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1
Content available remote A DFT study on the interaction between europium, uranium and SWCNT
100%
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2011
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tom 9
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nr 3
716-721
EN
We investigate the electronic and band structure for the (8; 0) single-wall carbon nanotube (SWCNT) with a europium (Eu) and a uranium (U) atom outside by using the first-principles method with the density functional theory (DFT). The calculated band structure (BS), total density of state (TDOS), and projected density of state (PDOS) can elucidate the differences between the pure (8; 0) SWCNT and the nuclei outside the SWCNT. The indirect band gaps are obtained when Eu and U atom are put outside the (8; 0) CNT; they are 0.037 eV and 0.036 eV, respectively, which is much smaller than 0.851 eV for pure CNT. Compared with pure (8; 0) SWCNT, the bottom of the conduction band moves down by 0.383 eV and 0.451 eV with the Eu and U outside, and the top of valence band moves up by 0.127 eV and 0.162 eV, respectively. More significantly, the top of the valence band has exceeded the fermi-level. So, a single nucleus changes the semiconductor character of pure nanotube to semi-metal.
2
100%
EN
Fe-Co/MgO is one of the most common catalyst mix applied to carbon nanotubes (CNTs) growth in chemical vapor deposition process. Therefore, here we present detailed study on the preparation and characterization of Fe-Co/MgO. The precursors of Fe and Co are iron (II) acetate and cobalt acetates, correspondingly. The molar ratio of the catalyst mix is Fe:Co:MgO=1:1:100. Initially, thermogravimetric analysis (TGA) of the mixture was performed. TGA analysis of it indicated the stepwise mass losses which pointed out the crucial thermal conditions for the changes in the elemental composition, morphology, crystallographic structure and vibrational properties. In current state of the art the lowest growth temperature for singlewalled carbon nanotubes is 550°C in CVD technique and here the characterization of the catalyst mix strongly suggest that this temperature can be decreased what would enhance the compatibility of CNT growth with current complementary metal-oxide-silicon (CMOS) technology for CNTs-based nanoelectronics. The morphology, crystallographic structure, elemental composition of the samples and its spectroscopic properties were performed via high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (IR), respectively.
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2011
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tom 9
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nr 2
369-371
EN
This contribution reports on charge and spin transport through graphene nanoribbons (GrNs) and carbon nanotubes (CNTs). The paper focuses on the giant magnetoresistance effect in these materials, and their potential usefulness for spintronic applications. As examples, the following devices are shortly discussed: GrNs in the ballistic transport regime, a CNT-based Schottky-barrier field effect transistor (CNT SB-FET), as well as CNT quantum dots in the Coulomb blockade limit.
EN
This work presents the results of the synthesis of carbon nanotubes using the CVD method. Fe: MgO catalyst was used, also in combination with rare earth elements (gadolinium (Gd), dysprosium (Dy)), which when used alone, are not efficient as catalysts in nanotube growth. Synthesis was performed both at reduced pressure (10-3 mbar) and atmospheric pressure, with constant parameters dependent on the process parameters.
5
Content available remote Utilization of spent iron catalyst for ammonia synthesis
100%
EN
Several methods of the utilization of spent iron catalyst for ammonia synthesis have been presented. The formation of iron nitrides of different stoichiometry by direct nitriding in ammonia in the range of temperatures between 350°C and 450°C has been shown. The preparation methods of carbon nanotubes and nanofibers where iron catalyst catalyse the decomposition of hydrocarbons have been described. The formation of magnetite embedded in a carbon material by direct oxidation of carburized iron catalyst has been also presented.
EN
In this study, the electrospray deposition (ESD) method was used to deposit carbon nanotubes (CNT) onto the surfaces of carbon fibers (CF) in order to produce hybrid carbon fiber-carbon nanotubes (CF-CNT) which is rarely reported in the past. Extreme high-resolution field emission scanning electron microscopy (XHR-FESEM), high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS) were used to analyse the hybrid carbon fiber-carbon nanotube (CF-CNT). The results demonstrated that CNT was successfully and homogenously distributed on the CF surface. Hybrid CF-CNT was then prepared and compared with CF without CNT deposition in terms of their tensile properties. Statistically, the tensile strength and the tensile modulus of the hybrid CF-CNT were increased by up to 3% and 25%, respectively, as compared to the CF without CNT deposition. The results indicated that the ESD method did not cause any reduction of tensile properties of hybrid CF-CNT. Based on this finding, it can be prominently identified some new and significant information of interest to researchers and industrialists working on CF based products.
7
Content available remote STM/STS investigation of carbon nanotubes deposited on Bi2Te3 surface
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EN
This paper reports our scanning tunneling microscopy and spectroscopy (STM/STS) study of double-walled and multi-walled carbon nanotubes (CNTs) of different diameter deposited on Bi2Te3 (narrow gap semiconductor). The approximate diameter of the studied double-walled and multi-walled CNTs was 2 nm and 8 nm, respectively. Crystalline Bi2Te3 was used as a substrate to enhance the contrast between the CNTs and the substrate in the STS measurements performed to examine peculiarities of CNT morphology, such as junctions, ends or structural defects, in terms of their electronic structure.
