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This study presents the synthesis, structure and characterization of a novel two-dimensional coordination polymer (CP) constructed from Pb(II) ions and m-sulfanilic acid. The CP was characterized using various techniques, including element analysis, FTIR-, UV-Visible spectrometry, TG- DTA analysis, powder and single-crystal X-ray diffraction. The crystal structure of the catena-(bis(µ3-3-aminobenzenesulfonato)lead(II)) complex shows that each lead(II) ion is surrounded by two nitrogen atoms and six oxygen atoms from the amino and sulfonate groups of the 3-aminobenzenesulfonate ligands. Importantly, the lead(II) ions have a stereochemically active lone pair of electrons, which results in a distorted coordination geometry. This distortion, known as hemidirected coordination, arises from the uneven distribution of ligands around the lead ion due to the influence of the lone pair. Its electrical conductivity was measured, revealing its potential for electronic applications. Adsorption properties were evaluated for gas N2. The BET surface area was calculated to be 383.108 m²/g, with a monolayer capacity of 4.2 mmol/g and a C value of 120. The molecular cross-sectional area for nitrogen was taken as 0.162 nm²/molecule. The porosity (ε) of the sample was determined to be 0.65, considering both open and closed pores. Additionally, Hirshfeld surface analysis provided insights into intermolecular interactions within the CP, primarily O—H/H—O interactions (32.1%), H—H interactions (24.8%), and C—H/H—C interactions (16.7%). Pb—O/O—Pb interactions contribute 10.1%, and O—C/C—O interactions contribute 7.3%. Other interactions, such as Pb—N/N—Pb, O—O, O—N/N—O, Pb—H/H—Pb, and Pb—C/C—Pb, contribute smaller percentages. The Continuous Symmetry Measure (CSM) analysis of the lead complex indicates a nearly symmetric structure with slight distortions, as evidenced by its coordination number of 7.7369 and a distortion index of 0.02089. Bond Valence Sum (BVS) analysis confirms that the lead ion is in an oxidation state close to + 2, with a total BVS of 1.87. [ABSTRACT FROM AUTHOR]

Water, one of the most important sources of life, is very important for living life. In this case, improving the quality of water resources is indispensable for life. Electrical Conductivity (EC) is one of the criteria affecting water quality. An increase in conductivity indicates a higher amount of non-water substances and suggests that the water is losing its essential properties. Therefore, accurately predicting EC greatly contributes to the management strategies of water resources. In this paper, we present GA-ML, a novel approach that utilizes a Genetic Algorithm (GA) for end-to-end hyperparameter tuning across five different machine learning methods to improve the prediction of water’s EC. The GA was employed to select the optimal machine learning algorithm in the recursive feature elimination (RFE) for feature selection. Subsequently, the best normalization method was applied to the selected features, followed by comprehensive hyperparameter optimization. The results demonstrated that the Extra Trees based GA-ML (GA-ET) model achieved the lowest root mean squared error (RMSE) of 11.8508, while XGBoost based GA-ML (GA-XGBoost) provided the best performance in terms of mean absolute error (MAE) with a value of 9.2238. To our knowledge, this is the first study to use GA for both parameter tuning and optimizing preprocessing and feature engineering. Future research will explore applying this multi-step metaheuristic approach to various prediction problems. [ABSTRACT FROM AUTHOR]

Incorporating nanomaterials into liquid crystals has gained popularity since the rise of nanotechnology in the 1990s. The modifications of the physical and chemical properties of liquid crystals are envisioned with the formulation of nanocomposites. In this work, we provide the experimental evidence for the enhancement in the conductivity observed in composites of ZnO nanoparticles (NPs) doped in hydrogen bonded liquid crystals (HBLCs) (P18:FBA) built with (4-pyridyl)-benzylidene-4ʹ-n-octadecylaniline as proton acceptors and 4-Fluorobenzoic acids as proton donors. The FTIR and Photoluminescence studies confirmed the decreased H-bonding interactions proving an efficient pathway for the observed conductivity in the nanocomposites. A theoretical model is proposed for the quantitative explanation of observed conductivity which emphasizes mixed ionic-electronic conductivity.Article Highlights: Enhanced conductivity is achieved with nanocomposites of ZnO NPs with HBLCs. FTIR and Photoluminescence studies confirmed the decreased H-bonding interactions. Application of a recently developed elementary model to analyze the direct current conductivity λDC. Mixed ionic-electronic conductivity is realized. [ABSTRACT FROM AUTHOR]

This paper aims at development and characterization of copper metal matrix composites (MMCs) reinforced with graphene particles for application in electrical contacts. The composite specimens were synthesized using pressure-less sintering. The copper powders were mixed using ball milling process and thereafter were cold pressed in a closed mold. The powdered mix was then heated in a sintering furnace at a temperature of 900 ºC. The composite samples were synthesized with 0.5 wt%, 1.0 wt%, 1.5 wt% and 2.0 wt% of graphene concentration. The characterizations included X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), measurement of density, hardness, tensile strength, compressive strength, electrical conductivity, thermal conductivity and wear rate. XRD and SEM indicated uniform dispersion of graphene within the Cu matrix. Elemental mapping indicated by EDS confirmed the presence of graphene with in the matrix with higher peak intensities for the specimen containing higher wt% of the reinforcement concentration. Density of the composites was found to decrease with the increase in graphene content. Lowest density (8.06 g/cc) was observed in the composite specimen containing 2.0 wt% of graphene. Hardness of the composites increased with the increase in graphene concentration. Highest hardness was exhibited by composite specimen containing 2.0 wt% graphene. Maximum tensile (145 MPa) and compressive strength (156 MPa) was obtained for composite specimen containing 0.5 wt%, beyond which the strengths showed a decreasing trend. Electrical and thermal conductivity values of 74% IACS and 398 W/Mk were obtained for composite specimen containing 0.5 wt% graphene. Wear behavior of the composite materials was found to be dependent on graphene concentration. Resistance to wear was found to increase with the concentration of graphene. Lowest volume loss was observed for composite specimen containing 2.0 wt% reinforcement. [ABSTRACT FROM AUTHOR]

In this work, we investigated the electrical and dielectric properties of a new biocomposite-based vinyl resin emulsion reinforced with microparticles of green microcrystalline cellulose. We measured the electrical response of each sample by assessing AC electrical conductivity in the temperature range of 260–340 K and in the frequency range of 100 Hz–1 MHz. The electrical conductivity dispersion is well described by Jonscher’s power law. Accordingly, the associated mechanism conductivity is due to the correlated barrier-hopping conduction mechanism. Dielectric properties were performed using the electric modulus formalism and analyzed according to the Havriliak-Negami model. For the neat vinyl resin emulsion, the observed relaxation process is attributed to the α-relaxation. When the fillers are added to the vinyl resin emulsion, a water dipolar polarization is identified for temperatures below the glass transition temperature and a superposition of α-relaxation and an interfacial polarization, known as Maxwell–Wagner-Sillars, for temperatures above the glass transition point. The activation energies of these are determined according to the Arrhenius law. Dielectric analysis allowed for probing the reinforcement/matrix adhesion, which can control the electrical conductivity performance of the composite materials. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to investigate the stochastic plasma-mechanical-elastic wave propagation at the boundary of an elastic half-space in a semiconductor material using photo-thermoelasticity theory. The novelty of this work lies in the combination of stochastic simulation with temperature-dependent electrical conductivity and variable thermal conductivity, applied to a two-dimensional (2D) electromagnetic problem based on the electron-hole interaction model. Unlike previous studies, this work incorporates white noise as the randomness factor, providing a more realistic representation of random processes in semiconductor materials. The normal mode analysis technique is used to derive both deterministic and stochastic wave behaviors, focusing on short-time dynamics. The results, which are numerically analyzed and graphically represented, provide new insights into the differential behavior of stochastic versus deterministic distributions in magneto-photo-thermoelastic wave propagation, contributing to a more comprehensive understanding of semiconductor behavior under random influences. [ABSTRACT FROM AUTHOR]

