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Revealing the role of site occupation in phase stability,magnetic and electronic properties of Ni-Mn-In alloys by ab initio approach

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Journal of Materials Science & Technology 2021年第24期83卷 90-101页

作者： Xinzeng Liang Jing Bai Ziqi Guan Jianglong Gu Haile Yan Yudong Zhang Claude Esling Xiang Zhao Liang Zuo Key Laboratory for Anisotropy and Texture of Materials Northeastern UniversityShenyang110819China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao066004China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004China Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province Qinhuangdao066004China Laboratoire d'Étude des Microstructures et de Mécanique des Matériaux LEM3 CNRSUMR 7239University of Lorraine57045MetzFrance

The effects of site occupation on the phase stability,martensitic transformation,and the magnetic and electronic properties of a full series of Ni-Mn-In alloys are theoretically studied by using the ab initio *** indicate that the excess atoms of the rich component directly take the sublattices of the deficient components of the Ni2Mn_(1+x)In_(1-x),Ni2-xMn_(1+x)In,and Ni_(2+x)Mn_(1-x)In ***,the mixed and indirect site occupations may coexist in the Ni_(2+x)Mn In_(1-x)*** relevant magnetic configurations of the austenite for the four alloy systems have also been *** results show that,except for the austenite in the Ni2-xMn_(1+x)In alloys,which tend to be ferrimagnetic,the other alloys all present ferromagnetic ***,the site occupation and associated magnetic states are the crucial influencing factors of the phase stability,martensitic transformation,and the total magnetic *** electronic structure of the austenite phase also shows that the covalent bonding plays an important role in the phase *** key finding of this work is both Ni2Mn_(1+x)In_(1-x)and Ni_(2+x)Mn In_(1-x)alloys serve as the potential shape memory alloys.

关键词： Ni-Mn-In ab initio calculations Site occupation Phase stability Magnetic property

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Coexistence of plastic and partially diffusive phases in a helium-methane compound

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National Science Review 2020年第10期7卷 1540-1547页

作者： Hao Gao Cong Liu Andreas Hermann Richard J.Needs Chris J.Pickard Hui-Tian Wang Dingyu Xing Jian Sun National Laboratory of Solid State Microstructures School of Physics and Collaborative Innovation Center of Advanced MicrostructuresNanjing University Centre for Science at Extreme Conditions and The School of Physics and Astronomy The University of Edinburgh Theory of Condensed Matter Group Cavendish Laboratory Department of Materials Science & Metallurgy University of Cambridge Advanced Institute for Materials Research Tohoku University

Helium and methane are major components of giant icy planets and are abundant in the universe. However,helium is the most inert element in the periodic table and methane is one of the most hydrophobic molecules, thus whether they can react with each other is of fundamental importance. Here, our crystal structure searches and first-principles calculations predict that a He;CH;compound is stable over a wide range of pressures from 55 to 155 GPa and a HeCH;compound becomes stable around 105 GPa. As nice examples of pure van der Waals crystals, the insertion of helium atoms changes the original packing of pure methane molecules and also largely hinders the polymerization of methane at higher pressures. After analyzing the diffusive properties during the melting of He;CH;at high pressure and high temperature, in addition to a plastic methane phase, we have discovered an unusual phase which exhibits coexistence of diffusive helium and plastic methane. In addition, the range of the diffusive behavior within the helium-methane phase diagram is found to be much narrower compared to that of previously predicted helium-water compounds. This may be due to the weaker van der Waals interactions between methane molecules compared to those in helium-water compounds, and that the helium-methane compound melts more easily.

关键词： crystal structure prediction ab initio molecular dynamics ab initio calculations high pressure and high temperature melting and phase transition collective motion

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Photoelectron Imaging Spectroscopy of ZrO-Diatomic Anion

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Chinese Journal of Chemical Physics 2015年第4期28卷 -页

作者： Qing-yu Liu Lian-rui Hu Hui Chen Sheng-gui He Beijing National Laboratory for Molecular Sciences State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing 100190China Beijing National Laboratory for Molecular Sciences Key Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China

The diatomic ZrO− anion has been prepared by laser ablation and studied by photoelectron imaging spectroscopy combined with quantum chemistry calculations. The observed photoelectron spectra can be well assigned on the basis of reported optical spectroscopy and high-level ab initio calculations. The ground state of ZrO− is a 2Δ state with spin-orbit splitting of 578±12 cm−1. The electron affinity of ZrO is 1.249±0.005 eV. For the first time, the c3∑− state of ZrO has been experimentally observed at 13316±24 cm−1 with respect to the X1∑+ ground state. A comparison between ZrO and the isoelectronic molecule NbN has been made.

