Changes In Electrical Conductivity Research Articles

Dual‑carbon confined Sb2Se3 nanorods for potassium ion batteries anode with improved capacity and cycling stability

Sb2Se3 is regarded as a promising conversion-alloying type anode material for potassium ion batteries (PIBs) owing to its high theoretical specific capacity. However, the low electric conductivity and large volume change during the charge/discharge process hinder its practical applications. Herein, we proposed a novel ‘dual carbon coating’ strategy to construct carbon confined Sb2Se3 nanorods for high performance PIBs anode. Owing to the enhanced electric conductivity resulted from the inner carbon and the strengthened mechanical stability from the outer graphene layer, the confined Sb2Se3 exhibit outstanding electrochemical potassium ion storage performances with a specific capacity of 482.1 mAh g−1 after 50 cycles at a current density of 0.1 A g−1. Even at a high current density of 1 A g−1 after 500 cycles, it still maintains a specific capacity of 283.7 mAh g−1. These results outperform the pure Sb2Se3 and those traditional ‘single carbon’ coated Sb2Se3 from both specific capacity and cycling stability. This ‘dual carbon coating’ method could also be applied to other conversion or alloying type anode materials of PIBs with high theoretical capacities and large volume variation during the repeated charge/discharge process.

Визначення величини енергетичної невпорядкованості в аморфних оксидних напівпровідниках

The amorphous material films are resistant to high-energy irradiation. Therefore, devices built using the properties of these materials can work in conditions of increased radiation much longer than devices using the properties of crystals. An important characteristic of these materials is their degree of disorder. To determine this characteristic, a model of random fluctuations of the local edge of the conduction band is considered for the theoretical study of magnetoconductivity in amorphous oxide semiconductors. The effective medium approximation is used. An approach to determining the amount of energy disorder based on experimental measurement of changes in longitudinal and transverse electrical conductivity in a magnetic field is proposed.

Pomegranate-like heterostructured SnS2/CoS2 particles encapsulated in S, N dual-doped carbon framework enabling high-rate and durable sodium ion storage

As a promising anode material for sodium-ion batteries, SnS2 has attracted increasing attention owing to its high theoretical capacity and abundant reserves. Unfortunately, the poor electrical conductivity and drastic volume changes lead to unsatisfactory cycling and rate performance, largely limiting its practical application. Herein, we report a pomegranate-like composite of heterostructured SnS2/CoS2 spheres encapsulated in S, N dual-doped carbon framework (SnS2/CoS2@SNC) obtained by a simple ion adsorption, in situ polymerization coating of polydopamine and subsequent calcination strategy. The integration of CoS2 with SnS2 particles with abundant interfaces can provide rich redox chemistry and accelerated ion diffusion kinetics, while the coated S, N dual-doped carbon shell enables good electrical conductivity and reinforced structural integrity as well by accommodating the volume changes and inhibiting the collapse/pulverization of active materials during the cycling process. As a consequence, the pomegranate-like heterostructured SnS2/CoS2@SNC anode exhibited a higher capacity (743 mAh g−1 at 1 A g−1), excellent rate capability (213 mAh g−1 at 50 A g−1) and outstanding cycling stability (560 mAh g−1 at 5 A g−1 after 1000 cycles), showing the application feasibility of this anode material for developing high-rate and durable SIBs.

