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Central role of d-band energy level in Cu-based intermetallic alloys

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npj Computational Materials 2024年第1期10卷 2497-2504页

作者： Jing Zhao Wenming Xia Zhi Zeng Xianlong Wang Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China science Island Branch of Graduate school University of Science and Technology of ChinaHefei 230026China

Cu-Au intermetallic alloys are classic paradigms in the history of alloy theory for studying orderdisorder transition,phase stability,and so ***,density functional theory with a generalized gradient approximation(GGA)fails to describe their formation energies and Au-rich ground states,e.g.,calculated formation energies are nearly 40%smaller than experimental *** this work,we found that these discrepancies,which are also common in other Cu-transition metal(TM)intermetallic alloys,are actually caused by the fact that GGA produces Cu-3d bands with a shallower energy level than the experimental results,leading to incorrect d-d *** using the Hubbard U correction to adjust the d-bands to the correct position,the discrepancies in GGA calculations are *** finding that the correct d-bands position is the key to characterize Cu-TMs,which can be achieved efficiently by applying the Hubbard U correction.

关键词： intermetallic alloys alloy

Route to stabilize Cubic Gauche Polynitrogen to Ambient Conditions via surface saturation by Hydrogen

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Chinese Physics Letters 2023年第8期40卷 36-40页

作者：陈果牛草萍夏文明张洁曾雉王贤龙 Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of science and Technology of China Hefei 230026China

Cubic gauche polynitrogen(cg-N)is an attractive high-energy density ***,high-pressure synthesized cg-N will decompose at low pressure and cannot exist under ambient ***,the stabilities of cg-N surfaces with and without saturations at different pressures and temperatures are systematically investigated based on first-principles calculations and molecular dynamics *** surfaces at 0 GPa are very brittle and will decompose at 300 K,especially(110)surface will collapse completely just after structural relaxation,whereas the decompositions of surfaces can be suppressed by applying pressure,indicating that surface instability causes the cg-N decomposition at low *** to the saturation of dangling bonds and transferring electrons to the surfaces,saturation with H can stabilize surfaces under ambient conditions,while it is impossible for OH saturation to occur solely from obtaining electrons from *** suggests that polynitrogen is more stable in an acidic environment or when the surface is saturated with less electronegative adsorbates.

关键词： saturation ambient attractive

One-step synthesis of cubic gauche polymeric nitrogen with high yield just by heating

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Chinese Physics B 2024年第12期33卷 127-129页

作者： Liangfei Wu Yuxuan Xu Guo Chen Junfeng Ding Ming Li Zhi Zeng Xianlong Wang Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of science and Technology of China Hefei 230026China

A high-efficient one-step synthesis of cubic gauche polymeric nitrogen was developed just by thermal treatment of *** and infrared spectra confirm the formation of cubic gauche polymeric *** thermogravimetric differential scanning calorimeter measurements show that the content of cubic gauche polymeric nitrogen is as high as 1.5 wt%with high thermal stability,which is the highest content value reported so far.

关键词： cg-N thermal treatment polymeric nitrogen high-energy-density materials KN_(3)

Porous polyimide-based phase change materials with enhanced mechanical properties, thermal conductivity, and thermal shock resistance through precisely designed triple-functional layers

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science China(Technological sciences) 2023年第9期66卷 2716-2724页

作者： JIANG Miao XIAO Chao DING Xin WANG YanYan ZHANG Xian DU YuHang LI XiaoFei ZHENG Kang LIU XiangLan CHEN Lin TIAN XingYou Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China science Island Branch University of Science and Technology of ChinaHefei 230026China Lu’an Branch Anhui Institute of Innovation for Industrial TechnologyLu’an 237000China

Numerous scenarios of direct contact between electronic components and skin appear in wearable electronic devices. As the “second skin” that lies next to the biological skin of the human body, flexible wearable devices need to be equipped with thermal protection. However, the use of flexible phase change materials(PCMs) for wearable devices remains a challenge due to their low thermal conductivity, weakened mechanical strength, and liquid leakage. Herein, we developed a multilayered polyimide(PI) composite film integrating stable latent heat absorption, high thermal conductivity, and enhanced mechanical strength. This single piece of material achieved more prominent hotspot protection than traditional foams. The in-plane thermal conductivity of the resultant substrate layer is up to 2.655 W/(m K), which provides a fast response and in-plane dissipation for heat flow. The deliberately arranged interlayer of the material significantly improved the tensile strength(37.6 MPa) of the composite film,representing 128.9% greater strength than that of a bilayer film without a dense layer. The top layer with abundant pores provides reversibly latent heat storing and releasing function after being well infiltrated with paraffin wax. The resulting synergistic effect between three functional layers shows superb heat-suppressing performance in the thickness direction in both thermal shockresistant tests and simulation results. Impressively, the maximum temperature drop reached 40.2℃ compared with the pure PI film. The heating time was delayed by 12 s, providing sufficient warning time for human emergency response. This strategy can potentially pave the way for the design and fabrication of multifunctional films for wearable electronics in thermal protection applications.