关键词： Diatomic molecules Electronic structure Spin-orbit splitting Photoelectron imaging spectroscopy ab initio calculations

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Lattice dynamical and thermodynamical properties of ReB_2,RuB_2,and OsB_2 compounds in the ReB_2 structure

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Chinese Physics B 2012年第10期21卷 355-361页

作者： E.Deligoz K.Colakoglu Y.O.Ciftci Department of Physics Aksaray University68100AksarayTurkey Department of Physics Gazi UniversityTeknikokullar06500AnkaraTurkey

Structural and lattice dynamical properties of ReB2,RuB2,and OsB2 in the ReB2 structure are studied in the framework of density functional theory within the generalized gradient *** present results show that these compounds are dynamically stable for the considered *** temperature-dependent behaviors of thermodynamical properties such as internal energy,free energy,entropy,and heat capacity are also *** obtained results are in good agreement with the available experimental and theoretical data.

关键词： ab initio calculations lattice dynamical properties thermodynamical properties diborides

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Investigation of hydrogen bonding in neat dimethyl sulfoxide and binary mixture(dimethyl sulfoxide + water) by concentration-dependent Raman study and ab initio calculation

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Chinese Physics B 2010年第12期19卷 154-160页

作者：欧阳顺利吴楠楠刘靖尧孙成林里佐威高淑琴 College of Physics Jilin University Institute of Theoretical Chemistry State Key Laboratory of Theoretical and Computational ChemistryJilin University

In this study, our vibrational spectroscopic analysis is made on hydrogen-bonding between dimethyl sulfoxide and water comprises both experimental Raman spectra and ab initio calculations on structures of various dimethyl sulfoxide/water clusters with increasing water content. The Raman peak position of the v（S=O） stretching mode of dimethyl sulfoxide serves as a probe for monitoring the degree of hydrogen-bonding between dimethyl sulfoxide and water. In addition, the two vibrational modes, namely, the CH3 symmetric stretching mode and the CH3 asymmetric stretching mode have been analysed under different concentrations. We relate the computational results to the experimental vibrational wavenumber trends that are observed in our concentration-dependent Raman study. The combination of experimental Raman data with ab initio calculation leads to a better knowledge of the nature of the hydrogen bonding and the structures of the hydrogen-bonded complexes studied.

关键词： hydrogen-bonding Raman spectroscopy ab initio calculations dimethl sulphoxide

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Structural Stability, Electronic Structure and Mechanical Properties of Li–N–H System

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Acta Metallurgica Sinica(English Letters) 2015年第5期28卷 550-558页

作者： Ratnavelu Rajeswarapalanichamy Manoharan Santhosh Ganesapandian Sudhapriyanga Shanmugam Kanagaprabha Kombaih Iyakutti Department of Physics N.M.S.S.V.N College Department of Physics Kamaraj College Department of Physics and Nanotechnology SRM University

ab initio calculations are performed to investigate the ground state properties, structural phase transition, electronic structure and mechanical properties of lithium nitride （Li3N）, lithium imide （Li2NH） and lithium amide （LiNH2）. The computed ground state properties like equilibrium lattice constant, cell volume, valence electron density, cohesive energy, bulk modulus and its derivatives are in good agreement with available experimental data. The structural phase transitions from α-P6/mmm to β-P63/mmc phase at a pressure of 17.5 GPa in LiaN and cubic （Fm3m） to hexagonal （P63/ mmc） phase at a pressure of 102 GPa in lithium imide （Li2NH） are observed. A new high pressure hexagonal （P63/mmc） phase is predicted for LiENH. Electronic structure reveals that Li3N and LiNH2 are semiconductors, whereas Li2NH is an insulator. The calculated elastic constants indicate that these materials are mechanically stable at ambient condition.

