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Search Results: 1 - 10 of 57948 matches for " 程正富 "
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尖品石CSi2N4化合物的电子结构和硬度分析

重庆大学学报 , 2007, DOI: 10.11835/j.issn.1000-582X.2007.10.027
Abstract: 采用密度泛函理论在广义梯度近似下的赝势平面波方法,对尖晶石CSi2N4体系进行晶格优化,得到能量最低的稳定结构,获得平衡态时的晶格常数,并计算了总能量、弹性常数、体变模量、能带结构和态密度,再根据计算结果对其稳定性和电子结构进行分析。最后,计算了尖晶石CSi2N4化合物的硬度,并与尖晶石结构的氮化碳(C3N4)进行了比较。
现代物理中的黑箱方法
石东平,
现代物理知识 , 1997,
Abstract: 在现代物理的研究方法中,黑箱方法占有非常重要的地位。所谓黑箱,就是内部结构、层次和性能未知的、有待于人们进行研究和控制的对象或系统。现代物理中,α粒子散射实验可以说是黑箱方法的典型代表。
LiNi0.8 Co0.15 A10.05 O2正极材料的表面包覆改性研究
汤梦云,,
- , 2017, DOI: 10.11951/j.issn.1005-0299.20160198
Abstract: LiNi0.8Co0.15A10.05O2正极材料具有容量高、价格低等优点,被认为是最具发展前景的锂离子电池正极材料之一.但LiNi0.8Co0.15A10.05O2材料本身存在充放电过程中容量衰减较快、倍率性能差和储存性能差等缺陷,影响了其进一步发展.本文以LiNi0.8Co0.15A10.05O2为研究对象,采用共沉淀法制备氢氧化物前驱体,在前驱体的表面包覆一层Ni1/3Co1/3 Mn1/3(OH)2,制备成具有核壳结构的正极材料.通过XRD、SEM、EDX、电化学测试等分析手段,系统地研究了其结构、形貌以及电化学性能.分析表明:包覆改性后,LiNi0.8Co0.15Al0.05O2正极材料在0.1、0.2、0.5、1 C倍率下,材料的首次充放电比容量分别为167.6,160.1,150.4,138.5 mAh·g-1.由0.1到1 C,包覆改性前后的正极材料的放电比容量衰减量由34.7 mAh·g-1降为29.1 mAh·g-1,容量衰减百分比由22.1%降低到17.4%.综合性能分析认为,包覆改性后电化学性能有一定的改善.
The LiNi0.8Co0.15A10.05O2 cathode material, which is considered to be one of the most promising lithium-ion battery cathode materials, has several advantages, such as high capacity, low cost and low toxicity. However, there are also some disadvantages of this material, such as the loss of capacity in charging and discharging process, poor rate performance and storage performance, which have seriously effect on the application. In this paper, the LiNi0.8Co0.15A10.05O2 was taken as the research object. The precursor was prepared through the co-precipitation method, which was coated with Ni1/3Co1/3Mn1/3(OH)2 and in the form of core-shell structure. The structure, morphology and electrochemical performance of LiNi0.8Co0.15A10.05O2 were studied systematically by the XRD, SEM, EDX and electrochemical testing. The results showed that the initial discharge capacities of 167.6, 160.1, 150.4, 138.5 mAh·g-1 at 0.1, 0.2, 0.5, 1 C for coated LiNi0.8Co0.15Al0.05O2, respectively. This leads to an irreversible capacity loss of 22.1% and 17.4% at 0.1 C to 1 C before and after coated. The electrochemical performance can be improved through the modification.
高压下金属Mo熔化性质与其熔化结构的理论研究
Theoretical study on melting properties and structures of Mo under high pressure

