Variation Of Resistivity Research Articles

Relationship between interstitial oxygen,substitutional carbon, resistivity and minority carrier lifetime in metallurgical multicrystalline silicon

. In this study we try to indentify relation between carrier lifetime, resistivity and two mains impurities concentration in a p-type upgrade metallurgical multicrystalline (UMG) silicon ingot. Thanks to this relation, we could prevent the Light Induced Degradation (LID) phenomenon and the SiC particles formation which are, respectively, at the origin of Voc losses and shunts in solar cells. So these 2 parameters are important for photovoltaic panels’ efficiency. Lifetime measurements are achieved by means of the Microwave Photoconductivity Decay “μw-PCD” technique, and concentration measurements are determined by FTIR. We demonstrate that resistivity variations depend on oxygen’s concentration but carbon analyses must be continued.

ESTIMATION DES TASSEMENTS DIFFÉRENTIELS DES SOLS DE FONDATION DE BÂTIMENT : CONTRIBUTION DES SONDAGES DE RÉSISTIVITÉ ÉLECTRIQUE

To estimate differential settlements of building foundation soils, the site on which the structure is based must be geotechnically surveyed in order to determine the deformation parameters and the thickness of the compressible soil layers in various places. This involves conducting destructive surveys. In this study, the use of geophysical methods (electrical soundings) as a substitute for the conventional methods used was considered. The Schlumberger electrodes array was deployed at the level of a control borehole and at three projected footings. The combination of the results of the electrical soundings with the lithological section of the borehole reveals a significant correlation between the variations of cumulative resistivities and the lithological section of the subsoil. The thickness of the compressible layers at the level of the projected footings is estimated to vary between 5 and 6 m. Œdometric differential settlements have an estimated maximum value of 4.56 cm

Ensemble Kalman inversion of induced polarization data

SUMMARY This paper explores the applicability of ensemble Kalman inversion (EKI) with level-set parametrization for solving geophysical inverse problems. In particular, we focus on its extension to induced polarization (IP) data with uncertainty quantification. IP data may provide rich information on characteristics of geological materials due to its sensitivity to characteristics of the pore–grain interface. In many IP studies, different geological units are juxtaposed and the goal is to delineate these units and obtain estimates of unit properties with uncertainty bounds. Conventional inversion of IP data does not resolve well sharp interfaces and tends to reduce and smooth resistivity variations, while not readily providing uncertainty estimates. Recently, it has been shown for DC resistivity that EKI is an efficient solver for inverse problems which provides uncertainty quantification, and its combination with level set parametrization can delineate arbitrary interfaces well. In this contribution, we demonstrate the extension of EKI to IP data using a sequential approach, where the mean field obtained from DC resistivity inversion is used as input for a separate phase angle inversion. We illustrate our workflow using a series of synthetic and field examples. Variations with uncertainty bounds in both DC resistivity and phase angles are recovered by EKI, which provides useful information for hydrogeological site characterization. Although phase angles are less well-resolved than DC resistivity, partly due to their smaller range and higher percentage data errors, it complements DC resistivity for site characterization. Overall, EKI with level set parametrization provides a practical approach forward for efficient hydrogeophysical imaging under uncertainty.

Engineering NiO Thin Film Properties using Ag9+ Ion Irradiation at Various Fluences

The impact of the Ag9+ ion irradiation on the characteristics of nickel oxide (NiO) films with several ion fluences including 1 × 1012, 1 × 1013 and 1 × 1014 ions cm−2 has been studied. These films were deposited over fluorine-doped tin oxide (FTO) substrate via spin coating technique. After that, structural, optical, vibrational, and electrical characteristics of all films were investigated employing different techniques. The change in the structure due to Ag9+ ion has been studied by GIXRD technique. A slight improvement in crystalline nature of NiO thin film was observed at 1 × 1012 ions cm−2 ion fluence that can be understood via thermal spike model. A decrement in value of transmission has been observed in the case of all thin films with ion fluence of Ag9+ ion. In addition, it was also observed that samples exposed to Ag9+ ions resulted in reduced intensity of the 1LO and 2LO modes in Raman spectrum. The reduced intensity of the Raman modes indicates the increment in the lattice defects. Further, AFM analysis showed that increment in the ion fluences of incident Ag9+ on NiO thin films led to an enhancement in surface roughness. Moreover, the Hall effect measurements were also carried out to examine the electrical characteristics of NiO films. From this measurement, it was observed that the conductivity of NiO varies along with the Ag9+ ions fluence, and it appears that the variation in resistivity follows the change in band gap.

