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We found an error in our previous report [Chin. Phys. Lett. 26(2009)077809] concerning the JCPDS data which was used to compare with our data. It should read as JCPDS No 21-1272 (α = 3.7850A, c = 9.5140A, c/α = 2.5140, and V = 136.30A^3),  相似文献   

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Abstract

It is shown that one system of coupled KdV equations, found in J. Nonlin. Math. Phys., 1999, V.6, N 3, 255–262 to possess the Painlevé property, is integrable but not new.  相似文献   

5.
As the definition in the Letter, the preparation efficiency should be calculated according to Eq. (2). However, the data in Fig. 4 were not divided by ηΩSPD2 = 0.15, while all the pertinent discussion is correct. We correct this mistake and show the revised figure here.  相似文献   

6.
Anisotropic evolution of the step edges on the compressive-strained In0.2Ga0.8As/GaAs(001) surface has been investigated by scanning tunneling microscopy (STM). The experiments suggest that step edges are indeed sinuous and protrude somewhere a little way along the [110] direction, which is different from the classical waviness predicted by the theoretical model. We consider that the monatomic step edges undergo a morphological instability induced by the anisotropic diffusion of adatoms on the terrace during annealing, and we improve a kinetic model of step edge based on the classical Burton Cabrer-Frank (BCF) model in order to determine the normal velocity of step enlargement. The results show that the normal velocity is proportional to the arc length of the peninsula, which is consistent with the first result of our kinetic model. Additionally, a significant phenomenon is an excess elongation along the [110] direction at the top of the peninsula with a higher aspect ratio, which is attributed to the restriction of diffusion lengths.  相似文献   

7.
《光谱实验室》2007,24(1):71
哈里顿是前苏联发展原子弹的第二把手。他于1925年毕业于列宁格勒多科工业大学。1926-1928年,他被前苏联政府选派到卡文迪许实验室,在卢瑟福指导下工作,并获博士学位。他是卢瑟福的学生中去世最晚的。1931年他在化学物理研究所工作,研究金属蒸气的凝结和离心法分离气体的理论。1939年他和泽尔多维奇对铀的链式裂变反应进行了计算,他们发表于1939-1941年的一系列论文为后来苏联发展原子武器打下了基础。  相似文献   

8.
Here, we make comments to the conclusions of the paper: LIU Shi-Da, Sill Shao-Ying, LIU Shi-Kuo, et al., "Vortex of Fluid Field as Viewed from Curvature" [Commun. Theor. Phys. 43 (2005) 604].  相似文献   

9.
An epitaxial graphene (EG) layer is successfully grown on a Si-terminated 6H-SiC ((9001) substrate by the method of thermal annealing in an ultrahigh vacuum molecular beam epitaxy chamber. The structure and morphology of the EG sample are characterized by reflection high energy diffraction (RHEED), Raman spectroscopy and atomic force microscopy (AFM). Graphene diffraction streaks can are clearly observed in the Raman spectrum. The AFM about 4-10 layers. be seen in RHEED. The G and 2D peaks of graphene results show that the graphene nominal thickness is  相似文献   

10.
三片具有不同载流子浓度的n型6H-SiC体材料用于83K到673K的变温拉曼散射研究,能够得到变温的拉曼散射模。通过测量可以得到,随着温度的增长,不同的声子散射模的拉曼峰逐渐变小。运用声子频率的温度特性计算公式,对三片样品的三个声子模的峰位进行拟合能够得到很好的拟合结果。6H-SiC样品的纵光学声子模(LOPC)的拉曼位移像其他的拉曼模一样,随着温度的增加而变小。在较高的温度时所有的声子模明显展宽。  相似文献   

