scholarly journals The Electrical Conductivity of Molten Oxide-Fluoride Cryolite Mixtures

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7419
Author(s):  
Pavel Arkhipov ◽  
Olga Tkacheva
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Energy Consumption ◽  
Viscous Flow ◽  
Activation Energies ◽  
Experimental Results ◽  
Cryolite Ratio ◽  
Aluminum Reduction ◽  
Molten Oxide ◽  
Molten Cryolite

A new way to reduce the energy consumption during the operation of powerful aluminum reduction cells is suggested via reducing the resistance of the electrolyte, i.e., increasing its electrical conductivity. The electrical conductivity of molten cryolite mixtures NaF-AlF3-CaF2-Al2O3 with cryolite ratio (CR) of 2.1–3.0 and content of CaF2 and Al2O3, up to 8 wt%, was measured at the temperatures from liquidus to 1300 K. Based on the experimental results, a multifunctional equation for the electrical conductivity of oxide-fluoride cryolite melts was evaluated. The experimental and calculated values of the electrical conductivity agree within 1.5%. The activation energy of the electrical conductivity of the NaF-AlF3-CaF2-Al2O3 melts was estimated. The activation energy of electrical conductivity for molten NaF-AlF3 mixtures with CR 3.0 and 2.1, determined by the most mobile cations Na+, increased from 15.8 kJ/mol up to 18.5 kJ/mol. It was found that CR had a greater impact on the activation energy than the changes in the Al2O3 or CaF2 concentrations. Based on the ratio of the activation energies of the electrical conductivity and the viscous flow, the correlation between the electrical conductivity and viscosity of molten cryolite mixtures NaF-AlF3-CaF2-Al2O3 was illustrated.

scholarly journals The effect of additives metal on the D.C conductivity of epoxy resin

2011 ◽  
Vol 8 (1) ◽  
pp. 168-174
Author(s):  
Baghdad Science Journal
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Epoxy Resin ◽  
Filler Content ◽  
Experimental Results ◽  
Filler Concentration ◽  
Effect Of Additives

The present studies are focused on the modification of the properties of epoxy resin with different additives namely aluminum, copper by preparing of composites systems with percentage (20%, 40% and 50%) of the above additives. The experimental results show that the D.C of conductivity on wt% filler content at ( 293-413 ) K electrical conductivity of all above composites increased with temperature for composites with filler contact and find the excellent electrical conductivity of copper and lie between (2.6*10-10 - 2.1*10-10)?.cm . The activation energy of the electrical conductivity is determined and found to decrease with increasing the filler concentration.

scholarly journals Preparation and Study of some Electrical Properties of PVA-Ni(NO3)2 Composites

2014 ◽  
Vol 40 ◽  
pp. 36-42 ◽  
Author(s):  
Sabah A. Salman ◽  
Nabeel A. Bakr ◽  
Mohammed H. Mahmood
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Filler Content ◽  
Experimental Results ◽  
Casting Technique ◽  
Different Temperatures

The aim of this paper is to prepare and study the (D.C.) electrical conductivity of (PVA-Ni (NO3)2) composites at different temperatures. For that purpose, PVA films with Ni (NO3)2 salt additive were prepared with different concentrations‎ 2, 4, 6, 8 and 10 wt. % and with thickness of 45μm by using casting technique. The experimental results for PVA-Ni (NO3)2) ‎films show that the (D.C.) electrical‏ ‏conductivity increased with increasing ‎the filler content and the‏ ‏temperature, and the activation energy was ‎decreased with increasing the filler content‎.

COMPUTATION OF EQUILIBRIUM CONFIGURATIONS OF DISSOCIATED JOGS IN F.C.C. CRYSTALS

1967 ◽  
Vol 45 (10) ◽  
pp. 3357-3366 ◽  
Author(s):  
Torstein Jössang
Keyword(s):  
Activation Energy ◽  
Activation Energies ◽  
Experimental Results ◽  
Dislocation Segment ◽  
Segment Model ◽  
Equilibrium Configurations ◽  
Order Of Magnitude ◽  
Straight Dislocation

Extensions and the activation energies necessary for the constriction of dissociated jogs are calculated in the piecewise-straight dislocation segment model. Because the energy of the stair-rod pair in the jog is quite uncertain, the results are presented in such a way that one may predict jog extensions and activation energies as a function of the stair-rod energy. The energy of a stair-rod pair is estimated from experimental results on vacancy energies. The results indicate a considerable variation in the activation energy for different materials. For silver it is almost an order of magnitude larger than for copper and gold, which materials in turn have a considerably higher activation energy than aluminium and nickel.