Variation of the Electrical Resistivity of Peruvian Tropical Woods

Variation of the Electrical Resistivity of Peruvian Tropical Woods

Unconventional thickness dependence of electrical resistivity of silver film electrodes in substoichiometric oxidation states

The scaling down of metallic electrodes into ultrathin film geometries presents significant challenges in precisely controlling electrical resistivity. This difficulty stems from the rapid variation in resistivity with thickness, particularly near the percolation threshold. Currently, our understanding of the prediction of thickness-dependent resistivity in metallic film electrodes in volatile substoichiometric oxide (suboxide) states is limited. This study offers experimental and numerical evidence demonstrating a marked resistivity fluctuation spanning four to five orders of magnitude during the initial growth stages of suboxidized Ag film electrodes. These stages range from cluster coalescence to reaching the percolation threshold. The unusual resistivity change is attributed to the variation in suboxidation states with thickness, as well as the outward migration of interstitial O ions. These findings offer a crucial framework for controlling the electrical properties of thin metallic oxide films in extreme suboxidation states, extending beyond the conventional understanding applicable to thermodynamically stable metallic oxide phases.

Application of the electrical resistivity method and the estimation of limestone volume: a case study

The present work used the electrical resistivity approach to conduct a three-dimensional modeling and initial volume estimation of the limestone layer in the Mintom region located in southern Cameroon. In order to achieve the objectives of the study, a total of 21 electrical soundings spaced 250 m were first collected in the field using the Schlumberger array. These soundings were conducted along three profiles oriented in an east–west direction, spaced 500 m. Additionally, a geological survey was conducted to identify and emphasize the presence of limestone formations within the designated study region. The interpretation of the sounding data was conducted based on the analysis of the sounding curves. The interpretation outcomes, specifically resistivity and thickness, were compared with the geological field data, resulting in the development of lithostratigraphic logs for each sounding. The geological sections were constructed using the logs of the designated profile. The lithological logs were utilized to establish a lithological interface model and calculate the volume of the limestone layer at 260 ± 13 × 106 m3, utilizing the inverse distance method built into RockWorks software. A resistivity value is assigned to each geological layer in a sounding curve, allowing for the development of a resistivity variation model specific to the limestone layer. The proposed model facilitates the categorization of limestone layers based on their resistivity variations, thus serving as a fundamental reference for prospective exploratory activities within the designated study region. Our integrated approach provides a replicable model for a better understanding of the limestone reserve and effective management of this valuable resource.

Electrical transport mechanism of manganite-based trilayer heterostructures in the Cusp and insulating regions

In the present study, efforts are made to study the temperature dependent resistivity (ρ-T) variations of manganites (La0.7Sr0.3MnO3 (LSMO) single layer) and manganites-based systems ((LSMO/γ-Fe2O3/LSMO) trilayer heterostructures) in two distinct regions (Cusp region and Insulating region). Cusp region is an intermediate region between Metallic region and Insulating region. The resistivity-temperature curves are studied and analysed by various resistive models and fitting equations. The co-existence of ferromagnetic clusters and polarons manifests in the Cusp region. The Insulating region is explored and fitted under two regimes: Low Temperature Insulating region and High Temperature Insulating region. Various mathematical models viz. Thermal Activation model, Small Polaron Hopping model and Variable Range Hopping model were employed to study the ρ-T variations under various temperature ranges for LSMO (60 nm) single layer system and LSMO/γ-Fe2O3/LSMO (150 nm) trilayer heterostructures. In Insulating region, the deviations in the fitted curves from the experimental data is due to intrinsic disorder at the R/A site in case of LSMO single layer system while in case of trilayer system disorder exists at both R/A and B sites. The study is crucial to understand the microscopic picture of electrical transport behavior in both the systems near and above Metal-Insulator Transition.