关键词： foams layered structures thermal properties thermal analysis

Performance evaluation of ultra-long lithium heat pipe using an improved lumped parameter model

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Nuclear science and Techniques 2021年第12期32卷 89-102页

作者： Chong-Ju Hu Da-Li Yu Mei-sheng He Hua-Ping Mei Jie Yu Tao-sheng Li Institute of Nuclear Energy safety Technology Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of science and Technology of China Hefei 230026China suzhou University Suzhou 234000China

Lithium heat pipes have broad applications in heat pipe cooling reactors and hypersonic vehicles owing to their ultra-high working *** particular,when the length of the lithium heat pipe is ultra-long,the flow and heat transfer characteristics are more *** this study,an improved lumped parameter model that considers the Marangoni effect,bending effect,and different vapor flow patterns and Mach numbers was ***after,the proposed model was verified using the University of New Mexico’s Heat Pipe and HTPIPE ***,the verified model was applied to simulate the steady-state operation of an ultra-long lithium heat pipe in a Heat Pipesegmented Thermoelectric Module Converters space *** on the results:(1)Vapor thermal resistance was dominant at low heating power and decreased with increasing heating *** vapor flow inside the heat pipe developed from the laminar to the turbulent phase,whereas the liquid phase in the heat pipe was always laminar.(2)The vapor pressure drop caused by bending was approximately 22–23%of the total,and the bending effect on the liquid pressure drop could be ignored.(3)The Marangoni effect reduced the capillary limit by hindering the liquid reflux,especially at low vapor *** considering the Marangoni effect,the capillary limit of the lithium heat pipe was overestimated by 9%when the vapor temperature was 1400 K.(4)The total thermal resistance of the heat pipe significantly increased with increasing adiabatic length when the vapor temperature was ***,the wick dryness increased with increasing adiabatic length at any vapor *** findings improve on current knowledge for the optimal design and safety analysis of a heat pipe reactor,which adopts ultra-long lithium heat pipes.

关键词： Lithium heat pipe Bending effect Marangoni effect Capillary limit Heat Pipe-segmented Thermoelectric Module Converters(HP-sTMC)

Raman spectroscopy investigation on the pressure-induced structural and magnetic phase transition in two-dimensional antiferromagnet FePs_(3)

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Chinese Physics B 2022年第5期31卷 547-552页

作者： Hong Zeng Tingting Ye Peng Cheng Deyuan Yao Junfeng Ding Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of science and Technology of China Hefei 230026China

The layered van der Waals antiferromagnetic Fe Ps_(3) has received considerable attention because long range magnetic ordering can remain with single atoms layer,which offers potential applications in future ultrathin ***,we perform Raman spectroscopy to systematically explore the variations of lattice vibration and crystal structure under pressure up to 18.9 *** observe two structural phase transitions at approximately 4 GPa and 13 GPa,***,by monitoring spin-related Raman modes,we demonstrate a pressure-induced magnetic structure transition above 2 *** modes disappear accompanying the second structural phase transition and insulator-to-metal transition(IMT),indicating the suppression of long-range magnetic ordering,in agreement with earlier neutron powder diffraction experiments.