In this paper, functional ether-based ionic liquids with bromide and dicyanamide anions were prepared and characterized. The introduction of ether group into imidazolium cation decreased the relative viscosity of ionic liquids, while increased density and electrical conductivity values of ionic liquids. The refractive index, density, thermal stability, electrical conductivity, and ESW values of ionic liquids decreased with the increase of alkoxyalkyl chain length from methoxyethyl to methoxypropyl, while the relative viscosity of ionic liquid increased from the methoxyethyl to the methoxypropyl group. The refractive index, relative viscosity, density, and thermal stability of bromide ionic liquids were higher than those of dicyanamide ionic liquids, while the electrical conductivity and ESW values of dicyanamide ionic liquids were higher than those of bromide ionic liquids. DFT simulation results demonstrated the introduction of ether group into imidazolium cation increased anion-cation interactions of ionic liquids, resulting as lower HOMO–LUMO (Egap), lower interaction energy (ΔE), and shorter average hydrogen bond length values. The anion-cation interactions among ionic liquids decreased when ether group changed from methoxyethyl to methoxypropyl. The cation–anion interactions of dicyanamide ionic liquids were much stronger than those of bromide ionic liquids. These results will shed light on the design and preparation of functional ionic liquid electrolytes for the renewable energy storage devices. [ABSTRACT FROM AUTHOR]

There is an increasing demand for polyimide-based conductive composite materials with excellent mechanical properties and good thermostability for engineering and biomedical applications. A strategy has been proposed to produce composites based on polyimide matrices of various rigidities filled with graphene particles. The results of dynamic mechanical analysis demonstrate that the values of glass transition temperature and elastic modulus of these composites increase (from 3.1 GPa to 9.6 GPa) with increasing rigidity of the PI matrix. An increase in the PI rigidity also leads to a decrease in volume conductivity of samples (from 10–4 to 5 × 10–7 S/m), while their surface conductivity increases (from 0.04 S/m to 2 S/m). Apparently, this is due to expulsion of graphene into the near-surface area of the composite film, which is confirmed by independent methods (X-ray photoelectron spectroscopy and IR spectroscopy). The macromolecules of rigid-chain polyimide demonstrate planar orientation, which facilitates the appearance of strong π–π-interactions between monomer units of polymer chains and prevents uniform distribution of graphene particles within the volume of this polyimide matrix. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have garnered great attention in recent years due to their outstanding electrical, thermal, and mechanical properties. The incorporation of small amounts of CNTs in polymers can substantially improve the sensitivity of the polymer's electrical conductivity. This paper presents a modified Maxwell model to evaluate the electrical conductivity of CNTs-filled polymer composites by introducing a transition zone to account for the tunneling effect. In this modified Maxwell model, the CNTs-filled polymer composite is modeled as a three-phase composite, consisting of a matrix (polymer), inclusions (CNTs), and a transition zone (tunneling zone). The effective electrical conductivity (EEC) of the composite is calculated based on the volume fractions and electrical conductivities of the matrix, inclusions, and transition zone. The model's validity is confirmed through the use of available test data, which demonstrates its capability to accurately capture the nonlinear conductivity behavior observed in CNTs-polymer composites. This study offers valuable insights into the design of high-performance conductive polymer nanocomposites, and enhances the understanding of electrical conduction mechanisms in CNT-dispersed polymer composites. [ABSTRACT FROM AUTHOR]

This study investigates the properties of the double perovskite compound Ba2BTaO6 (B = Gd, Yb) using the "full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT)" with various exchange-correlation potentials (GGA, GGA+U, and mBJ-GGA). The structural, electronic, magnetic, optical, and thermoelectric properties are explored. Ba2GdTaO6 is found to be a ferromagnetic half-semiconductor with two spin-dependent energy gaps, exhibiting stability in the ferromagnetic phase and possessing an integral magnetic moment of 7μB. On the other hand, Ba2YbTaO6 is ferrimagnetic. It shows half-metallic behavior with a semiconductor nature in the spin-up state and metallic in the spin-down state, having an integral magnetic moment of 1μB. The optical characteristics suggest their potential use in UV optoelectronic systems, including UV sensors, photodetectors, and efficient UV reflectors. Additionally, the investigated thermoelectric properties, such as the Seebeck coefficient, electrical conductivity, and Figure of merit, indicate that Ba2BTaO6 (B = Gd, Yb) materials have promising potential for practical thermoelectric applications. [ABSTRACT FROM AUTHOR]

Aluminum alloys are light and corrosion-resistant materials, which is why they are widely used in structures in many industrial fields (construction, automotive, electric cables). The article deals with the aluminum busduct structure. Therefore, the mechanical and especially electrical properties of busduct welds are the basic criteria for assessing the quality of welds. The aim of the work was to present the advantages of a process combining metal inert gas welding with immediate microjet cooling (MJC). The parameters of aluminum welding using the micro-jet method were estimated in order to obtain products with the desired strength, mechanical and electrical parameters. Information regarding the influence of various microjet parameters on the metallographic structure was also recorded. Then, the metallographic properties and some physical properties of the welding structures (mechanical resistance, electrical conductivity) were examined. In addition, computer simulations of the welding process with micro-jet cooling were performed. The heat affected zone in the welded material was determined. The proposed numerical method will allow the assessment of the parameters of the welding process with micro-jet cooling depending on the parameters of the materials undergoing the welding process. The numerical approach will significantly reduce costly and time-consuming in situ work. Planning the welding of large structures (such as busducts) will be more economical using the results of computer simulations. [ABSTRACT FROM AUTHOR]

This study investigates the surface properties, micellization, and electrical conductivity of betaine-based ionic liquids (ILs) composed of [R-bet][Br] where R represents the C4, C6 and C8 (specifically [C4bet][Br], [C6bet][Br], and [C8bet][Br]) in aqueous gabapentin solutions at concentrations of (0.0000, 0.0100, 0.0300, and 0.0500) mol kg−1 at 298.15 K. The surface tension measurements revealed that increasing gabapentin concentration and alkyl chain length decrease surface tension, indicating significant hydrophobic and hydrophilic interactions. The related thermophysical micellization parameters, including critical micelle concentration (CMC) and minimum surface area per molecule (Amin), exhibited improved micellization and interfacial efficiency with longer alkyl chains. Thermodynamic analysis confirm the spontaneous nature of micelle formation, with more negative Gibbs free energy values for SAILs with longer alkyl chains. The electrical conductivity studies indicate lower limiting molar conductivity (Λ0) at higher gabapentin concentrations, due to increased viscosity and ion-ion interactions. Ion association constants (KA) and DFT-COSMO calculations support stronger hydrophobic interactions and molecular packing influenced by alkyl chain length and gabapentin. [ABSTRACT FROM AUTHOR]

