scholarly journals Critical Temperature in Zigzag Graphene Nanoribbon: a First-principles Study

2021 ◽  
Vol 2019 (1) ◽  
pp. 012072
Author(s):  
T B Prayitno ◽  
E Budi
Keyword(s):  
Critical Temperature ◽  
Brillouin Zone ◽  
Room Temperature ◽  
High Energy ◽  
Graphene Nanoribbon ◽  
Pristine Graphene ◽  
Ribbon Width ◽  
The Mean ◽  
Magnon Spectrum ◽  
Good Agreement

Abstract The critical (Néel) temperature in the zigzag graphene nanoribbon was calculated using the mean-eld approximation within the generalized Bloch theorem. This calculation was carried out over the Brillouin zone of the magnon spectrum. We found a nearly at magnon dispersion at the high energy in one-third of the Brillouin zone. Our calculation showed the critical temperature below room temperature, in good agreement with the prediction in the previous works. Our last work (Prayitno 2021 Physica E 129 114641) revealed that the critical temperature may be enhanced by increasing the ribbon width. In this brief report, we justified that the critical temperature becomes almost constant up to a certain ribbon width. This result indicates that the critical temperature in the graphene nanoribbon will never reach room temperature for any ribbon widths, thus it is likely difficult to apply pristine graphene nanoribbon in any practical devices working near room temperature.

Silver Nanocrystals at Cavities Created by High Energy Helium Implantation in Bulk Silicon

2007 ◽  
Vol 994 ◽  
Author(s):  
Rachid El Bouayadi ◽  
Gabrielle Regula ◽  
Maryse Lancin ◽  
Eduardo Larios ◽  
Bernard Pichaud ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Energy ◽  
Nickel Silicide ◽  
Bulk Silicon ◽  
Shape Characteristic ◽  
Transmission Electron ◽  
Helium Implantation ◽  
Ag Deposition ◽  
First Time ◽  
Good Agreement

AbstractHigh resolution transmission electron microscopy observations show for the first time the presence of two orientations of pure silver precipitates in nanocavities induced in bulk silicon by implantation at 1.6 MeV with a dose of 5×1016 He+ cm−2 and a two hour annealing at 1050°C. These precipitates were called A and B to refer to the two well-known nickel silicide (NiSi2) precipitates or Ag films on a {111} silicon surface. Thus, the A precipitate corresponds to a growth of silver nanocrystal on {111} cavity walls in epitaxy with the Si matrix with an orientation relationship Ag(-111)[211]||Si(-111)[211]. The B precipitate develops on a {111} plane parallel to a {111} cavity wall as well, but in a twin orientation with respect to the Si matrix defined by Ag(-111)[211]||Si(-111)[-2-1-1]. The Ag nanocrystals have a size ranging from a few nm to 50 nm. Most of them have the faceted-shape characteristic of “clean” cavities. They are either A precipitates or they contain alternatively A and B bands in good agreement with both the low stacking fault energy of silver and the two types of nanocrystal orientations obtained by Ag deposition on (111) Si substrate at room temperature. Some Ag precipitates were also found at dislocations located at the He+ projection range, but these trapping sites were found thermally unstable as compared to the cavity ones. Indeed, during a second identical annealing, the precipitates grow in cavities whereas they fade at dislocations.

The Range Distribution of Nd Ions Implanted in Silicon-on-Insulator

2011 ◽  
Vol 306-307 ◽  
pp. 315-318
Author(s):  
Yi Liang ◽  
Hong Zhen Li ◽  
Shuang Li ◽  
Feng Xiang Wang ◽  
Xi Feng Qin
Keyword(s):  
Monte Carlo ◽  
Room Temperature ◽  
Silicon On Insulator ◽  
Monte Carlo Code ◽  
Experiment Data ◽  
Lateral Deviation ◽  
Projected Range ◽  
The Mean ◽  
The Difference ◽  
Good Agreement

In view of the influence of the projected range, the range straggling, and the lateral deviation of ions in materials on the property of photoelectric integration devices fabricated by ion implantation, the mean projected ranges and range straggling for energetic 200 – 500 keV neodymium (Nd) ions implanted in silicon-on-insulator (SOI) at room temperature were measured by means of Rutherford backscattering followed by spectrum analysis.The measured results are compared with Monte Carlo code (SRIM2006) predictions. Our results show that the measured values of the mean projected rangeRpare good agreement with the SRIM calculated values; for the range straggling ΔRp, the difference between the experiment data and the calculated results is much higher than that ofRp.