王浩,夏继宏,
- , 2016,
Abstract: 本文采用分子动力学结合镶嵌原子势方法研究了高温高压下金属Mo的熔化性质.详细分析了Mo的熔化曲线并给出了熔化曲线T-P(温度-压强)方程, 计算得到了Mo的等温压缩曲线和等压曲线. 理论上获得Mo在常压下的平衡点温度为2695K, 与其他实验和理论数据都符合的很好. 同时我们还通过径向分布函数和HA指数研究了Mo在熔化过程中的结构变化情况.
In this work, the melting properties of Mo under high temperature and high pressure are studied by using the molecular dynamics simulations with embedded atom potential. We analyze the melting curves of Mo in detail and give the temperature-pressure equation. The isothermal compression curve and isobaric curve are computed at the same time. We obtain that the equilibrium temperature at atmospheric pressure is 2695K, which is in good agreement with experimental data. We also studied the structure change of Mo in the melting process through the radial distribution function and the HA index
Co对单层MoS2电子结构与磁性的影响
Electronic and magnetic properties of monolayer MoS2 with cobalt doping

伏春平,孙凌涛,
- , 2017,
Abstract: 为了研究Co对单层MoS2电子结构和磁性的影响. 本文基于第一性原理, 采用数值基组的方法计算了Co吸附式掺杂、Co替代式掺杂单层MoS2的能带结构、态密度以及分析了其结构的稳定性.结果发现:Co替换式掺杂体系的形成能较低,实验上容易实现;Co在Mo位吸附的稳定性强于在S位吸附; Mo位吸附体系的总磁矩为0.999μB,其磁矩的主要来源于Co原子的吸附所贡献的0.984μB,Co原子的掺杂体系总磁矩为1.029μB,其磁矩的主要由Co原子替代掉一个Mo原子所贡献的磁矩为0.9444μB,相比于吸附体系,Co原子对磁矩的贡献率有所降低;论是Co 吸附在单层MoS2表面还是Co直接替代掉Mo原子的掺杂体系,Co原子3d轨道的引入是引起单层MoS2体系磁性的主要原因.
In order to study, the electronic structure and magnetic properties of monolayer MoS2 were affected by doping Co atoms, this paper based on the first principles, calculated the band structures and density of states of Co-doped monolayer MoS2 and analyzed the stability of the structure by adopting the numeric basis sets method. It was identified that the formation energy of Co substitution doping system is lower and easy to implement in the experiment. The adsorption of cobalt at Mo position is more stable than at S. The total magnetic moment of Co adsorption at Mo site system is 0.999μB, and mainly comes from 0.984μB which contribute by adsorption of Co atom. The total magnetic moment of Co doped monolayer MoS2 is 0.999μB. The magnetic moment of Mo atom, which is replaced by a Co atom, is 0.9444μB. Compared with the adsorption system, the contribution rate of Co atoms to the magnetic moment decreased. Whether Co adsorption on the surface of monolayer MoS2 or Co doped Mo atoms replace directly, the Co atom 3d orbitals is the main reason for the magnetic properties of monolayer MoS2 system.
Si掺杂Al2O3电子结构的第一性原理计算
First principles calculation of electronic structures of Si-doped Al2O3

伏春平,孙凌涛,
- , 2016,
Abstract: 本文采用第一性原理对纯Al2O3和Si掺杂的Si 0.167Al0.833O1.5, Si 0.25Al0.75O1.5晶体体系的能带结构、态密度进行了计算分析. 结果发现:随着Si在Al2O3晶体中所占比例的增加,体系能隙变小,在Si 0.25Al0.75O1.5晶体体系中能隙已降到2.5eV,表明该体系为半导体材料;而在掺杂的体系中有数条分散的能带穿过了费米能级,即可以预测该掺杂体系有特别的光电性质;同时对比纯Al2O3和Si掺杂的Si 0.167Al0.833O1.5, Si 0.25Al0.75O1.5晶体体系的总态密度,发现掺杂体系的价带和导带向低能区域移动.
The first-principles methods are used to study the band structures and the densities of states of the pure Al2O3 and the Si0.167Al0.833O1.5, Si0.25Al0.75O1.5 of Si-doped Al2O3. It is shown that the energy gap decreases as the proportion of Si increases in Al2O3 crystal and it is reduced to 2.5eV in the crystal system of Si 0.25Al0.75O1.5. These indicate that the Si-doped Al2O3 is semiconductor material. However, in the Si-doped system, there are several band energies across the Fermi level, predicting that the doped system has special photoelectric properties. Comparing the total density of states of the pure Al2O3 with those of Si 0.167Al0.833O1.5 and Si0.25Al0.75O1.5 crystal systems, it is found that the valence band and the conduction band of the Si-doped Al2O3 move to the low-energy region.
Mg、Ge、Te、Zn掺杂LiFePO4电子结构的第一性原理计算
First principles calculation on the electronic structure of Mg、Ge、Te、Zn doped LiFePO4