Printable conductive composites show potential in wearable electronic, capacitor, stretchable sensors, and conductors. Incorporating metal nanoparticles in composites is a leading method to achieve high performance. In this study, we present a method for preparing silver flakes with ultra-smooth surfaces and excellent electron transfer properties by combining a waterborne acrylic resin template method with an intensive energy ultrasonic technique. By varying the ultrasonic treatment time from 20 to 80 min, the size distribution of the silver flakes was controlled, ranging from 15.7 to 5.04 μm. Scanning electron microscopy results indicate that the intensive energy ultrasonic treatment does not affect the surface morphology of the silver flakes. Additionally, the electron transport difficulties arising from internal defects in silver flakes prepared by traditional methods have been mitigated. The influence of size distribution and filler content on the electrical conductivity of silver conductive composites has been investigated. The study identified a correlation between the particle size distribution of flake silver powder and the volume resistivity of the conductive composite material, wherein a reduction in particle size distribution leads to a corresponding decrease in volume resistivity. Furthermore, an increase in the filler content of the composite material was found to result in a reduction in its volume resistivity. Using flake silver powder with a median particle size (d0.5) of 5.38 μm as a representative sample, the volume resistivity was observed to increase from 8.50 × 10−5 Ω·cm to 8.63 × 10−3 Ω·cm as the silver content was decreased from 25 to 4 wt %. Concurrently, an examination of the conductive properties and the formation of the conductive network demonstrated alignment with the theoretical steady-state model. Silver flakes with ultra-smooth surface and excellent electron transfer property is prepared by combining vacuum-evaporated nanofilms method and intensive energy ultrasonic technique. [ABSTRACT FROM AUTHOR]

This paper presents a novel study on the microstructure and electrical properties of gadolinium (Gd) doped maghemite (γ-Fe₂O₃) nanoparticles, emphasizing their significance for advanced applications in efficient materials. X-ray diffraction analysis confirmed that both pure and doped samples crystallized in a cubic structure (P4332 space group) with high purity. Gd doping significantly increased crystallite size and altered particle morphology, as shown by transmission electron microscopy (TEM), which revealed larger nanoparticles with cubic shapes. Thermal analysis (TGA and DTG) indicated that higher Gd concentrations enhanced thermal instability, affecting structural integrity. FTIR spectra showed shifts in Fe-O bond vibrations, suggesting lattice distortions and increased disorder. BET measurements indicated that higher Gd doping led to greater mesoporosity and surface area, countering expectations of densification. Electrical conductivity and impedance studies revealed two distinct regions: a constant conductivity at low frequencies and an exponential increase at high frequencies, attributed to small polaron hopping. Activation energy values below 200 meV support this mechanism. Gd doping decreased overall conductivity due to disrupted atomic arrangements, increased electron scattering, and modifications in the electronic band structure. Complex impedance spectroscopy illustrated higher real impedance values for doped samples, with increased Gd concentration leading to enhanced impedance. These findings elucidate the impact of Gd on the electrical properties of maghemite nanoparticles and highlight their importance in meeting the growing demands for highly efficient technologies in energy storage and electronic devices. Highlights: Gd doping enhances crystallite size and alters nanoparticle morphology. Increased Gd concentration induces thermal instability and structural changes. BET analysis shows higher Gd levels increase mesoporosity and surface area. Electrical conductivity decreases with Gd doping due to lattice distortions. Small polaron hopping dominates high-frequency conductivity behavior. [ABSTRACT FROM AUTHOR]

Tin dioxide plays a crucial role in gas detection, solar cells, and photocatalysis. This study focuses on nanostructured antimony-doped tin dioxide (ATO) synthesized via a modified sol–gel technique under supercritical co-solvent conditions. The crystalline structure and electrical properties were investigated with varying levels of antimony doping (1, 2, and 3 at.%). X-ray diffraction analysis revealed tetragonal rutile structure nanoparticles with sizes ranging from 13 to 22 nm, depending on the doping content. Impedance spectroscopy confirmed its semiconductor behavior, and dc conductivity exhibited a thermal activation, wherein the energy required for conduction progressively increased alongside Sb content. The ac conductivity followed the Jonscher law, dominated by the tunneling hopping mechanism. Nyquist diagrams assessed grain and grain boundary contributions, modeling samples through an equivalent circuit. The dielectric study identified interfacial polarization as the source of dielectric permittivity. The observed behavior of the imaginary component of impedance (Z′′) indicates a dielectric relaxation phenomenon within the sample, with activation energies closely matching those derived from the conductivity study. These findings elucidate the origins of conductivity and active sites in ATO nanoparticles, with deep implications for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Highlights: Investigation of dispersing solvents on processing Ti3C2Tx thin films revealed that deionized water is superior to realize tight stacking and high orientation of MXene nanosheets. A simultaneous elevation of Seebeck coefficient and electrical conductivity of neat Ti3C2Tx films is achieved by increasing the centrifugal speed of MXene aqueous suspensions due to the energy filtering effect. Further construction of Ti3C2Tx nanocomposites significantly strengthens Seebeck coefficient yet disrupts the stacking of MXene nanosheets. Emerging two-dimensional MXenes have been extensively studied in a wide range of fields thanks to their superior electrical and hydrophilic attributes as well as excellent chemical stability and mechanical flexibility. Among them, the ultrahigh electrical conductivity (σ) and tunable band structures of benchmark Ti3C2Tx MXene demonstrate its good potential as thermoelectric (TE) materials. However, both the large variation of σ reported in the literature and the intrinsically low Seebeck coefficient (S) hinder the practical applications. Herein, this study has for the first time systematically investigated the TE properties of neat Ti3C2Tx films, which are finely modulated by exploiting different dispersing solvents, controlling nanosheet sizes and constructing composites. First, deionized water is found to be superior for obtaining closely packed MXene sheets relative to other polar solvents. Second, a simultaneous increase in both S and σ is realized via elevating centrifugal speed on MXene aqueous suspensions to obtain small-sized nanosheets, thus yielding an ultrahigh power factor up to ~ 156 μW m−1 K−2. Third, S is significantly enhanced yet accompanied by a reduction in σ when constructing MXene-based nanocomposites, the latter of which is originated from the damage to the intimate stackings of MXene nanosheets. Together, a correlation between the TE properties of neat Ti3C2Tx films and the stacking of nanosheets is elucidated, which would stimulate further exploration of MXene TEs. [ABSTRACT FROM AUTHOR]

Gas sensors based on wide-gap metal-oxide materials (including tin dioxide) make it possible to detect a wide range of organic and inorganic gases. However, the number of materials used to obtain them is limited, and they are environmentally hazardous. For the development of "green" semiconductor technologies, the creation of new materials and structures with gas-sensitive properties, as well as competitive methods for their production, is of considerable interest from both fundamental and applied points of view. The work investigates the possibilities of using diamond-graphite film structures obtained in the plasma of a microwave gas discharge of ethanol vapor as gas-sensitive materials. The patterns of the effect of the electron-injection voltage and the air temperature and humidity on the current–voltage characteristics and surface resistivity of diamond-graphite film structures are studied. It is shown that the patterns can be described using the theory of space-charge-limited currents in noncrystalline structures with capture traps. The existence of a band with an increased density of localized electron states with an energy of about 0.032 eV at the edge of the allowed band of the electronic structure of the material used, which determines the nature of the dependences of the surface resistivity of the sensor structure on the parameters of detection of the gas environment, is established. The high efficiency of using diamond-graphite film structures for detecting water vapor is shown in the form of a more than threefold decrease in their surface resistivity compared to the absence of water vapor in the atmosphere. [ABSTRACT FROM AUTHOR]

