Decrease In Electrical Conductivity Research Articles

Mitigating the detrimental impacts of low- and high-density polyethylene microplastics using a novel microbial consortium on a soil-plant system: Insights and interactions

The accumulation of polyethylene microplastics (PE-MPs) in soil has raised considerable concerns; however, the effects of their persistence and mitigation on agroecosystems have not been explored. This study aimed to assess the detrimental effects of PE-MPs on a soil-plant system and evaluate their mitigation using a novel microbial consortium (MC). We incorporated low-density polyethylene (LDPE) and high-density polyethylene (HDPE) at two different concentrations, along with a control (0 %, 1 %, and 2 % w/w) into the sandy loam soil for a duration of 135 days. The samples were also treated with a novel MC and incubated for 135 days. The MC comprised three bacterial strains (Ralstonia pickettii (MW290933) strain SHAn2, Pseudomonas putida strain ShA, and Lysinibacillus xylanilyticus XDB9 (T) strain S7–10F), and a fungal strain (Aspergillus niger strain F1–16S). Sunflowers were subsequently cultivated, and physiological growth parameters were measured. The results showed that adding 2 % LDPE significantly decreased soil pH by 1.06 units compared to the control. Moreover, adding 2 % HDPE resulted in a more significant decrease in soil electrical conductivity (EC) relative to LDPE and the control. A dose-dependent increase in dissolved organic carbon (DOC) was observed, with the highest DOC found in 2 % LDPE. The addition of higher dosages of LDPE reduced soil bulk density (BD) more than HDPE. The addition of 2 % HDPE increased the water drop penetration time (WDPT) but decreased the mean weight diameter of soil aggregates (MWD) and water-stable aggregates (WSA) compared to LDPE. The results also revealed that higher levels of LDPE enhanced soil basal respiration (BR) and microbial carbon biomass (MBC). The interaction of MC and higher MP percentages considerably reduced soil pH, EC, BD, and WDPT but significantly increased soil DOC, MWD, WSA, BR, and MBC. Regarding plant growth, incorporating 2 % PE-MPs significantly reduced physiological responses of sunflower: chlorophyll content (Chl; −15.2 %), Fv/Fm ratio (-25.3 %), shoot dry weight (ShD; −31.3 %), root dry weight (RD; −40 %), leaf area (LA; −38.4 %), and stem diameter (StemD; −25 %) compared to the control; however, the addition of novel MC considerably reduced and ameliorated the harmful effects of 2 % PE-MPs on the investigated plant growth responses.

Influence of the presence of ions on the dielectric properties of reverse micelle systems

AOT/isooctane/water reverse micelle solution was doped with ionic salts solutions: sodium chloride, potassium chloride, tetramethylammonium chloride, tetramethylammonium bromide, sodium butyrate and sodium benzoate. Each system was investigated for the influence of ionic additives on dielectric properties: electric permittivity, conductivity and nonlinear dielectric effect (NDE). Studies showed that addition of salts noticeably changes the dielectric parameters. Based on the salts used in this research, the most common effect is a decrease of electric permittivity, conductivity and NDE effect. However, addition of some ions can lead to their increase, which was proved in the case of sodium benzoate. The registered changes were explained based on the percolation effect and changes in rigidity of the micellar surfactant shell due to the incorporation of the dissolved ions into the micellar structure.

Evolution of thermoelectric transport properties of Sb2Te3–Sb2Se3 solid-solution alloys depending on phase formation behavior

