检索结果-南通市图书馆

National Science Open 2024年第2期3卷 7-20页

作者： Fu-Qiang Gong Ke Xiong Jun Cheng State Key Laboratory of Physical Chemistry of Solid Surface iChEMCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Laboratory of AI for Electrochemistry(AI4EC) Tan Kah Kee Innovation Laboratory(IKKEM)Xiamen 361005China Institute of Artificial Intelligence Xiamen UniversityXiamen 361005China

Nanoparticles,distinguished by their unique chemical and physical properties,have emerged as focal points within the realm of materials *** theoretical approaches for atomic simulations mainly include empirical force field and ab initio simulations,with the former offering efficiency but limited reliability,and the latter providing accuracy but restricted to systems of relatively small ***,we propose a systematic strategy and automated workflow designed for collecting a diverse types of atomic local environments within a training *** includes small nanoclusters,nanoparticles,as well as surface and bulk systems with periodic boundary *** objective is to construct a machine learning potential tailored for pure metal nanoparticle simulations of varying *** rigorous validation,we have shown that our trained machine learning potential is capable of effectively driving molecular dynamics simulations of nanoparticles across a wide temperature range,especially within the nanoscale ***,this is achieved while preserving the accuracy typically associated with ab initio methods.

关键词： condensed matter physics nanoparticles machine learning potential workflow

Roles of Te and Mn in the two phases of manganite with nominal composition La_(0.6)Sr_(0.1)Te_xMnO_3

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2011年第3期30卷 232-240页

作者： LI Yanfeng JI Denghui ZHAO Zhiwei TANG Guide LIU Shaopeng ZHANG Yuge LI Zhuangzhi HOU Denglu ZHU Minggang Department of physics Hebei Normal University Hebei Advanced Thin Films Laboratory Shijiazhuang 050016 China Division of Functional Materials Research Central Iron ＆ Steel Research Institute Beijing 100081 China

Powder samples with nominal composition La0.6Sr0.1TexMnO3 （x = 0.00, 0.05, 0.10, 0.15, 0.20） were prepared using the sol-gel method with thermal treatment up to 1473 K. On the basis of powder X-ray diffraction （XRD）, thermogravimetric and magnetic measurements, it was found that almost all of the Te and a few of the Mn ions were lost from the samples when they were calcined at 1473 K. The reason for the Te loss and a quantitative phase analysis for the samples calcined at 1473 K are discussed in detail.

关键词： condensed matter physics crystal defects X-ray diffraction perovskite manganite magnetic properties

Modeling and Numerical Investigation of the Inlet Circumferential Fluctuationsof Swept and Bowed Blades

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2017年第1期26卷 1-10页

作者： TANG Mingzhi JIN Donghai GUI Xingmin Aeroengine Numerical Simulation Research Center Beihang University Beijing China.

The circumferential fluctuation (CF) source terms induced by the inviscid blade force can affect the inlet distribution of flow parameters and radial equilibrium of swept and bowed blades. However, these phenomena cannot be adequately described by throughflow methods based on the axisymmetric assumption. A transport model for the CF stresses is proposed and correlated to the distribution of circulation to reflect the effect of the inviscid blade force. To investigate the effect of the inlet CFs on swept and bowed blades, the model is integrated into a throughflow model and applied to a series of cascades with different sweep and bow angles. For swept cascades, the CF source terms change the distributions of incidence angles, as well as the radial equilibrium at the inlet of the blade passage. And the influence is enhanced as the absolute value of the sweep angle increases. For bowed cascades, the distributions of incidence angles are also altered. For both cases, the model can offer a good prediction of the inlet CF source terms, and prove to exert a better prediction of blade design key parameters such as flow angles. © 2017, Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

关键词： condensed matter physics

Research on charge ordering and magnetic properties in La_(0.3)Ca_(0.7)Mn_(1-x)W_xO_3 system

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第4期26卷 317-322页

作者： PENG Zhensheng GUO Huanyin YAN Guoqing MAO Qiang physics Department Suzhou College Suzhou 234000 China Structure Research Laboratory University of Science and Technology of China Hefei 230026 China

