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Two-dimensional Stiefel-Whitney insulators in liganded Xenes

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npj Computational Materials 2022年第1期8卷 9-14页

作者： mingxiang pan Dexin Li Jiahao Fan Huaqing Huang School of Physics Peking University100871BeijingChina Collaborative Innovation Center of Quantum Matter 100871BeijingChina Center for High Energy Physics Peking University100871BeijingChina

Two-dimensional(2D)Stiefel-Whitney insulator(SWI),which is characterized by the second Stiefel-Whitney class,is a class of topological phases with zero Berry *** an intriguing topological state,it has been well studied in theory but seldom realized in realistic *** we propose that a large class of liganded Xenes,i.e.,hydrogenated and halogenated 2D group-IV honeycomb lattices,are 2D *** nontrivial topology of liganded Xenes is identified by the bulk topological invariant and the existence of protected corner ***,the large and tunable bandgap(up to 3.5 eV)of liganded Xenes will facilitate the experimental characterization of the 2D SWI *** findings not only provide abundant realistic material candidates that are experimentally feasible but also draw more fundamental research interest towards the topological physics associated with Stiefel-Whitney class in the absence of Berry curvature.

关键词： materials. topological Stiefel

Giant enhancement of magnetocaloric effect in metallic glass matrix composite

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Science China(Physics,Mechanics & Astronomy) 2008年第4期51卷 337-348页

作者： WANG YongTian BAI HaiYang pan mingxiang ZHAO DeQian WANG WeiHua Institute of Physics Chinese Academy of SciencesBeijing 100080China

The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (ΔSm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum ΔSm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.

关键词： metallic glass magnetocaloric effect composite

Correlation between boson peak and thermal expansion manifested by physical aging and high pressure

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Science China(Physics,Mechanics & Astronomy) 2022年第4期65卷 72-77页

作者： Rongjie Xue Linzhi Zhao Yunqi Cai Jiaojiao Yi Jinguang Cheng Ping Wen Weihua Wang mingxiang pan Haiyang Bai Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Materials Engineering Jiangsu University of TechnologyChangzhou 213001China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of SciencesBeijing 100049China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China

We investigate the effects of high pressure and physical aging on the boson peak and thermal expansion of a typical metallic glass. Specifically, the thermal expansion coefficient and boson peak intensity monotonically decrease during physical *** the increase of high pressure, the boson peak intensity and the thermal expansion coefficient coincidently experience an incipient decrease and then a subsequent increase. The boson peak intensity shows an approximately linear relationship with the thermal expansion coefficient. The thermal expansion can be affected by structural relaxation or rejuvenation, which can reflect the flow units variation and atomic packing of a metallic glass. Our results indicate a direct link between structural relaxation or rejuvenation and fast boson peak dynamics, providing insights into the boson peak behavior and structural heterogeneity of metallic glasses.

关键词： metallic glass thermal expansion boson peak high pressure aging

Domain structure of hard magnetic NdAlFeCo bulk metallic glass

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Chinese Science Bulletin 2001年第19期46卷 1595-1598页

作者： WEI Bingchen WANG Weihua pan mingxiang HAN Baoshan ZHANG Zhenrong HU Wenrui National Microgravity Laboratory Institute of MechanicsBeijing 100080China Institute of Physics and Center for Condensed Matter Physics Chinese Academy of SciencesBeijing 100080China State Key Laboratory of Magnetism Institute of Physics and Center for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100080China

Magnetic domain structure of hard magnetic Nd60Al10Fe20Co10 bulk metallic glass (BMG) has been studied by using magnetic force microscopy. In the magnetic force images it is shown that the exchange interaction type magnetic domains with a period of about 360 nm do exist in the BMG, which is believed to be associated with the appearance of hard-magnetic properties in this system. As the scale of the magnetic domain is much larger than the size of the short-range ordered atomic clusters existing in the BMG, it is believed that the large areas of magnetic contrast are actually a collection of a group of clusters aligned in parallel by strong exchange coupling interaction. After fully crystallization, the BMG exhibits paramagnetism. No obvious magnetic contrast is observed in the magnetic force images of fully crystallized samples, except for a small quantity of ferromagnetic crystalline phase with low coercivity and an average size of 900 nm.