A promising approach to increasing the thermoelectric figure of merit ZT is the development of nanostructured thermoelectric materials, including those based on lead telluride PbTe and germanium telluride GeTe. To optimize the nanostructuring technology, it is important to know the mechanisms of heat and electricity transfer in thermoelectric materials, which depend on the charge-carrier concentration and mobility. In this study, nanostructured middle-temperature n-PbTe- and p-GeTe-based thermoelectric materials are obtained using the developed technique, which involves synthesis by the direct fusion of components, grinding of the synthesized PbTe and GeTe into nanopowders in a planetary ball mill, and their consolidation into a bulk material by spark plasma sintering. To perform electrical measurements, ohmic contacts are formed on the thermoelectric material samples by the electrochemical deposition of nickel. The temperature dependences of the thermoelectric parameters of the nanostructured thermoelectric materials are examined. The concentration and mobility of majority carriers are measured by the van der Pauw method. It is found that the majority-carrier concentrations in the thermoelectric materials obtained by hot pressing and spark plasma sintering lie in the range of 1019–1020 cm–3, which is optimum for them. It is established that the mobility of majority carriers in PbTe is much higher than in GeTe. The majority-carrier mobility in nanostructured PbTe decreases by 36% as compared with the value for PbTe obtained by hot pressing. However, this does not lead to a noticeable decrease in the electrical conductivity due to an increase in the majority-carrier concentration. As a result, the maximum ZT values are obtained for nanostructured PbTe and GeTe: higher by 14% and 13%, respectively, than in the thermoelectric materials formed by hot pressing. [ABSTRACT FROM AUTHOR]

The effect of alloying with 0.3 wt % of Cu on the microstructure and properties of an Al–0.5 wt % Fe alloy, obtained by continuous casting in an electromagnetic crystallizer and subjected to deformation treatment by equal-channel angular pressing and subsequent cold rolling, is studied. The implementation of two-stage deformation processing ensured the formation of a homogeneous ultrafine-grained structure in the alloy, as well as the fragmenting of the second phase intermetallic particles, which made it possible to achieve an ultimate tensile strength and electrical conductivity of 309 MPa and 55.9% IACS (International Annealed Copper Standard), respectively. It has been shown that the refinement of the grain structure and intermetallic particles caused by deformation treatment also ensures the preservation of a high level of strength of the material after annealing for 1 hour at a temperature of 230°C. Based on a generalization of the results, including those obtained in previous studies, the role of Cu alloying in achieving increased strength and thermal stability of the Al–Fe alloy with an ultrafine-grained structure was determined. The possible area of using ultrafine-grained alloys of the Al‒Fe‒Cu system as promising conductor materials is discussed. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) films have been grown by reactive DC magnetron sputtering, high-power impulse magnetron sputtering (HIPIMS), and a hybrid process (DC + HIPIMS). Their resistivity has been measured by the four probe van der Pauw method, and their rms surface roughness has been assessed by atomic force microscopy. The phase composition of the films has been determined by X-ray diffraction, and their chemical state has been studied by X-ray photoelectron spectroscopy. Their band gap has been determined by the Tauc method using their transmission and reflection spectra measured on a spectrophotometer. The results have been used for a comparative analysis of the properties of the CuO films grown in different deposition modes and to demonstrate advantages and drawbacks of the magnetron sputtering modes used. [ABSTRACT FROM AUTHOR]

This study was carried out to develop a conceptual framework for determining the best interpolation method which mainly is employed to calculate the variability maps of electrical conductivity (EC) in neighboring regions. The considered case study is parts of the Khorasan Razavi province, Iran (including five aquifers Kashmar, Fariman, Doruneh, Sarakhs and Joveyn). In the first step, the empirical variogram (semi-variogram) was computed for the study area. The methods of the variability of a variable with spatial or temporal distance were considered to measure the semi-variogram function. In the next step, the best variogram model (e.g. spherical, exponential or Gaussian) was considered in the Geographic Information System (GIS) environment and f for the Environmental Sciences (GS+) software. By plotting the semi-variogram in GS+ program based on different method as Global Polynomial Interpolation (GPI), Inverse distance weighing (IDW), Radial basis function (RBF), Kriging method, Global Polynomial Interpolation (GPI), Local Polynomial Interpolation (LPI), the best variogram model fitted to spatial structure of the EC. Finally, by considering the acceptable range for different parameters which impact on EC and evaluating their impacts by scaling, the best interpolation method has been selected for that area for employing their neighborhood basin. Result indicated that the precipitation located within the range of 140 to 180 mm, RBI has the priority. This process is continued for all 14 parameters and eventually one method gets the most points. [ABSTRACT FROM AUTHOR]

The paper proposed the methodology for research findings on developing a Cu-SiO2 sintered composite produced by powder metallurgy. In a copper matrix, SiO2 particles were added in concentrations of 5%, 7.5%and 10%. Mixtures of finished powders were pressed with a crushing pressure of 620 MPa using a single press and then applied to sintering processes in the dissociated ammonia atmosphere at 910 °C. It was 65 min for sintering. Sintered compact specimens were tested for electrical conductivity, wear resistance, density and hardness. A composite comprising 5% SiO2, which was 7.94 g/cm3, obtained the maximum density. A composite with 10% SiO2 corresponds to 50 HB, and the maximum hardness was achieved. The highest electrical conductivity was 59 MS/m for the composite containing 5% SiO2. The greater abrasive wear resistance strength was achieved by 10% SiO2 composite. Along with the rise of composite SiO2, the density and electric conductivity have decreased. [ABSTRACT FROM AUTHOR]

Thermoelectric materials-based devices are used to convert heat energy into electrical energy. Magnesium silicide-based thermoelectric-based devices are considered commercially viable due to their low cost compared to other contemporary materials. The current study investigates the influence of Sb doping on the thermoelectric properties of the Mg2.15Si0.28Sn0.714Sb0.006 (Sample-A) compound with an excess Mg content (7.5 mol %). The excess Mg induces point defects through interstitial Mg and Si/Sn vacancies, significantly enhancing the electron concentration (ne). Moreover, Sb is recognized as an effective single-electron donor in Mg2Si-based materials, leading to notable increases in ne and electrical conductivity. Consequently, in the current investigation, excess Mg combined with appropriate Sb doping, resulted in the selection of Mg2.15Si0.28Sn0.714Sb0.006 (Sample-A), which exhibited high ne and superior thermoelectric performance. Further, the current study was extended by incorporating 3 vol.% of reduced graphene oxide (rGO) into Mg2.15Si0.28Sn0.714Sb0.006 + 3 vol.% rGO (Sample-B) to enhance mechanical performance and reduce thermal conductivity (k). Consequently, Sample-B showed a ∿ 28% increase in fracture toughness (from 1.48 to 1.9 MPa√m) and a ∿ 137% improvement over conventional Mg2Si. Moreover, the inclusion of rGO resulted in a substantial reduction in k ∿ 40% in the mid-temperature range, due to intensified phonon scattering caused by the higher interface density within the matrix. However, adding more than 3 vol.% rGO negatively impacts both thermoelectric and mechanical properties by obstructing the charge carriers. Therefore, achieving an optimal balance between rGO addition and compositional modulation is essential to enhance both thermoelectric and mechanical performance in these composites. [ABSTRACT FROM AUTHOR]

We present the results of experimental and computational studies of the physicochemical properties and structure of a newly synthesized tripropylammonium 2-sulfobenzoate (TPrA/SBA) protic ionic liquid (PIL). Quantum-chemical methods were used to evaluate the hydrogen-donor properties of the SBA molecule and to model the proton transfer between the acid and base molecules. The results revealed that the ionic liquid was formed through an acid-base interaction between the proton of the –SO3H group in the acid and the nitrogen atom in the amine. Additionally, we conducted a molecular dynamics simulation to determine the hydrogen bond topology in the PIL bulk as well as the average number of hydrogen bonds between the ions. To provide further insights, we compared the structural parameters and properties of the TPrA/SBA ionic liquid with the data on the two other tripropylammonium-based PILs with hydrogen sulfate (SA) and triflate (TfO) anions. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) are widely used in the field of organic electronics as the material basis of high-performance devices, due to their obvious advantages including electrical conductivity, lightness, processability and so on. Research on CPCs has focused on the enhancement of their electrical features and the exploration of their application prospects from conventional fields to heated emerging areas like flexible, stretchable, wearable, biological and biomedical electronics, where their mechanical properties are quite critical to determine their practical device performances. Also, a main challenge to ensure their safety and reliability is on the synergistic enhancement of their electrical behavior and mechanical properties. Herein, we systematically reviews the research progress of CPCs with different conductive fillers (metals and their oxides, carbon-based materials, intrinsically conductive polymers, MXenes, etc.) relying on rich material forms (hydrogel, aerogel, fiber, film, elastomer, etc.) in terms of mechanical property regulation strategies, mainly relying on optimized composite material systems and processing techniques. A summary and prospective overview of current issues and future developments in this field also has been presented. [ABSTRACT FROM AUTHOR]

