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基于第一性原理的平面波超软赝势法对(6, 0)单壁氮化硼纳米管、Cr掺杂、Ag掺杂、以及Cr-O共掺纳米管进行电子结构和光学性质的计算.结果表明:Cr掺杂和Cr-O共掺体系相比于本征体系的带隙值均减小,掺杂体系的导带底穿过费米能级从而实现了氮化硼纳米管的n型掺杂. Ag掺杂实现了纳米管的p型掺杂.本征氮化硼纳米管、Ag掺杂、Cr掺杂、以及Cr-O共掺纳米管的静态介电常数分别为1.17、1.61、1.32和1.48,相对于本征体系静介电性能有所提高. 相似文献
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基于第一性原理的平面波超软赝势法对(6, 0)单壁氮化硼纳米管、Cr掺杂、Ag掺杂、以及Cr-O共掺纳米管进行电子结构和光学性质的计算。结果表明:Cr掺杂和Cr-O共掺体系相比于本征体系的带隙值均减小,掺杂体系的导带底穿过费米能级从而实现了氮化硼纳米管的n型掺杂。Ag掺杂实现了纳米管的p型掺杂。本征氮化硼纳米管、Ag掺杂、Cr掺杂、以及Cr-O共掺纳米管的静态介电常数分别为1.17、1.61、1.32和1.48,相对于本征体系静介电性能有所提高。 相似文献
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用第一性原理方法系统地研究硫化锌纳米管的稳定性、电子性质和掺杂磁性质.比较三种纳米管的稳定性.研究表明,六边形截面的双壁管的稳定性最高,相同截面的单壁管稳定性次之,而圆截面的之字形和扶手椅纳米管稳定性最低.电子能带结构计算表明它们都是直接带隙半导体.纳米管表面氢吸附后,六边形截面的单壁管转变为间接带隙半导体.研究了磁性原子掺杂六边形截面管的磁性质.发现掺杂纳米管的形成能比纯纳米管的形成能低,说明掺杂过程是一个放热反应.纳米管的总磁矩等于掺杂的磁性原子的磁矩.这些单掺杂纳米管在可调磁的新材料方面有潜在的应用价值. 相似文献
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共掺杂是提高二氧化钛纳米管可见光催化性能的一种有效方式. 采用基于密度泛函理论的第一性原理方法, 研究了N单掺杂、F单掺杂及N-F共掺杂二氧化钛纳米管的原子结构、电子性质和光学性质. 计算结果表明, 相比N单掺杂和F单掺杂, N-F共掺杂二氧化钛纳米管的形成能更低, 掺杂后的体系热力学稳定性更好. 此外, 相比未掺杂时的带隙, N-F共掺杂后体系的带隙变化最多, 减少了0.557 eV, 而这主要源于价带顶附近的杂质能级的贡献. 此外, 通过分析掺杂后的光催化活性发现, N-F共掺杂时纳米管的还原性和氧化性都有所降低, 但并没有丧失活性, 并且光吸收谱表明, 共掺杂体系的红移现象最为明显. 因此, N-F共掺杂可有效提高二氧化钛纳米管可见光的光催化性能. 相似文献
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碳纳米管作为最先进的纳米材料之一, 在电子和光学器件领域有潜在的应用前景, 因此引起了广泛关注. 掺杂、变形及形成超晶格为调制纳米管电子、光学性质提供了有效途径. 为了理解相关机理, 利用第一性原理方法研究了不同剪切形变下扶手椅型硼氮交替环状掺杂碳纳米管超晶格的空间结构、电子结构和光学性质. 研究发现, 剪切形变会改变碳纳米管的几何结构, 当剪切形变大于12%后, 其几何结构有较大畸变. 结合能计算表明, 剪切形变改变了掺杂碳纳米管超晶格的稳定性, 剪切形变越大, 稳定性越低. 电荷布居分析表明, 硼氮掺杂碳纳米管超晶格中离子键和共价键共存. 能带和态密度分析发现硼氮交替环状掺杂使碳纳米管超晶格从金属转变为半导体. 随着剪切形变加剧, 纳米管超晶格能隙逐渐减小, 当剪切形变大于12%后, 碳纳米管又从半导体变为金属. 在光学性能中, 剪切形变的硼氮掺杂碳纳米管超晶格的光吸收系数及反射率峰值较未受剪切形变的均减小, 且均出现了红移. 相似文献
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We investigated the effect of uniaxial tensile strength on a pristine carbon nanotube, boron-doped carbon nanotube, nitrogen-doped carbon nanotube and co-doped carbon nanotube with boron and nitrogen atoms. To achieve our goal, we performed our calculations with the aid of density functional theory. We studied the changes in the electrical properties after the atomic substitution of a carbon atom by boron, nitrogen, and boron and nitrogen in pristine carbon nanotubes. We also applied uniaxial tensile strength to doped structures as well as pristine one. In addition to studying the band gap, we studied the changes in the Fermi energy, valence bands, and conduction bands. We found that defects as well as stress and strain play a crucial rule on modifying the electrical properties of carbon nanotubes. 相似文献
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Jamal A. Talla 《Physica B: Condensed Matter》2012,407(6):966-970
We investigated the interactions between two different geometrical configurations of single-walled carbon nanotubes and boron atoms using first-principle calculations within the framework of the density functional theory. With the aid of ab initio calculations, we introduced a new type of toxic gas sensor that can detect the presence of CO, NO and H2 molecules. We proved that the dopant concentration on the surface of the nanotube plays a crucial role in the sensitivity of this device. Furthermore, we showed that small concentrations of dopants can modify the transport and electronic properties of the single-walled carbon nanotube and can lend metallic properties to the nanotube. Band-gap narrowing occurs when the nanotube is doped with boron atoms. The emerged new energy level near the Fermi level upon boron doping clearly indicates the coupling between the p orbital of the boron atom and the large p bond of the carbon nanotube. We also predicted a weak hybridization between the boron atoms and the nanotube for the valence-band edge states; this weak coupling leads to conducting states around the band gap. 相似文献
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S. Azevedo C. Chesman J. R. Kaschny 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(1):123-128
We apply first-principles method to investigate the
effect of the diameter on the stability and electronic properties of zigzag
carbon nanotubes doped with iron, nickel and manganese impurity atoms. In
this contribution we follow the evolution of the electronic and structural
properties as a function of the nanotube diameter. As a general result, we
found that the binding energy decreases with the increasing nanotube radius.
