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Universal insertion of molecules in ionic compounds under pressure

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National Science Review 2024年第1期11卷 120-128页

作者： Feng Peng Yanming Ma Chris J.Pickard Hanyu Liu Maosheng Miao College of Physics and Electronic Information Luoyang Normal University Department of Chemistry and Biochemistry California State University Northridge State Key Laboratory of Superhard Materials & Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University International Center of Future Science Jilin University Department of Materials Science & Metallurgy University of Cambridge Advanced Institute for Materials Research Tohoku University Department of Earth Science University of California Santa Barbara

Using first-principles calculations and crystal structure search methods, we found that many covalently bonded molecules such as H2, N2, CO2, NH3, H2O and CH4may react with NaC l, a prototype ionic solid,and form stable compounds under pressure while retaining their molecular structure. These molecules,despite whether they are homonuclear or heteronuclear, polar or non-polar, small or large, do not show strong chemical interactions with surrounding Na and Cl ions. In contrast, the most stable molecule among all examples, N2, is found to transform into cyclo-N5-anions while reacting with NaC l under high pressures. It provides a new route to synthesize pentazolates, which are promising green energy materials with high energy density. Our work demonstrates a unique and universal hybridization propensity of covalently bonded molecules and solid compounds under pressure. This surprising miscibility suggests possible mixing regions between the molecular and rock layers in the interiors of large planets.

关键词： molecule-solid hybrid materials high-pressure crystal structure prediction density functional theory planet interior

Application of high-pressure technology in exploring mechanical properties of high-entropy alloys

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Tungsten 2023年第1期5卷 50-66页

作者： Shu-Cong Li Qing-Lin Wang Yu Yao Dan-Dan Sang Hai-Wa Zhang Guo-Zhao Zhang Cong Wang Cai-Long Liu Shandong Key Laboratory of Optical Communication Science and Technology School of Physics Science&Information TechnologyLiaocheng UniversityLiaocheng 252059China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China

In recent years,high-entropy alloys(HEAs) have developed a lot as the new style of materials,which have become a research focus in the materials fields.It breaks the normal procedure of traditional alloy design(based on one/two elements as the main component,and adds some other elements to improve the micro structure and required related performance of the alloy),and consists of five or more equal or nearly equal elements,with multiple principal elements.Therefore,HEAs have many excellent mechanical properties compared with traditional alloys,which have aroused great research interest of researchers.The rapid development of high-pressure technology makes it a powerful tool to modulate the structures of HEAs,and brings new chance for the study and optimization of mechanical properties of HEAs.In this paper,the application of high-pressure technology in exploring and improving the mechanical properties of HEAs is reviewed,which could deepen the understanding of high-pressure technology and provide a new avenue for further exploration of HEAs’ mechanical properties.

关键词： high-entropy alloys Mechanical properties high-pressure torsion high-pressure Diamond anvil cells

Anomalous bond lengthening in compressed magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)

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Journal of Semiconductors 2024年第4期45卷 36-41页

作者： Fei Sun Yi Peng Guoqiang Zhao Xiancheng Wang Zheng Deng Changqing Jin Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physics University of Chinese Academy of SciencesBeijing 101408China Center for high pressure Science and Technology Advanced Research Beijing 100094Chin

Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolutions under external pres-sures are required to analyze the mechanisms.Herein high-pressure structure of a magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)is studied with combination of in-situ synchrotron X-ray diffractions and diamond anvil cells.The materials become ferromagnetic with Curie temperature of 105 K after further 20%K doping.The title material undergoes an isostruc-tural phase transition at around 19 GPa.Below the transition pressure,it is remarkable to find lengthening of Zn/Mn-As bond within Zn/MnAs layers,since chemical bonds are generally shortened with applying pressures.Accompanied with the bond stretch,interlayer As-As distances become shorter and the As-As dimers form after the phase transition.With further compres-sion,Zn/Mn-As bond becomes shortened due to the recovery of isotropic compression on the Zn/MnAs layers.

