scholarly journals Free and partially encapsulated manganese ferrite nanoparticles in multiwall carbon nanotubes

2020 ◽  
Vol 11 ◽  
pp. 1891-1904
Author(s):  
Saja Al-Khabouri ◽  
Salim Al-Harthi ◽  
Toru Maekawa ◽  
Mohamed E Elzain ◽  
Ashraf Al-Hinai ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Ferrite Nanoparticles ◽  
Photoemission Spectroscopy ◽  
Manganese Ferrite ◽  
X Ray Diffraction ◽  
Band Emission ◽  
Structure Surface ◽  
Diffraction Peaks ◽  
Multiwall Carbon

Free and partially encapsulated manganese ferrite (MnFe2O4) nanoparticles are synthesized and characterized regarding structure, surface, and electronic and magnetic properties. The preparation method of partially encapsulated manganese ferrite enables the formation of a hybrid nanoparticle/tube system, which exhibits properties of manganese ferrite nanoparticles inside and attached to the external surface of the tubes. The effect of having manganese ferrite nanoparticles inside the tubes is observed as a shift in the X-ray diffraction peaks and as an increase in stress, hyperfine field, and coercivity when compared to free manganese ferrite nanoparticles. On the other hand, a strong charge transfer from the multiwall carbon nanotubes is attributed to the attachment of manganese ferrite nanoparticles outside the tubes, which is detected by a significant decrease in the σ band emission of the ultraviolet photoemission spectroscopy signal. This is followed by an increase in the density of states at the Fermi level of the attached manganese ferrite nanoparticles in comparison to free manganese ferrite nanoparticles, which leads to an enhancement of the metallic properties.

Effect of Urea on the Shape and Structure of Carbon Nanotubes

2018 ◽  
Vol 73 (2) ◽  
pp. 113-120 ◽  
Author(s):  
M. R. Elamin ◽  
Babiker Y. Abdulkhair ◽  
Kamal K. Taha
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Chemical Vapour ◽  
Multiwall Carbon Nanotubes ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Adsorption Analysis ◽  
Bet Analysis ◽  
Multiwall Carbon

AbstractCoiled multiwall carbon nanotubes (MWCNTs) were prepared on Fe, Co, and Ni metal oxides supported on α-Al2O3 using urea as fuel and catalyst surface modifying agent by catalytic chemical vapour deposition (CCVD). The shape of the nanotubes was influenced by the addition of urea, where coiled and uncoiled tubes were obtained in the presence and absence of urea, respectively. The MWCNTs were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption analysis. The coiling/uncoiling of the nanotubes was visualized from the SEM and TEM images of the prepared specimens. The XRD data showed the characteristic peaks of the nanotubes. BET analysis of the coiled tubes revealed 85.57 m2 g−1 surface area with a pore diameter 102.2–110.8 Å. A mechanism for the nanotubes coiling is suggested.

Ni-Coated Carbon Nanotubes/Mn-Zn Ferrite Composite as Viable Microwave Absorbing Materials

2011 ◽  
Vol 399-401 ◽  
pp. 310-314 ◽  
Author(s):  
Wen Jie Wang ◽  
Chong Guang Zang ◽  
Qing Jie Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Spinel Ferrite ◽  
Multiwall Carbon Nanotubes ◽  
Frequency Interval ◽  
Design Development ◽  
X Ray Diffraction ◽  
Microwave Absorbing Materials ◽  
Zn Ferrite ◽  
Multiwall Carbon

