Understanding resonant tunnel transport in non-identical and non-aligned clusters as applied to disordered carbon systems

2014 ◽  
Vol 116 (15) ◽  
pp. 154305
Author(s):  
Somnath Bhattacharyya ◽  
Dmitry Churochkin
Keyword(s):  
Disordered Carbon ◽  
Resonant Tunnel

scholarly journals Novel Approach Through the Harmonized Sulfur in Disordered Carbon Structure for High-Efficiency Sodium-Ion Exchange

2020 ◽  
Vol 12 (39) ◽  
pp. 43750-43760 ◽  
Author(s):  
Hanvin Kim ◽  
Dae-Yeong Kim ◽  
Shungo Zen ◽  
Jun Kang ◽  
Nozomi Takeuchi
Keyword(s):  
Ion Exchange ◽  
High Efficiency ◽  
Sodium Ion ◽  
Carbon Structure ◽  
Novel Approach ◽  
Disordered Carbon

scholarly journals Understanding the local structure of disordered carbons from cellulose and lignin

2021 ◽  
Author(s):  
Yujie Meng ◽  
Cristian I. Contescu ◽  
Peizhi Liu ◽  
Siqun Wang ◽  
Seung-Hwan Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Treatment Temperature ◽  
Graphite Sheet ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation ◽  
Scanning Transmission ◽  
Disordered Carbon ◽  
Biomass Components ◽  
Softwood Kraft Lignin

AbstractAn electron microscopy investigation was performed to understand the relationship between the microstructure and properties of carbonized cellulose and lignin (softwood kraft lignin) relative to the structure of the original biomass components. Structure details at micro- and molecular levels were investigated by scanning transmission electron microscopy. Atomic-resolution images revealed the presence of random disordered carbon in carbonized cellulose (C-CNC) and of large domains of well-ordered carbon with graphite sheet structure in carbonized lignin (C-Lignin). These structural differences explain why C-CNC exhibits higher surface area and porosity than C-Lignin. The presence of certain well-ordered carbon in carbonized lignin indicates some of the carbon in lignin are graphitized with heat treatment temperature up to 950 °C. This result is encouraging for future endeavors of attaining acceptable modulus of carbon fiber from lignin given suitable modifications to the chemistry and structure of lignin. The results of this research contribute to an improved understanding of the carbonization mechanism of the key cellulose and lignin components of biomass materials.

Magnetism of pure, disordered carbon films prepared by pulsed laser deposition

2004 ◽  
Vol 272-276 ◽  
pp. E839-E840 ◽  
Author(s):  
R. Höhne ◽  
K.-H. Han ◽  
P. Esquinazi ◽  
A. Setzer ◽  
H. Semmelhack ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Carbon Films ◽  
Laser Deposition ◽  
Disordered Carbon

AlAs/GaAs Schottky-collector resonant-tunnel-diodes

1993 ◽  
Vol 36 (12) ◽  
pp. 1673-1676 ◽  
Author(s):  
Y. Konishi ◽  
S.T. Allen ◽  
M. Reddy ◽  
M.J.W. Rodwell ◽  
R.P. Smith ◽  
...  
Keyword(s):  
Tunnel Diodes ◽  
Resonant Tunnel

The structure of disordered carbon solids studied using a hybrid reverse Monte Carlo algorithm

2005 ◽  
Vol 17 (17) ◽  
pp. 2605-2616 ◽  
Author(s):  
G Opletal ◽  
T C Petersen ◽  
D G McCulloch ◽  
I K Snook ◽  
I Yarovsky
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Algorithm ◽  
Reverse Monte Carlo ◽  
Disordered Carbon

Magnetism and Spin Tunneling in Nanostructures

1997 ◽  
Vol 491 ◽  
Author(s):  
Alexander Bratkovsky
Keyword(s):  
Spin Polarization ◽  
Tunnel Junctions ◽  
Iron Group ◽  
Defect States ◽  
Resistance Change ◽  
Half Metallic ◽  
Spin Tunneling ◽  
Inelastic Tunneling ◽  
Resonant Tunnel ◽  
General Method

ABSTRACTIn the present paper different tunneling mechanisms in conventional and half-metallic ferromagnetic tunnel junctions are analyzed within the same general method. Theoretically calculated direct tunneling in iron group systems leads to about a 30% change in resistance, which is close but lower than experimentally observed values. It is shown that the larger observed values of the TMR might be a result of tunneling involving surface polarized states. We find that tunneling via resonant defect states in the barrier radically decreases the TMR (down to 4% with Fe-based electrodes), and a resonant tunnel diode structure would give a TMR of about 8%. With regards to inelastic tunneling, magnons and phonons exhibit opposite effects: one-magnon emission generally results in spin mixing and, consequently, reduces the TMR, whereas phonons are shown to enhance the TMR. The inclusion of both magnons and phonons reasonably explains an unusual bias dependence of the TMR.The model presented here is applied qualitatively to half-metallics with 100% spin polarization, where one-magnon processes are suppressed and the change in resistance in the absence of spin-mixing on impurities may be arbitrarily large. Even in the case of imperfect magnetic configurations, the resistance change can be a few 1000 percent. Examples of half-metallic systems are CrO2/TiO2 and CrO2/RuO2, and an account of their peculiar band structures is presented. The implications and relation of these systems to CMR materials, which are nearly half-metallic, are discussed.

Metal-insulator transition in highly disordered carbon fibers

1992 ◽  
Vol 7 (4) ◽  
pp. 940-945 ◽  
Author(s):  
K. Kuriyama ◽  
M.S. Dresselhaus
Keyword(s):  
Carbon Fibers ◽  
Structural Changes ◽  
Dark Conductivity ◽  
Activated Carbon Fibers ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
Heat Treated ◽  
Insulator Metal Transition ◽  
Disordered Carbon ◽  
Diffraction Patterns

The electronic transition from localized to delocalized states of carriers in a disordered carbon material is investigated by photoconductivity measurements. Phenol-derived activated carbon fibers, where the carriers are strongly localized due to disorder, are heat treated in the range 300–2500 °C to give rise to the insulator-metal transition. Dark conductivity, Raman spectra, and x-ray diffraction patterns are also measured to characterize their structural changes. As a result, the transition temperature was determined to be rather low, around 1000 °C, considering the rapid decrease in the photoconductivity above this temperature. This decrease was ascribed to a fast recombination between the photoexcited carriers and the delocalized carriers generated by heat treatment.

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