Sb2Te3-based alloys exhibit decent thermoelectric transport properties in the mid-temperature range above 550 K. However, the study on Sb2Te3 alloys has been limited in simple doping approach. Herein, evolution in the thermoelectric transport properties associated with the phase formation of solid solution alloys of Sb2(Te1−xSex)3 (x = 0, 0.25, 0.33, 0.5, 0.75, and 1.0) compositions is investigated to widen the strategy to solid solution alloying. A single phase of the Sb2Te3 rhombohedral structure formed from x = 0 to 0.5, whereas mixed phases with an orthorhombic structure of Sb2Se3 was observed at x = 0.75. The electrical conductivity weighted mobility were gradually decreased as Se content increases to x = 0.75. Consequently, the power factor was decreased gradually and significantly to 0.076 mW/mK2 for x = 0.75 (Sb2(Te0·25Se0.75)3) compared with 2.6 mW/mK2 of the pristine sample. The total thermal conductivity of 2.0 W/mK for the Sb2Te3 was significantly reduced gradually to 0.64 W/mK for x = 0.75 owing to simultaneous decrease in electrical and lattice thermal conductivities. The reduction in lattice thermal conductivity is mainly owing to the addition point defect scattering caused by the Se addition. Nevertheless, thermoelectric figure of merit zT of Sb2Te3 is gradually decreased from 0.64 to 0.11 for x = 0.75 at 650 K due to the degradation in electrical transport properties. Furthermore, the theoretical zT was estimated for all samples with varying carrier concentration based on single parabolic band model.

Effect of Intermediate Annealing on Microstructure and Cold Rolling Hardness of AlFeMn Alloy

The microstructure and texture of an AlFeMn alloy were studied under different intermediate annealing processes, and the changes in microhardness during cold rolling were analyzed. After annealing at 420 °C with a slow heating rate, the alloy showed a high number of small dispersed particles and recrystallization textures dominated by R texture, with deformation textures of 23.5%. Annealing at 610 °C with a rapid heating rate resulted in a significant decrease in the number of small-sized particles and an increase in recrystallization texture contents, with CubeND being the majority. The deformation texture contents decreased to 14.9%. The electrical conductivity of the 420 °C annealed sheet was higher than before annealing, whereas the sheet annealed at 610 °C showed a decrease in electrical conductivity after annealing. This indicated that annealing at 610 °C led to a higher degree of recrystallization and the development of Cube/CubeND due to the dissolution of dispersed particles. During the subsequent cold rolling process, the microhardness of both annealed sheets initially increased and then decreased. However, the microhardness of the 420 °C annealed sheet with varying cold rolling reductions consistently remained lower than that of the 610 °C annealed sheet, as was the cold rolling reduction corresponding to the peak microhardness. The results showed that the precipitation at 420 °C facilitated work softening, while the dissolution at 610 °C promoted work hardening.

Effect of particle size and concentration on foodborne pathogen inactivation by pulsed ohmic heating in tomato sauce

This research investigated the effects of the size and concentration of diced tomato particles in tomato sauce on the performance of pulsed ohmic heating (POH). Samples were prepared by adding 5 and 10 g of tomato particles (square shapes with sides of 2.5, 5, 10, and 15 mm) to 20 and 15 g of tomato sauces, and tomato sauce without particles was used as the control group. As the size and concentration of tomato particles increased, the passage of electric current was hindered, resulting in a decrease in electrical conductivity and consequently a deceleration in the heating rate of POH. Through infrared camera image analysis, it was determined that tomato particles formed cold areas in the tomato sauce, inhibiting uniform heating of POH. Because particles reduced efficiency of POH, there was an inverse relationship between the size and content of particles and the reduction of pathogens. At 20% tomato particles, the reduction levels of Escherichia coli O157:H7 were 1.60, 1.85, 2.12, 2.28, and 3.07 log CFU/ml for tomato sauces with particle sizes of 2.5, 5, 10, and 15 mm and without particles, respectively. When the size of the tomato particles was the same, increasing the particle concentration in the sauce from 20 to 40% resulted in an average reduction of 0.47 in the inactivation levels of E. coli O157:H7 by POH. Therefore, the size and concentration of particles dispersed in food should be contemplated when designing a POH process to inactivate harmful bacteria in food.