Additionally, depending on the interaction of transition metal impurity with
the tubular carbon structure, it is observed that the total magnetization
varies with the tube diameter due to hybridization and confinement effects.
It is also shown that such magnetization varies with the curvature radius,
increasing for manganese impurity atoms and decreasing for iron and nickel. 相似文献
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Multiwall carbon nanotubes and conducting polyaniline, doped with dodecylbenzenesulfonic acid, are blended by employing the solubility of both materials in chloroform. Pellets are made by pressing the dried powder of the obtained composite, and films by sedimentary deposition onto a plastic substrate. In these composites, the advantageous properties of carbon nanotubes can be utilized in fully conducting bulk and planar structures while the strong decrease of the conductivity of doped polyaniline at low temperatures is simultaneously suppressed. The nanotube content in pellets can be as high as 40% by weight, and this wide range leads to a control over the shape and magnitude of the conductivity versus temperature curves. As the nanotube content grows, the temperature dependence of the conductivity becomes less steep, which is similar to the effect of annealing temperature on the conductivity of certain polycrystalline graphene films. In our case, this change is most likely caused by the increase of the density of highly conducting channels and not by homogeneous delocalization effects. 相似文献
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J. W. Wei H. Zeng L. C. Pu J. W. Liang P. Peng 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,81(1):133-136
We investigate the structures and properties of boron/nitrogen co-doped carbon nanotube with water molecules adsorbing. The electronic and optical properties of the systems are calculated by using the first-principles theory in detail. The results reveal that the doped nanotubes show hydrophilic behavior when the oxygen atoms are close to the nanotubes. The Mulliken charges redistribute and transfer between the doped carbon nanotubes and the water molecules. The band gaps of the nanotubes vary with the positions of H2O. The positions and intensities of the reflectivity peaks are affected by the distributions of boron/nitrogen atoms and the positions of water molecules. The investigations are beneficial to further biological applications of co-doped nanotubes. 相似文献
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J.-W. Wei H.-F. Hu H. Zeng Z.-Y. Wang L. Wang L.-J. Zhang 《Applied Physics A: Materials Science & Processing》2007,89(3):789-792
Using density functional theory combined with nonequilibrium Green’s functions, we investigated and found that boron substitutional
doping affects the transport properties of single-walled carbon nanotubes with different distribution. The results reveal
that the semiconducting nanotube transits to the quasi-metallic state with nonlinear current–voltage curve after boron doping.
Some regular regions of total transmission coefficient with integral values appear with the varying of electron energy and
bias voltage. The transport properties of the doped tubes are affected remarkably by the impurity states of quasi-bound defect
states which are tuned by the distance between the boron atoms. The current of metallic nanotube is reduced by the impurities
and changed with doping patterns.
PACS 72.80.Rj; 73.22.2f; 73.61.Wp; 73.63.Rt 相似文献
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利用实验的方法研究了甲基红掺杂碳纳米管悬浮液对波长为532 nm激光的光限幅效应.分析了样品厚度和入射激光重复频率对光限幅特性的影响,并与纯碳纳米管悬浮液的光限幅特性进行了比较.实验结果表明,对于线性透过率为60%(500 nm)的碳纳米管悬浮液,掺入甲基红后其沉淀速度明显减慢,限幅阈值由250 μJ降低为200 μJ;对于2和5 mm 厚度的样品,掺杂甲基红使碳纳米管悬浮液的箝位输出激光脉冲能量分别由45和20 μJ降低为35和9 μJ.
关键词:
非线性光学
光限幅效应
甲基红
染料掺杂碳纳米管悬浮液 相似文献
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Physics of the Solid State - Al-doped single wall carbon nanotube with Stone Wales defect was theoretically analyzed, two different orientations of chiral (8, 4) carbon nanotubes was doped among... 相似文献
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研究了掺杂两种分散染料橙的向列型液晶E7的性质以及碳纳米粒子(单壁碳纳米管或富勒烯C60)的影响. 两种分散染料橙11和13具有较高的溶解度和有序参数,被作为掺杂剂同时使用. 与掺杂单染料相比,同时加入两种染料橙使液晶的有序参数明显提高. 与纯液晶相比,掺杂可引起向列相向各向同性相转变温度的升高. 相似文献