EN
Herein, the effects of multi-walled carbon nanotubes (CNTs) on the mechanical and dielectric performance of hybrid carbon nanotube-woven glass fiber (GF) reinforced epoxy laminated composited are investigated. CNTs are deposited on woven GF surface using an electrospray deposition method which is rarely reported in the past. The woven GF deposited with CNT and without deposited with CNT are used to produce epoxy laminated composites using a vacuum assisted resin transfer moulding. The tensile, flexural, dielectric constant and dielectric loss properties of the epoxy laminated composites were then characterized. The results confirm that the mechanical and dielectric properties of the woven glass fiber reinforced epoxy laminated composited increases with the addition of CNTs. Field emission scanning electron microscope is used to examine the post damage analysis for all tested specimens. Based on this finding, it can be prominently identified some new and significant information of interest to researchers and industrialists working on GF based products.
EN
The introduction of carbon nanotubes (CNTs) onto glass fibre (GF) to create a hierarchical structure of epoxy laminated composites has attracted considerable interest due to their merits in improving performance and multifunctionality. Field emission scanning electron microscopy (FESEM) was used to analyze the woven hybrid GF-CNT. The results demonstrated that CNT was successfully deposited on the woven GF surface. Woven hybrid GF-CNT epoxy laminated composites were then prepared and compared with woven GF epoxy laminated composites in terms of their tensile properties. The results indicated that the tensile strength and tensile modulus of the woven hybrid GF-CNT epoxy laminated composites were improved by up to 9% and 8%, respectively compared to the woven hybrid GF epoxy laminated composites.
EN
The effect of titanium nitride (TiN) thickness as the support layer for carbon nanotubes (CNTs) growth was investigated by depositing three different thicknesses: 20 nm, 50 nm and 100 nm. This TiN support layer was deposited on SiO2 pads before depositing nickel (Ni) as the catalyst material. The Ni distribution on different TiN thicknesses was studied under hydrogen environment at 600°C. Then, the samples were further annealed at 600°C in acetylene and hydrogen environment for CNTs growth. The results show that, the optimum TiN thickness was obtained for 50 nm attributed by the lowest D to G ratio (0.8).
EN
An ammonium perchlorate (AP, NH4(ClO4)3)-based molecular perovskite energetic material (H2dabco)[NH4(ClO4)3]/carbon nanotubes (DAP/CNTs) composite was prepared and characterized. Molecular perovskite DAP samples were synthesized by a facile one-pot reaction of triethylenediamine, perchloric acid (PCA, HClO4), and AP via a molecular assembly strategy. The results showed that the mechanical sensitivity (impact and friction sensitivities: >120 cm and 20%) and electrostatic spark sensitivity (8.90 J) of the DAP/CNTs energetic composite with 10 wt.% CNTs exhibited less sensitivity than that of DAP (impact, friction and electrostatic spark sensitivities: 112.3 cm, 45%, and 5.39 J, respectively), because of the mixing desensitization mechanism of CNTs. Compared with the pure DAP, the DAP/CNTs energetic composite has better performance with respect to thermal stability, exothermic capacity, and excellent continuous combustion properties. The DAP/CNTs energetic composite has potential application in a weapons system.
12
Content available remote Characterisation of Ni-C films obtained in PVD/CVD process
88%
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2011
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tom 9
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nr 2
330-337
EN
The work presents the results of the scanning electron microscopy (SEM) and Raman spectrometry studies of carbonaceous nanostructures containing nickel nanocrystallites. The films were obtained using a two-step method. In the first phase the Physical Vapour Deposition (PVD) method was applied, whereas in the second Chemical Vapour Deposition (CVD) method was used. The paper presents results for samples with various Ni content obtained with different parameters of the two-phase technological process. The research confirms that the thin films obtained by PVD method contain Ni nanocrystallites distributed in a carbonaceous matrix. The matrix is composed of various carbon allotropes (amorphous carbon, graphite, fullerene). The thin films made by CVD method make a matrix when multiwalled, carbonaceous nanotubes are obtained. Depending on the technological process parameters of each phase, we obtain multiwall nanotubes with a various degree of defects.
EN
Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described.
14
88%
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nr 2
EN
Polypropylene (PP) and polyethylene (PE) plastic waste is accumulating in the environment and the oceans at an alarming rate. The current management methods, mostly landfilling and incineration, are becoming unsustainable. In this study, thermal catalytic conversion of waste PP and PE polymers into carbon nanotubes (CNTs) using a trimetallic catalyst prepared from the nitrate salts of iron, cobalt, and molybdenum supported with calcium carbonate was reported. The yield and quality of multi-walled carbon nanotubes (MWCNTs) produced were investigated. The findings showed a high graphitic value for the CNTs obtained from PP and PE, as corroborated by the d-spacing of XRD. The ID/IG ratio of CNTS synthesized from PP and PE as carbon sources were 0.6724 and 0.9028, respectively, which showed that CNT produced from PP has more ordered graphite. The functional groups present in the produced CNTs were determined via FITR analysis. The BET and Langmuir surface areas were found to be (6.834 and 70.468 m2/g) and (6.733 and 70.347 m2/g) for CNTs obtained from PP and PE respectively. The d-spacing was computed as 0.3425 nm and 0.3442 nm for CNTs made from PP and PE. These fall within the graphite's d-spacing at 0.335 nm. The TGA showed high percentage purity of 94.71 and 94.40% for the products obtained from PP and PE, respectively. The findings showed that recycled PP and PE could be good alternative carbon sources for CNT production.