The perovskite manganite sample La0.3Ca0.7Mn1-xWxO3 （x = 0.08, 0.12） was prepared by the solid-state reaction method. The effect of W doping on the Mn site to La0.3Ca0.7MnO3 charge ordering phase and the changing process of magnetic properties were studied through the measurement of the M-T curve, M-H curves, and ESR curves of the sample. The results showed that when x = 0.08, the charge ordering （CO） phase exists in the system, the transition temperature Tco= 275 K, and the system exhibits PM when T 〉 275 K. The system transforms from spin-disordering paramagnetism to spin-ordering antiferromagnetism in the charge ordering state with the temperature decreasing from 275 K to 230 K. The long-range antiferromagnetism forms and AFM/CO states coexist between 230 K and 5 K. There is a little ferromagnetic component in the AFM/CO background in a low temperature range. When x = 0.12, the CO phase in the system has almost melted completely. There is a little remnant of the CO phase below 150 K. The system exhibits paramagnetism when T 〉 150 K and transforms from paramagnetism to ferromagnetism when T〈 150 K.

关键词： condensed matter physics charge ordering melting solid-state reaction method magnetic properties

Giant Low-Field Magnetoresistance in Polycrystalline La_(2/3)Ca_(1/3)Mn_(1-x)Cu_x O_3 Sintered at 1100 ℃

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2004年第3期22卷 414-417页

作者：杨应平袁松柳刘洁张国庆夏正才 Department of physics Huazhong University of Science and Technology Wuhan 430074 China Department of physics Wuhan University of Technology Wuhan 430070 China

The La_(2/3)Ca_(1/3)Mn_(1- x )Cu_ x O_3 (0≤ x <6%) samples were prepared by sol-gel method. Transport properties, conductive mechanism and low-field magnetoresistance ( MR _0) were investigated. It is found that conductive mechanism is described by Mott′s variable-range hopping and the MR _0 near the insulator-metal transition temperature ( T _p) increases from 2% to 80% with x from 0 to 4% for a low field of 0.3 T. The experiment also shows that the intergrain magnetoresistance is largely improved. The results indicate that a proper amount of Cu doping can substantially improve magnetoresistance effects.

关键词： condensed matter physics magnetoresistance Sol-Gel Cu doping rare earths

Relationship and Discrepancies Among Typical Interatomic Potential Functions

在线全文

学校读者我要写书评

暂无评论

Chinese physics Letters 2004年第11期21卷 2167-2170页

作者： LIMTeik-Cheng FhcultyofEngineering NanoscienceandNanotechnologyInitiativeNationalUniversityofSingapore9EngineeringDrive1S117576RepublicofSingapore

We develop a simultaneous relationship among parameters of the generalized version of the Lennard-Jones, Morse, Rydberg and Buckingham pair potentials, and the two-body portion of the Kaxiras–Pandey potential function by introducing a set of scaling factors. These potential functions are selected according to their frequent adoption in condensed matter and molecular computation. In addition to verifying the parametric relations, theoretical plots of these potential curves show that each of these potential functions is unique in terms of their characteristic shape. However, gaps between these potential functions are narrowed for interatomic interactions possessing lower separation energy and longer interatomic equilibrium distance. Finally, comparison with the ab initio results shows that the extended-Rydberg potential energy curve gives the best agreement among the five empirical potential functions, for the specific case of hydrogen molecule.

