排序方式: 共有29条查询结果,搜索用时 15 毫秒
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不同氧压下脉冲激光沉积LiCoO2薄膜的研究 总被引:1,自引:0,他引:1
使用脉冲激光沉积(PLD)法,在不同的氧压下制备了锂离子二次电池正极材料LiCoO2的薄膜.利用X射线衍射(XRD)、原子力显微镜(AFM)等分析测试方法,对沉积的薄膜进行了晶体结构和表面形貌的分析.结果显示,氧压达到正常标准时(加Pa),LiCoO:薄膜具有明显的c轴择优取向,同时薄膜的晶粒尺寸更为均匀,表面更为光滑.而氧压较低(1 Pa)时,薄膜表现为随机取向.这些结果表明,PLD方法制备LiCoO2薄膜时应该充分考虑腔体气压对等离子体的散射作用以提高薄膜表面的质量. 相似文献
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In this paper we consider the movement of an electron in the single electron tunnel process through a mesoscopic capacitor. The results show that, due to the Coulomb force, there is a threshold voltage Vt in the mesoscopic LC circuit. When the external voltage is lower than the threshold voltage, the tunnel current value is zero, and the Coulomb blockade phenomenon arises. Furthermore, considering that the mesoscopic dimension is comparable to the coherence length in which charge carriers retain the phase remembrance, a weak coupling can be produced through the proximity effect of the normal metal electrons of both electrodes of a mesoscopic capacitor. By varying the external voltage, we can observe the Shapiro current step on the current-voltage characteristic curve of a mesoscopic LC circuit. 相似文献
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First principles study on the structural, electronic and optical properties of diluted magnetic semiconductors Zn1-xCoxX (X=S, Se, Te)
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The electronic and optical properties of zincblende ZnX(X=S, Se, Te) and ZnX:Co are studied from density functional theory (DFT) based first principles calculations. The local crystal structure changes around the Co atoms in the lattice are studied after Co atoms are doped. It is shown that the Co-doped materials have smaller lattice constant (about 0.6%-0.9%). This is mainly due to the shortened Co-X bond length. The (partial) density of states (DOS) is calculated and differences between the pure and doped materials are studied. Results show that for the Co-doped materials, the valence bands are moving upward due to the existence of Co 3d electron states while the conductance bands are moving downward due to the reduced lattice constants. This results in the narrowed band gap of the doped materials. The complex dielectric indices and the absorption coefficients are calculated to examine the influences of the Co atoms on the optical properties. Results show that for the Co-doped materials, the absorption peaks in the high wavelength region are not as sharp and distinct as the undoped materials, and the absorption ranges are extended to even higher wavelength region. 相似文献
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This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries, from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12: n-type and p-type. The two unit cells have different structures and electronic properties:the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator. It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating. The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V. 相似文献
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本文给出了接续式和循环接续式构造一维准晶格链的方法。以典型的准晶格链—Fibonacci链为例分析了准晶格链的结构特点。讨论了准晶体的生长等问题。 相似文献
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The electronic structure and magnetism of eskolaite are studied by using first-principles calculations where the on-site Coulomb interaction and the exchange interaction are taken into account and the LSDA+U method is used. The calculated energies of magnetic configurations are very well fitted by the Heisenberg Hamiltonian with interactions in five neighbour shells; interaction with two nearest neighbours is found to be dominant. The Néel temperature is calculated in the spin-3/2 pair-cluster approximation. It is found that the measurements are in good agreement with the calculations of lattice parameters, density of states, band gap, local magnetic moment, and the Néel temperature for the values of U and J that are close to those obtained within the constrained occupation method. The band gap is of the Mott--Hubbard type. 相似文献
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类克尔介质中受激三能级原子的光子统计演化 总被引:8,自引:3,他引:5
本文讨论了类克尔介质腔内光场与三能级原子相互作用时场模平均光子数的统计演化性质。结果表明,非线性介质会使场与原子的相互作用减弱,并较强地依赖于场与介质的耦合程度。 相似文献