scholarly journals Pore-scale modeling of electrical and fluid transport in Berea sandstone

Geophysics ◽  
2010 ◽  
Vol 75 (5) ◽  
pp. F135-F142 ◽  
Author(s):  
Xin Zhan ◽  
Lawrence M. Schwartz ◽  
M. Nafi Toksöz ◽  
Wave C. Smith ◽  
F. Dale Morgan
Keyword(s):  
Electrical Conductivity ◽  
Transport Properties ◽  
Electrical Transport ◽  
Fluid Transport ◽  
Sample Volume ◽  
Image Resolution ◽  
Hydraulic Permeability ◽  
Sandstone Sample ◽  
Numerical Predictions ◽  
Surface Conduction

The purpose of this paper is to test how well numerical calculations can predict transport properties of porous permeable rock, given its 3D digital microtomography [Formula: see text] image. For this study, a Berea 500 sandstone sample is used, whose [Formula: see text] images have been obtained with resolution of [Formula: see text]. Porosity, electrical conductivity, permeability, and surface area are calculated from the [Formula: see text] image and compared with laboratory-measured values. For transport properties (electrical conductivity, permeability), a finite-difference scheme is adopted. The calculated and measured properties compare quite well. Electrical transport in Berea 500 sandstone is complicated by the presence of surface conduction in the electric double layer at the grain-electrolyte boundary. A three-phase conductivity model is proposed to compute surface conduction on the rock [Formula: see text] image. Effects of image resolution and computation sample size on the accuracy of numerical predictions are also investigated. Reducing resolution (i.e., increasing the voxel dimensions) decreases the calculated values of electrical conductivity and hydraulic permeability. Increasing computation sample volume gives a better match between laboratory measurements and numerical results. Large sample provides a better representation of the rock.

scholarly journals Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 746
Author(s):  
Meiling Hong ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Xinyu Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
High Pressure ◽  
Phase Transformation ◽  
Transport Properties ◽  
Electrical Transport ◽  
Structural Phase ◽  
Structure Evolution ◽  
Systematic Research ◽  
Electrical Transport Properties

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

Computational Analysis of Strain Effects on Electrical Transport Properties of Crystalline Nanocomposite Thin Films

2011 ◽  
Author(s):  
Hua Li ◽  
Gang Li
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Band Structure ◽  
Transport Properties ◽  
Electrical Transport ◽  
Electronic Band Structure ◽  
Electrical Transport Properties ◽  
Electronic Band ◽  
Strain Effects ◽  
Nanocomposite Thin Films

In this work, we model the strain effects on the electrical transport properties of Si/Ge nanocomposite thin films. We utilize a two-band k·p theory to calculate the variation of the electronic band structure as a function of externally applied strains. By using the modified electronic band structure, electrical conductivity of the Si/Ge nanocomposites is calculated through a self-consistent electron transport analysis, where a nonequilibrium Green’s function (NEGF) is coupled with the Poisson equation. The results show that both the tensile uniaxial and biaxial strains increase the electrical conductivity of Si/Ge nanocomposite. The effects are more evident in the biaxial strain cases.

scholarly journals Tuning the Electrical and Thermoelectric Properties of N Ion Implanted SrTiO3 Thin Films and Their Conduction Mechanisms

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Anuradha Bhogra ◽  
Anha Masarrat ◽  
Ramcharan Meena ◽  
Dilruba Hasina ◽  
Manju Bala ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Temperature Regime ◽  
Electrical Transport ◽  
Ion Beam ◽  
Temperature Range ◽  
Conduction Mechanisms ◽  
Band Conduction

