Theoretical and experimental studies of electrical conductivity for functionally graded, heterogeneous surfaces

2019 ◽  
Vol 125 (3) ◽  
pp. 035106 ◽  
Author(s):  
J. M. Jennings ◽  
R. Vaidyanathan ◽  
A. Kar
Keyword(s):  
Electrical Conductivity ◽  
Experimental Studies ◽  
Functionally Graded ◽  
Heterogeneous Surfaces

scholarly journals Температурные зависимости электропроводности и магнитной восприимчивости кристаллов твердых растворов Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=--Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

2021 ◽  
Vol 55 (12) ◽  
pp. 1162
Author(s):  
Н.П. Степанов ◽  
В.Ю. Наливкин ◽  
А.К. Гильфанов ◽  
А.А. Калашников ◽  
Е.Н. Трубицына
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Susceptibility ◽  
Solid Solutions ◽  
Thermoelectric Materials ◽  
Materials Science ◽  
Practical Importance ◽  
Experimental Studies ◽  
Electronic System ◽  
Temperature Dependences ◽  
The Subject

Solid solutions Bi2Te3-Sb2Te3 continue to be the subject of numerous and versatile experimental studies due to their practical importance for thermoelectric materials science. In this regard, the problem of studying the regularities of changes in the state of the electronic system of these semiconductors from composition and temperature remains urgent. This paper presents the results of studying the temperature dependences of the magnetic susceptibility of Bi2Te3-Sb2Te3 crystals containing 10, 25, 40, 50, 60 mol. % Sb2Te3. The correlation of the behavior of the temperature dependences of the magnetic susceptibility and electrical conductivity is analyzed.

scholarly journals An Overview of the Experimental Studies on the Electrical Conductivity of Major Minerals in the Upper Mantle and Transition Zone

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 408 ◽  
Author(s):  
Lidong Dai ◽  
Haiying Hu ◽  
Jianjun Jiang ◽  
Wenqing Sun ◽  
Heping Li ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Transition Zone ◽  
Oxygen Fugacity ◽  
Upper Mantle ◽  
Activation Enthalpy ◽  
Small Polaron ◽  
Experimental Studies ◽  
Transport Processes ◽  
Structural Water ◽  
Nominally Anhydrous Minerals

In this paper, we present the recent progress in the experimental studies of the electrical conductivity of dominant nominally anhydrous minerals in the upper mantle and mantle transition zone of Earth, namely, olivine, pyroxene, garnet, wadsleyite and ringwoodite. The main influence factors, such as temperature, pressure, water content, oxygen fugacity, and anisotropy are discussed in detail. The dominant conduction mechanisms of Fe-bearing silicate minerals involve the iron-related small polaron with a relatively large activation enthalpy and the hydrogen-related defect with lower activation enthalpy. Specifically, we mainly focus on the variation of oxygen fugacity on the electrical conductivity of anhydrous and hydrous mantle minerals, which exhibit clearly different charge transport processes. In representative temperature and pressure environments, the hydrogen of nominally anhydrous minerals can tremendously enhance the electrical conductivity of the upper mantle and transition zone, and the influence of trace structural water (or hydrogen) is substantial. In combination with the geophysical data of magnetotelluric surveys, the laboratory-based electrical conductivity measurements can provide significant constraints to the water distribution in Earth’s interior.

scholarly journals EXPLICIT FORMULA FOR DEPTH OF PENETRATION OF CONE-NOSED IMPACTOR INTO ANISOTROPIC SHIELDS

2020 ◽  
Vol 82 (1) ◽  
pp. 100-106
Author(s):  
A.V. Dubinsky
Keyword(s):  
Finite Thickness ◽  
Normal Component ◽  
Experimental Studies ◽  
Quadratic Function ◽  
Functionally Graded ◽  
Ballistic Limit ◽  
Depth Of Penetration ◽  
Explicit Formulas ◽  
Penetration Mechanics ◽  
Ballistic Limit Velocity