关键词： condensed matter physics

Fabrication of ZnO-based thick film varistors with high potential gradient

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2010年第4期29卷 390-395页

作者： KE Lei JIANG Dongmei MA Xueming State Key Laboratory of Precision Spectroscopy Department of Physics East China Normal University Shanghai 200062 China

ZnO-based thick film varistors have been fabricated by Y203 doping and low-temperature sintering, of which the sample with the best electrical properties has a high potential gradient value of 3159.4 V/mm. The effects of Y2O3 doping concentration and sintering temperature on the potential gradient of the samples were systematically investigated. The results show that the sample with the best electrical properties can be obtained by doping 0.08 mol% Y2O3 and sintering at 725℃. Under these optimum preparation conditions, the leakage current and the nonlinear coefficient are found to be 36.4 gA and 13.1. The sample with the best electrical properties has a grain size of 1.290um, a single grain boundary voltage of 4.08 V, a barrier height of 0.81 eV, and a depletion layer width of 10.2 nm, which are determined by thermionic emission. Small grain size with good grain boundary characteristics is beneficial to improve the electrical properties of varistors and promote the potential gradient.

关键词： condensed matter physics thick film varistors low-temperature sintering doping potential gradient

Site Selective Excitation and Energy Transfer in LiKGdF_5 Crystal Co-doped with Er^(3+) and Tb (3+)

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2004年第1期22卷 22-26页

作者：尹民 Khaidukov N M Krupa J C Structure Research Laboratory Kurnakov Institute of General and Inorganic Chemistry Institut de Physique Nucléaire

Crystals of LiKGdF 5∶Er 3+, Tb 3+ grown by the hydrothermal synthesis technique with concentrations of 2% and 0.4% were analysed. By using site selective excitation measured at low temperature, luminescence and excitation spectra from Er 3+ and Tb 3+ ions embedded in LiKGdF 5 were clearly separated. The lifetimes of the emitting levels 4S 3/2 of Er 3+ and 5D 4 of Tb 3+ were also determined. Following the site selective spectroscopy study, the dominant energy transfer process from Tb 3+ to Er 3+ in the crystal was then investigated via transient experiments.

关键词： optics condensed matter physics energy transfer luminescence LiKGdF 5∶Er3+, Tb3+ rare earths

Phase Synchronization as a Mechanism of Controlling Spatiotemporal Chaos via External Periodic Signal

在线全文

学校读者我要写书评

暂无评论

Chinese physics Letters 2004年第2期21卷 254-257页

作者：桑海波贺凯芬 TheKeyLaboratoryofBeamTechnologyandMaterialsModificationofEducationMinistry BeijingNormalUniversityBeijing100875 InstituteofLowEnergyNuclearphysics BeijingNormalUniversityBeijing100875

We find that phase synchronization (PS) is a mechanism in which the spatiotemporal chaos (STC) can be suppressed to a spatially regular (SR) state by applying an external periodic signal in a one-dimensional driven drift-wave system. In the driving wave coordinate, the nonlinear system can be transformed to a set of coupled oscillators moving in a periodic potential. In this multi-dimensional system, the internal modes are slaved one by one through PS by the control signal. Two types of responses of the internal modes to the external periodic signal are observed. For some modes, the stabilization is through frequency-locking; while for the other modes, a special kind of PS without frequency-locking, namely multi-looping PS, is developed.

关键词： condensed matter physics

Thermal expansion anomaly and spontaneous magnetostriction of Tb_2Fe_(15)Cr_2 compound

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2006年第2期25卷 156-160页

作者： HAO Yanming ZHOU Yan ZHAO Miao Department of physics Tianjin Normal University Tianjin 300074 China

The structural and magnetic properties of Tb2Fe15CF2 compound were investigated by means of X-ray diffraction and magnetization measurements. Tb2Fe15Cr2 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Tb2Fe15Cr2 compound from 372 to 452 K by X-ray dilatometry. The coefficient of the average thermal expansion is α^- =-3.14×10^-5 K^-1. The magnetostrictive deformations from 292 to 450 K were calculated. The result showed that the spontaneous volume magnetostrictive deformation ms remains nearly constant with increasing temperature up to 360 K, but decreases with the further increase of temperature. The spontaneous linear magnetostrictive deformation λc along the c axis decreases with increasing temperature. The spontaneous linear magnetostrictive deformation, λa, in the basal-plane increases with increasing temperature up to 360 K, but decreases with further increasing temperature.

关键词： condensed matter physics spontaneous magnetostriction X-ray diffraction Tb2Fe15Cr2 compound negative thermal expansion