Analysis of Electric Conductive Activation Energy from the Electric Conductivity of Silicate and Borate Glasses

2008 ◽  
Vol 368-372 ◽  
pp. 1451-1453
Author(s):  
Young Joon Jung ◽  
Young Seok Kim ◽  
Kyu Ho Lee ◽  
Tae Ho Kim ◽  
Bong Ki Ryu
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Electric Conductivity ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Arrhenius Equation ◽  
Activation Energies ◽  
Borate Glasses ◽  
Sio2 System

This work is to compare the electric conductive activation energies with increasing Na2O in SiO2 and B2O3 glasses. The electrical conductivity is measured by TER2000 analyzer and it is compared with value calculated by Arrhenius equation. The conductivity of SiO2 system glasses is higher than B2O3 system glasses, and the highest value is 1.36 × 10-4 cm-1 in 60SiO2-40Na2O glass. The activation energy from conductivity is proportion to temperature and inverse proportion to Na2O contents. The activation energy is analyzed from density and CTE (thermal expansion coefficient).

scholarly journals Role of ZnO in Dc Electrical Conductivity of Lithium Bismuthate Glasses

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Shashidhar Bale ◽  
Syed Rahman
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Quaternary System ◽  
Activation Energies ◽  
Lithium Ions ◽  
Arrhenius Plots ◽  
Dc Electrical Conductivity ◽  
Straight Line

Glasses of various compositions belonging to the Bi2O3-B2O3-ZnO-Li2O quaternary system were prepared using melt quench technique. Dc electric measurements were done on the samples, and activation energies are determined. Arrhenius plots showed straight line behaviour. It is observed that the conductivity of the samples increased with temperature and also with Li2O content, whereas the activation energy decreased with Li2O content. The isothermal plots for constant ZnO and constant Bi2O3 glasses revealed that the conduction in these glasses is due to lithium ions only. The isothermal plots for constant lithium containing glasses varied nonlinearly with two maxima, which is attributed to mixed former effect. The variation is explained based on Anderson-Stuart model.

Influence of annealing on the electrical conductivity of single crystals of Cu2O

1970 ◽  
Vol 48 (1) ◽  
pp. 63-69 ◽  
Author(s):  
F. L. Weichman ◽  
R. Kužel
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Low Temperature ◽  
Single Crystals ◽  
Activation Energies ◽  
Conductivity Measurements ◽  
Different Temperatures ◽  
Temperature Activation ◽  
The Stability ◽  
Stability Ranges

A series of conductivity measurements were made on single crystals of Cu2O from 20 to 840 °C to explain the various activation energies which appear at different temperatures and oxygen pressures. Crystals were annealed in the 10−8 and 10−4 Torr region in the stability ranges of Cu2O, Cu, and CuO at various temperatures. For the low-temperature activation energies ranging from 0.60 to 0.26 eV, an excellent agreement with the empirical Meyer–Neldel rule was found. The highest activation energy of 1.12 eV in the 570 to 680 °C range at 10−8 Torr is associated with the boundary between the two stable phases Cu and Cu2O. The changes in defect concentration are ascribed to the mechanism of self-compensation. The energy-level diagram proposed by Bloem is adequate to explain the present results.

scholarly journals Влияние примеси железа на электрическую проводимость кристаллов LiNbO-=SUB=-3-=/SUB=-

2020 ◽  
Vol 62 (3) ◽  
pp. 427
Author(s):  
А.В. Яценко ◽  
С.В. Евдокимов
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Activation Energies ◽  
Electron Conductivity ◽  
Small Radius ◽  
Low Concentration

The electrical conductivity of a series of LiNbO3 of congruent composition with a relatively low concentration of iron (up to 0.15 wt.% Fe2O3 in the melt) was experimentally studied. It has been established that at temperatures close to 300 K, two types of centers with close activation energies make the main contribution to the electrical conductivity of these crystals. The first type of these centers — Fe2+ ions — is responsible for impurity electron conductivity with an activation energy (0.34  0.01) eV. The second type of these centers is small-radius polarons with an activation energy (0.29  0.02) eV. It was shown that for nominally pure and lightly doped “as grown” LiNbO3 crystals at T = 300 K, polaron conductivity is dominant.

