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单层氮化硼纳米材料具有与石墨烯相似的原子排列方式, 但是由于硼原子和氮原子之间的电荷转移, 两种材料的电子特性具有较大的差异. 本文采用Hubbard模型和量子力学第一性原理计算相结合的方法研究了具有氢原子饱和的锯齿型边界的三角形氮化硼纳米片(Nanoflake) 的电子结构, 发现:与相应的石墨烯纳米片不同, 出现在氮化硼纳米片费米能级附近的零能态(zero-energy-states)要么被电子完全占据, 要么是全空的, 表现出自旋简并的特点; 通过对氮化硼纳米片进行电子(或空穴)掺杂可以有效地调控"零能态"上的电子占据, 进而对氮化硼纳米片的自旋进行调控. 这将为氮化硼纳米材料在自旋电子学等领域的应用提供重要的理论依据.
关键词:
氮化硼纳米片
电子结构调控
Hubbard 模型
量子力学第一性原理 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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采用基于密度泛函理论的第一性原理计算方法, 研究了氮化硼纳米管六元环中心吸附5d过渡金属原子后体系的几何结构, 电子结构和磁性性质. 研究发现, 吸附原子向一个氮原子或硼原子偏移; 吸附体系在费米能级附近出现明显的杂质能级; 各个体系的总磁矩随原子序数出现规律性变化, 局域磁矩主要分布在吸附原子上. 相似文献
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采用基于密度泛函理论的第一性原理计算方法,研究了氮化硼纳米管六元环中心吸附5d过渡金属原子后体系的几何结构,电子结构和磁性性质.研究发现,吸附原子向一个氮原子或硼原子偏移;吸附体系在费米能级附近出现明显的杂质能级;各个体系的总磁矩随原子序数出现规律性变化,局域磁矩主要分布在吸附原子上. 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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采用巨正则蒙特卡罗方法模拟常温、中等压强下单壁氮化硼纳米管阵列的物理吸附储氢,重点研究压强、纳米管阵列的管径和管间距对单壁氮化硼纳米管阵列物理吸附储氢的影响.计算结果表明,氮化硼纳米管阵列的储氢性能明显优于碳纳米管阵列,在常温和中等压强下的物理吸附储氢量(质量百分数)可以达到和超过美国能源部提出的商业标准.并给出相应的理论解释. 相似文献
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本文发现CoB_(16)~-团簇由两个对称、上下错位相连的B_8环和位于中心的Co原子组成,它代表了金属掺杂硼纳米管结构的潜在雏形,这一发现为设计一维金属-硼纳米结构提供了机会.本文报道了CoB_(16)~-新的实验光电子能谱,并采用量子化学方法对其电子结构和化学成键特性进行了详细的电子结构分析,为进一步了解金属掺杂硼纳米管结构的化学键和稳定性提供了深入的见解.有趣的是,发现该类体系的中心Co原子具有异常低的氧化态,即负一价钴(-1).因此中性CoB_(16)分子可以被视为配体到金属的电荷转移化合物(Co~-@B_(16)~+).研究表明,掺杂金属和硼管之间的相互作用来源于共价和静电作用的相互协调,硼元素低的电负性使得硼团簇成为形成各种低价态化合物的重要化学配体. 相似文献
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以液相沉积法在FTO衬底上制备了TiO_2纳米管阵列,在室温下利用光沉积法在TiO_2纳米管表面修饰金属纳米Ag颗粒,并采用SEM、EDS、XRD对样品的形貌、成分、结构等进行表征.实验结果表明,制备的TiO_2纳米管分布均匀,由锐钛矿相组成,并在管壁有明显的纳米Ag颗粒附着.以Pt为对电极制备了Ag/TiO_2纳米管紫外探测器,光响应测试结果表明,Ag/TiO_2纳米管紫外探测器具有可见光盲特性,可以实现对紫外光的探测.与TiO_2纳米管紫外探测器相比,Ag修饰TiO_2纳米管紫外探测器光电流密度提高至91μA/cm2,开关比可达2 251,紫外探测性能显著提高. 相似文献
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X. Chen X. Wang J. Liu Z. Wang Y. Qian 《Applied Physics A: Materials Science & Processing》2005,81(5):1035-1037
Multiwalled boron nitride nanotubes were synthesized through a simple reduction–nitridation route, in which boron trifluoride etherate ((C2H5)2OBF3) and sodium azide (NaN3) were used as reactants in the presence of Fe-Ni powder at 600 °C for 12 h. The obtained BN nanotubes have an average outer diameter of 60 nm, an average inner diameter of 30 nm, and an average length up to 300 nm. Some nanobamboo structured BN were found coexisting with the BN nanotubes. The experimental results show that the reaction temperature and Fe-Ni powder play important roles in the formation of BN nanotubes. Finally, a possible formation mechanism is also discussed. PACS 81.07.De; 81.16.Be; 81.16.Rf; 81.16.Hc 相似文献
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S. K. Singhal A. K. Srivastava Anil K. Gupta Z. G. Chen 《Journal of nanoparticle research》2010,12(7):2405-2413
We report a new method for the synthesis of boron nitride (BN) nanotubes employing a two-step process in which some oxides
have found to catalyze the growth of BN nanotubes. In the first step, a precursor containing B–N–O–Fe/Mg was prepared by ball
milling a mixture of B, B2O3, Fe2O3 and MgO (1:7:2:1 mass ratio) in NH3 for 3 h. BN nanotubes (diameter: 20–100 nm) were grown in the second step from this precursor by isothermal annealing at
1,350 °C in NH3 for about 4 h. XRD, SEM and HR-TEM studies elucidated the spindle-like morphology of these nanotubes of hexagonal crystal