关键词： magnetic semiconductor high-pressure in-situ X-ray diffraction phase transition

high-pressure new phases of V–N compounds

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Chinese Physics B 2023年第5期32卷 560-565页

作者：时旭含李志慧刘媛媛王元元刘冉胡阔姚震 Synergetic Extreme Condition high-pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China Aviation University of Air Force Changchun 130022China

The high-pressure diagram of V–N compounds is enriched by proposed seven new stable high-pressure phases.The P-1-VN_4with the armchair N-rich structure may be quenched to ambient conditions.The formed N–N covalent bond plays an important role for the structural stability of N-chain.The charge transfer results in a V–N ionic bond interaction,which further improves the stability of N-chain structure.The P-1-VN_4,P4mnc-VN_8,and Immm-VN_(10)with the outstanding detonation properties have potential application in explosive field.

关键词： high-pressure N-rich V–N compounds phase diagram stability DFT calculation

Numerical simulation and experimental verification of a novel double-layered split die for high-pressure apparatus used for synthesizing superhard materials

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International Journal of Minerals,Metallurgy and Materials 2019年第3期26卷 377-385页

作者： Zhuo Yi Wen-zhi Fu Ming-zhe Li Rui Li Liang Zhao Li-yan Wang Roll Forging Institute Jilin University College of Materials Science and Engineering Jilin University Changchun Ruiguang Science & Technology Co. Ltd.

Based on the principles of massive support and lateral support, a novel double-layered split die(DLSD) for high-pressure apparatus was designed to achieve a higher pressure-bearing capacity and larger sample cavity. The stress distributions of the DLSDs with different numbers of divided blocks were investigated by the finite element method and compared with the stress distributions of the conventional belt-type die(BTD). The results show that the cylinders and first-layer supporting rings of the DLSDs have dramatically smaller stresses than those of the BTD. In addition, increasing the number of divided blocks from 4 to 10 gradually increases the stress of the cylinder but has minimal influence on the stress of the supporting rings. The pressure-bearing capacities of the DLSDs with different numbers of divided blocks, especially with fewer blocks, are all remarkably higher than the pressure-bearing capacity of the BTD. The contrast experiments were also carried out to verify the simulated results. It is concluded that the pressure-bearing capacities of the DLSDs with 4 and 8 divided blocks are 1.58 and 1.45 times greater than that of the BTD. This work is rewarding for the commercial synthesis of high-quality, large-sized superhard materials using a double-layered split high-pressure die.

关键词： split die prismatic cylinder pressure-bearing capacity high-pressure apparatus superhard material FEM

Understanding formation of Mg-depletion zones in Al-Mg alloys under high pressure torsion

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Journal of Materials Science & Technology 2019年第5期35卷 858-864页

作者： Jing Xue Shenbao Jin Xianghai An Xiaozhou Liao Jiehua Li Gang Sha Herbert Gleiter Institute of Nanoscience School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China School of Aerospace Mechanical and Mechatronic Engineering The University of Sydney Sydney NSW 2006 Australia Institute of Casting Research Montanuniversitat Leoben A-8700 Leoben Austria

Redistribution of elements may take place in alloys during severe plastic deformation, which significantly alters the mechanical properties of the alloys. Therefore, comprehensive knowledge about deformationinduced redistribution of elements has to be established. In the present paper, the distribution of Mg in an Al-Mg alloy processed by high pressure torsion was examined using atom probe tomography(APT).With crystallographic information extracted by APT data analysis, this research reveals that the movement of dislocations plays an important role in the formation of Mg-depletion zones in the deformed microstructure.

关键词： high-pressure torsion Atom probe tomography Aluminum alloys Grain boundary diffusion Dislocation

Numerical analysis of LaBi at high temperature and pressure

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Journal of Rare Earths 2011年第3期29卷 271-276页

作者： Purvee Bhardwaj Sadhna Singh high pressure Physics Lab Department of Physics Barkatullah University

In this paper we focused on the structural,elastic and thermodynamic properties of the B1 phase of LaBi by using the modified TBP model,including the role of temperature.We successfully obtained the phase transition pressure and volume change at different temperatures.In addition,elastic constants and bulk modulus of B1 phase of LaBi at different temperatures were discussed.Our results were comparable with the previous ones at high temperatures and pressures.The thermodynamical properties of the B1 phase of LaBi were also predicted.

