydride. The mechanical response of borophene hydride was found to be anisotropic in which it can yield an elastic modulus of 131 N/m and a high tensile strength of 19.9 N/m along the armchair direction. Notably, it was shown that by applying mechanical loading the metallic electronic character of borophene hydride can be altered to direct band gap semiconducting, very appealing for the application in nanoelectronics. The absorption edge of the imaginary part of the dielectric function was found to occur in the visible range of light for parallel polarization. Finally, it was estimated that this novel 2D structure at the room temperature can exhibit high thermal conductivities of 335 W/mK and 293 W/mK along zigzag and armchair directions, respectively. Our study confirms that borophene hydride benefits an outstanding combination of interesting mechanical, electronic, optical and thermal conduction properties, promising for the design of novel nanodevices.
Bohayra Mortazavi Meysam Makaremi Masoud Shahrokhi Mostafa Raeisi Chandra Veer Singh Timon Rabczuk Luiz Felipe C Pereira
39410051
Increase of Cooling Performance of Conduction Cooled Superconducting Coils Using High Thermal Conduction Plastic
We experimentally study thermal stability of conduction cooled superconducting coils from a viewpoint of structural materials of the coils. The materials are Dyneema fiber reinforced plastics (DFRPs) The DFRP has properties of high thermal conduction and negative thermal expansion. We evaluated the stability of the conduction cooled coils having DFRP bobbins with changing the DFRP's thermal expansion. According to the experimental results, when the expansion became large, the stability also became better. It is expected that the DFRP is the effective heat sink bobbin material.
IEEE Transactions on Applied Superconductivity
Tomoaki Takao Daigo Hachisuka Shunsuke Asano Takuroh Yuhara Takayuki Goto Atsuhiko Yamanaka Arata Nishimura
104342722
Intrinsically Low Thermal Conductivity in BiSbSe3: A Promising Thermoelectric Material with Multiple Conduction Bands
Bi2Se3, as a Te free alternative of room temperature state of the art thermoelectric (TE) Bi2Te3, has attracted little attention due to its poor electrical transport properties and high thermal conductivity. Interestingly, BiSbSe3, a product of alloying 50% Sb on Bi sites, shows outstanding electron and phonon transports. BiSbSe3 possesses orthorhombic structure and exhibits multiple conduction bands, which can be activated when the carrier density is increased as high as 3.7 x 1020 cm 3 through heavily Br doping, resulting in simultaneously enhancing the electrical conductivities and Seebeck coefficients. Meanwhile, an extremely low thermal conductivity (0.6 0.4 W m 1 K 1 at 300 800 K) is found in BiSbSe3. Both first principles calculations and elastic properties measurements show the strong anharmonicity and support the ultra low thermal conductivity of BiSbSe3. Finally, a maximum dimensionless figure of merit ZT 1.4 at 800 K is achieved in BiSb(Se0.94Br0.06)3, which is comparable to the most n type Te free TE materials. The present results indicate that BiSbSe3 is a new and a robust candidate for TE power generation in medium temperature range.
Xiaoying Liu Dongyang Wang Haijun Wu Jinfeng Wang Yuheng Zhang Guangtao Wang Stephen John Pennycook Li-dong Zhao
102379426
MoS2 graphene in plane contact for high interfacial thermal conduction
Recent studies have indicated that two dimensional (2D) MoS2 exhibits low in plane and inter plane thermal conductivities. This poses a significant challenge to heat management in MoS2 based electronic devices. To address this challenge, we have designed MoS2 graphene interfaces that fully utilize graphene, a 2D material that exhibits very high thermal conductivity. First, we performed ab initio atomistic simulations to understand bonding and structural stability at the interfaces. The interfaces that we designed, which were connected via strong covalent bonds between Mo and C atoms, were energetically stable. We then performed molecular dynamics simulations to investigate interfacial thermal conductance in these materials. Surprisingly, the interfacial thermal conductance was high and comparable to those of covalently bonded graphene metal interfaces. Importantly, each interfacial Mo C bond served as an independent thermal channel, enabling modulation of the interfacial thermal conductance by controlling the Mo vacancy concentration at the interface. The present work provides a viable heat management strategy for MoS2 based electronic devices.
Nano Research
Xiangjun Liu Junfeng Gao Gang Zhang Yong-Wei Zhang
24355985
Evaluating Cooling Performance of High Thermal Conduction Composite in Conduction Cooled Superconducting Coils
Aluminum nitride (AlN) has been widely used as a heat sink material in conduction cooled superconducting coils but is hard to process. We have therefore developed an easily processed Dyneema fiber reinforced plastic (DFRP) with high thermal conductivity. Making small superconducting coils with DFRP or AlN bobbins, cooling them to a cryogenic temperature by using a refrigerator, and comparing their voltage profiles when DC currents were applied to them, we found the heat sink effect of DFRP to be almost same as that of AlN because DFRP has a high thermal conductivity and expands when cooled. This expansion increases the contact force between superconducting windings and the DFRP bobbin and thereby improves the transfer of heat from the winding to the DFRP. We think DFRP will be the next generation heat sink material.
