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Doping mechanism of fullerenes into carbon nanotubes
碳纳米管中封装富勒烯的机理

Wang Feng,Zeng Xiang-Hua,Xu Xiu-Lian,
王锋
,曾祥华,徐秀莲

物理学报 , 2002,
Abstract: Based on a classical molecular dynamics model, a novel insertion mechanism of C 60 into single wall carbon nanotubes(SWNTs) has been demonstrated. The potential barrier of tube\|end area of the SWNTs plays an important role in attracting C 60 into the SWNTs and to encapsulate C 60 in the SWNTs. The C 60 moves freely along the tube axis direction in tube\|inner area of the SWNTs. Finally, a series of potential barrier heights of attracting and encapsulating C 60 of SWTNs with different diameters are calculated, indicating that SWNTs cannot attract C 60 unless its diameter is greater than the minimum value 1\^238 nm.
Investigation Effects of Magnetetic Impurity Doping on Average Magnetization of Semiconducting Carbon Nanotubes
Saeedeh Ghafourian,Ali Fathalian,Iraj Kazeminezhad
International Nano Letters , 2011,
Abstract: Single wall carbon nanotubes (SWCNT) extensively are attractive from both theoretical and experimental point of view, due to its technological applications such as nano electronics devises. SWCNT are created by rolling a graphen sheet into a cyclindrical form. We have investigated the possibility of making a ferromagnetic semiconductor zigzag SWCNT by doping magnetic impurities. We found by increasing magnetic impurities doping on a zigzag SWCNT, average magnetization is increased and one can make a ferromagnetic semiconductor
Theoretical studies of C36encapsulated in zigzag single-wall carbon nanotubes
Theoretical studies of C36 encapsulated in zigzag single-wall carbon nanotubes

