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Utilization of spent iron catalyst for ammonia synthesis

100%
Arabczyk W., Narkiewicz U., Lendzion-Bieluń Z., Moszyński D., Pełech I., Ekiert E., Podsiadły M., Pelka R., Jędrzejewski R., Moszyńska I., Sibera D.
Polish Journal of Chemical Technology
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2007
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vol. 9
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issue 3
108-113
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.
2
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Synthesis of carbon nanotubes via chemical vapor deposition by using rareearth metals as catalysts

100%
Jędrzejewska A., Wnuk K., Kaleńczuk R., Borowiak-Paleń E.
Polish Journal of Chemical Technology
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2010
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vol. 12
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issue 3
29-32
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.
3
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STM/STS investigation of carbon nanotubes deposited on Bi2Te3 surface

100%
Bazarnik M., Cegiel M., Biskupski P., Jazdzewska M., Mielcarek S. a., Sliwinska-Bartkowiak M. g., Czajka R.
Open Physics
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2009
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vol. 7
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issue 2
295-298
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.
4
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Preparation and characterization of catalyst mix Fe-Co/MgO for carbon nanotubes growth

100%
Steplewska A., Jedrzejewski R., Borowiak-Palen E.
Polish Journal of Chemical Technology
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2008
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vol. 10
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issue 3
1-3
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.
5
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A DFT study on the interaction between europium, uranium and SWCNT

100%
Xie J.-C., Yong-Jian-Tang, Zhang H.
Open Physics
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2011
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vol. 9
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issue 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.
6
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Remarks on theoretical modelling of spin-dependent electronic transport in carbon nanotubes and graphene

100%
Krompiewski S.
Open Physics
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2011
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vol. 9
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issue 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.
7
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Characterisation of Ni-C films obtained in PVD/CVD process

88%
Kęczkowska J.
Open Physics
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2011
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vol. 9
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issue 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.
8
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Vibration Analysis of a Carbon Nanotube Reinforced Uniform and Tapered Composite Beams

88%
Babu Arumugam A., Rajamohan V., Bandaru N., Edwin S. P., Kumbhar S. G., Babu Arumugam A., Rajamohan V., Bandaru N., Edwin S. P., Kumbhar S. G.
Archives of Acoustics
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2019
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vol. 44
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issue 2
9
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Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts

88%
Pełech I., Narkiewicz U., Kaczmarek A., Jędrzejewska A.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 1
117-122
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.
10
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Discrete-continuum transition at interfaces of nanocomposites

88%
Pyrz R., Bochenek B.
Bulletin of the Polish Academy of Sciences: Technical Sciences
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2007
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vol. 55
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issue 2
11
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Miniaturized sample preparation based on carbon nanostructures

75%
Cárdenas S.
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issue 1
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.
12
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Silicon nitride/carbon nanotube composites: preparation and characterization

75%
Mikuśkiewicz M., Mikuśkiewicz M.
Bulletin of the Polish Academy of Sciences: Technical Sciences
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2021
13
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Buckling analysis of composite cylindrical shells reinforced by carbon nanotubes

71%
Jam J. E., Asadi E., Jam J. E., Asadi E.
Archive of Mechanical Engineering
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2012
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vol. 59
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issue 4
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