IEEE Transactions on Applied Superconductivity
Tomoaki Takao Takuroh Yuhara Ryohei Sakuma Takayuki Goto Atsuhiko Yamanaka
21527864
Heat Drain Effects From HTS Tapes to High Thermal Conduction Plastics for Conduction Cooled Magnets
In conduction cooled HTS magnets, it is important to design effective heat drains from the HTS tapes to a cold head of a refrigerator. Aluminum nitride (AlN) is often used as a heat drain material because thermal conductivity and electric insulation of the material are good. However, the AlN is hard and brittle, and hence it is difficult for magnet makers and users to process the AlN. To address this issue, we have studied to use the plastic having both high thermal conduction and high electric insulation properties as the heat drain material. The plastic is the Dyneema fiber reinforced plastic (DFRP) We fabricated an experimental arrangement in which the Bi 2223 tape and the DFRP block were contacted, and a steady current was applied to the tape. Based on the measured voltage between terminals, thermal drain properties from the tape to the DFRP block were estimated. In the same conditions, experiments using the glass fiber reinforced plastic (GFRP) were also performed. Furthermore, the coil shape sample made of the AlN and DFRP were used. The paper presents the difference of the thermal drain performance in the AlN, the DFRP and the GFRP.
IEEE Transactions on Applied Superconductivity
Tomoaki Takao A Watanabe T Takiyama K Nakamura Atsuhiko Yamanaka
207171208
Multiple Converged Conduction Bands in K2Bi8Se13: A Promising Thermoelectric Material with Extremely Low Thermal Conductivity.
We report that K2Bi8Se13 exhibits multiple conduction bands that lie close in energy and can be activated through doping, leading to a highly enhanced Seebeck coefficient and a high power factor with elevated temperature. Meanwhile, the large unit cell, complex low symmetry crystal structure, and nondirectional bonding lead to the very low lattice thermal conductivity of K2Bi8Se13, ranging between 0.42 and 0.20 W m 1 K 1 in the temperature interval 300 873 K. Experimentally, we further support the low thermal conductivity of K2Bi8Se13 using phonon velocity measurements; the results show a low average phonon velocity (1605 ms 1) small Young's modulus (37.1 GPa) large Gruneisen parameter (1.71) and low Debye temperature (154 K) A detailed investigation of the microstructure and defects was carried out using electron diffraction and transmission microscopy which reveal the presence of a K2.5Bi8.5Se14 minor phase intergrown along the side of the K2Bi8Se13 phase. The combination of enhanced power factor and low thermal conductivity results in a high ZT value of ~1.3 at 873 K in electron doped K2Bi8Se13 material.
Journal of the American Chemical Society
Yan-Ling Pei Cecile Chang Zhe Wang Meijie Yin Minghui Wu Gangjian Tan Haijun Wu Yue Chen Lei Zheng Sheng-Kai Gong Tiejun Zhu Xinbing Zhao Li Huang Jiaqing He Mercouri G Kanatzidis Li-dong Zhao
42441435
Cooling performance of high thermal conduction plastics on conduction cooled Bi2223 tapes
Dyneema fiber has a high thermal conduction property. Using the property, we applied a Dyneema fiber reinforced plastic (DFRP) as a heat drain material for a conduction cooled magnet. In the experiments, the DFRP was contacted on a surface of HTS tape, and a short time over current exceeding its critical current was applied to the tape. The heat drain effect was measured from a voltage of the tape and a thermocouple. The experimental results showed that the effects depended on the fiber directions in the plastic. In case that the fibers in the plastic contacted perpendicular to the tape's face, the effect was good. When the DFRP is used as the heat drain material, we should pay attention to the fiber directions in the DFRP.
IEEE Transactions on Applied Superconductivity
Tomoaki Takao Mitsugi Yamaguchi H Yamamoto A Watanabe Atsuhiko Yamanaka
119117217
The Launching of Cold Clouds by Galaxy Outflows II: The Role of Thermal Conduction
We explore the impact of electron thermal conduction on the evolution of radiatively cooled cold clouds embedded in flows of hot and fast material, as occur in outflowing galaxies. Performing a parameter study of three dimensional adaptive mesh refinement hydrodynamical simulations, we show that electron thermal conduction causes cold clouds to evaporate, but it can also extend their lifetimes by compressing them into dense filaments. We distinguish between low column density clouds, which are disrupted on very short times, and high column density clouds with much longer disruption times that are set by a balance between impinging thermal energy and evaporation. We provide fits to the cloud lifetimes and velocities that can be used in galaxy scale simulations of outflows, in which the evolution of individual clouds cannot be modeled with the required resolution. Moreover, we show that the clouds are only accelerated to a small fraction of the ambient velocity because compression by evaporation causes the clouds to present a small cross section to the ambient flow. This means that either magnetic fields must suppress thermal conduction, or that the cold clouds observed in galaxy outflows are not formed of cold material carried out from the galaxy.
Marcus Bruggen Evan Scannapieco