关键词： rare earth pnictides high-pressure crystal structure mechanical properties phase transition

Detailed structural,mechanical,and electronic study of five structures for CaF2 under high pressure

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Chinese Physics B 2021年第3期30卷 194-204页

作者：郭颖方钰萌李俊 Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Jiangsu Key Laboratory of Big Data Analysis TechnologyNanjing University of Information Science and TechnologyNanjing 210044China Mingde New Material Technology Co. LTDAnji 313300China

Detailed density functional theory(DFT)calculations of the structural,mechanical,thermodynamic,and electronicproperties of crystalline CaF2 with five different structures in the pressure range of 0 GPa–150 GPa are performed byboth GGA(generalized gradient approximation)-PBE(Perdew–Burke–Ernzerhof)and LDA(local density approximation)-CAPZ(Cambridge Serial Total Energy Package).It is found that the enthalpy differences imply that the fluorite phase→PbCl2-type phase→Ni2In-type phase transition in CaF2 occurs at PGGA1=8.0 GPa,PGGA2=111.4 GPa by usingthe XC of GGA,and PLDA1=4.5 GPa,PLDA2=101.7 GPa by LDA,respectively,which is consistent with previousexperiments and theoretical conclusions.Moreover,the enthalpy differences between PbCl2-type and Ni2In-type phases inone molecular formula become very small at the pressure of about 100 GPa,indicating the possibility of coexistence of twophase at high pressures.This may be the reason why the transition pressure of the second phase transition in other reportsis so huge(68 GPa–278 GPa).The volume changed in the second phase transition are also consistent with the enthalpydifference result.Besides,the pressure dependence of mechanical and thermodynamic properties of CaF2 is studied.Itis found that the high-pressure phase of Ni2In-type structure has better stiffness in CaF2 crystal,and the hardness of thematerial has hardly changed in the second phase transition.Finally,the electronic structure of CaF2 is also analyzed withthe change of pressure.By analyzing the band gap and density of states,the large band gap indicates the CaF2 crystal isalways an insulator at 0 GPa–150 GPa.

关键词： density functional theory(DFT) high-pressure phase transition coexistence

Effect of high-pressure homogenization on stability of emulsions containing zein and pectin

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Asian Journal of Pharmaceutical Sciences 2017年第1期12卷 21-27页

作者： Maneerat Juttulapa Suchada Piriyaprasarth Hirofumi Takeuchi Pornsak Sriamornsak Department of Pharmaceutical Technology Faculty of PharmacySilpakorn UniversityNakhon Pathom 73000Thailand Pharmaceutical Biopolymer Group(PBiG) Faculty of PharmacySilpakorn UniversityNakhon Pathom 73000Thailand Laboratory of Pharmaceutical Engineering Gifu Pharmaceutical University1-25-4 Daigaku-NishiGifu 501-1196Japan

The aim of this study was to investigate the effect of high-pressure homogenization on the droplet size and physical stability of different formulations of pectin–zein stabilized rice bran oil emulsions. The obtained emulsions, both before and after passing through highpressure homogenizer, were subjected to stability test under environmental stress conditions,that is, temperature cycling at 4 °C/40 °C for 6 cycles and centrifugal test at 3000 rpm for 10 min. Applying high-pressure homogenization after mechanical homogenization caused only a small additional decrease in emulsion droplet size. The droplet size of emulsions was influenced by the type of pectin used;emulsions using high methoxy pectin(HMP) were smaller than that using low methoxy pectin(LMP). This is due to a greater emulsifying property of HMP than LMP. The emulsions stabilized by HMP–zein showed good physical stability with lower percent creaming index than those using LMP, both before and after passing through high-pressure homogenizer. The stability of emulsions after passing through high-pressure homogenizer was slightly higher when using higher zein concentration, resulting from stronger pectin–zein complexes that could rearrange and adsorb onto the emulsion droplets.

关键词： Pectin Zein Emulsions high-pressure homogenization Stability