关键词： FePs3 layered magnetic materials high pressure Raman spectroscopy

simulation of three-stage operating temperature for supersaturation water-based condensational growth tube

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Journal of Environmental sciences 2020年第4期32卷 275-285页

作者： Jiejie Bian Huaqiao Gui Zhibo Xie Tongzhu Yu Xiuli Wei Wenyu Wang Jianguo Liu Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China University of science and Technology of China Hefei 230026China CAs Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of sciences Beijing 100049China

In order to realize accurate dynamic control of supersaturation and to study condensation growth characteristics of nanoparticles through different levels of super saturation,a series of parametric analyses and systematic comparisons between two-stage and three-stage operating temperature designs were simulated with COMsOL *** simulation results showed that the three-stage operating temperature did not change peak supersaturation compared with two operating temperatures,and the three-stage operating temperature was superior in decreasing the amount of water vapor and the temperature,thus lowering particle loss and variation in detection and *** peak supersaturation level increased by 0.3 as the flow rate increased from 0.6 to 2.0 L/min,but the supersaturation peak moved from 0.0027 z0 to 0.08 z0(i.e.,the growth time and the final size decreased by 40%).Peak supersaturation increased as the temperature difference increased or the temperature difference window was shifting left,and minimum activation size *** the 70℃temperature difference window from 9℃,79℃-1℃,71℃for the condenser and initiator temperatures resulted in peak supersaturation in the centerline being above 5.8,and the activation size changed as low as 1 *** with flow rates varying by a factor of 2.5(from 0.6 to 1.5 L/min)resulted in a final size decrease of 43%(from 3.2 to 1.8μm),and experimental results of outlet particle size distributions were equivalent with theoretical analysis as the operating temperature was changed.

关键词： Operating temperature supersaturation profile Flow rate Minimum activation size Temperature difference

synthesis of ternary compound in H-s-se system at high pressures

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Chinese Physics B 2021年第12期30卷 596-600页

作者： Xiao Zhang Key Laboratory of Materials Physics Institute of Solid State PhysicsHFIPSChinese Academy of Sciences(CAS)Hefei 230031China University of science and Technology of China Hefei 230026China

The chemical reaction products of elemental sulfur(s),selenium(se),and molecular hydrogen(H_(2))at high pressures and room temperature are probed by Raman *** known compounds H_(2)s and H_(2)se can be synthesized after laser heating at pressures lower than 1 *** further compression at room temperature,an H_(2)s-H_(2)se and an H_(2)s-H_(2)se-H_(2)van der Waals compounds are synthesized at 4 GPa and 6 GPa,*** later is of guest-host structure and can be identified as(H_(2)s)x(H_(2)se)(2-x)H_(2).It can be maintained up to 37 GPa at least,and the stability of its H_(2)se molecules is extended:the H-se stretching mode can be detected at least to 36 GPa but disappears at 22 GPa in(H_(2)se)2H_(2).The pressure dependence of s-H and se-H stretching modes of this ternary compound is in line with that of(H_(2)s)2 H_(2)and(H_(2)se)2H_(2),***,its hydrogen subsystem only shows the relevance to(H_(2)s)2H_(2),indicating that this ternary compound can be viewed as H_(2)se-replaced partial H_(2)s of(H_(2)s)2H_(2).

关键词： hydride high pressure Raman spectroscopy

skin mimicking-sweating evaporation polyimide cooling film for electronic devices

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science China(Technological sciences) 2023年第10期66卷 2797-2807页

作者： JIANG Miao XIAO Chao HE Xusheng DU HuiChao WANG YanYan DING Xin ZHANG Xian LI XiaoFei ZHENG Kang LIU XiangLan CHEN Lin TIAN XingYou Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid State PhysicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China science Island Branch University of Science and Technology of ChinaHefei 230026China Lu’an Branch Anhui Institute of Innovation for Industrial TechnologyLu’an 237000China school of Materials science and Engineering Anhui UniversityHefei 230039China

In hot environments,the human body shows an efficient capability to maintain a stable temperature by benefiting from sweating *** by this skin perspiration strategy,in this study,we demonstrated an innovative polyimide foam(PIF)-based mimetic skin with excellent cooling capability by integrating a silver coating and reusable hydrogel for the first *** of the hybrid thermal dissipating system,the successive silver coating quickly transferred heat to the inside of the polyacrylamide ***,the hydrogel absorbed a large amount of heat due to its large enthalpy and effectively dissipated heat to the environment through the evaporation of moisture,similar to the sweating of ***,the temperature of the skin-like film was reduced by 25.4℃compared with pure PIF under a high-power laser heating *** and remarkable cooling effects were also obtained in mobile phone and battery applications,far better than commercially available thermally conductive polyimide(PI).This outstanding performance paves a new way for the thermal management application of PI in wearable electronics,microprocessors,and flexible electronics.

关键词： skin-mimicking polyimide hydrogel thermal management sweat cooling