Effect of lattice defects on crystal structure and microwave properties of Ba(Ga1/2Ta1/2)O3 doped Ba(Zn1/3Nb2/3)O3 ceramics

Traditionally, B-site cation ordering structure in Ba(B′1/3B″2/3)O3 based ceramics with complex perovskite structure is considered to be the dominant factor in determining the dielectric loss. The crystal structure of BZN-BGT ceramics changes to the B-site disordering from B-site 1:2 ordering accompanying with remarkably reduced dielectric loss. Ba(Ga1/2Ta1/2)O3 doping also inhibits the formation of Nb-rich secondary phases induced by Zn volatilization on the surface of BZN-BGT ceramics as well. The conductive activation energy Ea, an energy required for electrons to escape from the traps, increases to 0.55eV from 0.40eV, indicating the decrease of lattice defects concentration. As Ba(Ga1/2Ta1/2)O3 doping concentration increases, the dielectric thermal relaxation process of BZN-BGT ceramics weakens and the electrical conductivity decreases. These results indicate that the dielectric loss of BZN-BGT ceramics containing volatile Zn could be controlled by the lattice defects and secondary phases rather than B-site 1:2 ordering structure.

Building a Layer-Structured Aluminum/Graphene Composite with Significant Improvement in Electrical Conductivity.

Aluminum (Al) and its alloys are widely used in various fields due to their excellent physical properties. Although many efforts have been made to fabricate an Al-based composite, they usually results in a significant decrease in electrical conductivity. Herein, a special layer-structured Al/graphene (Gr)/Al composite was successfully designed and fabricated through a facile method using the ultrasonic spraying of graphene powder with alumina removal and a subsequent vacuum hot-pressing process. The as-obtained Al/Gr/Al composite presents a significantly enhanced electrical conductivity of 66% IACS, which is much higher than that of other reported Al-based composites, while it still maintains similar mechanical properties. This work provides a new strategy for the development of highly conductive Al-based composites, which would be very useful and important for practical applications.

Structural and electrical conductivity studies of Polyaniline - WO3 hybrid nanocomposites for gas sensing applications

Abstract Conducting polymer – metal oxide based hybrid nanocomposites are a fascinating class of materials for miniaturized and flexible gas sensor devices. They exhibit enhanced physiochemical properties such as sensitivity, selectivity towards various volatile and hazardous chemical and bioanalytes. Our study focuses on conducting polyaniline (PANI) and WO3 nanocomposites, where different weight percentages (wt.%) of WO3 nanoparticles are embedded within the conducting PANI matrix using an in-situ oxidation polymerization synthesis technique. The surface morphology analysis indicated that the WO3 nanoparticles with an average grain size of ~200 nm are homogeneously distributed within the PANI nanofibers. The Fourier Transform Infra-Red (FTIR) spectrum analysis showed that the absorption peaks at 1111,1291, 1385, 1474, and 1560 cm−1 are typical of the conducting PANI emeraldine phase. We attribute the additional broad peak ranging between 840 to 720 cm−1 in the spectrum to WO3 phase, wherein, the intensity of the peak increases with WO3 content in case of hybrid composites. Current-voltage (I-V) characteristics for all our samples showed linear behaviour up to 1.2 volts. Temperature-dependent DC electrical conductivity (σ) studies measured from room temperature to 120°C for pure PANI, and PANI-WO3 composites showed an enhanced electrical conductivity of values up to 0.12 S/cm for PANI as compared to WO3 with σ ~ 1.4 x 10−3 S/cm. Pure PANI exhibits semiconducting behavior with an increase in electrical conductivity with temperature due to the charge carrier delocalization within the dispersed PANI backbone. The addition of higher concentrations of WO3 in composites leads to a metallic-like behavior, characterized by a decrease in electrical conductivity with temperature. These observations are attributed to the field-assisted band bending effects at the interfaces of PANI and WO3. Our composites show desired electrical characteristics suitable for gas sensing applications.

Reproducible graphene synthesis by oxygen-free chemical vapour deposition.