11.
Polycrystalline rare-earth hexaborides (NdxGdl-x)B6 (x = 0, 0.2, 0.6, 0.8, 1) were prepared by the reactive spark plasma sintering (SPS) method using mixed powder of GdH2, NdH2 and B. The effects of Nd doping on the crystal structure, the grain orientation, the thermionie emission and the magnetic properties of the hexaboride were investigated by X-ray diffraction, electron backscattered diffraction and magnetic measurements. It is found that all the samples sintered by the SPS method exhibit high densities (〉95%) and high values of Vickers hardness (2319 kg/mm2). The values are much higher than those obtained in the traditional method. With the increase of Nd content,the thermionic emission current density increases from 11 to 16.30 A/cm2 and the magnetic phase transition temperature increases from 5.85 to 7.95 K. Thus, the SPS technique is a suitable method to synthesize the dense rare-earth hexaborides with excellent properties.  相似文献   

12.
This paper reports that the equilibrium structure of NH2 has been optimized at the QCISD/6-311++G (3df, 3pd) level. The ground-state NH2 has a bent (C2v, X^2B1) structure with an angle of 103.0582°. The geometrical structure is in good agreement with the other calculational and experimental results. The harmonic frequencies and the force constants have also been calculated. Based on the group theory and the principle of microscopic reversibility, the dissociation limits of NH2(C2v, X^2B1) have been derived. The potential energy surface of NH2(X^2B1) is reasonable. The contour lines are constructed, the structure and energy of NH2 reappear on the potential energy surface.  相似文献   

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采用Sol-Gel方法首次在比较低的温度下制备了具有氧磷灰石结构的发光体Mg2Y8-x-y(SiO4)6O2:Eu,Bi(x,y≥0),利用XRD、IR、TG-DTA三种手段研究了发光体的形成过程。室温(293K)和液氮温度(77K)的荧光光谱表明Eu3+和Bi3+在这种基质中分别发射红光和蓝光,每mol基质中其最佳掺杂浓度分别为0.14mol和0.03mol,并且其发光都存在温度猝灭。Eu3+的激光感生荧光光谱中存在两条5D0-7F0跃迁线,表明Eu3+同时进入4f格位和6h格位。在Eu3+、Bi3+共掺杂的发光体中,观察到了Bi3+→E3+的部分能量传递。  相似文献   

14.
A nonpolar SiC(1120) substrate has been used to fabricate epitaxial graphene (EG). Two EGs with layer numbers of 8-10 (referred to as MLG) and 2-3 (referred to as FLG) were used as representative to study the substrate effect on EG through temperature dependent Raman scattering. It is found that Raman lineshifts of G and 2D peaks of the MLG with temperature are consistent with that of a free graphene predicted by theory calculation, indicating that the substrate influence on the MLG is undetectable. While Raman G peak lineshifts of the FLG to that of the free graphene are obvious, however, its lineshift rate (-0.016 cm-1/K) is almost one third of that (-0.043 cm-1/K) of a EG on 6H-SiC (0001) in the temperature range from 300 K to 400 K, indicating a weak substrate effect from SiC (1120) on the FLG. This renders the FLG a high mobility around 1812 cm2- ·V-1-·s-1 at room temperature even with a very high carrier concentration about 2.95× 1013 cm-2 (p-type). These suggest SiC (1120) is more suitable for fabricating EG with high performance.  相似文献   

15.
We examine the effects of an unparticle U as a possible source of missing energy in the p-wave decays of a B meson. The dependence of the differential branching ratio on the K0^* (K1) - meson's energy is discussed in the presence of scalar and vector unparticle operators and significant deviation from the standard model value is found after addition of these operators. Finally, we have shown the dependence of the branching ratio for the above-mentioned decays on the parameters of unparticle stuff like effective couplings, cutoff scale Au and the scale dimensions du.  相似文献   

16.
本文通过测量HT─6B等离子体中OⅥ的线辐射强度随放电参数的变化,利用杂质输运分析的数值结果,给出了在等离子体参数很大的变化范围内[ne=(0.2-2.0)×10(13),qa=3-8.5]Z(eff)及杂质相对浓度随放电参数的变化规律。在外加共振螺旋磁场(RHF)抑制外撕裂模的实验中,OⅢ、CⅢ的线辐射测量表明RHF具有改善杂质约束的迹象,此时光谱信号中反映出的相应频率的粒子扰动也被RHF所抑制。  相似文献   