The field of application of Functionally Graded Materialsis steadily expanding, which stimulates research in the relevant areas. In relation to penetration mechanics, these are primarily experimental studies of multilayer barriers consisting of plates “in contact” with various mechanical properties. Despite intensive research, explicit formulas for integral penetration characteristics (penetration depth and ballistic limit) cannot be obtained, except for the case when sequential penetration of layers (barriers with large gaps between layers). In this article, explicit formulas for the depth of penetration into an semi-infinite shield and for the ballistic limit velocity applying penetration into a shield of a finite thickness are derived assuming that the hardness of the barrier material varies continuously depending on barrier depth. The theoretical analysis is based on a model that represents the normal stress at points on the surface of the penetrating body that are in contact with the barrier as a quadratic function of the normal component of local impactor velocity with a zero linear term (the Vitman - Stepanov model). Difference of the dynamic hardness in different points of impactor-barrier contact is taken into account. It is also assumed that the nose of the striker has the form of a straight circular cone and the initial stage of penetration when the striker is not completely immersed in the barrier is ignored.

scholarly journals О природе аномальной температурной зависимости коэффициента Холла, наблюдающейся в полупроводниковых кристаллах твердых растворов Bi-=SUB=-2-=/SUB=-Te_3-Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

2020 ◽  
Vol 54 (1) ◽  
pp. 13
Author(s):  
Н.П. Степанов
Keyword(s):  
Electrical Conductivity ◽  
Temperature Increase ◽  
Opposite Effect ◽  
Experimental Studies ◽  
Plasma Energy ◽  
Subsequent Decrease ◽  
Abnormal Increase

Based on the analysis of the results of experimental studies, it is shown that in crystals Bi2Te3-Sb2Te3, in which the amount of electrical conductivity at 4.2 K exceeds 1.5•106 Cм/м , a certain process is being intensified to increase electrical conductivity in the range of 4.2 to 15 K. Subsequent decrease in the amount of electrical conductivity with a temperature increase from 15 K and before the beginning of the dominance of its own conductivity, accompanied by an abnormal increase in the coefficient Hall may be partly due to the decrease in the intensity of the process. It is suggested that in the conditions of convergence of plasma energy and the width of the prohibited zone, the influence of plasmon-phonon-polaritones can provide the opposite effect polarization that forms the basis of this process.

scholarly journals Electrical Conductivity of Fluorite and Fluorine Conduction

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 72 ◽  
Author(s):  
Hanyong Liu ◽  
Qiao Zhu ◽  
Xiaozhi Yang
Keyword(s):  
Electrical Conductivity ◽  
Charge Carrier ◽  
Electrical Conduction ◽  
Experimental Studies ◽  
Conductivity Data ◽  
Arrhenius Law ◽  
Piston Cylinder ◽  
Sample Composition ◽  
Increasing Temperature ◽  
Loaded Piston

Fluorine is a species commonly present in many minerals in the Earth’s interior, with a concentration ranging from a few ppm to more than 10 wt. %. Recent experimental studies on fluorine-bearing silicate minerals have proposed that fluorine might be an important charge carrier for electrical conduction of Earth materials at elevated conditions, but the results are somewhat ambiguous. In this investigation, the electrical conductivity of gem-quality natural single crystal fluorite, a simple bi-elemental (Ca and F) mineral, has been determined at 1 GPa and 200–650 °C in two replication runs, by a Solartron-1260 Impedance/Gain Phase analyzer in an end-loaded piston-cylinder apparatus. The sample composition remained unchanged after the runs. The conductivity data are reproducible between different runs and between heating-cooling cycles of each run. The conductivity (σ) increases with increasing temperature, and can be described by the Arrhenius law, σ = 10^(5.34 ± 0.07)·exp[−(130 ± 1, kJ/mol)/(RT)], where R is the gas constant and T is the temperature. According to the equation, the conductivity reaches ~0.01 S/m at 650 °C. This elevated conductivity is strong evidence that fluorine is important in charge transport. The simple construction of this mineral indicates that the electrical conduction is dominated by fluoride (F−). Therefore, fluorine is potentially an important charge carrier in influencing the electrical property of Fluorine-bearing Earth materials.

Accuracy and reliability of total body electrical conductivity (TOBEC) for determining body composition of rats in experimental studies

1994 ◽  
Vol 56 (4) ◽  
pp. 767-773 ◽  
Author(s):  
Rhonda C. Bell ◽  
Amy J. Lanou ◽  
Edward A. Frongillo ◽  
David A. Levitsky ◽  
T.Colin Campbell
Keyword(s):  
Electrical Conductivity ◽  
Body Composition ◽  
Experimental Studies ◽  
Total Body
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