Background and aims: Growth of Pinus pinea forests and plantations in native countries is known to be affected by soil and climate characteristics. However, edaphoclimatic drivers of growth and fruiting have been scarcely studied outside the species' native range; in addition, the role of soil nutrients, particularly in juvenile trees' development, has been poorly explored. Methods: Relationships between edaphoclimatic variables and the performance of 54 young plantations were studied in Chile. Vegetative growth and fruiting were measured in 100 randomly selected trees per plantation. Composite soil samples were taken from each site to analyze soil chemical characteristics and texture. A principal component analysis was performed including climatic, soil data, and growth and fruiting variables. Results: Annual growth was 1.3 cm year−1 for stem diameter, 28.3 cm year−1 for crown diameter, and 38.9 cm year−1 for height; cone production per crown area was 0.07 cones m−2. Negative correlation of height growth, crown growth and cone production with EC, Na, and pH were found, along with positive correlations with OM, PP and the index PP × AT. Stem diameter growth was favored by less acidic soils with high sand content, and showed no correlation with cone production. Furthermore, vegetative growth was positively correlated with N, P, Mg and clay content. In young plantations, vegetative growth was higher than in the species' native habitat. Conclusion: Soil properties, in particular low EC and Na were identified as favorable for growth of young stone pine trees, along with high content of soil N, P and Mg, and PP. [ABSTRACT FROM AUTHOR]

Asymmetric rolling is a high-tech method based on the principles of severe plastic deformation. In the present paper, it is shown that Cu-0.8Cr-0.1Zr alloy is highly strengthened during asymmetric rolling due to structure refinement to an ultrafine-grained state. For example, in only one pass, at the accumulated strain 0.94 ± 0.20, the strength increases from 265 to 425 MPa. During the deformation process, the structure becomes refined, with the average size of fragments reaching 235 ± 90 nm. Structure heterogeneity is also observed in the cross section of a sample, which is associated with different rotation speeds of the rolls. The shape of grains in the central zone of samples corresponds to the state after conventional symmetric rolling. However, in the zone adjacent to the roll rotating at a higher speed, mechanical texture of grains is similar to that after shear. Subsequent aging of Cu-0.8Cr-0.1Zr alloy at 450°C makes it possible to achieve the ultimate strength 560 MPa and electrical conductivity 82% IACS, which exceeds the characteristics of the strengthened steel by 10–15%. The analysis of contributions to strengthening during asymmetric rolling reveals that the main contribution comes from the refinement of the grain structure to an ultrafine-grained state, which amounts to 58%. The fractions of the dislocation and dispersion contributions comprise 15 and 20%, respectively. Compared to conventional rolling, as well as other deformation methods that provide the same level of accumulated strain and strengthening in one cycle, such as equal channel angular pressing-conform, asymmetric rolling is the most promising due to its simpler process scheme. [ABSTRACT FROM AUTHOR]

The article presents experimental results of the synthesis and study of thin films of polycrystalline vanadium dioxide (VO2), as well as multilayer optoresonance structures based on them. The role of the influence of thermal annealing on the structural, electrical and optical properties of VO2 films is shown. Based on these films, photonic crystal heterostructures were fabricated, in which excitation of optical resonance modes of the Fabry–Perot type is observed. A study of the optical transmission of such a structure showed that the spectral position of the Fabry–Perot mode can be controlled by varying the thickness of the VO2 gradient optical layer. It is shown that the first-order semiconductor-metal phase transition, which occurs in VO2 films and is accompanied by a change in their electrical conductivity by 3–5 orders of magnitude, leads to a change in the optical parameters of both the films themselves and multilayer optoresonance structures. [ABSTRACT FROM AUTHOR]

Electroactive biomass materials based on chitosan (CS), cellulose, etc. have great potential for applications in non-contact switches, smart wearable devices, environmental monitoring, etc. However, due to low electroactivity and susceptibility to overhydration, it is necessary to add carbon materials, synthetic conductive polymers or metal oxides, etc. and introduce numerous chemical crosslinking, which makes them face the problems of poor filler-matrix dispersion, high preparation cost and environmental pollution. In this study, citrate-modified cellulose (EMC) was prepared and introduced into the CS matrix, and a multi network structure with hydrogen bonding, chemical crosslinking and ionic complexation crosslinking was constructed by adding chemical crosslinking and Cu2+ ion complexation. Flexible conductive composite film (CS-EMC-Cu film) and paper (CS-EMC-Cu impregnated paper) were prepared. The results showed that the incorporation of Cu2+ and EMC effectively improved the flexibility (elongation at break of 106%), water resistance and surface hydrophilicity of the films. The composite conductive film (conductivity of 0.277 S/m) has good wet-responsive deformation properties, can be used as a non-contact smart switch, and has good humidity (0.745 RH−1) and pressure sensing properties, but the durability still needs to be improved. The CS-EMC-Cu impregnated conductive paper (conductivity of 0.0737 S/m) has good flexibility (elongation at break of 7.9%) and water resistance, and is capable of lighting a light bulb. Its brightness is enhanced with humidity and has good wet response characteristics. This flexible conductive film and paper are prepared in an environmentally friendly way, which provides ideas for the preparation and design of biomass-based flexible sensors, and is also of great significance for the high value-added utilization of biomass materials. [ABSTRACT FROM AUTHOR]

Raw materials were etched by nitric acid to release utterly carbon dioxide. An excess of citric acid was then employed as fuel to prime the combustion reaction for the synthesis of Sr0.95Ba0.05Bi2−xSmxNb2O9 (x = 0 (SrBi2Nb2O9), 0.1, and 0.2) compounds. X-ray diffraction, Fourier-transformed infrared, and Raman techniques revealed quite certain that there is a link between dopant amounts and structural changes. One is that the cell volume was smoothly reduced. Second, the bond force constant decreased slightly when the dopant was introduced into the lattice. Even though the SrBi2Nb2O9 compound is not only doped by samarium but also by barium, samarium is the only dopant that affects dielectric and electrical properties. Doping with samarium enhances the dielectric constant at room temperature by reducing the Curie temperature, and it turns ferroelectric normal into relaxor behavior. The results of AC conductivity and electrical modulus laid out that one extreme defect was that a significant amount of cation exchange occurs in Sr0.95Ba0.05Bi2−xSmxNb2O9 samples and a large amount of oxygen vacancies were released. Overlapping large polaron tunneling model (OLPT) mechanisms was the adequate model for these compounds. [ABSTRACT FROM AUTHOR]