关键词： metallic glass hard magnetism magnetic force microscopy exchange coupling interaction.

Space Materials Science in China:*** Studies under Microgravity

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空间科学学报 2020年第5期40卷 946-949页

作者： ZHANG Xingwang YIN Zhigang YU Jianding YUAN Zhangfu ZHAO Jiuzhou LUO Xinghong pan mingxiang Institute of Semiconductors Chinese Academy of SciencesBeijing 100083 Centre of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049 Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050 Collaborative Innovation Center for Steel Technology University of Science and Technology BeijingBeijing 100083 Institute of Metal Research Chinese Academy of SciencesShenyang 110016 School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016 Institute of Physics Chinese Academy of SciencesBeijing 100191 School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049 Songshan Lake Materials Laboratorij Dongguan 523808

The virtual absence of gravity-dependent phenomena in microgravity allows an in-depth understanding of fundamental events that are normally obscured and therefore are difficult to study quantitatively on *** particular interest is that the low-gravity environment aboard space provides a unique platform to synthesize alloys of semiconductors with homogeneous composition distributions,on both the macroscopic and microscopic scales,due to the much reduced buoyancy-driven *** the other hand,the easy realization of detached solidification in microgravity suppresses the formation of defects such as dislocations and twins,and thereby the crystallographic perfection is greatly ***,the microgravity condition offers the possibilities to elucidate the liquid/solid interfacial structures,as well as clarify the microstructure evolution path of the metal alloys(or composites)during the solidification *** by these facts,growths of compound semiconductors and metal alloys were carried out under microgravity by using the drop tube,or on the scientific platforms of Tiangong-2 and *** following illustrates the main results.

关键词： Space materials Microgravity Bubble behavior Microstructural evolution

Effect of Li and Ti Additions on Lα(Al)+Mg_2Si Pseudobinary Eutectic Reaction

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Journal of Materials Science & Technology 1997年第6期13卷 487-490页

作者： Shengxu ZHAO Shunpu LI Deqian ZHAO mingxiang pan and Xichen CHEN(Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China) Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Effect of Li and Ti additions on Lα(AI)+Mg2Si pseudobinary eutectic reaction in ternary Al-Mg-Si system has been investigated by thermoanalysis, directional solidification and metallographic techniques in this study. It has been found that Li addition causes decreasing of the volume fraction of Mg2Si, while a little amount of Ti causes to increasing, which is of a great importance to the adjustment of phase constitution and alloy properties. Doping components have little influence on the eutectic temperature.

关键词： Si Al Mg2Si Pseudobinary Eutectic Reaction Effect of Li and Ti Additions on L Li Ti

Glassy metallic plastics

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Science China(Physics,Mechanics & Astronomy) 2010年第3期53卷 409-414页

作者： LI JianFu, WANG JunQiang, LIU XiaoFeng, ZHAO Kun, ZHANG Bo, BAI HaiYang, pan mingxiang & WANG WeiHua Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China Chinese Academy of Sciences Institute of Physics Beijing China (GRID:grid.9227.e) (ISNI:***)

This paper reports a class of bulk metallic glass including Ce-, LaCe-, CaLi-, Yb-, and Sr-based metallic glasses, which are regarded as glassy metallic plastics because they combine some unique properties of both plastics and metallic alloys. These glassy metallic plastics have very low glass transition temperature (Tg^25oC to 150oC) and low Young’s modulus (~20 GPa to 35 GPa). Similar to glassy plastics, these metallic plastics show excellent plastic-like deformability on macro-, micro- and even nano-scale in their supercooled liquid range and can be processed, such as elongated, compressed, bent, and imprinted at low temperatures, in hot water for instance. Under ambient conditions, they display such metallic properties as high thermal and electric conductivities and excellent mechanical properties and other unique properties. The metallic plastics have potential applications and are also a model system for studying issues in glass physics.

