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A novel non-stoichiometric medium-entropy carbide stabilized by anion vacancies

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Journal of Materials science & technology 2020年第16期47卷 161-166页

作者： Chong Peng Hu Tang Yu He Xiaoqian Lu Peng jia Guoying Liu Yucheng Zhao Mingzhi Wang State Key Laboratory of Metastable Materials science and technology Yanshan UniversityQinhuangdao 066004China center for high pressure science and technology advanced research Beijing 100190China

Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and ***,as a newly emerging class of materials,the synthesis,performance and applications of high-entropy ceramics are subject to further ***,we reported a new non-stoichiometric TiC0.4/WC/0.5Mo2C medium-entropy carbide(MEC)with a rock-salt *** to the solid solution strengthening and twinning strengthening,the TiCO0.4/WC/0.5Mo2C sintered at 1900℃by spark plasma sintering(SPS)shows superior mechanical behaviors of microhardness(21.7 GPa),which exceeds that expected from the rule of mixture(ROM)of three individual metal carbides(19.1 GPa)and good fracture toughness(5.3 MPa m1/2).Significantly,the bulk synthesized via high-pressure and high-temperature(HPHT)sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness(23.7 GPa)and fracture toughness(6.2 MPa m1/2).In addition,the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC0.4/WC/0.5Mo2C was analyzed via quantitatively calculated *** could significantly enhance the configuratio nal entropy of mixing of the solid *** introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics,especially for multi-component high tempe rature refractory ceramics.

关键词： Anion vacancies Medium-entropy carbide Solid solution strengthening Twinning

Ultrafast dynamics in photo-excited Mott insulator Sr_(3)Ir_(2)O_7 at high pressure

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Chinese Physics B 2024年第1期33卷 149-155页

作者：尹霞张建波王东 Takeshi Nakagawa 夏春生张曹顺郭伟程昌峻丁阳 center for high-pressure science and technology advanced research Beijing 100094China College of Physics and Information technology Shaanxi Normal UniversityXi'an 710119China

high-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for studying delicate phase transitions caused by complex interactions in Mott *** time-resolved transient reflectivity measurements,we identified the new phases in the spin–orbit Mott insulator Sr_(3)Ir_(2)O_7 at 300 K that was previously unidentified using conventional approaches such as x-ray *** pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity?R/R reveal the changes of electronic structure caused by lattice distortions,and reflect the critical phenomena of phase *** findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators.

关键词： ultrafast dynamics high pressure phase transition Mott insulator

Sex differences in aging and injured brain

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Neural Regeneration research 2025年第10期20卷 2901-2902页

作者： Jordan N.Williamson Yuan Yang University of Illinois Urbana-Champaign Grainger College of EngineeringDepartment of BioengineeringUrbanaILUSA Carle Foundation Hospital Stephenson Family Clinical Research InstituteClinical Imaging Research CenterUrbanaILUSA University of Illinois Urbana-Champaign Beckman Institute for Advanced Science and TechnologyUrbanaILUSA Northwestern University Department of Physical Therapy and Human Movement SciencesChicagoILUSA

Background:The prevalence,age of onset,and symptomatology of traumatic brain injury,stroke,and neurodegenerative diseases(such as Alzheimer’s disease(AD),Parkinson’s disease,amyotrophic lateral sclerosis,and Huntington’s disease)differ substantially between males and *** higher prevalence of these brain disorders has been attributed to females having a greater longevity compared with *** one of the greatest risk factors of acquired brain injury(such as stroke,traumatic brain injury caused by fall)and neurodegenerative disease is age.

关键词： Huntington prevalence traumatic

Mineralogy of the deep lower mantle in the presence of H2O

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National science Review 2021年第4期8卷 21-28页

作者： Qingyang Hu Jin Liu Jiuhua Chen Bingmin Yan Yue Meng Vitali B.Prakapenka Wendy L.Mao Ho-Kwang Mao center for high pressure science and technology advanced research(HPSTAR) Department of Geological sciences Stanford University center for Study of Matter under Extreme Conditions Department of Mechanical and Materials Engineering Florida International University high pressure Collaborative Access Team(HPCAT) X-ray Science Division Argonne National Laboratory center for advanced Radiation Sources University of Chicago

Understanding the mineralogy of the Earth's interior is a prerequisite for unravelling the evolution and dynamics of our planet. Here, we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle（DLM, 1800–2890 km in depth） and observed surprising mineralogical transformations in the presence of water. Ferropericlase,（Mg,Fe）O, which is the most abundant oxide mineral in Earth, reacts with H;2;O to form a previously unknown（Mg,Fe）O;2;H;x;（x ≤ 1）phase. The（Mg,Fe）O;2;H;x;has a pyrite structure and it coexists with the dominant silicate phases,bridgmanite and post-perovskite. Depending on Mg content and geotherm temperatures, the transformation may occur at 1800 km for(Mg;0.6;Fe;0.4;)O or beyond 2300 km for(Mg;0.7;Fe;0.3;)O. The（Mg,Fe）O;2;H;x;is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences(Mg;2+;, Fe;3+;and H;+;). This important phase has a number of far-reaching implications including extreme redox inhomogeneity, deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere.