In order to ensure the service reliability of flexible electronic products, flexible electronic interconnection wires need to have good conductivity and good resistance and mechanical reliability. In this study, Ag microwire samples were prepared on flexible substrates by aerosol inkjet printing. The electrical tests show that the resistivity of the Ag microwire treated by high-density pulsed electric current was reduced. At the same time, the bending resistance tests show that the resistance of Ag microwire changes less when treated by high-density pulsed electric current under the same bending angle. Thus, the electrical conductivity and flexural behavior of the samples can be simultaneously enhanced by applying high-density pulsed electric current. After pulsing under the specified electrical parameters, the microstructure of the Ag microwire was denser, and the grain distribution was more uniform owing to the decrease in grain porosity, which was caused by atomic filling. The atomic diffusion was controlled directionally by the electron wind and Joule thermal effect. Ultimately, a significant accumulation of Ag atoms occurred, healing the voids and cracks. The technique holds promise for utilization in the realm of flexible printed circuits. [ABSTRACT FROM AUTHOR]

Conductive particle-containing granular composites with tuneable negative permittivity are being studied to improve the performance of electromagnetic devices, such as shielding materials. In this study, we investigated the relative complex permittivity and electrical conductivity of granular composites of polyphenylene sulfide (PPS) resin and Ag-coated Cu flakes in the radio- to microwave-frequency range and compared them with those of PPS/bare Cu flake composites. Electrical conductivity measurements revealed that the PPS/Ag-coated Cu flake composites have a lower percolation threshold (φc) than the PPS/bare Cu flake composites, whereas the electrical conductivity of the PPS/Ag-coated Cu flake composites in the percolated particle state was higher at the same particle volume fraction. At particle contents above φc, a low-frequency plasmonic state of conduction electrons was achieved in the percolated particle chains in both composites, and negative permittivity spectra were obtained. The percolated PPS/Ag-coated Cu flake composites had a negative permittivity up to a higher frequency than the percolated PPS/bare Cu flake composites. Furthermore, the Drude model was used to analyze the negative permittivity spectra of the composites in the percolated particle state. The plasma frequency of the composites with percolated Ag-coated Cu flakes was higher than that of the composites with percolated bare Cu flakes. Thus, coating Ag on Cu particles improved the conductivity of the composite, leading to negative permittivity up to higher frequencies. This study contributes to the enhancement of the negative permittivity achieved by granular composites, which is useful for microwave technology applications. [ABSTRACT FROM AUTHOR]

Cu2Se thermoelectric compound containing up to 5 wt % SiC was prepared via self-propagating high-temperature synthesis. Doping SiC was shown to improve the thermoelectric properties and get 20% increase in the electrical conductivity and 60% increase in the Seebeck coefficient. The thermoelectric power factor of Cu2Se–5 wt % SiC was found to be 14.4 μW cm–1 K–2 at 900 K, which is 3 times higher than that of Cu2Se. [ABSTRACT FROM AUTHOR]

Using waste such as prickly pear (Opuntia lasiacantha P.) peel to obtain value-added compounds such as pectin is possible with emerging technologies. This study used the Taguchi optimization model to maximize the extraction of chelating-soluble pectin (CSP) through an ohmic heating (OH) process. The maximum pectin yield obtained was 3.32% under the best processing conditions, and the galacturonic acid content was 726.26 mg/g, as well as a range of pectin with a low degree of esterification. The electric field and sodium hexametaphosphate concentration significantly affected the quality and yield of CSP. Additionally, the flow of electrical current during pectin extraction was governed by the concentration of added sodium hexametaphosphate (SHMP), which acted as an electrolyte and chelating agent for CSP. The use of OH in the recovery of CSP from red prickly pear with potential application and care of the proportions of GalA and %yield is presented as an effective option for the recovery of value-added additives from agro-industrial waste. [ABSTRACT FROM AUTHOR]

The physicochemical analysis of 292 groundwater samples from the Sarakhs Plain revealed significant variations in water quality, influenced by natural factors. The pH values ranged from 6.4 to 8.6, with an average of 7.97, indicating that most of the samples (98.97%) meet WHO drinking water standards. However, electrical conductivity (EC) levels were alarmingly high, ranging from 1020 to 37,500 μS cm−1, making all samples unsuitable for drinking. Ca2+ and Mg2+ concentrations were within acceptable limits for approximately 88.39% and 61.09% of the samples, respectively. Spatial distribution analysis showed that higher salinity levels were concentrated in the western and central regions, while the eastern areas benefited from fresher water due to the influence of the Harirud River, which enhances groundwater quality through natural dilution processes. Hydrogeochemical assessments indicated a predominance of mixed-type water, with significant intrusion processes affecting chemical composition. The Gibbs diagram highlighted evaporation as a major factor influencing water chemistry. Groundwater quality index (GWQI) indicated that nearly half of the samples were classified as unsuitable for drinking, while agricultural suitability varied significantly. Although salinity was a critical concern, many samples were deemed suitable for irrigation based on specific ion concentrations. Overall, this study addressed the necessity for sustainable groundwater management practices in the Sarakhs Plain to mitigate salinity issues and enhance water quality for both human consumption and agricultural use. [ABSTRACT FROM AUTHOR]

Main conclusion: Optimizing environmental factors can significantly increase the growth and secondary metabolite synthesis of hydroponically grown medicinal plants. This approach can help increase the quality and quantity of pharmacologically important metabolites to enhance therapeutic needs. Medicinal plants are key therapeutic sources for treating various ailments. The increasing demand for medicinal plants has resulted in the overharvesting of these plants in their natural habitat, which can lead to their extinction in the future. Soil-based cultivation faces challenges, such as a lack of arable land, drastic climatic changes, and attacks by soil-borne pathogens. To overcome these challenges, hydroponic cultivation, known as soilless cultivation, is a sustainable method. The yield and quality of medicinal plants depend on environmental factors, such as nutrients, pH, electrical conductivity, temperature, light, nanoparticles, phytohormones, and microorganisms. This article explores the impact of these environmental factors on the growth and secondary metabolite content of hydroponically grown medicinal plants. Our review reveals how environmental factors qualitatively and quantitatively influence the growth and secondary metabolites of medicinal plants grown in hydroponic systems and how these factors can be integrated into the enhancement of therapeutic compounds. [ABSTRACT FROM AUTHOR]

Copper laser powder bed fusion (Cu-LPBF) is known as a challenging manufacturing process. Since copper is an excellent thermal and electrical conductor, low to medium laser power is insufficient to provide good wettability and fusion between either adjacent tracks or deposited layers due to heat dissipation and high reflectivity. Particle surface modification has therefore been proposed to improve optical absorptivity. A simple method to enhance optical absorptivity is to create a thin oxide film by heating copper powder in an air furnace. The first phase of the current work emphasizes that this technique is detrimental to the part quality if a medium laser power range is used. The second phase presents a novel technique of two stages of in-situ copper oxide reduction during LPBF. It provides an innovative approach for combining laser cleaning and melting in LPBF. The newly suggested technique uses recycled and surface oxidized Cu powders to develop a simple and chemical-free method to recover the contaminated powder. A significant improvement is achieved by applying laser surface cleaning to the powder and solidified layers. The oxygen content is reduced by 70% in the LPBF samples compared to the initial state of the oxidized powder. [ABSTRACT FROM AUTHOR]

Measurements of elastic wave velocity and electrical conductivity were conducted on brine-saturated granitic rocks under confining pressure to quantitatively characterize the closure of cracks. The number of contacting asperities and radius ratio of contact over crack were estimated. Contacting asperities were assumed to deform elastically and/or plastically. The number of contacts increases steeply at low pressure (< 10 MPa) and decreases gradually at higher pressure, while the radius ratio of contact over crack linearly increases. Though the area fraction of contacts increases to no more than 30% even at the highest confining pressure (150 MPa), the stiffness of the solid phase is recovered, and the connectivity of fluid is maintained in a crack. Cracks under pressure are closed for elastic properties, but open for transport properties. The effective aperture is of the order of 100 nm at atmospheric pressure, and steeply decreases at low pressure (< 10 MPa) and then gradually at higher pressure. Observed seismic velocity and electrical conductivity in the crust should be interpreted by considering contacts in cracks. Microstructures of closing cracks should be further investigated to seek relationships between structural parameters and effective pressure. [ABSTRACT FROM AUTHOR]

