The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical appl...The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical application.In this study,by utilizing first-principles calculations and semi-classical Boltzmann transport theory,it is found that hole doping with an experimentally achievable concentration of 1.83×10^(14)cm^(-2)can reduce the lattice thermal conductivity of monolayer MoS_(2) from 151.79 W·m^(-1)·K^(-1)to 12.19 W·m^(-1)·K^(-1),achieving a high thermal switching ratio of 12.5.The achieved switching ratio significantly surpasses previously reported values,including those achieved by extreme strain methods.This phenomenon mainly arises from the enhanced lattice anharmonicity,which is primarily contributed by the S atoms.These results indicate that hole doping is an effective method for tuning the lattice thermal conductivity of materials,and demonstrate that monolayer MoS_(2) is a potential candidate material for thermal switches.展开更多
With its commercialization, the second-generation(2G) high temperature superconducting(HTS) RE–Ba–Cu–O(REBCO, RE is rare earth) tape is extensively applied to the superconducting magnets in the high magnetic fields...With its commercialization, the second-generation(2G) high temperature superconducting(HTS) RE–Ba–Cu–O(REBCO, RE is rare earth) tape is extensively applied to the superconducting magnets in the high magnetic fields. However,unlike low temperature superconducting(LTS) magnets, the HTS magnet cannot operate in the persistent current mode(PCM) due to the immature superconducting soldering technique. In this paper, an exciting method for two HTS sub-loops,so-called charging and load loops, is proposed by flux pump consisting of exciting coil and controllable thermal switch.Two HTS sub-loops are made of an REBCO tape with two slits. An exciting coil with iron core is located in one sub-loop and is supplied with a triangular waveform current so that magnetic field is generated in another sub-loop. The influence of magnetic flux on induced current in load loop is presented and verified in experiment at 77 K. The relationship between the induced magnetic flux density and the current on the sub-loops having been calibrated, magnetic flux density, and induced current are obtained. The results show that the HTS sub-loops can be excited by a coil with thermal switch and the induced current increases with magnetic flux of exciting coil increasing, which is promising for persistent current operation mode of HTS magnets.展开更多
In the animal kingdom,sex is determined genetically(genotypic sex determination,GSD)or environmentally(environmental sex determination,ESD).For GSD species,the chromosomal constitution is responsible for determining a...In the animal kingdom,sex is determined genetically(genotypic sex determination,GSD)or environmentally(environmental sex determination,ESD).For GSD species,the chromosomal constitution is responsible for determining an individual's sexual development at fertilization.展开更多
Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport o...Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.展开更多
The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the rever...The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.展开更多
The realization of reversible thermal conductivity through ferromagnetic ordering can improve the heat management and energy efficiency in magnetic materials-based devices.VI_(3),as a new layered ferromagnetic semicon...The realization of reversible thermal conductivity through ferromagnetic ordering can improve the heat management and energy efficiency in magnetic materials-based devices.VI_(3),as a new layered ferromagnetic semiconductor,exhibits a structural phase transition from monoclinic(C2/m)to rhombohedral(R3^(-))phase as temperature decreases,making it a suitable platform to investigate thermal switching in magnetic phase transition materials.This work reveals that the thermal switching ratio of VI_(3)can reach 3.9 along the a-axis.Mechanical properties analysis indicates that the C2/m structure is stiffer than the R^(-)one,causing the larger phonon velocity in C2/m phase.Moreover,due to the fewer phonon branches in C2/m phase,the number of phonon–phonon scattering channels in C2/m phase is smaller compared to that of R^(-)phase.Both the larger phonon velocity and the longer phonon lifetime lead to larger lattice thermal conductivity in C2/m phase.This study uncovers the mechanical and thermal properties of VI_(3),which provides useful guides for designing magnetic materials-based devices such as thermal switch.展开更多
This paper presents a new thermal computer, which is driven by heat current and not electricity current. The basic thermal logic gate, such as thermal logic AND gate. thermal logic NOT gate, thermal logic OR gate are ...This paper presents a new thermal computer, which is driven by heat current and not electricity current. The basic thermal logic gate, such as thermal logic AND gate. thermal logic NOT gate, thermal logic OR gate are discussed in this paper. Compared with electronic computer, it can work at some special environment, such as high temperature and high pressure Consequently, the heat computer is not only a new special computer, but also a lot of new heat computation cell or device could be invented in the future. The thermal computer and control device are a new thermal energy machines powered by heat energy, it is significant for the environmental protection, energy usage and developed and new discipline development.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12104145 and 12374040)。
文摘The thermal switch plays a crucial role in regulating system temperature,protecting devices from overheating,and improving energy efficiency.Achieving a high thermal switching ratio is essential for its practical application.In this study,by utilizing first-principles calculations and semi-classical Boltzmann transport theory,it is found that hole doping with an experimentally achievable concentration of 1.83×10^(14)cm^(-2)can reduce the lattice thermal conductivity of monolayer MoS_(2) from 151.79 W·m^(-1)·K^(-1)to 12.19 W·m^(-1)·K^(-1),achieving a high thermal switching ratio of 12.5.The achieved switching ratio significantly surpasses previously reported values,including those achieved by extreme strain methods.This phenomenon mainly arises from the enhanced lattice anharmonicity,which is primarily contributed by the S atoms.These results indicate that hole doping is an effective method for tuning the lattice thermal conductivity of materials,and demonstrate that monolayer MoS_(2) is a potential candidate material for thermal switches.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51977078)。
文摘With its commercialization, the second-generation(2G) high temperature superconducting(HTS) RE–Ba–Cu–O(REBCO, RE is rare earth) tape is extensively applied to the superconducting magnets in the high magnetic fields. However,unlike low temperature superconducting(LTS) magnets, the HTS magnet cannot operate in the persistent current mode(PCM) due to the immature superconducting soldering technique. In this paper, an exciting method for two HTS sub-loops,so-called charging and load loops, is proposed by flux pump consisting of exciting coil and controllable thermal switch.Two HTS sub-loops are made of an REBCO tape with two slits. An exciting coil with iron core is located in one sub-loop and is supplied with a triangular waveform current so that magnetic field is generated in another sub-loop. The influence of magnetic flux on induced current in load loop is presented and verified in experiment at 77 K. The relationship between the induced magnetic flux density and the current on the sub-loops having been calibrated, magnetic flux density, and induced current are obtained. The results show that the HTS sub-loops can be excited by a coil with thermal switch and the induced current increases with magnetic flux of exciting coil increasing, which is promising for persistent current operation mode of HTS magnets.