Detection of Seepage Paths in Dam by Electrical Resistivity Tomography

The stability of the dam can be compromised by water erosion and seepage, which primarily affect the resistivity distribution underground. Seepage pathways in the dam are detected through electrical resistivity tomography (ERT), utilizing variations in resistivity for delineation. The 2D profiles show that the resistivity structure of the dam is relatively higher resistivity values (100~400Ωm), while the seepage paths exhibit significantly lower resistivity values (10–50 Ω m). it can outline five seepage paths.

Improvement of thermoelectric performance of flexible compound Ag2S0.55Se0.45 by means of partial V-substitution for Ag

The effects of the partial V-substitution for Ag on the thermoelectric (TE) properties are investigated for a flexible semiconducting compound Ag2S0.55Se0.45. Density functional theory calculations predict that such a partial V-substitution constructively modifies the electronic structure near the bottom of the conduction band to improve the TE performance. The synthesized Ag1.97V0.03S0.55Se0.45 is found to possess a TE dimensionless figure-of-merit (ZT) of 0.71 at 350 K with maintaining its flexible nature. This ZT value is relatively high in comparison with those reported for flexible TE materials below 360 K. The increase in the ZT value is caused by the enhanced absolute value of the Seebeck coefficient with less significant variation in electrical resistivity. The high ZT value with the flexible nature naturally allows us to employ the Ag1.97V0.03S0.55Se0.45 as a component of flexible TE generators.

Application of Vertical Electrical Sounding Method Using Damped Least-Square Inversion for Leachate Identification at Bakung Landfill, Lampung

This paper has reviewed the application of the damped least square inversion method for the VES (vertical electrical sounding) with Schlumberger array. The damped least squares solved using singular value decomposition were applied in Bakung Landfill to determine the aquifer contaminated by leachate. The ability of damped Least Squares inversion algorithm were verified using the resistivity variation of synthetic model which simulates aquifer layer of subsurface. Based on the results of 1D resistivity model, low resistivity zone can be used to identify the existence leachate contaminants of aquifer.

Groundwater Investigation Using Electrical Resistivity Imaging Technique in Western Ramadi, Iraq

The two-dimensional electrical resistivity imaging technique was used to examine groundwater in western Ramadi. The survey was performed with a factor (n) and a-spacing values of 6 and 5 m, respectively. The inverse models clearly show the resistivity variation between the anomalous parts of the water table and all the sediments. The vertical extension of the saturation sediments is between 1.5–9.5 m, which is identical to the groundwater level in the three existing wells located in the University of Anbar, with an area of 7 kilometers and an area of 18 kilometers. The extreme thickness of the water saturation layer was determined to be about 10.5 meters. It was concentrated in gypsum and mudstone soils with secondary gypsum and siltstone, considered the upper components of the Injana Formation at the University of Anbar. At 7 Kilometer area which starts from a depth of 1 m to depths of up to 12 m, it is also considered a groundwater reservoir. While 18 Km area is considered to have dry soil and the groundwater in it is far from the surface at 12 m depth.

GEOPHYSICAL MODELLING OF AN AREA OF CERRITOS, PEREIRA (RISARALDA)

A geophysical project was developed in Cerritos area, near Pereira city, where gravity, magnetic, electrical and seismic data were acquired over a 210.75 km 2 area. The data were processed and interpreted according the geological information acquired and also available; as result a free to confined aquifer was defined in the Plio-Pleistoce Pereira formation (Tqp), that is characterized by non-homogeneous lateral layers and constituted by a superior sequence of volcanic ashes and an inferior of volcano-clastic flows which reaches 750 m thick. The Pereira fm is controlled by the tectonic controlled Cartago and Barroso formations, with inverse faults that indicate uplift of the basement and variations of the Pereira formation thick, affecting the underwater circulation system and expressed by variations in the electric resistivity of the subsoil.

Stability of industrial gallium-doped Czochralski silicon PERC cells and wafers

The carrier lifetime stability of gallium-doped silicon wafers and performance stability of industrial PERC solar cells produced from sister wafers were investigated under four different illumination conditions and temperatures. The seven investigated materials feature a resistivity variation of 0.4–1.0 Ωcm and lifetime samples were processed to create high hydrogen content (with PECVD SiNx) or low hydrogen content (with ALD Al2O3 or HfO2). Our results confirm that the material itself is prone to light and elevated temperature induced degradation (LeTID), however experiments on PERC cells produced utilising the same silicon material indicate that the production process can successfully suppress LeTID. In contrast to earlier studies, we observe only small levels of degradation at the cell level, with some showing an improvement in cell parameters under LeTID testing conditions. Our results indicate that LeTID is not necessarily a major issue for the performance of modern passivated emitter and rear cells made from gallium-doped silicon substrates.