伏春平,孙凌涛,
- , 2016,
Abstract: 本文采用第一性原理研究了Mg、Ge、Te、Zn掺杂的LiFePO4的能带结构、总态密度以及分态密度. 研究结果显示:Mg、Ge、Te、Zn掺杂的LiFePO4的带隙低于本征体系,有利于电子的跃迁.本征LiFePO4的能带与掺Mg、Ge、Te、Zn体系带隙之差分别为0.04 eV,0.263eV,0.691eV,1.251eV, 说明掺杂Mg、Ge、Te、Zn能够有效的对其能带实现精确调控.在费米能级处,Mg、Ge、Te、Zn掺杂LiFePO4的态密度主要由Fe的d轨道贡献.
The first-principles methods are used to study the band structures and the densities of states of the Mg、Ge、Te、Zn doped LiFePO4. It is shown that the band gap of doping system lower than the pure LiFePO4, which is conducive to electron transition. The doping of Mg、Ge、Te、Zn to LiFePO4 band to achieve precise control because of the band gap difference between the pure LiFePO4 and the Mg、Ge、Te、Zndoped LiFePO4 is 0.04 eV,0.263eV,0.691eV,1.251eV; respectively. Meanwhile, the density of states is mainly composed of Fe d orbital contribution in all doping system at the Fermi level.
形变和非简谐振动对SiC有效电荷和热膨胀系数以及弹性模量的影响
Effects of Deformation and Non - harmonic Vibration on Effective Charge, Thermal Expansion and Elastic Modulus of SiC

查小婷,,郑瑞伦,周恩民,杨文耀
- , 2018,
Abstract: 应用哈里森(Harrison)键联轨道法和固体物理方法, 考虑到形变和原子作非简谐振动, 得到六角形二维类石墨烯AN-B8-N 化合物的热膨胀系数和弹性模量以及有效电荷的解析表示式, 以SiC为例, 探讨了形变和原子非简谐振动对它们的影响. 结果表明:SiC的热膨胀系数和弹性模量均随温度升高而缓慢增大, 但变化较缓慢;若不考虑非简谐项, 则SiC的热膨胀系数和弹性模量均为零, 非简谐效应是SiC的热膨胀系数和弹性模量均随温度升高而增大的原因;形变会使SiC的正负离子的有效电荷的大小均减小, 减小幅度分别为14.5% 和8.56% , 形变对正离子有效电荷的影响大于负离子. 在所述的大小、剪切、轴向拉伸、原子振动形变这几种形变中, 以轴向拉伸形变对有效电荷的的影响最大, 以大小形变和剪切形变的影响最小温度愈高, 原子的非简谐振动效应愈显著, 形变对SiC的极性和有效电荷的影响愈大.
On the consideration of the deformation and atomic non-harmonic vibration, this paper applies the methods of Harrison bonding orbit and solid state physics to obtain thermal expansion coefficient and elastic modulus of hexagonal two-dimensional graphene compounds, and analytical formula of effective charge. Take SiC as an example, the paper discusses the effect of deformation and atomic non-harmonic vibration on SiC. The result shows that thermal expansion coefficient and elastic modulus of SiC enlarges slowly with increasing temperature, the thermal expansion coefficient and elastic modulus of SiC would be zero if not considering non-harmonic term, therefore, thermal expansion coefficient and elastic modulus enlarge with the increase of temperature is caused by non-harmonic effect. The deformation reduces the effective charge of SiC’s positive and negative ions by 14.5% and 8.56% respectively. The effect of deformation on positive ions is greater than negative ions. Among the deformations of size, shear, axial tensile and atomic vibrations, axial tensile deformation has the greatest effect on effective charge, while size deformation and shearing deformation has the smallest influence. When temperature increases, atomic non-harmonic vibration effect is presented more obvious, the deformation exerts greater influence on SiC polarity and effective charge
冷却过程中Pd923 团簇的结构转变研究
Structural changes of Pd923 clusters during freezing