Soil microbial communities play a crucial role in maintaining diverse ecosystem functions within the saline-alkali soil ecosystems. Therefore, in this study, we collected various saline-alkaline soils from across the Inner Mongolia Hetao irrigation area. The soil chemical properties were analyzed, and the microbial diversity of bacteria and fungi was measured using 16 S rRNA and ITS rRNA amplicon sequencing. The dynamic relationship between the soil microbial community and soil factors was analyzed using the ABT (Aggregate Enhanced tree) model, the co-occurrence network, and the structural equation model. The results indicated that electrical conductivity (EC) was the biggest driving force of various saline-alkaline soils, affecting the community structure of bacteria (22.80%) and fungi (21.30%). The soil samples were categorized into three treatment levels based on their EC values: the low-salinity group (L, EC: 0–1 ms/cm, n = 10), the medium-salinity group (M, EC: 1–2 ms/cm, n = 8), and the high-salinity group (H, EC > 2 ms/cm, n = 6). The results demonstrated a negative correlation between microbial abundance and salinity-alkalinity, while revealing an enhanced interrelationship among species. The alterations in bacterial (12.36%) and fungal (22.92%) communities in various saline-alkali soils were primarily driven by saline-alkali ions, which served as the principal direct factors. The negative correlation between EC and SOM exhibited the highest magnitude, whereas the positive correlation between soil organic carbon and EC demonstrated the greatest strength. Therefore, it was further substantiated that EC played a pivotal role in shaping the distinct microbial communities in saline-alkali soils. [ABSTRACT FROM AUTHOR]

The nutshell waste streams (pine nut shells (PNS), walnut shells (WNS), and almond shells (ANS)) were effectively converted into biocarbon materials employing slow pyrolysis in a fixed bed horizontal reactor at 500 and 900 °C with a 10 °C min−1 heating rate and 60 min holding time. The acquired biocarbon materials were then characterized to understand the influence of pyrolysis temperature on their ash content, elemental composition, thermal stability, graphitic content, functionality, surface morphology, and electrical conductivity. The obtained results established that the pyrolysis temperature has a leading impact on the yield and physicochemical properties of biocarbon. Increasing the pyrolysis temperature of PNS, WNS, and ANS from 500 to 900 °C, respectively, decreases the biocarbon yields from 32, 28, and 28 wt.% to 28, 24, and 25 wt.%. Furthermore, the increasing pyrolysis temperature increases the carbon content and purity of PNS, WNS, and ANS biocarbon due to the elimination of oxygen. Thus, the electrical conductivity of PNS, WNS, and ANS biocarbon acquired at 900 °C was significantly higher than 500 °C. Overall, it can be surmised that biocarbon prepared at a higher temperature is preferable for material applications due to its greater characteristics. [ABSTRACT FROM AUTHOR]

Single-crystal samples of the 3R-CuCrO2 phase (R3m, a = 2.9613(2) Å, c = 17.098(2) Å) with a delafossite structure were grown by the flux method. Structural parameters were refined by X-ray structural analysis. The elemental composition of the grown crystals was confirmed by Auger electron spectroscopy. A threshold electric field switching effect from a high-resistance to a low-resistance state was discovered. The effect is characterized by a jump in electrical resistance (up to 5 orders of magnitude at E = 4.7 kV/cm, T = 120 K) and S-shaped current–voltage characteristics with a region of negative differential resistance. The temperature dependences of dielectric permittivity and dielectric loss tangent exhibit a Debye-type relaxation process with an activation energy of 0.51(3) eV. The observed features of dc conductivity, current–voltage characteristics, and dielectric properties interpreted on the basis of the existence of charge carriers in a small polaron state and the destruction of this state by the electric field. [ABSTRACT FROM AUTHOR]

Consideration is given to the state of the art in the production of materials of carbon felt-based gas diffusion layers. It is shown that the nature of a hydrophobic polymer (polyvinylidene-fluoride, PVDF, and polytetrafluorethylene, PTFE) has no crucial effect on the water contact angle (limiting wetting angle), however, it is of fundamental significance in terms of regulation of the macroporous structure and surface electrical resistance of the obtained materials. Thus, polytetrafluorethylene concentrates predominantly in the near-surface layers while polyvinylidenefluoride spreads uniformly through the thickness of the carbon support. Furthermore, the concentration of an impregnating solution of PTFE (fluorine plastic) suspension makes it possible to regulate efficiently the surface properties of felts, which can be directly used in the development of gas diffusion layers of fuel cells. On the whole, the use of viscose fiber-based carbon felts allows the production of gas diffusion materials with a level of surface electrical resistance below 1 Ω/m2. [ABSTRACT FROM AUTHOR]

As an electrochemical device that converts the chemical energy of fuel directly into electrical energy, the fuel cell is a new alternative technology that uses fuel from renewable sources and generates power for sustainable development and energy security. Among various types of fuel cells, the direct carbon fuel cell (DCFC) has higher efficiency because carbon fuel has higher energy density than liquid or gas fuel. However, the current development of DCFCs is still limited by the sluggish activity of the cathode reaction. In this study, a new composite cathode made of Gd0.2Ce0.8O1.9 (GDC) and SrFe1−xTixO3–δ (SFT) is developed for a Nicotiana tabacum-derived carbon fuel-based DCFC. The structural, optical, and electrochemical properties of the materials are systematically evaluated. X-ray diffraction analysis results show a cubic structure of GDC and cubic perovskite phase of SFT in the sample, with crystallite sizes of 37 and 15 nm, respectively. Ultraviolet–visible spectroscopy reveals an indirect band gap which exhibits a red shift. Fourier transform infrared spectroscopy confirms the presence of Ce–O, Sr–Ti–O, and Fe–O functional groups in all the samples. Scanning electron microscopy analysis shows the morphology and particle size of the materials. The sample Gd0.2Ce0.8O2-δ–SrFe0.96Ti0.04O1.9 exhibits the highest electrical conductivity of 4.96 S cm−1 in an oxygen atmosphere at 600 °C and a higher power density of 40 mW cm−2 at 600 °C compared to other samples using Nicotiana tabacum carbon fuel. These findings indicate that the developed composite cathode is an efficient cathode for low-temperature DCFCs. [ABSTRACT FROM AUTHOR]

This study investigates the properties of novel flexible polymer nanocomposite films made with polyethylene glycol (PEG), sodium alginate (NaAlg), and silver nitrate (AgNO3) nanoparticles. The nanocomposites were fabricated using a casting method and characterized by various techniques to understand the influence of AgNO3 content on their optical, electrical and dielectric properties. The frequency range for characterization was 10 Hz to 7 MHz. XRD analysis revealed a decrease in the intensity of the peaks in the nanocomposite films compared to the pristine blend, suggesting changes in the crystalline structure with increasing AgNO3 concentration. FT-IR spectroscopy confirmed the successful formation of the composite material through interaction between the components. Ultraviolet-visible (UV-Vis) spectroscopy was utilized to examine the optical properties of the films. Tauc's plot analysis was used to calculate the energy bandgap values for both direct and indirect transitions in the nanocomposites. The results showed a decrease in the bandgap (Eg) with increasing AgNO3 content. This trend was observed for both direct transitions (Eg decreasing from 5.59 eV to 5.16 eV) and indirect transitions (Eg decreasing from 4.93 eV to 3.95 eV). Electrical and dielectric characterization revealed that the nanocomposite with 20 wt% AgNO3 loading exhibited the most favorable electrical properties. The direct current conductivity (σdc) increased significantly from 2.55 × 10− 10 S/cm to 5.65 × 10− 9 S/cm, while the frequency exponent (S) decreased from 0.81 to 0.49. These observations suggest significant modifications in the electrical transport behavior of the films upon AgNO3 incorporation. The improved electrical properties make these PEG/NaAlg-AgNO3 nanocomposites promising candidates for applications in flexible solar cells and electrical energy storage devices. [ABSTRACT FROM AUTHOR]