关键词： lower mantle water-mantle interaction ferropericlase high pressure mantle mineralogy

Dehydro-Diels-Alder reaction and diamondization of bowl-shaped clusters C_(18)Te_(3)Br_(4)(Bu-O)_(6)

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Nano research 2022年第5期15卷 4606-4612页

作者： Jinbo Zhang Manli Ma Rong Zhou Hongqiang Chu Xue Wang Shaojie Wang Huhu Tian Zhipeng Yan Mingtao Li Zhongyan Wu Bin Li Jiafeng Yan Lan Anh Thi Nguyen Rongxing Cao Guoqing Wu Xianghua Zeng Hao-Li Zhang Jaeyong Kim Lin Wang Yongjun Tian College of Physical science and technology Yangzhou UniversityYangzhou 225002China center for high pressure science(CHiPS) State Key Laboratory of Metastable Materials Science and TechnologyYanshan UniversityQinhuangdao 066004China State Key Laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000China Baotou research Institute of Rare Earths Baotou 014000China Academy for advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China center for high pressure science and technology advanced research Shanghai 201203China Department of Physics and High Pressure Research CenterHanyang UniversitySeoul 04763Republic of Korea

Dehydro-Diels-Alder(DDA)reaction is a textbook reaction for preparing six-membered rings in solution but is scarcely seen in solid-state *** this work,using multiple characterization techniques,we demonstrate that the bowl-shaped clusters C_(18)Te_(3)Br_(4)(Bu-O)_(6) might experience a DDA reaction at room temperature and high pressure between 5.5 and 7.4 *** 17.0 GPa,it is found that the bonding conversion from the intramolecular sp^(2) to the intermolecular spa occurred,in the form of pressure-induced *** recovered samples from 20.0 and 36.1 GPa showed incomplete reversibility,while the decompression-induced graphitization of glassy carbon was observed during decompression from 46.5 *** electrochemical impedance spectroscopy results indicated that the transport properties changed from grain boundary dominant to grain dominant due to the DDA reaction and the grain boundary effect disappeared as the intermolecular sp3 bonding building-up and carrier transmission channel formation above 17.0 *** results in this study open a new route to construct the crystalline carbon materials with different transport properties.

关键词： polycyclic aromatic hydrocarbons dehydro-Diels-Alder reaction diamondization high-pressure

high-pressure structural properties of tetramethylsilane

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Chinese Physics B 2016年第2期25卷 327-332页

作者：秦振兴陈晓嘉 Department of Physics Taiyuan University of Science and Technology Taiyuan 030024 China Department of Physics South China University of Technology Guangzhou 510640 China center for high pressure science and technology advanced research Shanghai 201203 China

high-pressure structural properties of tetramethylsilane are investigated by synchrotron powder x-ray diffraction at pressures up to 31.1 GPa and room temperature. A phase with the space group of Pnma is found to appear at 4.2 GPa. Upon compression, the compound transforms to two following phases： the phase with space groups of P2_1/c at 9.9 GPa and the phase with P2/m at 18.2 GPa successively via a transitional phase. The unique structural character of P2_1/c supports the phase stability of tetramethylsilane without possible decomposition upon heavy compression. The appearance of the P2/m phase suggests the possible realization of metallization for this material at higher pressure.

关键词： hydrogen-rich compounds structural properties high pressure

Oxygen as a catalyst in the Earth's interior?

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National science Review 2021年第4期8卷 7-8页

作者： Yanhao Lin Wim van Westrenen center for high pressure science and technology advanced research Earth and Planets Laboratory Carnegie Institution for Science Department of Earth sciences Faculty of Science Vrije Universiteit Amsterdam

The abundance of the element oxygen is not only crucial for life at the surface of the Earth, but also greatly affects the properties and dynamics of the interior of our planet. The combination of a highly oxidized at...

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Deep Volatiles as the Key for Energy and Environments of the Four-Dimensional Earth System

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Engineering 2019年第3期5卷 393-394页

作者： Ho-Kwang Mao Craig M. Schiffries center for high pressure science and technology advanced research (HPSTAR) Shanghai 201203 China Geophysical Laboratory Carnegie Institution for Science Washington DC 20015 USA

Carbon, hydrogen, oxygen, nitrogen, sulfur, and their compounds are volatile components that dominate the thin and fragile atmosphere, hydrosphere, and biosphere on Earth’s habitable surface. However, the vast majority of these volatiles are hidden in the deep interior, where the high pressure–temperature conditions drastically and categorically alter the physics and chemistry of the volatiles. Like the bloodstream of an organism, the circulations and interactions of volatiles in the deep Earth modulate climate, resources, energy, natural hazards, and other factors that define the Earth as a unique living and changing planet.

关键词： Four-Dimensional Earth System Deep Volatiles

First-Principles Calculations about Elastic and Li^(+) Transport Properties of Lithium Superoxides under high pressure and high Temperature

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Chinese Physics Letters 2022年第2期39卷 47-52页

作者： Yufeng Li Shichuan Sun Yu He Heping Li Key Laboratory of high-Temperature and high-pressure Study of the Earth’s Interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of sciences Beijing 100049China center for high pressure science and technology advanced research Shanghai 201203China

Lithium superoxides,Li_(2)O_(3),LiO_(2),and LiO_(4),have been synthesized under high *** materials have potential applications in energy storage ***,we use first-principles calculations to investigate the elastic and Li^(+) transport properties of these oxides at high pressure and high *** elastic constants are calculated at 20-80 GPa,and they satisfy the Born stability criteria,indicating the good mechanical stability of these *** sound velocities calculated with elastic constants are close to each other,but difference in velocity anisotropy is ***_(2) presents significant shear sound wave anisotropy over 80%.The Li^(+) transport properties are investigated using first principles molecular dynamics(FPMD)and climbing-image nudged elastic band *** lowest Li^(+) migration barrier energies increase from 0.93,0.86 and 1.22 eV at 20 GPa to 1.43,1.12 and 1.77 eV at 50 GPa for Li_(2)O_(3),LiO_(2),and LiO_(4),*** most favorable path for LiO_(2) and LiO_(4) is along the[001]*** FPMD results suggest that these oxides become unstable with increasing temperature up to 2000 K due to O-O dimer clusters in these ***,a superionic transition is not observed in the simulations.

关键词： temperature anisotropy Lithium