scholarly journals Объемные и поверхностные эффекты при образовании и разрушении графена на родии

2021 ◽  
Vol 63 (10) ◽  
pp. 1711
Author(s):  
E.B. Pутьков ◽  
Е.Ю. Афанасьева ◽  
Н.П. Лавровская ◽  
H.P. Галль
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Carbon Concentration ◽  
Surface Concentration ◽  
Metal Substrate ◽  
Atomic Carbon ◽  
Island Area ◽  
Graphene Island ◽  
Equilibrium Phases ◽  
Carbon Concentrations

Growth and destruction of graphene islands on Rh have been studied accounting processes on the surface and in the substrate bulk simultaneously. Atomic carbon was shown to be distributed between three equilibrium phases: graphene, solid solution in the metal substrate, and chemisorbed carbon. An increase in graphene island area results in corresponding increase in carbon concentration in the solid solution and chemisorbed phase. Atomic carbon concentrations are measured for all three phases for various stages of graphene growth and decomposition. The activation energy of atomic carbon detachment from the graphene island perimeter on Rh has been determined, Edet = 2.7 eV. Surface concentration of graphene islands has been estimated to be about 1010 per сm2.

scholarly journals Traffic Density-Related Black Carbon Distribution: Impact of Wind in a Basin Town

2021 ◽  
Vol 18 (12) ◽  
pp. 6490
Author(s):  
Borut Jereb ◽  
Brigita Gajšek ◽  
Gregor Šipek ◽  
Špela Kovše ◽  
Matevz Obrecht
Keyword(s):  
Black Carbon ◽  
Carbon Concentration ◽  
Ground Level ◽  
Traffic Density ◽  
Carbon Distribution ◽  
Wind Speeds ◽  
Black Carbon Concentration ◽  
Low Wind Speeds ◽  
Temperature Inversions ◽  
Carbon Concentrations

Black carbon is one of the riskiest particle matter pollutants that is harmful to human health. Although it has been increasingly investigated, factors that depend on black carbon distribution and concentration are still insufficiently researched. Variables, such as traffic density, wind speeds, and ground levels can lead to substantial variations of black carbon concentrations and potential exposure, which is even riskier for people living in less-airy sites. Therefore, this paper “fills the gaps” by studying black carbon distribution variations, concentrations, and oscillations, with special emphasis on traffic density and road segments, at multiple locations, in a small city located in a basin, with frequent temperature inversions and infrequent low wind speeds. As wind speed has a significant impact on black carbon concentration trends, it is critical to present how low wind speeds influence black carbon dispersion in a basin city, and how black carbon is dependent on traffic density. Our results revealed that when the wind reached speeds of 1 ms−1, black carbon concentrations actually increased. In lengthy wind periods, when wind speeds reached 2 or 3 ms−1, black carbon concentrations decreased during rush hour and in the time of severe winter biomass burning. By observing the results, it could be concluded that black carbon persists longer in higher altitudes than near ground level. Black carbon concentration oscillations were also seen as more pronounced on main roads with higher traffic density. The more the traffic decreases and becomes steady, the more black carbon concentrations oscillate.

scholarly journals Removal of Chromium from Aqueous Solution Using Modified Pomegranate Peel:Mechanistic and Thermodynamic Studies

2009 ◽  
Vol 6 (s1) ◽  
pp. S153-S158 ◽  
Author(s):  
Tariq S. Najim ◽  
Suhad A. Yassin
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Aqueous Solution ◽  
Adsorption Process ◽  
Batch Process ◽  
The Other ◽  
Water Molecules ◽  
Pomegranate Peel ◽  
Solution Interface ◽  
Adsorbent Surface

Modified pomegranate peel (MPGP) and formaldehyde modified pomegranate peel (FMPGP) were prepared and used as adsorbent for removal of Cr(VI) ions from aqueous solution using batch process. The temperature variation study of adsorption on both adsorbents revealed that the adsorption process is endothermic, from the positive values of ∆H˚. These values lie in the range of physisorption. The negative values of ∆G˚ show the adsorption is favorable and spontaneous. On the other hand, these negative values increases with increase in temperature on both adsorbents, which indicate that the adsorption is preferable at higher temperatures. ∆S˚ values showed that the process is accompanied by increase in disorder and randomness at the solid solution interface due to the reorientation of water molecules and Cr(VI) ions around the adsorbent surface. The endothermic nature of the adsorption was also confirmed from the positive values of activation energy, Ea, the low values of Ea confirm the physisorption mechanism of adsorption. The sticking probability, S*, of Cr(VI) ion on surface of both adsorbents showed that the adsorption is preferable due to low values of S*(0< S*< 1 ), but S*values are lower for FMPGP indicating that the adsorption on FMPGP is more preferable .