The goal of this research is to create a perovskite ceramic with electrical and dielectric properties appropriate for energy storage, medical uses, and electronic devices. A bismuth ferric titanate, Bi0.7Ba0.3(FeTi)0.5O3, doped with barium and crystalline, was effectively synthesized at the A-site via sol–gel synthesis. A rhombohedral structure emerged in the R3́C space group, which was confirmed by room-temperature X-ray studies. An average grain size of 263 nm and a homogeneous grain distribution and chemical composition were confirmed by the results of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The study established a clear relationship between temperature, frequency, and the electrical properties of the material. Impedance spectroscopy and electrical modulus measurements, performed in the frequency range of 1 kHz to 1 MHz and at temperatures ranging from 200 K to 360 K, demonstrated a non-Debye type of relaxation. Furthermore, once the material was produced at various temperatures, its frequency-dependent electrical conductivity was examined using Jonscher's law. The results demonstrate that barium doping significantly improves the electrical conductivity and dielectric properties compared to pure BiFeTiO₃. Over the complete temperature range, consistent conduction and relaxation mechanisms were discovered. These findings suggest that the chemical may find widespread applicability across a broad temperature range, including electrical fields and capacitors. Highlights: Successful Synthesis: A perovskite ceramic, Bi0.7Ba0.3(FeTi)0.5O3, was synthesized using the sol–gel method, doped with barium at the A-site. Structural Properties: X-ray diffraction confirmed a rhombohedral structure in the R3́C space group, with an average grain size of 263 nm, as analyzed through SEM and EDX techniques. Enhanced Electrical and Dielectric Properties: Barium doping significantly improved the electrical conductivity and dielectric properties of the material compared to undoped BiFeTiO₃, making it suitable for energy storage and electronic applications. Non-Debye Relaxation Behavior: Impedance spectroscopy and electrical modulus analysis in the frequency range of 1 kHz to 1 MHz and temperature range of 200–360 K revealed non-Debye type relaxation. Wide Applicability: The study identified stable conduction and relaxation mechanisms over a broad temperature range, suggesting potential use in capacitors and electrical fields across various temperature conditions. [ABSTRACT FROM AUTHOR]

Conventional sutures used in surgical procedures often lack the capability to effectively monitor physical and chemical activities or the microbial environment of surgical wounds due to their inadequate mechanical properties, insufficient electrical accuracy and unstability. Here, we present a straightforward layer-by-layer coating technique that utilizes 3-glycidoxypropyltrimethoxysilane (CA), graphene oxide (GO), and ascorbic acid (AA) to develop conductive silk-based surgical sutures (CA-rGSFS). The CA-rGSFS feature a continuous reduced graphene oxide (rGO) film on their surface, forming robust hydrogen bonds with silk fibroin. The reduction process of rGO is confirmed through Raman analysis, demonstrating an enhanced D peak to G peak ratio. Notably, the CA-rGSFS exhibit exceptional mechanical properties and efficient electron transmission, with a knot-pull tensile strength of 2089.72 ± 1.20 cN and an electrical conductivity of 130.30 ± 11.34 S/m, respectively, meeting the requirements specified by the United States Pharmacopeia (USP) for 2-0 sutures. These novel CA-rGSFS demonstrate the ability to accurately track resistance changes in various fluid environments with rapid response, including saline, intestinal, and gastric fluids. The suture also retains remarkable stretchablility and stability even after enduring 3000 tensile cycles, highlighting their potential for precise surgical site monitoring during the wound healing process. [ABSTRACT FROM AUTHOR]

The effect of friction stir processing and subsequent aging on the microstructure and physicomechanical properties of the thermally hardened Cu–0.3% Cr–0.5% Zr alloy has been studied. Plastic deformation under friction stir processing leads to the formation of an ultrafinely grained structure with an average grain size of 0.5 µm, the decomposition of a supersaturated solid solution, and the precipitation of disperse particles in the stir zone. It has been shown that aging is accompanied by the additional precipitation of disperse particles and the development of recovery in the zone of processing. The refinement of a granular structure and the precipitation of particles leads to an increase in the strength properties and electrical conductivity in the stir zone. Aging is accompanied by a surplus increase in conductivity without any significant decrease in strength characteristics. The effect of structural evolution under friction stir processing and aging on the Cu–Cr–Zr alloy properties is discussed. [ABSTRACT FROM AUTHOR]

The positron annihilation lifetime (PAL) spectroscopy characteristics of ethylene-propylene-diene monomer rubber (EPDM) composites reinforced with treated wheat husk fibers (WHFs) were investigated for the first time. PAL spectroscopy is employed to study the free volume of polymers. The use of lignocellulosic materials as reinforcement in polymeric composites has gained attention due to their low cost, availability, and eco-friendliness. In this study, the impact of the loading concentration on the interfacial adhesion between the EPDM matrix and WHFs is quantified, along with the evaluation of swelling measurement and tensile properties. Additionally, the nanoscopic properties derived from PAL spectroscopy correlate with the composites' macroscopic properties. In addition, the dielectric properties of the investigated samples have been studied, and their conductivity has been calculated. To determine the conduction mechanism within these samples and how it is affected by the addition of WHF, the change in electrical conductivity with the frequency of the external electric field applied to the samples was studied, and from this, the conduction mechanism was determined, and the barrier height value was calculated. The experimental results provide insights into the relationship between the structure and properties of EPDM-WHF biocomposites, offering valuable knowledge for developing sustainable and high-performance materials. [ABSTRACT FROM AUTHOR]

La10−xNdxSi6O27 (x = 0, 0.1, 0.2, 0.3) was synthesized via planetary grinding, and dense ceramic discs were prepared using SPS technology. The structure, microstructure, density, open porosity, total conductivity and electronic conductivity of the samples were measured and analyzed, respectively. La10−xNdxSi6O27 is characterized by a hexagonal apatite structure. The elements in the sample are distributed in a uniform manner and the content is consistent with the stoichiometry. The total conductivity of La10−xNdxSi6O27 exhibits an increase with the incorporation of Nd3+ content in the doped samples of x = 0.1, 0.2, and 0.3. The total conductivity of La9.7Nd0.3Si6O27 is the highest, reaching 5.39 × 10−3 S cm−1 at 850 °C. The electron mobility of the sample is less than 1%, which is suitable for use as a solid electrolyte. [ABSTRACT FROM AUTHOR]

The electrification of automotive is growing rapidly, resulting in an increased need for aluminum alloys with high electrical conductivity. The core element of the electric vehicle, besides the batteries, is an electric motor, which replaces the internal combustion engines of a traditional gasoline vehicle. These applications require both high strength and high electrical conductivity. This paper presents the development of a new Al-Fe-Ni aluminum alloy that provides a good combination of mechanical properties and electrical conductivity. The alloy is well suited for high-pressure vacuum die casting (HPVDC). The as-cast microstructures, mechanical properties and electrical conductivity were studied for alloys with different Fe/Ni combination. The relationship between the microstructure and properties is analyzed, and the strengthening mechanisms of the studied alloy are discussed. Based on the experimental results, the new alloy demonstrates excellent potential for electric vehicle applications produced by high-pressure vacuum die casting. [ABSTRACT FROM AUTHOR]