Cellulose paper-based humidity power generator with high open circuit voltage based on zinc-air battery structure

The sensing mechanisms of common humidity sensors related to conductive active materials, which can be simply attributed to the variations in resistivity due to the separation of conductive materials and variations in polymer permittivity, are generally plagued by drawbacks such as cumbersome fabrication processes, high cost and low performance. Herein, we prepared Zn/Cellulose filter paper (CFP)/Nanoscale carbon ink (NCI)/Cu structure humidity power generators (ZHGs) based on the power generation principle of typical zinc-air batteries, using active metals with strong conductivity as electrodes, and the redox reactions that took place in the zinc-air battery can convert the chemical energy in the electrode into a stable electrical energy. The ZHG fabricated in this work can reach an extremely high open circuit voltage (Voc) of 0.803 V at 97 % RH and possesses an excellent power density of 312.24 μW/cm2, which has a good linear relationship (R2 = 0.9669) over a wide humidity range (20–97 % RH). In addition, 10 ZHGs in series can charge commercial capacitors up to 3.83 V. Finally, the proof of concept demonstrated that the humidity power generation sensor can be well applied in human respiratory monitoring, finger non-contact switch, and power supply for light emitting diode (LED).

Dual action of epigallocatechin-3-gallate in virus-induced cell Injury

BackgroundViral infections cause damage and long-term injury to infected human tissues, demanding therapy with antiviral and wound healing medications. Consequently, safe phytochemical molecules that may control viral infections with an ability to provide wound healing to viral-induced tissue injuries, either topically or systemically, are advantageous. Herein, we hypothesized that epigallocatechin-3-gallate (EGCG), the most abundant polyphenol in green tea, might be effective as a wound healing, antiviral, and antifibrotic therapy. ResultsThe antiviral activities of EGCG against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Herpes simplex virus type 2 (HSV-2) as well as its wound healing activities against different monolayer tissue (continuous and primary) systems were investigated. Consider its possible wound-healing advantages as well. To determine the safe concentrations of EGCG in green monkey kidney (Vero) and Vero-E6 cell lines, MTT assay was performed and showed high CC50 values of 405.1 and 322.9 μM, respectively. The antiviral activities of EGCG against SARS-CoV-2 and HSV-2, measured as half-maximal concentration 50 (IC50) concentrations, were 36.28 and 59.88 μM, respectively. These results confirm that the EGCG has remarkable viral inhibitory activities and could successfully suppress the replication of SARS-CoV-2 and HSV-2 in vitro with acceptable selectivity indices (SI) of 11.16 and 5.39, respectively. In parallel, the EGCG exhibits significant and dose/time-dependent anti-migration effects in human breast cancer cells (MCF-7), its resistant variation (MCF-7adr), and human skin fibroblast (HSF) indicating their potential to heal injuries in different internal and topical mammalian systems. ConclusionsThe EGCG has proven to be an efficient antiviral against SARS-CoV-2 and HSV-2, as well as a wound-healing phytochemical. We assume that EGCG may be a promising option for slowing the course of acute cellular damage induced by systemic (Coronavirus Disease 2019 (COVID-19)) or topical (HSV-2) viral infections.

High-value utilization of modified magnesium slag solid waste and its application as a low-carbon cement admixture