Heat activated VO2 (R) cathodes for high-performance aqueous zinc ion batteries

We introduce a novel approach for design and production of vanadium dioxide (VO2) cathodes activated by heat, specifically tailored for use in aqueous zinc-ion batteries (ZIBs). Our cathodes exhibit distinctive metal-insulator transition (MIT) characterized by the shift between monoclinic (M) and tetragonal rutile (R) phases. The employment of an aqueous electrolyte in ZIBs enables successful operation of VO2 cathodes, showcasing phase transition and enhanced electrochemical performance above a readily attainable temperature of approximately 68 °C. The MIT feature enhances the charge transfer properties at electrode-electrolyte interfaces, resulting in notable improvements in specific capacity and energy densities. Fabricated VO2(M) cathodes underwent heat-triggered transformation to VO2(R), resulting in a remarkable increase (400 %) in capacity. At 0.1 A g−1, VO2(R) cathodes show specific capacity of 354.6 mAh g−1, yielding an impressive energy density of 461.0 Wh kg−1 for aqueous ZIBs. This exceptional performance can be attributed to abrupt change in electrical conductivity upon thermal activation of MIT. This work underscores pivotal role of thermally activated MIT in finely tuning electrochemical performance of energy storage systems, prospecting a promising avenue for further advancements.

Effects of returning paddy field to wetland on composition and stability of soil aggregates in the Yellow River Delta.

The composition and stability of soil aggregates are important indicators for measuring soil quality, which would be affected by land use changes. Taking wetlands with different returning years (2 and 15 years) in the Yellow River Delta as the research object, paddy fields and natural wetlands as control, we analyzed the changes in soil physicochemical properties and soil aggregate composition. The results showed that soil water content, total organic carbon, dissolved organic carbon and total phosphorus of the returning soil (0-40 cm) showed an overall increasing trend with returning period, while soil pH and bulk density was in adverse. There was no significant change in clay content, electrical conductivity, and total nitrogen content. The contents of macro-aggregates and micro-aggregates showed overall increasing and decreasing trend with returning period, respectively. The stability of aggregates in the topsoil (0-10 cm) increased with returning years. Geometric mean diameter and mean weight diameter increased by 8.9% and 40.4% in the 15th year of returning, respectively, while the mass proportion of >2.5 mm fraction decreased by 10.5%. There was no effect of returning on aggregates in subsoil (10-40 cm). Our results indicated that returning paddy field to wetland in the Yellow River Delta would play a positive role in improving soil structure and aggregate stability.

Enhancement of riboflavin-mediated photodynamic inactivation against Salmonella on tuna fillets coupled with slightly basic electrolyzed water

This study aimed to develop an efficient PDI system to kill Salmonella in solution or on tuna fillets under 455 nm blue light-emitting diodes (LED) irradiation, by selecting slightly basic electrolyzed water (SBEW) as the solvent. Results showed that the solvent of SBEW increased the solubility of riboflavin, and notably strengthened the production of ROS compared to normal saline solution. On this basis, the riboflavin-mediated PDI coupled with SBEW enhanced the inactivation of Salmonella, supported by that the viability of Salmonella was significantly (P < 0.05) inactivated by 5.02 Log10 CFU/mL with 9.36 J/cm2 irradiation and 80 μM riboflavin, and no viable cells were detected when the irradiation dose was increased to 12.48 J/cm2. The action mechanisms showed that this novel PDI damaged the cell membrane causing the leakage of cellular contents, degraded the genomic DNA and enhanced the lipid peroxidation in Salmonella. In addition, the PDI system efficiently killed >4.0 Log10 CFU/g of Salmonella on tuna fillets with 120 μM riboflavin and 18.72 J/cm2 irradiation. Furthermore, the PDI system decelerated the proliferation of Salmonella, the changes of electrical conductivity, pH and color, and lipid oxidation in tuna fillets during the storage. This study provides a promising PDI system to control food pathogen contamination and preserve the storage quality of seafood.

Production and properties of electrically conductive polymer composites reinforced with cotton threads

AbstractThe problem of strength loss in electrically conductive composites made with dispersed fillers in the polymer binder is solved by spraying an aerosol of graphite on a textile material with a 3D weave of threads, or on knitwear of fibers with various structure and chemical composition. The loose microstructure of cotton fibers and the developed surface of elastic filaments made of synthetic polymers retain colloidal graphite particles in a layered composite during cyclic deformation. The electrical conductivity of knitwear with graphite changes during stretching due to the reversible displacement of graphite particles, first during straightening and then during stretching of elastic threads. The 130 ± 5 strain sensitivity GF and 12,000 ± 95 кPa−1 stress sensitivity QF of the composites presented in this paper exceed the corresponding parameters of known electrically conductive composites. The combination of a significant change in electrical conductivity with the elasticity of the developed knitwear‐based composite is important for the use in load cells, smart clothes, medical devices, and robotics.