structure. The Raman spectrum showed the peak broadening and shifts to higher frequency. The present method showed that some
oxides assisted the growth of BN nanotubes. A possible reaction mechanism on the formation of BN nanotubes in the presence
of these oxides is discussed. 相似文献
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S. V. Lisenkov G. A. Vinogradov T. Yu. Astakhova N. G. Lebedev 《Physics of the Solid State》2006,48(1):192-198
Planar and nanotubular structures that are based on boron and nitrogen and consist of tetragons, hexagons, and octagons are
considered. By analogy with carbon nanoobjects of the same topology, these structures are referred to as Haeckelites. The
geometric, electronic, and energy properties are thoroughly investigated for two variants of the regular mutual arrangement
of the polygons. It is established that planar and nanotubular BN structures of the Haeckelite type are dielectrics with a
band gap E
g ∼ 3.2–4.2 eV, which is less than the band gap E
g for BN nanotubes consisting only of hexagons. The cohesive energy of the BN nanotubes under investigation exceeds the cohesive
energy of BN hexagonal nanotubes by 0.3 eV/atom. 相似文献
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Growth of boron nitride nanotube film in situ 总被引:1,自引:0,他引:1
Z.W. Gan X.X. Ding Z.X. Huang X.T. Huang C. Cheng C. Tang S.R. Qi 《Applied Physics A: Materials Science & Processing》2005,81(3):527-529
A novel method was demonstrated to fabricate boron nitride nanotube films on silicon substrate in a location-controlled fashion. The pre-deposited SiO2 layer on the substrate controls the growth space of BN nanotubes synthesized by an ammonothermal reaction of boron and its oxide. PACS 71.20.Tx; 81.07.De; 81.10.Dn; 61.46.+w; 81.05.Tp 相似文献
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The authors’ endeavors over the last few years with respect to boron nitride (BN) nanotube metal filling are reviewed. Mo
clusters of 1–2 nm in size and FeNi Invar alloy (Fe ∼60 at. %; Ni ∼40 at. %) or Co nanorods of 20–70 nm in diameter were embedded
into BN nanotube channels via a newly developed two-stage process, in which multi-walled C nanotubes served as templates for
the BN multi-walled nanotube synthesis. During cluster filling, low-surface-tension and melting-point Mo oxide first filled
a C nanotube through the open tube ends, followed by fragmentation of this filling into discrete clusters via O2 outflow and C→BN conversion within tubular shells at high temperature. During nanorod filling, C nanotubes containing FeNi
or Co nanoparticles at the tube tips were first synthesized by plasma-assisted chemical vapor deposition on FeNi Invar alloy
or Co substrates, respectively, and, then, the nanomaterial was heated to the melting points of the corresponding metals in
a flow of B2O3 and N2 gases. During this second stage, simultaneous filling of nanotubes with a FeNi or Co melt through capillarity and chemical
modification of C tubular shells to form BN nanotubes occurred. The synthesized nanocomposites were analyzed by scanning and
high-resolution transmission electron microscopy, electron diffraction, electron-energy-loss spectroscopy and energy-dispersive
X-ray spectroscopy. The nanostructures are presumed to function as ‘nanocables’ having conducting metallic cores (FeNi, Co,
Mo) and insulating nanotubular shields (BN) with the additional benefit of excellent environmental stability.