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Content available remote Miniaturized sample preparation based on carbon nanostructures
75%
EN
The evolution of analytical methodologies has been driven by the objective to reduce the complexity of sample treatment while increasing the efficiency of the overall analytical process. For this reason, the analytical chemist takes into consideration advances in other scientific areas and systematically evaluates the potential influence that such discoveries might have on its own discipline. This is the present situation with nanostructured materials, which have already been recognized as a revolution in many scientific and technological fields, including analytical chemistry. Carbon nanoparticles have been a cornerstone in the advance of miniaturization of analytical processes. This review article considers the contribution of four reference carbon nanoparticles: nanotubes, graphene, nanohorns/ cones and fullerenes, in the context of miniaturized sample treatment, where their outstanding sorbent properties are by far the most exploited in (micro) solid phase extraction.
PL
Odkrycie nanorurek węglowych (CNT) w 1991 roku przez Sumio lijimę zapoczątkowało nową erę w materiałoznawstwie i nanotechnologii. Nanorurki węglowe to rodzaj alotropowej odmiany węgla, która budową przypomina walec. Twory te są niezwykle mocne i trudne do złamania, ale nadal lekkie. Ze względu na swoje fenomenalne właściwości elektryczne, termiczne, mechaniczne i chemiczne nanorurki węglowe są jednym z najlepiej przebadanych nanomateriałów. Wykorzystywane są w wielu dziedzinach, m.in. w medycynie, farmacji, nanoelektronice, nanokompozytach, w technologii elektronowej, przemyśle zbrojeniowym i wielu innych. Nanorurki węglowe są też często wykorzystywane w elektrochemii do konstrukcji czujników (tj. potencjometryczne), mających na celu poprawę ich odpowiedzi analitycznej. Nanomateriały te, ze względu na swoje unikatowe właściwości oraz ogromny obszar zastosowań, stanowią bardzo cenny materiał, który będzie zapewne głównym obiektem badań przyszłych technologii.
EN
The discovery of carbon nanotubes (CNTs) in 1991 by Sumio lijima gave rise to a new era in material science and nanotechnology. Carbon nanotubes are a kind of carbon allotrope that resembles a tube of carbon atoms. They are extremely strong and are difficult to break, but they are still light. Due to their phenomenal electrical, thermal, mechanical and chemical properties, carbon nanotubes are one of the most tested nanomaterials. They are used in many fields, including medicine, pharmacy, nanoelectronics, nanocomposites, electron technology, the defense industry and many others. Carbon nanotubes are also often used in electrochemistry for the construction of sensors (i.e. potentiometric ones), aiming to improve their analytical response. This nanomaterial, due to its unique properties and a vast area of application, is a very valuable material that will probably be the main object of research future technologies.
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2023
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tom Vol. 23, no. 3
art. no. e202, 2023
EN
Accurately predicting the 28-day compressive strength (CS) of carbon nanotubes-reinforced cement composites (CNTRCCs) and graphene oxide-reinforced cement composites (GORCCs) is crucial for accelerating their potential application in civil engineering. However, traditional experimental and theoretical modeling methods suffer from problems, including time-consuming, costly, and inefficient. Moreover, it is also challenging to consider the effects of multiple coupling factors. In this work, a multimodal machine learning (ML) approach is proposed as the first attempt to explore the complex relationships between the CS of hybrid system containing both CNTRCCs and GORCCs. The proposed multimodal ML shows great potential in estimating the nanomaterials-reinforced cement composites with a coefficient of determination (R2) of 0.96, surpassing the single-modal ML approaches. The results demonstrate the effectiveness of the developed model in accurately predicting the 28-day CS of hybrid system containing both CNTRCCs and GORCCs. Shapley additive explanations (SHAP) analysis illustrates that the optimal concentration of CNT is approximately 0.5 wt%, and preferred length of CNT and sheet size of GO are within a range of 20–30 μm and below 10 μm, respectively. Additionally, the enhancement effect of a single-layer GO is better than its multilayer counterparts.
PL
Omówiono wpływ grafitu oraz nanorurek węglowych dodanych do pasty powlekającej materiał tekstylny na podstawowe parametry mechaniczne. Przedstawiono wyniki badań odporności na przecięcie metodą TDM i coup test oraz odporności na ścieranie dla otrzymanych powlekanych materiałów tekstylnych.
EN
Meta-aramid fibers were coated with polyurethane paste mixed with graphite and C nanotubes in various configurations. Cutting and abrasion resistance as well as SEM anal. of composites were performed. The effect of the applied coating on the mech. parameters was examined.
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