Photothermal synergistic high-sensitivity self-driven vertical asymmetric Te/Bi2Te3/In2O3 heterojunction near-infrared imaging photodetector

Infrared detection and imaging devices have great potential in the fields of defense and security, medical monitoring, and food safety. As a novel method, photothermal assistants can expand the absorption in the case of low-angle dependence, which is one of the key factors in improving the performance of infrared detectors. Photo-heating accelerates the transfer of carrier, inducing a change in electrical conductance and exciting “hot” electrons promote a photoelectric response and extend the response photon energies well below the semiconductor band edge. However, photodetectors require cooling to prevent overheating and reduce thermal noise, thereby improving photoelectric detection. Therefore, it remains a formidable challenge to design a suitable heterojunction photodetector that can synergistically utilize optical and thermal energy. Here, a unique asymmetric Te/Bi2Te3/In2O3 heterojunction structure is designed by a simple physical deposition method, and a photothermal synergistic infrared detector is successfully fabricated. The Te/Bi2Te3/In2O3 heterojunction exhibits excellent self-driven photo-detection performance in the near-infrared wavelength bands of 850, 980, and 1050 nm, especially under prolonged laser irradiation at 850 nm. Under prolonged laser irradiation at 850 nm (0 bias), the heterojunction exhibits ultra-fast (response time < 55 ms), ultra-sensitive, and stable detection behavior, with a response rate as high as 0.4195 mA/W (Ri of 0.4724 mA/W, after 1,000 cycles), Iph/Idark is 281.55, and the detectivity as high as 4.296 × 109 Jones. A high-resolution current image was obtained under 980 nm illumination at room temperature without bias. Such excellent optoelectronic properties make the heterojunctions of the asymmetric Te/Bi2Te3/In2O3 heterojunction a potential candidate for future infrared detection and imaging.

Spatial distribution characteristics and degradation mechanism of microorganisms in n-hexadecane contaminated vadose zone

The damage caused by petroleum hydrocarbon pollution to soil and groundwater environment is becoming increasingly significant. The vadose zone is the only way for petroleum hydrocarbon pollutants to leak from surface into groundwater. The spatial distribution characteristics of indigenous microorganisms in vadose zone, considering presence of capillary zones, have rarely been reported. To explore the spatial distribution characteristics of indigenous microorganisms in vadose zone contaminated by petroleum hydrocarbons, a one-dimensional column migration experiment was conducted using n-hexadecane as characteristic pollutant. Soil samples were collected periodically from different heights during experiment. Corresponding environmental factors were monitored online. The microbial community structure and spatial distribution characteristics of the cumulative relative abundance were systematically analyzed using 16S rRNA sequencing. In addition, the microbial degradation mechanism of n-hexadecane was analyzed using metabolomics. The results showed that presence of capillary zone had a strong retarding effect on n-hexadecane infiltration. Leaked pollutants were mainly concentrated in areas with strong capillary action. Infiltration and displacement of NAPL-phase pollutants were major driving force for change in moisture content (θ) and electric conductivity (EC) in vadose zone. The degradation by microorganisms results in a downward trend in potential of hydrogen (pH) and oxidation-reduction potential (ORP). Five petroleum hydrocarbon-degrading bacterial phyla and 11 degradable straight-chain alkane bacterial genera were detected. Microbial degradation was strong in the area near edge of capillary zone and locations of pollutant accumulation. Mainly Sphingomonas and Nocardioides bacteria were involved in microbial degradation of n-hexadecane. Single-end oxidation involved microbial degradation of n-hexadecane (C16H34). The oxygen consumed, hexadecanoic acid (C16H32O2) produced during this process, and release of hydrogen ions (H+) were the driving factors for reduction of ORP and pH. The vadose zone in this study considered presence of capillary zone, which was more in line with actual contaminated site conditions compared with previous studies. This study systematically elucidated vertical distribution characteristics of petroleum hydrocarbon pollutants and spatiotemporal variation characteristics of indigenous microorganisms in vadose zone considered presence of capillary zone. In addition, the n-hexadecane degradation mechanism was elucidated using metabolomics. This study provides theoretical support for development of natural attenuation remediation measures for petroleum-hydrocarbon-contaminated soil and groundwater.