Chemical vapour deposition (CVD) synthesis of graphene on copper has been broadly adopted since the first demonstration of this process1. However, widespread use of CVD-grown graphene for basic science and applications has been hindered by challenges with reproducibility2 and quality3. Here we identify trace oxygen as a key factor determining the growth trajectory and quality for graphene grown by low-pressure CVD. Oxygen-free chemical vapour deposition (OF-CVD) synthesis is fast and highly reproducible, with kinetics that can be described by a compact model, whereas adding trace oxygen leads to suppressed nucleation and slower/incomplete growth. Oxygen affects graphene quality as assessed by surface contamination, emergence of the Raman D peak and decrease in electrical conductivity. Epitaxial graphene grown in oxygen-free conditions is contamination-free and shows no detectable D peak. After dry transfer and boron nitride encapsulation, it shows room-temperature electrical-transport behaviour close to that of exfoliated graphene. A graphite-gated device shows well-developed integer and fractional quantum Hall effects. By highlighting the importance of eliminating trace oxygen, this work provides guidance for future CVD system design and operation. The increased reproducibility and quality afforded by OF-CVD synthesis will broadly influence basic research and applications of graphene.

Assessment of Pistachio Shell-Based Biochar Application in the Sustainable Amendment of Soil and Its Performance in Enhancing Bell Pepper (Capsicum annuum L.) Growth

This study aimed to (a) analyze the influence of pyrolysis temperature on pistachio shell-based biochar (PSB) properties and (b) assess the PSB effect on green bell pepper (Capsicum annuum L.) growth. Pyrolysis experiments were conducted at different temperatures, determining 450 °C as optimal for soil amendment. The effect of PSB addition at different mass ratios was analyzed considering the physicochemical properties of the mixtures and the agronomic parameters of green bell pepper plants and fruits under greenhouse conditions. Results demonstrated enhancements in soil properties upon biochar incorporation, including a decrease in pH by 1%, a decrease in electrical conductivity (EC) by 4–14%, and increases in cation exchange capacity (CEC) by 4–8%, organic matter (OM) and organic carbon (OC) by 100–200%, and total nitrogen (TN) by 35%, relative to unamended soil. Agronomic variables revealed improvements, particularly during the reproductive and maturity stages, with plants treated with 1% biochar (SB1) exhibiting enhanced growth and chlorophyll content, alongside increased flower and fruit yields. Notably, the 2% biochar treatment (SB2) yielded superior fruit weight and length results, suggesting the potential for biochar to enhance both the quality and quantity of green bell pepper fruits, thereby contributing to sustainable agricultural practices.

Fabrication and Characterization of Functionally Graded Nanocomposites: Impact of Graphene and Vanadium Carbide on Aluminum Matrix

Abstract Functional graded nanocomposites (FGNCs) based on Al are artificially tailored heterogeneous materials intended to serve the demand for diverse and contradicting properties used in various industrial applications. FGNCs and hybrid FGNCs (HFGNCs) based on Al reinforced with graphene and vanadium carbide (VC) were prepared using powder metallurgy techniques and investigated. Both samples were designed with a gradient composition, where the bottom layer consisted of 100% pure Al, followed by three consecutive layers containing progressively increasing amounts of reinforcement. The incorporation of graphene and VC into layer powders resulted in a decrease in both particle and crystal dimensions compared to pure Al. Adding graphene has a negative effect on bulk density samples, while VC has a positive effect. Reinforcing materials led to a decrease in thermal conductivity that reached 26.7 % for samples reinforced with VC reinforcement, except for FGNCs reinforced with graphene, which increased by ~3.3 compared to Al. The samples’ CTE and electrical conductivity values decreased, although adding graphene alone led to a slight decrease in electrical conductivity. A significant improvement in all mechanical properties was noted with additional. The HFGCNs reinforced with the largest amount of hybrid reinforcement recorded an improvement in CTE value, Young's modulus, and compressive strength by about 38.1%, 22.2%, and 20.5%, respectively, compared to Al

Effects of spark plasma sintering and nanodiamond amount on titanium-nanodiamond composite properties