夏继宏,高雪梅,,肖绪洋
- , 2016,
Abstract: 本文利用分子动力学模拟方法, 研究了钯团簇在不同冷却条件下形成晶体及非晶的过程. 利用平均原子体积、双体分布函数、键对分析和键序参数方法研究了微观局域结构随温度的变化关系. 研究发现:在50 K/ps冷却过程中,液态Pd923团簇在1000 K发生玻璃化转变,在100 K下形成非晶结构; 而在0.1 K/ps冷却过程中,液态Pd923团簇发生结晶,并最终形成六角密排(hcp)晶体结构。
The structural transitions of Pd923 clusters during the different quenching processes were studied using molecular dynamics simulations. This work gives the structure properties including the variations of pair-correlation function, bond pairs and bond orientational order parameters with temperature in two rapid quenching processes. Our results indicate that the liquid Pd923 is frozen into amorphous structure at 300 K during the cooling rate 50 K/ps. While the liquid Pd923 is transformed to hexagonal close-packed (hcp) phase at the temperature 100 K during the cooling rate 0.1 K/ps.
非简谐振动和形变对ZnSe类石墨烯德拜温度热容量以及极性的影响
Influence of the anharmonic vibration and deformation on the Debye temperature heat capacity and polarity of ZnSe graphene-like

周恩民,,郑瑞伦,查小婷,李召红
- , 2018,
Abstract: 应用哈里森(Harrison)键联轨道法和固体物理理论和方法,考虑到原子的高阶非简谐振动,计算了ZnSe类石墨烯化合物的键和键的极性、简谐系数和非简谐系数,得到它的德拜温度和定容热容量随温度变化的解析式以及形变引起的极性参量的改变量,探讨了形变对ZnSe类石墨烯极性的影响,并讨论了原子非简谐振动对化合物热力学性质的影响,结果表明:在300K到1600K温度区间内,简谐近似下,ZnSe的德拜温度为常量,热容量随着温度的升高呈非线性增大,其中温度较低时变化较快,温度较高时变化较慢并随着温度的升高而趋于常量。考虑到非简谐项后,德拜温度随着温度升高而增大,几乎为正比关系,而热容量的值比简谐近似的值有所减小,与第一非简谐项的影响相比,第二非简谐项的影响很小。形变对ZnSe类石墨烯的极性有重要的影响,在它的几种形变中,剪切形变对键的极性的影响最大,而键长形变对键的极性的影响最小。温度愈高,非简谐效应愈显著。
Abstract:This work uses Harrison bonding orbital method and solid physical theory to calculate the polarities of and bonds, harmonic and anharmonic coefficients of ZnSe graphene-like compound on the consideration of high order anharmonic vibration of the atom. The Debye temperature, temperature-dependence analytical formula of heat capacity at constant volume, and change of polarity parameter caused by the deformation are therefore obtained, and the effect of deformation on the polarity of ZnSe class graphene and the influence of atomic anharmonic vibration on thermodynamic properties of compounds are discussed. The result shows that between 300k to 1600k temperatures, Debye temperature is constant under the harmonic approximation, heat capacity increases with the increase of temperature in a nonlinear way, it changed fast at low temperature, then changed slowly at high temperature, finally became constant with the increase of temperature. When non-simple harmonic term is considered, Debye temperature increases with the increase of temperature in a near proportional relation, the value of heat capacity reduces compared with that under the harmonic approximation. The research discloses that the second non-simple harmonic term has smaller influence compared with the first non-simple harmonic term. Therefore, the deformations have an important impact on polarity of ZnSe class graphene. Shear deformation has the greatest influence on polarity of bond, while bond length deformation has the smallest influence on polarity of bond. Anharmonic effect presents obviously with the increase of temperature. (The higher is temperature, the more obvious anharmonic effect is presented.)
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