Thermoelectric Properties of Single-Wall Carbon Nanotubes

1998 ◽  
Vol 545 ◽  
Author(s):  
L. Grigorian ◽  
G. Sumanasekera ◽  
P. C Eklund
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Magnetic Moments ◽  
Scattering Data ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Single Wall Carbon ◽  
Impurity Atoms ◽  
Kondo System

AbstractResults of the temperature dependence of the thermoelectric power and fourprobe resistance of single wall carbon nanotube mats are presented. The data are interpreted in terms of the response of a percolating network of metallic nanotube bundles. To the best of our knowledge, the work represents the first systematic study of the transport properties of a series of samples prepared using different transition metal-Y growth catalysts. Although x-ray diffraction and Raman scattering data indicate these samples are nominally the same, we find that the identity of the catalyst has a pronounced effect on the electrical transport properties. The data are interpreted qualitatively in terms of a dilute Kondo system involving the coupling of the the localized magnetic moments of impurity atoms (derived from the catalyst), and the conduction electron spins in the nanotube walls.

The Effect of Cooling Process on the Microstructure and Electrical Transport Properties of AgSbTe2 Compound

2013 ◽  
Vol 743-744 ◽  
pp. 59-64
Author(s):  
Liang Wei Fu ◽  
Jun You Yang ◽  
Ye Xiao ◽  
Jiang Ying Peng ◽  
Ming Yang Zhang
Keyword(s):  
Electrical Resistivity ◽  
Transport Properties ◽  
Liquid Nitrogen ◽  
Electrical Transport ◽  
Cooling Water ◽  
Air Cooling ◽  
X Ray Diffraction ◽  
Cooling Process ◽  
Electrical Transport Properties ◽  
Apparent Influence

AgSbTe2compounds have been synthesized via melting and subsequent cooling processes. The effect of cooling process, from air-cooling, water quenching to liquid nitrogen-quenching, on the microstructure and the electrical transport properties of AgSbTe2has been investigated by means of powder X-ray diffraction, electron microscope, electrical resistivity, and Hall coefficient measurements. It has been found that the cooling process has apparent influence on the microstructure and corresponding electrical properties. The phase components and morphology changed as the cooling process altered. The electrical resistivity and the Seebeck coefficient of the as-prepared samples increased from air-cooled to liquid nitrogen-quenched sample.

Study of Structural and Electrical Transport Properties of Polycrystalline La1-XCaXMnO3 (x=0.33, 0.5 and 0.9) Prepared by a Co-Precipitation Method

2013 ◽  
Vol 652-654 ◽  
pp. 576-580 ◽  
Author(s):  
Mya Theingi ◽  
Ji Ma ◽  
Hui Zhang ◽  
Xiang Gao ◽  
Jian Hong Yi ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Perovskite Phase ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
X Ray ◽  
Manganite Perovskite ◽  
Polycrystalline Ceramics ◽  
Co Precipitation

Manganite perovskite La1-xCaxMnO3(x=0.33, 0.5 and 0.9) have been prepared by chemical co-precipitation method. Ammonium carbonate was used to coprecipitate lanthanum, calcium and manganese ions as carbonates under basic condition. This precursor on calcining at 900°C yields La-Ca-Mn-O perovskite phase. Follow by sintering at 1200°C after the powders were pressed into pellets gave La1-xCaxMnO3(LCMO) polycrystalline ceramics. The crystal phases of the resulting powders and ceramics were examined by X-ray diffraction (XRD) technique. The morphology of the powders was observed by scanning electron microscopy (SEM) and electrical transport properties of ceramics were measured by conventional four-point probe technique.

scholarly journals The Undoped Polycrystalline Diamond Film—Electrical Transport Properties

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6113
Author(s):  
Szymon Łoś ◽  
Kazimierz Fabisiak ◽  
Kazimierz Paprocki ◽  
Mirosław Szybowicz ◽  
Anna Dychalska
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Localized States ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Temperature Range ◽  
Hot Filament ◽  
Si Wafer