Titanium/nanodiamond (ND) mixtures were sintered using spark plasma sintering (SPS). Densification was studied for Ti + x wt% ND mixtures (where x = 2, 5, 10 and 15) to determine the optimized cycles. Ti/ND mixtures were then sintered under these optimized conditions achieving relative densities higher than 96 %. The SPS temperatures for the Ti + 2 wt% ND, Ti + 5 wt% ND, Ti + 10 wt% ND and Ti + 15 wt% ND mixtures were 1000 °C, 1050 °C, 1150 °C and 1150 °C, respectively. Numerical simulation by finite elements were used to check the thermal homogeneity in the sample and to determine the maximal temperature in the sample to ensure avoiding graphitization. The effects of ND on the Ti/ND mixtures were investigated. Microstructural characterizations reveal the presence of three different phases including a Ti phase, a non-stoichiometric TiCx solid phase and NDs located inside the TiCx grains. Indeed, NDs react with Ti to form the TiCx solid phase. However, a fast sintering with temperature below graphitization of diamond allows to keep nanodiamond structure into the Ti/ND mixtures. Hardness and electrical conductivity of the Ti/ND mixtures were measured. The results show that the higher the ND content, the more the hardness of the composite increases and the more the electrical conductivity decreases. Hardness increased from 340 HV to 1346 HV for Ti and the Ti + 15 wt% ND mixture, respectively. Electrical conductivity is reduced by a factor of three for the Ti + 15 wt% ND mixture relative to Ti which can be explained by the microstructure exhibiting fewer Ti grains in favor of the TiCx solid phase when ND content was increased in the composite.

Electrical properties evaluation of corn oil biodiesel mixed with lubricant as a potential source of energy

The main aim of this study is to assess the electrical characteristics pertaining to a biodiesel derived from corn oil and lubricant. The first step in the synthesis of biodiesel from corn oil involves the transesterification process. Subsequently, the biodiesel is combined with a base lubricant (20W-40T) in varying proportions, spanning from 5% to 40% of the overall volume. The measurement and analysis of biodiesel blends necessitate consideration of crucial electrical parameters, including breakdown voltage, resistivity, permittivity and electrical conductivity. The decrease in breakdown voltage, permittivity, and electrical conductivity that ensues from an increase in diameter may be attributed to the corresponding increase in diameter. Nevertheless, a positive association exists between the greater quantity of base lubricant and an elevation in resistivity. Despite the positive correlation between resistivity and diameter, this phenomenon persists. The potential cause for the enhancement of the electrical properties might be attributed to the dispersion of the fundamental lubricant.

Electrical conductivity and thermal stability of polyaniline and water-soluble polymer nanocomposites

Electrically conductive composites with film-forming properties based on polyaniline (PANI), polyvinyl alcohol (PVA), and polymethacrylic acid (PMAA) were obtained. The composites were synthesized mechanochemically by mixing calculated amounts of PANI and PVA or PMAA. The electrical conductivity increases with an increase in the content of the conductive component in the composite up to a PANI–PVA ratio of 50 to 50. Further increase of PVA in the composite leads to a decrease in the specific electrical conductivity. Similar patterns are observed for PANI–PMAA composites. The study of the effect of temperature on the electrical conductivity of composites made it possible to determine the activation energy of charge transfer (Ea ). The numerical values of Ea lie in the range of 0.371 to 0.981 eV and depend on the ratio of PANI–PVA and PANI–PMAA polymers in the composites. The thermal decomposition of composites and starting components is complex. Several areas are observed on the mass change curves, which indicate a multi-stage thermal decomposition process.

Ultrasonication Influence on the Morphological Characteristics of Graphene Nanoplatelet Nanocomposites and Their Electrical and Electromagnetic Interference Shielding Behavior.