Abstract The SrTiO3 thin films were fabricated by pulsed laser deposition. Subsequently ion implantation with 60 keV N ions at two different fluences 1 × 1016 and 5 × 1016 ions/cm2 and followed by annealing was carried out. Thin films were then characterized for electronic structure, morphology and transport properties. X-ray absorption spectroscopy reveals the local distortion of TiO6 octahedra and introduction of oxygen vacancies due to N implantation. The electrical and thermoelectric properties of these films were measured as a function of temperature to understand the conduction and scattering mechanisms. It is observed that the electrical conductivity and Seebeck coefficient (S) of these films are significantly enhanced for higher N ion fluence. The temperature dependent electrical resistivity has been analysed in the temperature range of 80–400 K, using various conduction mechanisms and fitted with band conduction, near neighbour hopping (NNH) and variable range hopping (VRH) models. It is revealed that the band conduction mechanism dominates at high temperature regime and in low temperature regime, there is a crossover between NNH and VRH. The S has been analysed using the relaxation time approximation model and dispersive transport mechanism in the temperature range of 300–400 K. Due to improvement in electrical conductivity and thermopower, the power factor is enhanced to 15 µWm−1 K−2 at 400 K at the higher ion fluence which is in the order of ten times higher as compared to the pristine films. This study suggests that ion beam can be used as an effective technique to selectively alter the electrical transport properties of oxide thermoelectric materials.

scholarly journals Order–disorder phase transition in an anhydrous pyrazole-based proton conductor: the enhancement of electrical transport properties

2017 ◽  
Vol 19 (37) ◽  
pp. 25653-25661 ◽  
Author(s):  
M. Widelicka ◽  
K. Pogorzelec-Glaser ◽  
A. Pietraszko ◽  
P. Ławniczak ◽  
R. Pankiewicz ◽  
...  
Keyword(s):  
Phase Transition ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Transport Properties ◽  
Crystalline Structure ◽  
Electrical Transport ◽  
Proton Conductor ◽  
Electrical Transport Properties ◽  
Disorder Phase Transition

The heat treatment of the anhydrous proton conductor causes a change in the crystalline structure and improves electrical conductivity.

Synthesis and Electrical Transport Properties of TiCo1-xPdxSb Half-Heusler Compounds

2007 ◽  
Vol 280-283 ◽  
pp. 405-408 ◽  
Author(s):  
Min Zhou ◽  
Li Dong Chen ◽  
Chu De Feng ◽  
Xiang Yang Huang
Keyword(s):  
Electrical Conductivity ◽  
Transport Properties ◽  
Electrical Transport ◽  
Single Phase ◽  
Great Increase ◽  
Solid State Reaction Method ◽  
Heusler Compounds ◽  
Electrical Transport Properties ◽  
Large Power ◽  
Reaction Method

Pd-doped TiCo1-xPdxSb (0 £ x £ 0.08) half-Heusler compounds were synthesized by a solid-state reaction method and their electrical transport properties in the temperature range of 300-900 K were investigated. Single phase TiCo1-xPdxSb was obtained in the range of 0 £ x £ 0.08. The lattice parameters increased with Pd content. Doping of Pd on the Co site resulted in a great increase of electrical conductivity without significant decrease of Seebeck coefficient. A large power factor of 26 µW/K2 cm was observed for TiCo0.92Pd0.08Sb compound at 300 K.

Thermal and Electrical Transport Properties of Sheared and Un-Sheared Thin-Film Polymer/CNTs Nanocomposites

2014 ◽  
Vol 1660 ◽  
Author(s):  
Parvathalu Kalakonda ◽  
Georgi Y. Georgiev ◽  
Yaniel Cabrera ◽  
Robert Judith ◽  
Germano S. Iannacchione ◽  
...  
Keyword(s):  
Thin Film ◽  
Electrical Conductivity ◽  
Transport Properties ◽  
Electrical Transport ◽  
Multiwall Carbon Nanotubes ◽  
Film Plane ◽  
Conductivity Measurements ◽  
Electrical Transport Properties ◽  
Property Relations ◽  
Data Points

ABSTRACTTransport properties have been measured transverse to the plane of sheared and un-sheared thin-film nanocomposites of isotactic Polypropylene (iPP) and multiwall carbon nanotubes (MWCNTs) at various MWCNT concentrations. The sheared samples were processed in the melt at 200 0C at 1 Hz in a Linkan microscope shearing hot stage. The thermal and electrical conductivity measurements were performed on the same cell arrangement with the transport perpendicular to the thin-film plane using a DC method. The thermal and electrical conductivity perpendicular to the surface of the films are higher for the un-sheared as compared to the sheared samples. Interestingly, the percolation threshold appears smeared in both conductivity measurements likely due to pressing and shear treatment of the films, or the spacing between the data points. Important for electronics packaging and materials for which those anisotropic properties are highly desired this work presents important advances in understanding the structure-transport property relations.