Investigating arc and molten metal transport phenomena in gas metal arc welding with Ar–CO2 gas mixtures using a numerical method

This paper presents a numerical investigation of the transient transport phenomena of the arc and molten metal during gas metal arc welding (GMAW) using shielding gas mixtures ranging from 100% Ar + 0% CO2 to 80% Ar + 20% CO2. The thermophysical parameters of the Ar–CO2 mixtures, considering the presence of metal vapor, were calculated as a function for a temperature range of 1000–30 000 K. The influence of metal vapor content and CO2 proportion on the thermophysical properties of the mixed gas was discussed in detail. As the CO2 content increased from 0 to 20%, the shape of the arc changed from a bell to a cone due to the increase in mass density, specific heat, and thermal conductivity. The maximum arc temperature and velocity decreased with increasing CO2 content, resulting in larger droplets and a lower droplet transfer frequency. Although the change in electrical conductivity did not affect the arc shape, it did influence the arc temperature by altering the distribution of current density. Experiments of droplet transfer and arc behavior were carried out, and the results showed that the simulated droplet size, transfer frequency, and arc temperature distribution agreed well with the experimental values. These findings could serve as a theoretical tool for better understanding the underlying physical mechanisms of the GMAW process using different shielding gases, ultimately aiming to achieve high weld quality.

High-resolution EEG source localization in personalized segmentation-free head model with multi-dipole fitting

Objective. Electroencephalograms (EEGs) are often used to monitor brain activity. Several source localization methods have been proposed to estimate the location of brain activity corresponding to EEG readings. However, only a few studies evaluated source localization accuracy from measured EEG using personalized head models in a millimeter resolution. In this study, based on a volume conductor analysis of a high-resolution personalized human head model constructed from magnetic resonance images, a finite difference method was used to solve the forward problem and to reconstruct the field distribution. Approach. We used a personalized segmentation-free head model developed using machine learning techniques, in which the abrupt change of electrical conductivity occurred at the tissue interface is suppressed. Using this model, a smooth field distribution was obtained to address the forward problem. Next, multi-dipole fitting was conducted using EEG measurements for each subject (N = 10 male subjects, age: 22.5 ± 0.5), and the source location and electric field distribution were estimated. Main results. For measured somatosensory evoked potential for electrostimulation to the wrist, a multi-dipole model with lead field matrix computed with the volume conductor model was found to be superior than a single dipole model when using personalized segmentation-free models (6/10). The correlation coefficient between measured and estimated scalp potentials was 0.89 for segmentation-free head models and 0.71 for conventional segmented models. The proposed method is straightforward model development and comparable localization difference of the maximum electric field from the target wrist reported using fMR (i.e. 16.4 ± 5.2 mm) in previous study. For comparison, DUNEuro based on sLORETA was (EEG: 17.0 ± 4.0 mm). In addition, somatosensory evoked magnetic fields obtained by Magnetoencephalography was 25.3 ± 8.5 mm using three-layer sphere and sLORETA. Significance. For measured EEG signals, our procedures using personalized head models demonstrated that effective localization of the somatosensory cortex, which is located in a non-shallower cortex region. This method may be potentially applied for imaging brain activity located in other non-shallow regions.

Assessing the effects of free fall conditions on damage to chickpea seeds: A comprehensive examination of seed deterioration.