High Temperature Creep Behavior and Effects of Stacking Fault Energy in Mg-Y and Mg-Y-Zn Dilute Solid Solution Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 491-496
Author(s):  
Mayumi Suzuki ◽  
Yasuyuki Murata ◽  
Kyosuke Yoshimi
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Creep Behavior ◽  
Ternary Alloys ◽  
Dislocation Creep ◽  
Prismatic Slip ◽  
Dislocation Slip ◽  
Self Diffusion ◽  
Controlling Mechanism ◽  
Hot Rolled

Compressive creep behavior of hot-rolled (40%) Mg-Y binary and Mg-Y-Zn ternary dilute solid solution alloys are investigated in this study. Creep strength is substantially improved by the addition of zinc. Activation Energy for creep in Mg-Y and Mg-Y-Zn alloys are around 200 kJ/mol at the temperature range from 480 to 570 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults, which are planar type defects are observed on the basal planes of the magnesium matrix in Mg-Y-Zn ternary alloys. TEM observation has been revealed that the non-basal a-dislocation slip is significantly activated by these alloys. The rate controlling mechanism of Mg-Y and Mg-Y-Zn dilute alloys are considered to the cross-slip or prismatic-slip controlled dislocation creep with high activation energy for creep, more than 1.5 times higher than the activation energy for creep controlled dislocation climb.

Influence of Carbon Concentration as Coating on Electrical Conductivity of LiFeSi0.03P0.97O4/C

2021 ◽  
Vol 1028 ◽  
pp. 185-190
Author(s):  
Hafizhah Ellora Della ◽  
Mochamad Zainuri ◽  
Pelangi Az Zahra ◽  
Puri Olyvia Swastika ◽  
Triwikantoro
Keyword(s):  
Electrical Conductivity ◽  
Carbon Concentration ◽  
Research Study ◽  
Raw Materials ◽  
Carbon Sources ◽  
Xrd Analysis ◽  
Si Doping ◽  
Diffraction Peaks ◽  
Materials Used ◽  
Carbon Concentrations

This research study about the influence of carbon concenttration as coating on electrical conductivity of LiFeSi0.03P0.97O4/C. Synthesis of LiFeSi0.03P0.97O4/C was carried out different carbon concentrations of 7, 9, and 11 wt%. The raw materials used are Fe2O3, Li2CO3, (NH4)2HPO4, SiO2 as ion Si doping, and glucose as carbon sources. The XRD analysis results showed that all the diffraction peaks in samples were the olivine LiFePO4 phase. From the EIS result, Samples with the addition carbon concentration of 9 wt% produce the highest electrical conductivity values of 4.18 x 10-7 S/cm.

Optimization and modulation for the moderate and high temperature thermoelectric properties of PbSe via solid solution with PbS synthesized by HPHT

2020 ◽  
Vol 34 (17) ◽  
pp. 2050185 ◽  
Author(s):  
Baomin Liu ◽  
Hongan Ma ◽  
Qi Chen ◽  
Yao Wang ◽  
Guangyao Ji ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Electrical Conduction ◽  
Figure Of Merit ◽  
Solution Treatment ◽  
Conduction Type ◽  
Base Materials ◽  
Solid Solution Treatment ◽  
Electron Microscopes ◽  
Synthesis Stage

PbS synthesized at the same condition with PbSe exhibits an opposite electrical conduction type from it. Via the solid solution of PbS into PbSe, we attempt to change the major carries kind of PbSe-base materials and improve the thermoelectric (TE) property of synthesis samples in corresponding temperature areas. Introduction of high pressure into the synthesis stage could reduce the reactive activation energy and improve the synthesis efficiency. Characterizations via the electron microscopes demonstrate that synthesis samples are made of multiscale grains. Finally, characterizations on the thermoelectrical properties of [Formula: see text] demonstrate that the solid solution treatment could modulate the electrical conduction type and the figure of merit effectively.

Interface Controlled Diffusional Creep of Cu + 2.8 at.% Co Solid Solution

2012 ◽  
Vol 322 ◽  
pp. 33-39 ◽  
Author(s):  
Sergei Zhevnenko ◽  
Eugene Gershman
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Creep Behavior ◽  
Pure Copper ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Temperature Range ◽  
Different Temperatures

High-temperature creep experiments were performed on a Cu-2.8 ат.% Co solid solution. Cylindrical foils of 18 micrometers thickness were used for this purpose. Creep tests were performed in a hydrogen atmosphere in the temperature range of about from 1233 K to 1343 K and at stresses lower than 0.25 MPa. For comparison, a foil of pure copper and Cu-20 at.% Ni solid solution were investigated on high temperature creep. Measurements on the Cu foil showed classical diffusional creep behavior. The activation energy of creep was defined and turned out to be equal 203 kJ/mol, which is close to the activation energy of bulk self-diffusion of copper. There was a significant increase in activation energy for the Cu-20 at.% Ni solid solution. Its activation energy was about 273 kJ/mol. The creep behavior of Cu-Co solid solution was more complicated. There were two stages of diffusional creep at different temperatures. The extremely large activation energy (about 480 kJ/mol) was determined at relatively low temperature and a small activation energy (about 105 kJ/mol) was found at high temperatures. The creep rate of Cu-Co solid solution was lower than that of pure copper at all temperatures. In addition, the free surface tension of Cu-2.8 ат.% Co was measured at different temperatures from 1242 K to 1352 K. The surface tension increases in this temperature range from 1.6 N/m to 1.75 N/m. There were no features on the temperature dependence of the surface tension.