Effect of Cu doping on the electrical Properties of ZnTe by Vacuum Thermal Evaporation

2018 ◽  
Vol 31 (3) ◽  
pp. 20
Author(s):  
Sarmad M. M. Ali ◽  
Alia A.A. Shehab ◽  
Samir A. Maki
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Hall Effect ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Cu Doping ◽  
Before And After ◽  
Hall Effect Measurements ◽  
Evaporation Technique ◽  
P Type

In this study, the ZnTe thin films were deposited on a glass substrate at a thickness of 400nm using vacuum evaporation technique (2×10-5mbar) at RT. Electrical conductivity and Hall effect measurements have been investigated as a function of variation of the doping ratios (3,5,7%) of the Cu element on the thin ZnTe films. The temperature range of (25-200°C) is to record the electrical conductivity values. The results of the films have two types of transport mechanisms of free carriers with two values of activation energy (Ea1, Ea2), expect 3% Cu. The activation energy (Ea1) increased from 29meV to 157meV before and after doping (Cu at 5%) respectively. The results of Hall effect measurements of ZnTe , ZnTe:Cu films show that all films were (p-type), the carrier concentration (1.1×1020 m-3) , Hall mobility (0.464m2/V.s) for pure ZnTe film, increases the carrier concentration (6.3×1021m-3) Hall mobility (2m2/V.s) for doping (Cu at 3%) film, but  decreases by increasing Cu concentration.

scholarly journals High-Temperature Deformation of Naturally Aged 7010 Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 581
Author(s):  
Abdulhakim A. Almajid
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Threshold Stress ◽  
Activation Energies ◽  
Temperature Deformation ◽  
High Temperature Range ◽  
Temperature Range ◽  
True Activation Energy ◽  
Two Temperatures

This study is focused on the deformation mechanism and behavior of naturally aged 7010 aluminum alloy at elevated temperatures. The specimens were naturally aged for 60 days to reach a saturated hardness state. High-temperature tensile tests for the naturally aged sample were conducted at different temperatures of 573, 623, 673, and 723 K at various strain rates ranging from 5 × 10−5 to 10−2 s−1. The dependency of stress on the strain rate showed a stress exponent, n, of ~6.5 for the low two temperatures and ~4.5 for the high two temperatures. The apparent activation energies of 290 and 165 kJ/mol are observed at the low, and high-temperature range, respectively. These values of activation energies are greater than those of solute/solvent self-diffusion. The stress exponents, n, and activation energy observed are rather high and this indicates the presence of threshold stress. This behavior occurred as a result of the dislocation interaction with the second phase particles that are existed in the alloy at the testing temperatures. The threshold stress decreases in an exponential manner as temperature increases. The true activation energy was computed by incorporating the threshold stress in the power-law relation between the stress and the strain. The magnitude of the true activation energy, Qt dropped to 234 and 102 kJ/mol at the low and high-temperature range, respectively. These values are close to that of diffusion of Zinc in Aluminum and diffusion of Magnesium in Aluminum, respectively. The Zener–Hollomon parameter for the alloy was developed as a function of effective stress. The data in each region (low and high-temperature region) coalescence in a segment line in each region.

scholarly journals DV-DVFS: merging data variety and DVFS technique to manage the energy consumption of big data processing

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hossein Ahmadvand ◽  
Fouzhan Foroutan ◽  
Mahmood Fathy
Keyword(s):  
Big Data ◽  
Energy Consumption ◽  
Processing Time ◽  
Experimental Results ◽  
The Other ◽  
Data Sets ◽  
Multiple Sources ◽  
Evaluation Phase ◽  
Dynamic Voltage ◽  
Processing Resources

AbstractData variety is one of the most important features of Big Data. Data variety is the result of aggregating data from multiple sources and uneven distribution of data. This feature of Big Data causes high variation in the consumption of processing resources such as CPU consumption. This issue has been overlooked in previous works. To overcome the mentioned problem, in the present work, we used Dynamic Voltage and Frequency Scaling (DVFS) to reduce the energy consumption of computation. To this goal, we consider two types of deadlines as our constraint. Before applying the DVFS technique to computer nodes, we estimate the processing time and the frequency needed to meet the deadline. In the evaluation phase, we have used a set of data sets and applications. The experimental results show that our proposed approach surpasses the other scenarios in processing real datasets. Based on the experimental results in this paper, DV-DVFS can achieve up to 15% improvement in energy consumption.

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