关键词： glassy metallic plastic synthesizing low Tg thermoplastic properties

Space Materials Science in China:Ⅱ.Ground-based Researches and Academic Activities

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空间科学学报 2020年第5期40卷 950-955页

作者： pan mingxiang WANG Weihua FAN Shuqian ZHANG Qi pan Xiuhong DENG Weijie HU Liang WEI Bingbo WANG Haipeng YIN Zhigang FANG Jinghong YU Jianding ZHANG Xingwang YUAN Zhangfu JIANG Hongxiang ZHAO Jiuzhou WANG Gong Institute of Physics Chinese Academy of SciencesBeijing 100191 School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049 Songshan Lake Materials Lab. Dongguan 523808 Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714 Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 201899 Laboratory of Space Materials Science and Technology Northwestern Polytechnical UniversityXi’an 710072 Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 Collaborative Innovation Center of steel technology University of Science and Technology BeijingBeijing 100083 College of Engineering Peking UniversityBeijing 100871 Institute of Metal Research Chinese Academy of SciencesShenyang 110016 CAS Key Laboratory of Space Manufacturing Technology Technology and Engineering Center for Space UtilizationChinese Academy of SciencesBeijing 100094

Activities of space materials science research in China have been continuously supported by two main national *** is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Program(SPP)on Space Science since *** CSS plan in 2019,eleven space materials science experimental projects were officially approved for execution during the construction of the space *** the SPP Phase Ⅱ launched in 2018,seven pre-research projects are deployed as the first batch in 2018,and one concept study project in *** pre-research projects will be cultivated as candidates for future selection as space experiment projects on the recovery of scientific experimental satellites in the future.A new apparatus of electrostatic levitation system for ground-based research of space materials science and rapid solidification research has been developed under the support of the National Natural Science Foundation of *** order to promote domestic academic activities and to enhance the advancement of space materials science in China,the Space Materials Science and Technology Division belong to the Chinese Materials Research Society was established in *** also organized scientists to write five review papers on space materials science as a special topic published in the journal Scientia Sinica to provide valuable scientific and technical references for Chinese researchers.

关键词： Additive manufacturing Aerogel preparation Electrostatic levitation system Crystal growth Solidification Academic activities of space materials science

Experimental research on thermal transport properties of crystallized palladium-based alloys

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Frontiers in Energy 2018年第1期12卷 121-126页

作者： Siyuan CHENG Xuguo SHI Weigang MA Xing ZHANG Guanglai LIU mingxiang pan Weihua WANG Key Laboratory for Thermal Science and Power Engineering of Ministryof Education Department of Engineering Mechanics TsinghuaUniversity Beijing 100084 China Institute of Physics Chinese Academy of Sciences Beijing 100190China

Palladium-based alloy is a kind of material with a high glass forming ability and can be easily formed into an amorphous state. After an annealing process, it can also be maintained at a crystallized state. To study the thermal and electrical transport properties of crystallized palladium-based alloys, the steady-state T-type method, standard four-probe method, and AC heating-DC detecting T-type method were used to measure the thermal conductivity, electrical conductivity, and Seebeck coeffi- cient of crystallized Pd4oNiloCu3oP2o and Pd43Nilo- Cu27P2o alloys respectively. The results show that compared to amorphous samples, the thermal conductivity and electrical conductivity of crystallized palladium-based alloys are significantly higher, while the Seebeck coeffi- cient is lower. The ratio of crystallized and amorphous thermal conductivity is higher for Pd43Ni10Cu27P2o alloy fiber which has a higher glass forming ability, while the ratio of electronic thermal conductivity almost remains constant for both alloy fibers. The results also show that the slope of electrical resistivity to temperature is a function of elemental composition for crystallized quaternary palla- dium-based alloy fibers. The sensitivity of thermal conductivity and electrical conductivity to the composition is high, while the correlation between Seebeck coefficient and composition is relatively weak.

关键词： palladium-based alloy T-type method ther-mal conductivity electrical conductivity Seebeck coeffi-cient