Impact damage is the most destructive effect on the seeds during harvesting, handling, and storage, both on-farm and off-farm. The chickpea seeds' dicotyledonous characteristics and large mass and size make them susceptible to mechanical damage under impact loading. Tests were conducted to determine the extent of damage to chickpea seeds due to the impact caused by free fall. The extent of internal damage to the chickpea seeds was determined, which included the measurement of seed deterioration by the accelerated aging method (percentage loss in germination in the accelerated aging test) and the measurement of electrical conductivity. Three independent variables were used in the test, namely: (a) drop height (3, 6, 9, and 12 m), (b) impact surface (concrete, metal, plywood and seeds on seeds), and (c) seed moisture content (10%, 15%, 20%, and 25% w.b). The results showed that drop height, impact surface, and moisture content had significant effects (p < .01) on the loss in germination percentage and change in electrical conductivity of chickpea seeds. In terms of loss in germination, the highest damage to seeds occurred at the metal impact surface (41.96%) and the least at the seed on the seed (29.71%). The highest amount of electrical conductivity was related to the seeds dropped on the metal (36.09 μS cm-1 g-1) and the lowest was related to seed-on-seed contact (21.68 μS cm-1 g-1). By increasing the drop height from 3 to 12 m, the loss in germination and electrical conductivity of seeds increased from 27.74% to 48.08% and from 18.72 to 40.47 μS cm-1 g-1, respectively. Increasing the moisture content of chickpea seeds from 10 to 25% causes a decrease in the amount of damage to the seeds in terms of electrical conductivity (from 38.40 to 21.18 μS cm-1 g-1), but increases the damage in the form of a loss in the percentage germination in the accelerated aging test (from 29.22% to 42.88%). To reduce the impact damage to peas caused by free fall, the height of the fall should be limited to about 6 m, and they should be prevented from hitting hard and rough surfaces.

Hemodialysis Wastewater Treatment via Electrocoagulation and Electro-Oxidation: Modular Pilot-Level Modeling and Simulation.

Hemodialysis treatment in specialized clinics within the same hospital significantly impacts environmental water health due to contaminated wastewater. The issues observed included changes in electrical conductivity, the presence of dangerous bacterial loads, toxicity from heavy metals, total cyanide content, and helminth parasite eggs. The level of damage is dependent on the patient's health under treatment. This research will use a modular system that employs electrocoagulation and electro-oxidation processes at the laboratory and pilot levels to treat hemodialysis wastewater using synthetically prepared and real samples extracted from local clinics. The results showed that these hybrid systems improved various physicochemical parameters. Specifically, decreases in electrical conductivity of 49 %, total suspended solids of 27-100 %, chemical oxygen demand of 49 %, biochemical oxygen demand of 49 %, and cation and anion loading were observed at 96-100 % and pH 8.13 UpH in accordance with the established standards. With these results and the experimental conditions used, the proposed treatment system was modeled using the GPS-X program, and it was concluded that the modular system used and the electrocoagulation/electro-oxidation/activated carbon configuration is suitable for treating wastewater from hemodialysis and that scaling up this process to facilities that have dialysate machines more advanced than those considered in this work is possible.

The Release and Migration of Cr in the Soil under Alternating Wet-Dry Conditions.

In recent decades, chromium contamination in soil has emerged as a serious environmental issue, demanding an exploration of chromium's behavioral patterns in different soil conditions. This study aims to simulate the release, migration, and environmental impact of chromium (Cr) in contaminated soils under natural rainfall conditions (wet-dry cycles). Clean soils sourced from Panzhihua were used to cultivate chromium-containing soils. Simulated rainfall, prepared in the laboratory, was applied to the cultivated chromium-containing soils in indoor simulated leaching experiments. The experiments simulated three years of rainfall in Panzhihua. The results indicate that soils with higher initial Cr contents result in higher Cr concentrations in the leachate, but all soils exhibit a low cumulative Cr release. The leachate shows similar patterns in total organic carbon (TOC), pH, electrical conductivity, and Cr content changes. An analysis of the speciation of Cr in the soil after leaching reveals a significant decrease in the exchangeable fraction for each Cr species, while the residual and oxidizable Cr fractions exhibit notable increases. The wet-dry cycle has the following effects on the soil: it induces internal reduction reactions in the soil, leading to the reduction of Cr(VI) to Cr(III); it alters the binding of Cr ions to the soil, affecting the migration of chromium; and it involves microorganisms in chemical processes that consume organic matter in the soil. After three years of rainwater leaching, chromium-containing soils released a relatively low cumulative amount of total chromium, resulting in a reduced potential risk of groundwater system contamination. Most of the chromium in the chromium-containing soil is fixed within the soil, leading to less biotoxicity.