A large amount of magnesium slag solid waste, insufficient comprehensive disposal capacity, high disposal costs, and uncertain environmental stability hinder the low-carbon, green, and sustainable development of magnesium and magnesium alloy smelting. Therefore, this study proposed a high-quality, large-scale, and industrialized disposal method for modified magnesium slag (MMS). Through relevant experimental tests and microscopic characterization methods (physical and chemical performance, hydration heat, resistivity, and microstructure tests), the physical and chemical properties, curing mechanism, and social benefits of MMS low-grade magnesium slag were investigated. The physical and chemical properties, curing mechanism, and social benefits of modified magnesium slag low-carbon Portland cement (MMSPC) produced by MMS as a cement admixture were elucidated. The results showed that (1) the physical and chemical properties of MMSPC met the requirements of the GB 175–2007 “General Portland Cement” standard. (2) A significant difference was observed in the early hydration heat release of fresh MMSPC slurry, confirming a hydration composite effect between MMS and clinker, which was also the key reaction mechanism of MMS replacing clinker to produce MMSPC. (3) The resistivity of MMSPC increased, decreased, and then increased with time, which was mainly controlled by the settling of the aggregate, the dissolution of the binder, and the hydration reaction of the system. However, the variation in resistivity with time and value was influenced by the mixing ratio of the system. (4) MMSPC could also offer certain environmental and economic benefits. Carbon emissions per ton of cement produced were reduced by 7.95%, and the total cost per ton of cement produced was reduced by more than 10%. This study provided a theoretical basis for the high-value disposal of MMS and the reduction of carbon emissions in the cement industry.

Numerical analysis of 40 MW HTS motor electromagnetic characteristics for ship electric propulsion

In recent years, with the development of ship electric propulsion system, High Temperature Superconducting (HTS) motors have gained attention as a promising potential resolution due to their high-power density and the progression of cryogenic refrigeration technology. We present an electromagnetic characteristics numerical analysis of 40 MW, 120 rpm, HTS synchronous motor which is a semi-superconducting motor: in fact, it has a superconducting rotor composed of YBCO material and a conventional stator. Combining electric resistivity variation of rotor copper shielding sleeve in low temperature environment and YBCO coil critical current, the electromagnetic behavior of the 40 MW HTS synchronous motor is analyzed with non-ferromagnetic stator support structure. To assess the effects of varying stator winding currents and thickness on eddy current losses of the copper shielding sleeve, calculations were done, and a preliminary discussion was initiated. This study has certain reference significance for electromagnetic design and optimization of multi-ten MW HTS motors, especially used in ship electric propulsion system.

Ferroelectric Domain Wall p-n Junctions.

We have used high-voltage Kelvin probe force microscopy to map the spatial distribution of electrical potential, dropped along curved current-carrying conducting domain walls, in x-cut single-crystal ferroelectric lithium niobate thin films. We find that in-operando potential profiles and extracted electric fields, associated with p-n junctions contained within the walls, can be fully rationalized through expected variations in wall resistivity alone. There is no need to invoke additional physics (carrier depletion zones and space-charge fields) normally associated with extrinsically doped semiconductor p-n junctions. Indeed, we argue that this should not even be expected, as inherent Fermi level differences between p and n regions, at the core of conventional p-n junction behavior, cannot occur in domain walls that are surrounded by a common matrix. This is important for domain-wall nanoelectronics, as such in-wall junctions will neither act as diodes nor facilitate transistors in the same way as extrinsic semiconducting systems do.

Three-dimensional electric-field vector resistivity imaging for deep subsurface fractures network in heterogeneous crystalline rocks

SUMMARY Crystalline rocks, exposed in different parts of the world and over about one-third of India, have complex aquifer systems, which pose a challenge to mapping groundwater dynamics. Electrical resistivity tomography in quasi-3-D and electrical logging of some borewells carried out in an experimental ‘hydrogeological park’ in southern India, which has numerous boreholes and other geophysical information for validation, were unable to map the existence of deeper bedrock fractures and their connectivity. We have attempted electric-field vector resistivity imaging (EVRI), a new tool, to resolve the possible fracture-induced deep interconnectivity in a hard rock aquifer system. In the experiment, multiple two-orthonormal-channels independent receiver nodes for potential measurements are deployed and illuminated with several current injections between ∼ 0.9–3.7 A in full 3-D fashion, which allowed for improved mapping of resistivity variation than earlier approaches. The EVRI-derived full 3-D model shows the presence of fractures for depths between 20 and 70 m with substantial resistivity variations, supported by some borewells hydraulic investigations. It has also enhanced lateral resolution for depths > 30 m and almost doubled the depth of investigation than earlier electrical models. EVRI results revealed unweathered/unfractured granitic rock with no significant signature of fractures beyond 70 m depth that corroborates with existing borehole logs and hydrogeological conceptual model. Therefore, this study demonstrates the potential of EVRI for 3-D mapping of heterogeneous crystalline rocks, which would greatly help in groundwater management.