17.
We have investigated the low-temperature magnetism and spin-lattice coupling in (Bio.46Nao.46Bao.os)TiO3 :Co in order to understand the magnetoelectric effect in such artificially synthesized dilute magnetic ferroelectrics. It is revealed that the as-prepared (Bio.46Nao.46Bao.os)TiO3:Co at Co content of 20%~30% exhibits fascinating ferrimagnetism which is robust against magnetic field, the abnormal spin lattice coupling characterized by a negative magnetostriction effect; and the suppressed magnetic moment within the temperature range of 30 K-50 K is identified. These magnetic behaviours at low temperatures can be explained by the competition between the ferrimagnetic response and the magnetic moment suppression induced by the abnormal spin lattice coupling effect. Finally, the ferroelectric and magnetodielectric properties are also discussed.  相似文献   

18.
The effects of the addition of H3BO3 on the microstructure, phase formation, and microwave dielectric properties of (Zn0.TMg0.3)TiO3 ceramics sintered at temperatures ranging from 890 ℃ to 950 ℃ are investigated. H3BO3 as a sintering agent can effectively lower the sintering temperature of ZMT ceramics below 950 ℃due to the liquid-phase effect. The microwave dielectric properties are found to strongly correlate with the amount of H3BO3. With the increase in H3BO3 content, the dielectric constant (er) monotonically increases, but the quality factor (Q x f) reaches a maximum at 1 wt% H3BO3, and the apparent density of ZMT ceramics with H3BO3〉 1 wt% gradually decreases. At 950 ℃, the ZMT ceramics with 1% H3BO3 exhibit excellent microwave dielectric properties: er = 19.8, and Q x f -- 43800 GHz (8.94 GHz).  相似文献   

19.
The effects of BaCu(B2Os) (BCB) addition on the microstructure, phase formation, and microwave dielectric proper- ties of BasNb4015-BaWO4 ceramic are investigated. As a sintering aid, BaCu(B2Os) ceramic could effectively lower the sintering temperature of BasNb4015-BaWO4 ceramic from 1100 ℃ to 950 ℃ due to the liquid-phase effect. Meanwhile, BaCu(B2Os) addition effectively improves the densification of BasNb4015-BaWO4 ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that BasNb4015 and BaWO4 coexist with no crystal phase of BaCu(B2Os) in the sintered ceramics. The BasNb4015-BaWO4 ceramics with 1.0 wt% BaCu(B2Os) sintered at 950 ℃ for 2 h presents good microwave dielectric properties of er = 19.0, high Q× f of 33802 GHz and low vf of 2.5 ppm/℃.  相似文献   

20.
采用密度泛函理论中的广义梯度近似对C60(CF3nn=2,4,6,10)几何结构和电子性质的变化规律进行了计算研究.发现在C60(CF34可能稳定存在的三种同分异构体中,具有p p p加成方式的衍生物热力学性质最为稳定;在C60(CF36可能稳定存在的三种同分异构体中,具有p p p m p加成方式的衍生物热力学性质最为稳定.对C60(CF32,C60(CF34,C60(CF36和C60(CF310四种加成衍生物的几何结构分析可知:随着CF3加成个数的增加,C60中的C—C平均键长逐渐变大,笼子与CF3之间连接键CC60—CCF3逐渐变大.对它们的电子结构分析可知,随着CF3加成数目的增多,反应热几乎是线性增加.而C60(CF3nn=2,4,6,10)分子的平均反应热在n=6处为极大值,说明C60(CF36应该是最容易得到的加成产物.由Mulliken电荷可知,加成的CF3个数越多,CF3与笼子的相互作用也就越强,每个CF3转移到笼子上电荷数也就越多.C60(CF3n的自旋聚居数分布表明它们均为闭壳层结构.最后,从CF3对分子的前线轨道贡献可知,四种分子的得电子情况和失电子情况均发生在碳笼本身,并不随着CF3个数的增加而发生明显的改变. 关键词: 60(CF3nn=2')" href="#">C60(CF3nn=2 10) 几何结构和电子性质 密度泛函  相似文献   

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