基金supported by the National Key R&D Program of China(2023YFF1304900)the National Natural Science Foundation of China(32430012,32170486,32030013,31821001,32371570,and 32101252)+3 种基金the Heilongjiang Key Research and Development Program(2024ZXDXC28)the Fundamental Research Funds for the Central Universities(2572022DS03)the Heilongjiang Chunyan Support Program for Young Scientific and Technological Talents Team(CYQN24058)the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001).
文摘In the animal kingdom,sex is determined genetically(genotypic sex determination,GSD)or environmentally(environmental sex determination,ESD).For GSD species,the chromosomal constitution is responsible for determining an individual's sexual development at fertilization.
基金supported bythe Science and Technology Commission of Shanghai Municipality (Grant No.24CL2901702)The numerical calculations were performed at the Supercomputer Center (Project No.2024-Cb-0042)Institute for Solid State Physics,the University of Tokyo。
文摘Heat dissipation and thermal switches are vital for adaptive cooling and extending the lifespan of electronic devices and batteries. In this work, we conducted high-throughput investigations on the thermal transport of 24 experimentally realized two-dimensional(2D) materials and their potential as thermal switches, leveraging machine-learning-assisted strain engineering and phonon transport simulations. We identified several highperformance thermal switches with ratios exceeding 2, with germanene(Ge) achieving an ultrahigh ratio of up to9.64 within the reversible deformation range. The underlying mechanism is strain-induced bond softening, which sensitively affects anharmonicity represented by three-and four-phonon scattering. The widespread occurrence of four-phonon scattering was confirmed in the thermal transport of 2D materials. Opposite switching trends were discovered, with 2D transition metal dichalcogenide materials showing negative responses to tensile strain while buckled 2D elemental materials showed positive responses. We further proposed a screening descriptor based on strain-induced changes in the Gr¨uneisen parameter for efficiently identifying new high-performance thermal switch materials. This work establishes a paradigm for thermal energy control in 2D materials through strain engineering, which may be experimentally realized in the future via bending, substrate mismatch, and related approaches, thereby laying a robust foundation for further developments and applications.
基金the China Scholarship Council(Grant No.202107000030)RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic(Grant No.A1898b0043)A*STAR Aerospace Programme(Grant No.M2115a0092)。
文摘The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.
基金the National Natural Science Foundation of China(Grant No.52206092)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20210565)+4 种基金funded by Department of Science and Technology of Jiangsu Province,China(Grant No.BK20220032)Basic Science(Natural Science)Research Project of Higher Education Institutions of Jiangsu Province,China(Grant No.21KJB470009)Nanjing Science and Technology Innovation Project for Overseas Studentsfunded by“Shuangchuang”Doctor Program of Jiangsu Province,China(Grant No.JSSCBS20210315)open research fund of Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments,Southeast University(Grant No.KF202010)。
文摘The realization of reversible thermal conductivity through ferromagnetic ordering can improve the heat management and energy efficiency in magnetic materials-based devices.VI_(3),as a new layered ferromagnetic semiconductor,exhibits a structural phase transition from monoclinic(C2/m)to rhombohedral(R3^(-))phase as temperature decreases,making it a suitable platform to investigate thermal switching in magnetic phase transition materials.This work reveals that the thermal switching ratio of VI_(3)can reach 3.9 along the a-axis.Mechanical properties analysis indicates that the C2/m structure is stiffer than the R^(-)one,causing the larger phonon velocity in C2/m phase.Moreover,due to the fewer phonon branches in C2/m phase,the number of phonon–phonon scattering channels in C2/m phase is smaller compared to that of R^(-)phase.Both the larger phonon velocity and the longer phonon lifetime lead to larger lattice thermal conductivity in C2/m phase.This study uncovers the mechanical and thermal properties of VI_(3),which provides useful guides for designing magnetic materials-based devices such as thermal switch.
基金Acknowledgment： The paper was supported by the Nature Science Foundation of China （No. 50876034）, Ph.D. Science Foundation of Ministry. of Education of China （No. 20040487039）： Key Discipline Construction Foundation of Shanghai Education Commission （No. J5180｜）： Science Foundation of Shanghai Education Commission （No. 08ZY79） SSPU Science Foundation （No. DZ207004）.
文摘This paper presents a new thermal computer, which is driven by heat current and not electricity current. The basic thermal logic gate, such as thermal logic AND gate. thermal logic NOT gate, thermal logic OR gate are discussed in this paper. Compared with electronic computer, it can work at some special environment, such as high temperature and high pressure Consequently, the heat computer is not only a new special computer, but also a lot of new heat computation cell or device could be invented in the future. The thermal computer and control device are a new thermal energy machines powered by heat energy, it is significant for the environmental protection, energy usage and developed and new discipline development.