A High-Performance Solution-Processable Hybrid Thermoelectric Material

2012 ◽  
Author(s):  
Shannon K. Yee ◽  
Nelson Coates ◽  
Jeffrey J. Urban ◽  
Arun Majumdar ◽  
Rachel A. Segalman
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Transport Properties ◽  
Conducting Polymer ◽  
Thermoelectric Material ◽  
Electrical Transport ◽  
High Performance ◽  
Full Potential ◽  
Solution Processable ◽  
Electrical Generation

Thermoelectrics have the potential to become an alternative power source for distributed electrical generation as they could provide co-generation anywhere thermal gradients exist. More recent material and manufacturing advances have further suggested that thermoelectrics could independently generate primary power [1]. However, due to cost, manufacturability, abundance, and material performance, the full potential of thermoelectrics has yet to be realized. In the last decade, thermoelectric material improvements have largely been realized by diminishing thermal conductivities via nanostructuring without sacrificing performance in electrical transport [2]. An alternative approach is to decouple and optimize the electrical conductivity and thermopower using the unique properties of organic-inorganic interfaces [3]. One method to do this could leverage the electrical properties of a conducting polymer in combination with the thermoelectric proprieties of an inorganic semiconductor in such a way that the interaction between these materials breaks mixture theory. Furthermore, it is expected that the thermal conductivity of this hybrid material would be low due to the inherent vibration mode mismatch between polymers and inorganics. Previously, we have developed a method for producing a solution-processable thermoelectric material suitable for thin film applications using a hybrid polymer-inorganic systems consisting of crystalline tellurium nanowires coated in a thin layer of a conducting polymer (i.e., PEDOT:PSS) [4]. The interfacial properties could be realized in bulk and films demonstrate enhanced transport properties beyond those of either component. More recently, we have been able to significantly improve the thermoelectric properties of these materials by morphological and chemical modifications. Here, we present our methodology and experimental transport properties of this new material where the thermal conductivity, electrical conductivity, and thermopower predictably vary as a function of composition, size, and the structural conformation caused by the solvent. The mechanism for these improvements is currently under investigation, but experimental results suggest that transport is dominated by interfacial phenomena. Furthermore, experiments suggest that both the electrical conductivity and thermopower can be independently increased without appreciably increasing the thermal conductivity. These improvements, in concert with the solution processable nature of this material, make it ideal for new thermoelectric applications.

Viscosity, electrical conductivity and density of the system ammonium nitrate-dimethyl sulphoxide

1984 ◽  
Vol 49 (5) ◽  
pp. 1109-1115
Author(s):  
Jindřich Novák ◽  
Zdeněk Kodejš ◽  
Ivo Sláma
Keyword(s):  
Electrical Conductivity ◽  
Aqueous Solutions ◽  
Ammonium Nitrate ◽  
Transport Properties ◽  
Calcium Nitrate ◽  
Dimethyl Sulphoxide ◽  
Present System ◽  
Empirical Equations ◽  
Concentrated Solutions ◽  
Nitrate Solutions

The density, viscosity, and electrical conductivity of highly concentrated solutions of ammonium nitrate in dimethyl sulphoxide have been determined over the temperature range 10-60 °C and the concentration range 7-50 mol% of the salt. The variations in the quantities as a function of temperature and concentration have been correlated by empirical equations. A comparison is made between the transport properties for the present system, aqueous solutions of ammonium nitrate, and calcium nitrate solutions in dimethyl sulphoxide.

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