Graphene nanoplatelets (GNPs)/epoxy composites have been fabricated via gravity molding. The electrical and thermal properties of the composites have been studied with variable GNP type (C300, C500, and C750, whose surface areas are ~300, 500, and 750 m2/g, respectively), GNP loading (5, 10, 12, and 15 wt.%), and dispersion time via ultrasonication (0, 30, 60, and 120 min). By increasing the time of sonication of the GNP into the epoxy matrix, the electrical conductivity decreases, which is an effect of GNP fragmentation. The best results were observed with 10-12% loading and a higher surface area (C750), as they provide higher electrical conductivity, thereby preserving thermal conductivity. The influence of sonication over electrical conductivity was further analyzed via the study of the composite morphology by means of Raman spectroscopy and X-ray diffraction (XRD), providing information about the aspect ratio of GNPs. Moreover, electromagnetic shielding (EMI) has been studied up to 4 GHz. Composites with C750 and 120 min ultrasonication show the best performance in EMI shielding, influenced by their higher electrical conductivity.

Elucidating Amendment Resources for Reclaiming Efficacy of Sodic Soils around Abaya and Chamo Lakes, South Ethiopia Rift Valley.

Sodic soils are harmful to agricultural and natural environments in Ethiopia's semi-arid and arid regions, leading to soil degradation and reduced productivity. This study investigated how amendment resources could help improve the chemical properties of sodic soils around the Abaya and Chamo Lakes in the South Ethiopia Rift Valley. A factorial experiment was conducted to study the effects of gypsum (GYP) and farmyard manure (FYM) on sodic soil reclamation. The experiment had four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha-1), with three replications. The pots were incubated for three months and leached for one month, after which soil samples were collected and analyzed for chemical properties. ANOVA was performed to determine the optimal amendment level for sodic soil reclamation. The study found that applying 10 ton FYM ha-1 and gypsum at 100% gypsum required (GR) rate resulted in a 99.8% decrease in exchangeable sodium percentages (ESP) compared to untreated composite sodic soil and a 1.31% reduction over the control (GYP 0% + FYM 0 ton ha-1). As a result, this leads to a decrease in soil electrical conductivity, exchangeable sodium (Ex. Na), and ESP values. The results were confirmed by the LSD test at 0.05. It is fascinating to see how different treatments can have such a significant impact on soil properties. The prediction models indicate that ESP's sodic soil treatment effect (R2 = 0.95) determines the optimal amendment level for displacing Ex. Na from the exchange site. The best estimator models for ESP using sodic soil treatment levels were ESP = 1.65-0.33 GYP for sole gypsum application and ESP = 1.65-0.33 GYP + 0.28 FYM for combined GYP and FYM application, respectively. The study found that combined GYP and FYM applications reduced ESP to less than 10% in agriculture, but further research is needed to determine their effectiveness at the field level.

Simultaneous removal of sulfamethazine and sulfate via electrochemical oxidation and capacitive Deionization: Mechanisms of in-situ activation and strategies of the hybrid system

Electrochemical oxidation (EO) is a well-established method for pollutants removal. However, excessive addition of oxidant during EO may cause secondary pollution. Moreover, the unprocessed ions in the wastewater can cause further contamination. This research introduces a hybrid process that combines EO with capacitive deionization (CDI), in situ catalytically utilizing sulfate (SO42-) and removing sulfamethazine (SMZ). This process realized by layered porous MXene-modified biochar electrodes (BCM) that demonstrate electrocatalytic and adsorption properties. The electrochemical oxidation system, constructed using BCM cathode and boron-doped diamond anode, harnesses in situ generation of oxidants from SO42-, leading to the complete degradation of 30 mg/L sulfamethazine in 30 min through adsorbed radicals and metastable active species at the biphasic interface. Subsequently, the BCM-2 exhibits excellent CDI performance at 1.2 V, achieving a desalination capacity of 15.40–65.97 mg/g in 100–1000 mg/L Na2SO4 solution. By combining EO with CDI, BCM simultaneously removes sulfamethazine and sulfate, resulting in a 60 % reduction in total organic carbon and a 14.4 % decrease in electrical conductivity after one process cycle. Moreover, BCM exhibits favorable cytocompatibility.