This paper presents the design, development and characterization of the spinel ferrite [Mn0.2Zn0.8Fe2O4] powders and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs). A combination of Mn0.2Zn0.8Fe2O4 spinel ferrites particles and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs) were introduced into epoxy resin to be a microwave absorber. The structural characterizations and surface morphology of Mn0.2Zn0.8Fe2O4 and MWNTs were investigated by X-ray diffraction (XRD) and scanning electron microscopy respectively. The electromagnetic wave absorption characteristics of the composites have been studied in the frequency interval of 12-15GHz.The results for Mn0.2Zn0.8Fe2O4/EP, Mn0.2Zn0.8Fe2O4/MWNTs/EP and Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP microwave absorbers for the same thickness have been reported. It has been found that the Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP composites show the broadband characteristics with minimum absorption of 5 dB about 2.6 GHz and the maximum absorption of 37.05 dB at 14 GHz for a coating thickness of 2 mm. Therefore, Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP composites will be a suitable microwave absorptive material for 12-15GHz.

scholarly journals Preparation and Microwave Absorbing Properties of an Electroless Ni-Co Coating on Multiwall Carbon Nanotubes Using [Ag(NH3)2]+as Activator

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Qiao-ling Li ◽  
Xiao-yong He ◽  
Yue-qing Zhang ◽  
Xiao-feng Yang
Keyword(s):  
Carbon Nanotubes ◽  
Energy Dispersive Spectrometry ◽  
Multiwall Carbon Nanotubes ◽  
Nucleation Site ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Electroless Ni ◽  
Coated Carbon ◽  
Multiwall Carbon

Ni-Co-coated carbon nanotubes (CNTs) composites with different molar ratios of Ni/Co were synthesized using [Ag(NH3)2]+as activator andH2PO2-as reductant, thereby replacing the conventional noble metal Pd salt activator and Sn2+reductant. Scanning electron microscopy, X-ray diffraction, and X-ray energy dispersive spectrometry analyses demonstrated that the CNTs were deposited with a dense, uniform Ni-Co coating. The possible mechanism of the electroless method was studied, which indicates that pure Ag0acted as a nucleation site for subsequent Ni-Co-P deposition. Network vector analyzer measurements indicated that the composite with only Ni coated had an absorbing value of −12.6 dB and the composite with a Ni/Co ratio of four had the maximum wave absorption (−15.6 dB) and the widest absorption bandwidth (800 MHz, RL < −10 dB), while the saturation magnetization (Ms) was 4.28 emu·g−1and the coercive force (Hc) was 31.33 Oe.

scholarly journals Inverse photoemission spectroscopy of multiwall carbon nanotubes

2006 ◽  
Vol 36 (3b) ◽  
pp. 894-897 ◽  
Author(s):  
Samuel Hevia ◽  
Wladimir Ibáñez ◽  
Rodrigo Segura ◽  
Patricio Häberle
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Photoemission Spectroscopy ◽  
Inverse Photoemission ◽  
Inverse Photoemission Spectroscopy ◽  
Multiwall Carbon

scholarly journals Synthesis of Carbon Nanotubes from Graphite and Investigation of the Catalytic Activity of MWCNTs/Cr2O3–NiO with the Removal of Bismarсk Brown G Dye from Its Aqueous Solution

2019 ◽  
Vol 64 (4) ◽  
pp. 276 ◽  
Author(s):  
E. J. Mohammad ◽  
M. M. Kareem ◽  
A. J. Atiyah
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Drying Process ◽  
X Ray Diffraction ◽  
Photocatalytic Reactions ◽  
Synthesis Of Carbon Nanotubes ◽  
Multiwall Carbon

This work describes the synthesis of carbon nanotubes from graphite by the chemical precipitation method and nanocomposites of multiwall carbon nanotubes (MWCNTs) with co-oxide nanocomposite (MWCNTs)/MO(Cr2O3–NiO). Those nanocomposites were prepared with the use of a simple evaporation and a drying process. The obtained composites were characterized, by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The activity of the prepared composites was investigated by the following removal of a Bismarck brown G dye (BBG) from the aqueous solution via photocatalytic reactions. The efficiency of the photocatalytic dye removal over the prepared composites was 91.43% after one hour of reaction under the optimal conditions, which were a mass dosage of 0.03 g, pH = 5, and a temperature of 30 ∘C.

Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

2018 ◽  
Author(s):  
Gen Hayase
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Aqueous Solutions ◽  
High Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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