The Mean Projected Range and Range Straggling of Yb Ions Implanted in Silicon Crystal

2012 ◽  
Vol 476-478 ◽  
pp. 1249-1253
Author(s):  
Xi Feng Qin ◽  
Hui Ning Wang ◽  
Zi Wu Ji ◽  
Feng Xiang Wang ◽  
Gang Fu
Keyword(s):  
Room Temperature ◽  
Silicon Crystal ◽  
Single Crystal Silicon ◽  
Monte Carlo Code ◽  
Experiment Data ◽  
Crystal Silicon ◽  
Projected Range ◽  
The Mean ◽  
The Difference ◽  
Good Agreement

The mean projected ranges and range straggling for energetic 200 – 500 keV Yb ions implanted in single crystal silicon (c-Si) at room temperature were measured by means of Rutherford backscattering followed by spectrum analysis. The measured results are compared with Monte Carlo code (SRIM2010) predictions. Our results show that the measured values of the mean projected range Rp are good agreement with the SRIM calculated values; but the difference of the range straggling ΔRp between the experiment data and the calculated results is much higher than that of Rp.

Infrared analysis of Glycine dissociation by MeV ions and keV electrons

2021 ◽  
Author(s):  
C A P da Costa ◽  
J A Souza-Corrêa ◽  
E F da Silveira
Keyword(s):  
Solar Wind ◽  
Cross Sections ◽  
Room Temperature ◽  
Stopping Power ◽  
Infrared Analysis ◽  
Absorbed Energy ◽  
Power Threshold ◽  
The Mean ◽  
Good Agreement ◽  
Electronic Stopping Power

Abstract Knowledge on amino acid's dissociation rates by solar wind is relevant for the study of biomaterial resistance in space. The radiolysis and sputtering of glycine by 1 keV electron beam and by 1.8 MeV H+, 1.5 MeV He+ and 1.5 MeV N+ ion beams are studied in laboratory, at room temperature. The column density decrease rates due to each beam are measured via infrared spectroscopy and destruction cross sections are determined. Present results stand in good agreement with those found in the literature and show that over five orders of magnitude, apparent destruction cross sections (which includes sputtering), σdap, are approximately proportional to the electronic stopping power, Se, that is (σdap ≈ a Se), where 1/a ≈ 120 eV/nm3. This value corresponds to the mean absorbed energy density necessary to dissociate (and/or eject) glycine; it also suggests that the stopping power threshold for molecular destruction is 23 keV μm−1. Assuming σdap = a Se for electron and ion projectiles, the half-life of pure α-glycine is estimated for the solar wind processing at 1 AU: about 10 days for protons or electrons and 40 days for He ions.

A possible explanation of pressure dependence of critical temperature Tc of alkali doped C60 superconductors

2015 ◽  
Vol 29 (03) ◽  
pp. 1550003
Author(s):  
Rajiv Kumar Pandey
Keyword(s):  
Transition Temperature ◽  
Critical Temperature ◽  
Pressure Dependence ◽  
Interaction Mechanism ◽  
High Energy ◽  
Electronic Interaction ◽  
Conduction Electrons ◽  
Bond Polarization ◽  
Critical Temperature Tc ◽  
Good Agreement

The pressure dependent changes in transition temperature (Tc) of alkali doped C 60 superconductor has been studied theoretically considering the combination of phonon mediated mechanism and high energy electronic interaction mechanism. The latter mechanism involves bond polarization in interaction with conduction electrons. The expression for Tc, isotope effect coefficient (α) and (dTc/dP)P has been obtained to explain the observed experimental results of alkali doped C 60. A good agreement has been found in experimental (Tc) and (dTc/dP)P = 0 values and calculated values.

scholarly journals Phonon Characteristics of High Tc Superconductors from Neutron Doppler Broadening Measurements

1994 ◽  
Vol 376 ◽  
Author(s):  
Walter J Trela ◽  
J Eric lynn ◽  
George H Kwei ◽  
Kay Meggers
Keyword(s):  
Critical Temperature ◽  
National Laboratory ◽  
Neutron Cross Section ◽  
High Energy ◽  
Phonon Energy ◽  
High Energy Resolution ◽  
Los Alamos National Laboratory ◽  
Statistical Precision ◽  
Two Samples ◽  
The Mean