Anisotropic electrical conductivity changes in FeTiO3 structure transition under high pressure

Anisotropic electrical conductivity changes in FeTiO3 structure transition under high pressure

The Effect of Partial Substitution of Ge-S-Cd Alloys on the Density of Energy States

Five samples of the ternary alloy Ge-S-Cd were created using the melting point method, and the effects of partially substituting cadmium for germanium were determined. and partial substitution of germanium by cadmium was used to study the change in electrical conductivity. Electrical experiments were performed on Ge35-xS65Cdxternary alloy with x = 0, 5, 10, 15, and 20. It was discovered that the conductivity (σdc) rises with rising temperature in all samples under experiment. This confirms that the samples have semiconductor behavior. It has been observed that there are three regions of electrical conductivity in the electrical conductivity curve at low, moderate, and high temperatures. The preexponential elements and effective energies of each of the three conduction regions were calculated for each of the Cadmium values. It was found that all of them were impacted by a rise in the value of cadmium in the ingot. A numerical analysis of the conductivity equation was also performed to calculate the energy of the expanding states' density in local states and at the Fermi level. It has been observed that all of the values of samples change with the rising value of cadmium concentration.

Investigation of thermoelectric properties of high concentration PEDOT: PSS inks doped with graphene and multi-walled carbon nanotubes

The use of wearable technologies in various aspects of life, particularly in health and entertainment, is experiencing a remarkable increase. This intensity of usage brings with it the energy needs of these devices. Polymer-based thermoelectric generator solutions are one of the most emphasized issues in energy harvesting applications and stand out as a solution method. In this study, we introduce a high-concentration poly(3,4-ethylenedioxy-thiophene): polystyrene sulfonate (PEDOT: PSS)-based conductive polymer ink, which has been doped with graphene and multi-walled carbon nanotubes (MWCNT) for thermoelectric applications. We also explore the film properties derived from this ink. The fabrication process involves cryogenic freezing, lyophilization, and re-dispersion of a mixture of water and dimethyl sulfoxide (DMSO) with a commercial PEDOT: PSS aqueous solution, followed by the addition of specific additives. These added compounds have led to a significant increase in electrical conductivity, resulting in materials with high electrical conductivity levels ranging from 100 to 200 S/cm. Remarkably, even after subjecting the material to 100 bending cycles, no significant change in electrical conductivity was observed. All the materials produced exhibited p-type semiconductor properties, and the high concentration of PEDOT: PSS, along with the addition of graphene and multi-walled carbon nanotubes, notably enhanced the Seebeck coefficient, reaching a maximum of 25 μV K⁻1.

Carbon-nanotube field-effect transistors for resolving single-molecule aptamer-ligand binding kinetics.