Received: 10 October 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
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Thorn-like BN nanostructures that the nanosize hexagonal BN (h-BN) layers are randomly stacked looking like thorns were synthesized using thermal chemical vapor deposition of B/B2O3 under the flow of NH3 at 1200 °C. They can grow self-assembled forming the microsize lumps, and also deposit as sheathing layers on the pre-grown SiC nanowires with a controlled thickness in the range 20-100 nm. The spreading of the thorn-like BN layers as the sheathing layers results in a significantly enhanced surface area, 2400 m2/g. 相似文献
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P.N. D’yachkov 《Journal of Physics and Chemistry of Solids》2009,70(1):180-185
The effect of intrinsic defects and isoelectronic substitutional impurities on the electronic structure of boron-nitride (BN) nanotubes is investigated using a linearized augmented cylindrical wave method and the local density functional and muffin-tin approximations for the electron potential. In this method, the electronic spectrum of a system is governed by a free movement of electrons in the interatomic space between cylindrical barriers and by a scattering of electrons from the atomic centers. Nanotubes with extended defects of substitution NB of a boron atom by a nitrogen atom and, vice versa, nitrogen by boron BN with one defect per one, two, and three unit cells are considered. It is shown that the presence of such defects significantly affects the band structure of the BN nanotubes. A defect band π(B, N) is formed in the optical gap, which reduces the width of the gap. The presence of impurities also affects the valence band: the widths of s, sp, and pπ bands change and the gap between s and sp bands is partially filled. A partial substitution of the N by P atoms leads to a decrease in the energy gap, to a separation of the Ds(P) band from the high-energy region of the s(B, N) band, as well as to the formation of the impurity Dπ(P) and Dπ*(P) bands, which form the valence-band top and conduction-band bottom in the doped system. The influence of partial substitution of N atoms by the As atom on the electronic structure of BN nanotubes is qualitatively similar to the case of phosphorus, but the optical gap becomes smaller. The optical gap of the BN tubule is virtually closed due to the effect of one Sb atom impurity per translational unit cell, in contrast to the weak indium-induced perturbation of the band structure of the BN nanotube. Introduction of the one In, Ga or Al atom per three unit cells of the (5, 5) BN nanotube results in 0.6 eV increase of the optical gap. The above effects can be detected by optical and photoelectron spectroscopy methods, as well as by measuring electrical properties of the pure and doped BN nanotubes. They can be used to design electronic devices based on BN nanotubes. 相似文献
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First-principles study of nanotubes within the tetragonal,hexagonal and dodecagonal cycle structures
A systematic study has been done on the structural and electronic properties of carbon, boron nitride and aluminum nitride nanotubes with structure consisting of periodically distributed tetragonal (T ≡A2X2), hexagonal (H ≡A3X3) and dodecagonal (D ≡A6X6) (AX=C2, BN, AlN) cycles. The method has been performed using first-principles calculations based on density functional theory (DFT). The optimized lattice parameters, density of state (DOS) curves and band structure of THD-NTs are obtained for (3, 0) and (0, 2) types. Our calculation results indicate that carbon nanotubes of these types (THD-CNTs) behave as a metallic, but the boron nitride nanotubes (THD-BNNTs) (with a band gap of around 4 eV) as well as aluminum nitride nanotubes (THD-AlNNTs) (with a band gap of around 2.6 eV) behave as an semiconductor. The inequality in number of atoms in different directions is affected on structures and diameters of nanotubes and their walls curvature. 相似文献
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C.S. Guo 《Solid State Communications》2006,137(10):549-552
The structural and electronic properties of the armchair Cx(BN)y nanotubes are studied using the density functional theory with a generalized gradient approximation. The results show that the properties of the Cx(BN)y nanotubes are intermediate between those of carbon nanotubes and BN nanotubes, and also adjustable by their radius, ratio of carbon component, and configurations. 相似文献
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D. Golberg M. Mitome Y. Bando C.C. Tang C.Y. Zhi 《Applied Physics A: Materials Science & Processing》2007,88(2):347-352
High-resolution transmission electron microscopy (HRTEM) and electron diffraction analysis were performed on pure multi-walled novel type boron nitride nanotubes (BNNTs) by using a field-emission high-resolution 300 kV transmission electron microscope JEM-3100FEF (Omega filter). In contrast to commonly observed monochiral multi-walled BNNTs, the present tubular shells within every individual BNNT (up to ~50 shells) revealed the whole range of helixes, i.e., from zig-zag to arm-chair. This being paired with the wide variations in cross-sectional tubular shapes, i.e., from a faceted polygon to a cylinder, results in complex overall tubular structures. The BN atomic lattice fringe separations, down to 1.25 Å, on most symmetrical arm-chair (d10-10=1.25 Å) and zig-zag (d11-20=2.15 Å) tubular wall fragments within the same multi-walled BN nanotubes were ultimately achieved during HRTEM. 相似文献