ABSTRACTStatistical information on the phonon frequency spectrum of materials can be obtained by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened. We have carried out measurements using this technique for the doped 2-1-4 system, La2.xBaxCuO4. Two samples with slightly different concentrations of barium, one superconducting, the other not, were examined. Pure Lanthanum Cuprate was also studied. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 60m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Anisotropy of damage productions in electron irradiated molybdenum

1978 ◽  
Vol 36 (1) ◽  
pp. 354-355
Author(s):  
K. Izui ◽  
S. Furuno ◽  
H. Otsu ◽  
T. Nishida ◽  
H. Maeta
Keyword(s):  
Electron Flux ◽  
Threshold Energy ◽  
High Energy ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Displacement Threshold ◽  
The Mean ◽  
Channeling Effect ◽  
Different Origins ◽  
Threshold Energies

Anisotropy of damage productions in crystals due to high energy electron bombardment are caused from two different origins. One is an anisotropic displacement threshold energy, and the other is an anisotropic distribution of electron flux near the atomic rows in crystals due to the electron channeling effect. By the n-beam dynamical calculations for germanium and molybdenum we have shown that electron flux at the atomic positions are from ∽4 to ∽7 times larger than the mean incident flux for the principal zone axis directions of incident 1 MeV electron beams, and concluded that such a locally increased electron flux results in an enhanced damage production. The present paper reports the experimental evidence for the enhanced damage production due to the locally increased electron flux and also the results of measurements of the displacement threshold energies for the <100>,<110> and <111> directions in molybdenum crystals by using a high voltage electron microscope.

A New Condition of Formation and Stablity of All Crystalline Systems in a Good Agreement with Experimental Data

2015 ◽  
Vol 11 (3) ◽  
pp. 3224-3228
Author(s):  
Tarek El-Ashram
Keyword(s):  
Experimental Data ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Free Electron ◽  
Lattice Point ◽  
Valence Electron ◽  
Fermi Gas ◽  
Valence Electron Concentration ◽  
Fermi Sphere ◽  
Good Agreement

In this paper we derived a new condition of formation and stability of all crystalline systems and we checked its validity andit is found to be in a good agreement with experimental data. This condition is derived directly from the quantum conditionson the free electron Fermi gas inside the crystal. The new condition relates both the volume of Fermi sphere VF andvolume of Brillouin zone VB by the valence electron concentration VEC as ;𝑽𝑭𝑽𝑩= 𝒏𝑽𝑬𝑪𝟐for all crystalline systems (wheren is the number of atoms per lattice point).

scholarly journals Research Progress toward Room Temperature Sodium Sulfur Batteries: A Review

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1535
Author(s):  
Yanjie Wang ◽  
Yingjie Zhang ◽  
Hongyu Cheng ◽  
Zhicong Ni ◽  
Ying Wang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Room Temperature ◽  
High Energy ◽  
Safety Performance ◽  
High Energy Density ◽  
Research Progress ◽  
Storage Performance ◽  
Sulfur Battery ◽  
Sodium Sulfur Battery ◽  
Sodium Sulfur

Lithium metal batteries have achieved large-scale application, but still have limitations such as poor safety performance and high cost, and limited lithium resources limit the production of lithium batteries. The construction of these devices is also hampered by limited lithium supplies. Therefore, it is particularly important to find alternative metals for lithium replacement. Sodium has the properties of rich in content, low cost and ability to provide high voltage, which makes it an ideal substitute for lithium. Sulfur-based materials have attributes of high energy density, high theoretical specific capacity and are easily oxidized. They may be used as cathodes matched with sodium anodes to form a sodium-sulfur battery. Traditional sodium-sulfur batteries are used at a temperature of about 300 °C. In order to solve problems associated with flammability, explosiveness and energy loss caused by high-temperature use conditions, most research is now focused on the development of room temperature sodium-sulfur batteries. Regardless of safety performance or energy storage performance, room temperature sodium-sulfur batteries have great potential as next-generation secondary batteries. This article summarizes the working principle and existing problems for room temperature sodium-sulfur battery, and summarizes the methods necessary to solve key scientific problems to improve the comprehensive energy storage performance of sodium-sulfur battery from four aspects: cathode, anode, electrolyte and separator.

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