YANG Baohua,WANG Yang,HUANG Yuanhe,
YANG
,Baohua,WANG,Yang,HUANG,Yuanhe

科学通报(英文版) , 2006,
Abstract: The one-dimensional hybrid structures of C36 encapsulated in zigzag single-wall carbon nanotubes (C36@(n,0)) have been investigated using ab initio self-consistent-field crystal orbital method based on the density functional theory. The research focuses on the change of geometric and band struc- tures for the nanotubes upon C36 encapsulation. The obtained results show that the introduction of C36 can modify the electronic properties of CNT. The diameter of carbon nanotube plays an important role in the geometric and electronic properties of the peapod structures.
Theoretical studies of C36 encapsulated in zigzag single-wall carbon nanotubes
Baohua Yang,Yang Wang,Yuanhe Huang
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-005-0613-z
Abstract: The one-dimensional hybrid structures of C36 encapsulated in zigzag single-wall carbon nanotubes (C36@(n,0)) have been investigated using ab initio self-consistent-field crystal orbital method based on the density functional theory. The research focuses on the change of geometric and band structures for the nanotubes upon C36 encapsulation. The obtained results show that the introduction of C36 can modify the electronic properties of CNT. The diameter of carbon nanotube plays an important role in the geometric and electronic properties of the peapod structures.
Zigzag and armchair nanotubes in external fields  [PDF]
E. L. Korotyaev,A. A. Kutsenko
Physics , 2009,
Abstract: We consider the Schr\"odinger operator on the zigzag and armchair nanotubes (tight-binding models) in a uniform magnetic field $\mB$ and in an external periodic electric potential. The magnetic and electric fields are parallel to the axis of the nanotube. We show that this operator is unitarily equivalent to the finite orthogonal sum of Jacobi operators. We describe all spectral bands and all eigenvalues (with infinite multiplicity, i.e., flat bands). Moreover, we determine the asymptotics of the spectral bands both for small and large potentials. We describe the spectrum as a function of $|\mB|$. For example, if $|\mB|\to {163}({\pi2}-{\pi kN}+\pi s)\tan {\pi2N}, k=1,2,..,N, s\in \Z$, then some spectral band for zigzag nanotube shrinks into a flat band and the corresponding asymptotics are determined.
Selecting Boron Fullerenes by Cage-Doping Mechanisms  [PDF]
Paul Boulanger,Maxime Moriniere,Luigi Genovese,Pascal Pochet
Physics , 2013, DOI: 10.1063/1.4802775
Abstract: So far, no boron fullerenes were synthesized: more compact sp3-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011)] as "seeds" for a possible synthesis which would topologically protect the sp2 sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis.
Knowledge Emergence in Scientific Communication: From "Fullerenes" to "Nanotubes"  [PDF]
Diana Lucio-Arias,Loet Leydesdorff
Physics , 2009,
Abstract: This article explores the emergence of knowledge from scientific discoveries and their effects on the structure of scientific communication. Network analysis is applied to understand this emergence institutionally as changes in the journals; semantically, as changes in the codification of meaning in terms of words; and cognitively as the new knowledge becomes the emergent foundation of further developments. The discovery of fullerenes in 1985 is analyzed as the scientific discovery that triggered a process which led to research in nanotubes.
Atomistic Study of the Encapsulation of Diamondoids Inside Carbon Nanotubes  [PDF]
Karla S. Troche,Vitor R. Coluci,Douglas S. Galvao
Physics , 2007,
Abstract: The encapsulation of hydrogen-terminated nanosized diamond fragments (the so-called diamondoids) into armchair single walled carbon nanotubes with diameters in the range of 1.0 up to 2.2 nm has been investigated using classical molecular dynamics simulations. Diameter dependent molecular ordered phases were found for the encapsulation of adamantane (C10H16), diamantane (C14H20), and dihydroxy diamantane (C14H20O2). The same types of chiral ordered phases (double, triple, 4- and 5-stranded helices) observed for the encapsulation of C60 molecules were also observed for diamondoids. On the other hand, some achiral phases comprising layered structures were not observed. Our results also indicate that the modification of diamantane through functionalization with hydroxyl groups can lead to an enhancement of the packing of molecules inside the nanotubes compared to nonfunctionalized compounds. Comparisons to hard-sphere models are also presented revealing differences, specially when more asymmetrical diamondoids are considered. For larger structures (adamantane tetramers) we have not observed long-range ordering for nanotubes with diameters in the range of 1.49 to 2.17 nm but only a tendency to form incomplete helical structures.
Endohedral terthiophene in zigzag carbon nanotubes: Density functional calculations  [PDF]
W. Orellana,S. O. Vasquez
Physics , 2006, DOI: 10.1103/PhysRevB.74.125419
Abstract: The inclusion and encapsulation of terthiophene (T3) molecules inside zigzag single-walled carbon nanotubes (CNTs) is addressed by density functional calculations. We consider the T3 molecule inside five semiconducting CNTs with diameters ranging from 9.6 to 12.7 Ang. Our results show that the T3 inclusion process is exothermic for CNTs with diameters larger than 9.5 Ang. The highest energy gain is found to be of 2 eV, decreasing as the CNT diameter increases. This notable effect of stabilization is attributed to the positively charged CNT inner space, as induced by its curvature, which is able to accommodate the neutral T3 molecule. The band structure of the T3@CNT system shows that T3 preserves its electronic identity inside the CNTs, superimposing their molecular orbitals onto the empty CNT band structure without hybridization. Our results predict that the electronic states added by the T3 molecules would give rise to optical effects and nonradiative relaxation from excited states.
Enhanced encapsulation of metoprolol tartrate with carbon nanotubes as adsorbent
Kevin Garala,Jaydeep Patel,Anjali Patel,Abhay Dharamsi
Applied Nanoscience , 2011, DOI: 10.1007/s13204-011-0030-3
Abstract: A highly water-soluble antihypertensive drug, metoprolol tartrate (MT), was selected as a model drug for preparation of multi-walled carbon nanotubes (MWCNTs)-impregnated ethyl cellulose (EC) microspheres. The present investigation was aimed to increase encapsulation efficiency of MT with excellent adsorbent properties of MWCNTs. The unique surface area, stiffness, strength and resilience of MWCNTs have drawn much anticipation as carrier for highly water-soluble drugs. Carbon nanotubes drug adsorbate (MWCNTs:MT)-loaded EC microspheres were further optimized by the central composite design of the experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and t 50 (time required for 50% drug release). The optimized batch was compared with drug alone EC microspheres. The results revealed high degree of improvement in encapsulation efficiency for MWCNTs:MT-loaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 15 h, while by the same time only 50–60% drug was released for MWCNTs-impregnated EC microspheres. The optimized batch was further characterized by various instrumental analyses such as scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. The results endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres, which might have resulted in enhanced encapsulation and sustained effect of MT. Hence, MWCNTs can be utilized as novel carriers for extended drug release and enhanced encapsulation of highly water-soluble drug, MT.
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