Small molecules such as neurotransmitters are critical for biochemical functions in living systems. While conventional ultraviolet-visible spectroscopy and mass spectrometry lack portability and are unsuitable for time-resolved measurements in situ, techniques such as amperometry and traditional field-effect detection require a large ensemble of molecules to reach detectable signal levels. Here we demonstrate the potential of carbon-nanotube-based single-molecule field-effect transistors (smFETs), which can detect the charge on a single molecule, as a new platform for recognizing and assaying small molecules. smFETs are formed by the covalent attachment of a probe molecule, in our case a DNA aptamer, to a carbon nanotube. Conformation changes on binding are manifest as discrete changes in the nanotube electrical conductance. By monitoring the kinetics of conformational changes in a binding aptamer, we show that smFETs can detect and quantify serotonin at the single-molecule level, providing unique insights into the dynamics of the aptamer-ligand system. In particular, we show the involvement of G-quadruplex formation and the disruption of the native hairpin structure in the conformational changes of the serotonin-aptamer complex. The smFET is a label-free approach to analysing molecular interactions at the single-molecule level with high temporal resolution, providing additional insights into complex biological processes.

Understanding sensing mechanism of N-doped graphene-based toxic gas sensors using electronic, thermal, mechanical, electrical, and sensing properties:A DFT study

A facile and feasible protocol for the evolution of sensing characteristics of three dissimilar nitrogen-doped graphene (N-G)-based ethanol, methanol, and nitrogen-oxide gas sensors using first-principle calculations. Simulated X-ray diffraction (XRD) investigation demonstrates the sharp peak located at 7.9, 11, 13.8, and 15.4° represents (100), (111), (026), and (012) facets. Electronic properties calculations predict that toxic gas adsorption reduces the charge carrier concentration and induces internal resistance. Thermal properties analyses suggest that the nature of adsorption depends on changes in Gibbs free energy. Charge density and distribution analysis disclose that the adsorption of toxic gases leads to charge transfer between toxic gases and N-G. Mechanical properties analyses predict the mechanical superiority. The N-G's electrical conductivity and resistivity of are 49.95 × 103 Ω/m, and 2 × 10−5 Ω-m respectively. The electrical properties demonstrate that the adsorption of toxic gases would be a reason for the change in electrical conductivity and resistivity. The sensing response of N-G-M in terms of resistivity is 96.04 %. The sensing response of ethanol, NO are 17.12 %, and 5.95 %. Responses of N-G-E, N-G-M, N-G-N″-Z are 0.01, 0.06, 0.14 respectively.

First-principles calculations to investigate thermoelectric efficiency of β-In2S3 under pressure for renewable energy sources

The effect of hydrostatic pressure and temperature on thermoelectric properties of Indium sulfide (β-In2S3) in the tetragonal crystal structure is studied using the first principal calculations and the full potential-linearized augmented plane wave (FP-LAPW) method. The Pedrew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA), local density approximation (LDA) and Tran and Blaha modified Becke-Johnson (TB-mBJ) potential are used for calculation of exchange–correlation potentials. Calculated indirect bandgaps are 0.95, 1.17, and 2.19 eV by LDA, PBE-GGA, and TB- mBJ approximations. Obtained bandgap by TB-mBJ approximation is in good agreement with the experimental result. Calculated density of state spectra show the p orbital of S atoms have significant contribution near the Fermi level. The thermoelectric properties of β-In2S3 under pressure like the Seebeck coefficient SC, the electronic thermal conductivity κe, the electrical conductivity σ, the figure of merit ZT, the electronic specific heat CT,μ and Pauli magnetic susceptibility χT,μ are also calculated. As a result, ZTmax of 0.48 (at 500 K) and 0.41 (at 300 K) are obtained for β-In2S3 at zero pressure. The value of SC for p-type carrier was higher than that of n-type one for β-In2S3. By increasing temperature, electronic thermal conductivity increases but there is no change in electrical conductivity and it remains constant at all temperatures. The maximum values of electronic specific heat and Pauli magnetic susceptibility at zero pressure and room temperature are calculated about 17.168 (J/mol K) and 10.3 × 10−9 (m3/mol), respectively. The electronic specific heat increases with increasing temperature. According to the Curie-Weiss law, the Pauli magnetic susceptibility decrease with increasing temperature. Due to the low lattice thermal conductivity, suitable figure of merit ZT and wide band gap of β-In2S3 have possibilities of applications in the thermoelectric renewable energy sources and solar cells devices.