On the kinetics of the δ′ (Al3Li) phase precipitation in a rapidly solidified Al–Mn–Li–Zr alloy

1991 ◽  
Vol 6 (1) ◽  
pp. 46-52 ◽  
Author(s):  
J. Baram ◽  
A. N. Sembira
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Avrami Equation ◽  
Rate Parameter ◽  
Cast Material ◽  
Strain Gradients ◽  
Cast Sample ◽  
Rapidly Solidified ◽  
Kinetics Of ◽  
Conventionally Cast

The precipitation kinetics of the δ′ (Al3Li) phase in two rapidly solidified samples and one conventionally cast sample of an Al–2.3Li–6.5Mn–0.65Zr (in wt. %) alloy are compared. Following high cooling rates, manganese is retained in solid solution in the aluminum matrix (αAl) up to 6.0 wt.%, far beyond the thermodynamic equilibrium value (0.36 wt.% at 500 °C). Extended solid solution of manganese in aluminum induces strain gradients, similar to those produced by dislocations. The effect of such gradients, the size of which is proportional to the solute atomic fraction, is to enhance lithium precipitation by lowering the activation energy, as observed, and also by affecting the rate parameter. Kinetic thermal analysis has been performed in a series of nonisothermal experiments in the heat flux differential scanning calorimetry (DSC) mode. The precipitation of the δ′ (Al3Li) phase is evidenced by an exothermic peak whose characteristics were analyzed. The rate of transformation (precipitation) is assumed to obey the Johnson–Mehl–Avrami equation. The activation energy for the precipitation process as well as the kinetic rate parameter have been evaluated for the rapidly solidified and the conventionally cast specimens. The activation energy for precipitation is lowered, from 107.0 kJ mol−1 for the conventionally cast material, down to 81.8 kJ mol−1 and 77.0 kJ mol−1 for samples that exhibit manganese solid solubility extensions of 2.10 and 6.00 wt.%, respectively. The rate parameter for the precipitation reaction, which has the generally admitted value of 1.50, for a transformation involving diffusion controlled growth, is affected by the strain gradients, too. Its value is reduced from 1.40 for the slowly cast sample to 1.32 and 1.20, respectively, for the two rapidly solidified samples, as a result of competing mechanisms, namely: growth controlled by diffusion and strain-assisted precipitation.

Long-Range Diffusion of Hydrogen in Solid-Solution PdCe Alloys as Deduced from Absorption Experiments

2008 ◽  
Vol 273-276 ◽  
pp. 381-387 ◽  
Author(s):  
Giovanni Mazzolai
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Thermal Decomposition ◽  
Diffusion Coefficient ◽  
High Temperature ◽  
Diffusion Constant ◽  
Absorption Data ◽  
Friction Measurements ◽  
And Diffusion ◽  
Diffusion Of Hydrogen

The diffusion of H and the thermal decomposition of hydrides have been investigated at high temperatures in two PdCe alloys of composition 5% and 9% Ce. It has been found that the H diffusion coefficient obeys an Arrhenius-type of law with the following values of the activation energy W and diffusion constant D0, ( )     = ± × = ± − s m D W eV 2 7 0 2 2 10 0.20 0.02 (Pd95Ce5 alloy) ( )     = ± × = ± − s m D W eV 2 7 0 2 1 10 0.24 0.01 (Pd91Ce9 alloy) The high-temperature absorption data match the low-temperature ones deduced from internal friction measurements, indicating that Ce atoms do not act as strong trapping centres for H. Thermal decomposition of hydrides in the Pd95Ce5H0.008 alloy occurs in a single stage showing a homogeneous solid solution state of the H-Me system.

scholarly journals Распад твердого раствора межузельного магния в кремнии

2019 ◽  
Vol 53 (3) ◽  
pp. 314
Author(s):  
В.Б. Шуман ◽  
А.Н. Лодыгин ◽  
Л.М. Порцель ◽  
А.А. Яковлева ◽  
Н.В. Абросимов ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Single Crystal ◽  
Diffusion Activation Energy ◽  
Practical Application ◽  
Float Zone ◽  
Sandwich Method ◽  
Kinetics Of ◽  
Diffusion Activation

AbstractThe decomposition of a solid solution of interstitial magnesium Mg_ i in silicon is studied. Float-Zone dislocation-free single-crystal n -Si with a resistivity of ~8 × 10^3 Ω cm and oxygen and carbon contents of ~5 × 10^14 cm^–3 and ~1 × 10^15 cm^–3 is used in the experiments. The samples are doped using the diffusion sandwich method at T =1100°C followed by quenching. Decomposition of the supersaturated Mg_ i solid solution is studied by observing the kinetics of increasing the resistivity of doped samples resulting from their annealing in the range T = 400–620°C. It is found that the decomposition is characterized by an activation energy of E _ a ≈ 1.6 eV, which is close to the previously determined diffusion activation energy of Mg_ i in silicon. It is also shown that Si:Mg exhibits stable properties at temperatures not exceeding 400°C, which is important for its possible practical application.

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