The polycrystalline diamonds were synthesized on n-type single crystalline Si wafer by Hot Filament CVD method. The structural properties of the obtained diamond films were checked by X-ray diffraction and Raman spectroscopy. The conductivity of n-Si/p-diamond, sandwiched between two electrodes, was measured in the temperature range of 90–300 K in a closed cycle cryostat under vacuum. In the temperature range of (200–300 K), the experimental data of the conductivity were used to obtain the activation energies Ea which comes out to be in the range of 60–228 meV. In the low temperature region i.e., below 200 K, the conductivity increases very slowly with temperature, which indicates that the conduction occurs via Mott variable range hopping in the localized states near Fermi level. The densities of localized states in diamond films were calculated using Mott’s model and were found to be in the range of 9×1013 to 5×1014eV−1cm−3 depending on the diamond’s surface hydrogenation level. The Mott’s model allowed estimating primal parameters like average hopping range and hopping energy. It has been shown that the surface hydrogenation may play a crucial role in tuning transport properties.

Structural, Magnetic, and Transport Properties of La0.62Sb0.38MnO3 Ceramic

2013 ◽  
Vol 800 ◽  
pp. 398-401 ◽  
Author(s):  
Qiang Wang ◽  
Ping Duan ◽  
Ji You Wang ◽  
Lei Chang ◽  
Jin Liang Zhao ◽  
...  
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
State Transition ◽  
Ferromagnetic State ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Hexagonal Crystal ◽  
Electrical Transport Properties ◽  
Metal Insulator ◽  
X Ray

The polycrystalline La0.62Sb0.38MnO3 sample has been prepared by the solid-state reaction method. Structural, magnetic and electrical transport properties have been researched. X-ray diffraction analysis confirms the hexagonal crystal symmetry. Magnetization measurements indicate La0.62Sb0.38MnO3 experienced from paramagnetic to ferromagnetic state transition with decreasing temperature at about 225 K. Resistivity dependences on temperature exhibit metal-insulator transition (MIT), and the maximum magnetoresistance (MR) ratio is about 33 % at temperature of 189 K and magnetic field of 2 T.

Correlation of Microstructures with Electrical Transport Properties in Mn Doped Co Nanoferrite Particles

2012 ◽  
Vol 510-511 ◽  
pp. 487-492
Author(s):  
M. Akram ◽  
M. Anis-ur-Rehman ◽  
S. Nasir ◽  
G. Asghar
Keyword(s):  
Electrical Resistivity ◽  
Transport Properties ◽  
Cation Distribution ◽  
Electrical Transport ◽  
Research Work ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
Dc Electrical Resistivity ◽  
X Ray

Magnetic nanocomposites are offering a variety of novel features and tune able properties, mainly depending on particle size, cation distribution, morphology and porosity of the prepared materials. The aim of this research work is to understand the effects of Mn doping on the microstructures and hence consequences on the electrical transport properties with shift of cation distribution in CoFe2O4. Co1-xMnxFe2O4nanocrystallite particles with stoichiometric proportion (x) varying from 0.0 to 1.0 were prepared by co-precipitation method. X-ray diffraction patterns confirmed the FCC spinel structure of synthesized particles. The crystal structure is found to be inverse cubic spinel with a space group Fd3m and the lattice constants ranges from 8.36 Å to 8.46 Å The crystallite sizes were calculated from the most intense peak (311) using the Debye-Scherrer formula for all the samples those were synthesized at reaction temperature of 70°C. Then samples were sintered at 600°C for 3 hours, characterized by X-ray diffraction at room temperature and DC electrical resistivity measurements were done as a function of temperature by two-probe method from 370 K to 690 K. The measurements showed that DC electrical resistivity decreased with increase in temperature ensuring the semiconductor nature of the material in this temperature range. DC electrical resistivity results were discussed in terms of polaron hopping model under the effects of cation distribution. AC electrical properties were also analyzed. All the observed properties were correlated with observed microstructures.

Electrical transport properties of a single wall carbon nanotube network

2009 ◽  
Vol 246 (4) ◽  
pp. 744-746 ◽  
Author(s):  
J. S. Hwang ◽  
H. T. Kim ◽  
H. K. Kim ◽  
M. H. Son ◽  
S. W. Hwang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Transport Properties ◽  
Electrical Transport ◽  
Electrical Transport Properties ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Carbon Nanotube Network
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