Fabrication of thermoelectric Bi2Te2·5Se0.5 with adjustable porosity

Porous structures have attracted considerable interest for their impact on the transport and mechanical characteristics of materials. The fabrication of porous materials, however, often involves intricate preprocessing steps and typically lacks the ability to tailor porosity with ease. In the present study, we present a straightforward method to prepare porous Bi2Te2·5Se0.5 samples by employing low-pressure spark plasma sintering, with the porosity regulated by preset mass density using a modified graphite mold. This approach resulted in a substantial decrease in thermal conductivity, attributed to the introduction of pores that reduce mass density and disrupt phonon transmission. An accompanying decrease in electrical conductivity was also noted, arising from reduced carrier concentration and mobility. Despite these variations, all porous samples maintained similar levels of thermoelectric performance, with a peak zT of ca. 0.9 at 373 K. The average zT within the temperature range of 298–500 K remained slightly above 0.8 for all samples. Furthermore, the porous samples exhibited greatly enhanced mechanical properties. This work demonstrates a versatile and adaptable method to produce porous materials with controllable porosity, potentially applicable to other porous thermoelectric systems.

Light- and electro-driven phase change materials derived from activated porous biochar nanosheets and encapsulated polyethylene glycol

Biochar-based phase change materials (PCMs) are suitable for energy conservation to regulate the environment of greenhouses, but would benefit from higher specific surface area biochar to increase the polyethylene glycol (PEG) loading and enhanced thermal conductivity to promote efficient heat transfer. Moreover, since solar radiation is not constant for photo-thermal conversion, a material with an additional energy conversion process, e.g. electro-thermal conversion, would be advantageous. Herein, maize straw-derived activated porous biochar nanosheets were prepared and impregnated with PEG to afford PCMs. Due to their high specific surface area, the PEG loading capacity in the biochar nanosheets reaches 88.9%, with no leakage observed during phase transitions. The latent heat and photothermal conversion efficiency of the materials increase with the loading content of PEG. Hierarchical porous structures in the biochar nanosheets endow the material with a high thermal conductivity exceeding 0.585 W m−1 k−1. In addition, electro-thermal conversion of the materials was achieved due to increased graphitization of the biochar nanosheets. The electrical conductivity and electro-thermal conversion efficiency decrease with the loading content of PEG. The material with 85.7% PEG content is the most favorable in terms of thermal conductivity as well as light- and electro-driven phase change behaviors.

Effect of Ni addition on the microstructure, conductivities and mechanical properties of as-cast Al-Fe alloys

In this study, the microstructure, conductivity and mechanical properties of as-casted Al-1Fe-xNi (x= 0, 1, 4, 6 and 10, wt%) alloys were systematically investigated. The results exhibited the Al-1Fe-xNi alloys mainly consist of α-Al, Al3Fe, Al3Ni, and Al9FeNi phase. With the increase of Ni addition, the size of α-Al grain decreases and the dimension of Al9FeNi phase increased. The hardness of the as-cast alloys raises with increasing Ni content, whereas the elongation and electrical conductivity decreases and the ultimate tensile strength (UTS) first increases and then decreases dramatically. The Al-1Fe-6Ni alloy exhibited the highest Q-value, which was approximately 11.27% higher than that of the Ni-free alloys. This mechanism of mechanical properties change occurs mainly due to slightly Ni effectively refines the α-Al phase, and the excessive Ni content leads to formation of coarse needle-like or lath-like Al9FeNi phase. Additionally, the grain refinement and precipitation of the second phase upon Ni addition impede electron movement, leading to a decrease in the electrical conductivity of the alloy. The corresponding ductile fracture morphologies of Al-1Fe-xNi alloys are also analyzed. These high-strength Al-1Fe-xNi alloys could be helpful for developing novel Al-Fe alloys with a high strength and ductility.