关键词： ab initio calculations Crystal structure Phase transition Electronic structure Mechanicalproperties

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First-principle investigation on the thermodynamics of X_2N_2O(X = C, Si, Ge) compounds

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Chinese Physics B 2016年第2期25卷 360-366页

作者：熊青云沈启霞李蕊子申江田付阳 Institute for Applied Physics University of Science and Technology Beijing Department of Mathematics and Physics Zhengzhou University of Science and Technology

The structures under different pressures, elastic properties, electronic structures and lattice vibrations of the X_2N_2O（X = C, Si, Ge） compounds are investigated by using the first-principle method. Based on the phonon density of state,the thermodynamic properties of the present compounds are studied under different pressures and at different temperatures. The structural parameters including the bond lengths and bond angles are in agreement with available experimental measurements and theoretical calculations. We employ the elastic theory to calculate the nine independent elastic constants（C_（ij）） and the derived elastic moduli（B, G, E, v）. Results indicate that these X_2N_2O（X = C, Si, Ge） compounds are mechanically stable and show the brittle behaviors. The electronic properties of the present compounds are analyzed by using the band structure and density of states. The phonon dispersion calculations imply that the present compounds are dynamically stable. Based on the quasi-harmonic approximation, the calculations of the specific heat indicate that the temperature in a range of 0 K–1500 K and pressure in a range of 0 GPa–40 GPa have a large effect on the thermal quantities of Ge_2N_2O,compared with on those of the C_2N_2O and Si_2N_2O compounds.

关键词： ceramics ab initio calculations crystal structure elastic properties thermodynamic properties

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Bonding Character and Formation Energy of Point Defects of He and Vacancy on (001) Surface of bcc Iron by First Principle calculations

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Acta Metallurgica Sinica(English Letters) 2013年第1期26卷 25-32页

作者： Jun CAI Daogang LU School of Nuclear Science and Engineering North China Electric Power University

The structure and energy of He impurities and vacancy on （001） surface of bcc iron are investigated by an ab initio method. Three cases for stabilities of a He atom at the surface are found： some of He atoms at surface atomic layers （SAL） relax into vacuum gap; some of surface He atoms at octahedral interstitial site relax into more stable tetrahedral interstitial site; some of surface He atoms still stay at tetrahedral interstitial site. The un-stability of the He atom at the surface system can be explained by deformation mechanism of charge densities and electronic densities of states. It is found that formation energy of the point defects from the topmost SAL to bulk-like atomic layer increase gradually, for example, the formation energies of a monovacancy at the first five topmost SALs are equal to 0.33, 1.56, 2.04, 2.02 and 2.11 eV, respectively. The magnetic moments of Fe atoms in the surface atomic layers are also calculated.

关键词： ab initio calculations Single point defects bcc Fe (001) surface Electronicstructure

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γ-and α-Ce phase diagram: First-principle calculation

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Chinese Physics B 2016年第3期25卷 129-133页

作者：张林李英华李雪梅张祖根叶想平蔡灵仓 National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsCAEP

Controversies about the phase diagram for the isostructural y ＋＋ a phase transition of cerium have long been standing out for several decades. To seek insight into the problems, high-precision equations of state （EOS） for y- and a-cerium are constructed based on first-principle calculation. Versus previous works, the strong anharmonic effects of ion vibration and the variation of magnetism of y-cerium are stressed. The new EOS generally agrees well with experimental data regarding thermodynamics, phase diagrams, and phase transitions. However, new EOS predicts that another part of phase boundary in pressure-temperature space may exist except for the commonly known boundary. In addition, the well-known critical point seems to be a critical point for y-cerium to translate from a stable state to an unstable state.

关键词： ab initio calculations phase transition equation of states

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First-principles study of the electronic structure of a superstoichiometric rare earth dihydride GdH2.25

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Journal of Rare Earths 2016年第1期34卷 66-70页

作者： z.ayat a.boukraa b.daoudi Univ Ouargla Fac. Des Mathematiques et des Sciences de la Matidre Lab. Developpement des energies nouvelles et renouvelables dans les zones arides et sahariennes Ouargla 30000 Algeria

We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linearized augmented plane wave method （FP-LAPW） approach within the density functional theory （DFT） in the generalized gradient approximation （GGA） and local density approximation （LDA） as implemented in the WIEN2k simulation code at 0 K. The equilibrium properties were determined, the density of states, electronic density and the energy band structures were studied in details. It was concluded that the GGA optimized lattice parameter agreed much better with the experimental findings than the LDA one, The non negligible electronic density of states at the Fermi level confirmed that the GdH2.25 had a metallic character. The Fermi energy EF fell at a level where most of the states were rare-earth 5d-eg conduction states while negligible contributions of both interstitial （tetrahedral and octahedral） H s-states were observed near EF, From electronic density, the bonding between Gd and tetrahedral H atoms was of prominent covalency, while was ionic between Gd and octahedral H atoms.

关键词： rare-earth dihydrides GdU2.25 density functional theory ab initio calculations WIEN2k

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