Excellent Electrical Conductivity Research Articles

Electric Field‐induced Orientation of Carbon Nanomaterials in Dispersions

AbstractCarbon nanomaterials (CNMs) exhibit excellent performance and potential application value in optical, electric, magnetic and thermal owing to their unique low dimensional structures, high specific surface areas and excellent electrical conductivities, however, the random orientation of CNMs in polymer dispersions negatively affects their optimal performances. Herein, the orientation of CNMs induced by an electric field in dispersions was investigated. The arrangement of carbon black, carbon nanotubes and graphite nanoplatelets in solvents under an electric field was characterized using a stereoscopic microscope. The effects of solvent type, nanomaterial concentration and electric field conditions on the orientation of the CNMs were systematically investigated. The results showed that the CNMs generally exhibited good electric field‐induced orientations in solvents with a low relative dielectric constant. The orientation structure resulting from using an appropriate CNMs concentration was relatively uniform and continuous. In particular, a more regular orientation structure was achieved upon applying an electric field (100 V/mm; 1000 Hz) for 30 s. Interestingly, well‐oriented CNMs in a solvent can also orient in polymer dispersions that are soluble in such a solvent. This extension of the orientation of CNMs from solvents to polymer dispersion systems provides a novel idea for preparing high‐performance composites.

Nonmetallic graphite for tumor magnetic hyperthermia therapy

Magnetic hyperthermia therapy (MHT) has garnered immense interest due to its exceptional spatiotemporal specificity, minimal invasiveness and remarkable tissue penetration depth. Nevertheless, the limited magnetothermal heating capability and the potential toxicity of metal ions in magnetic materials based on metallic elements significantly impede the advancement of MHT. Herein, we introduce the concept of nonmetallic materials, with graphite (Gra) as a proof of concept, as a highly efficient and biocompatible option for MHT of tumors in vivo for the first time. The Gra exhibits outstanding magnetothermal heating efficacy owing to the robust eddy thermal effect driven by its excellent electrical conductivity. Furthermore, being composed of carbon, Gra offers superior biocompatibility as carbon is an essential element for all living organisms. Additionally, the Gra boasts customizable shapes and sizes, low cost, and large-scale production capability, facilitating reproducible and straightforward manufacturing of various Gra implants. In a mouse tumor model, Gra-based MHT successfully eliminates the tumors at an extremely low magnetic field intensity, which is less than one-third of the established biosafety threshold. This study paves the way for the development of high-performance magnetocaloric materials by utilizing nonmetallic materials in place of metallic ones burdened with inherent limitations.

Study on the impact of Cr content on the microstructure and properties of Cu-Cr alloys

Copper has excellent electrical conductivity, but the disadvantages of low strength and hardness limit its application range. In this paper, Cu-XCr (X=5, 7, and 9, where 5, 7, and 9 are all mass percentages) alloys were treated as the object of study; the impacts of Cr contents on the microstructure, Vickers hardness, and conductivity of Cu-XCr alloys were investigated using an XHC-SV2 upright metallographic microscope, a digital display Vickers hardness tester, and a Sigma2008C digital metal conductivity meter; the optimal Cr content was determined by the comprehensive performance parameter Z. The research results showed that the second phase of Cu-XCr alloys contained dendritic, nearly spherical, and other shapes. The size was relatively small, and the distribution was relatively uniform; the Vickers hardness improved and the electrical conductivity declined with climbing Cr content; when X=7, the comprehensive performance parameter Z of Cu-XCr alloys reached a maximum of 6.7×105 HV2·%IACS.

Enhanced photoelectric performance of ZnFe2O4 catalysts for oxidative carboxylation of styrene by tuning crystal planes and thermal and electrical conductivity

The photocatalytic oxidative carboxylation to yield cyclic carbonates was a promising approach for value-added utilization of olefins. Herein, various ZnFe2O4 (ZFO) based catalysts with different morphologies and supports were successfully prepared. Layered ZFO exposed highly active (422) crystal planes, which endowed the catalyst with narrow band gap and favorable electron transfer and charge separation, thereby promoting photocatalytic styrene epoxidation. Consequently, a 95 % selectivity for styrene oxide along with the complete conversion of styrene was achieved. Graphene with excellent electrical and thermal conductivity was compounded into ZFO based catalysts. On the one hand, ZFO/Graphene hybrids composed of 50 wt% graphene promoted fast charge transport in oxygen evolution reaction (OER), and the OER performance was comparable to the commercial RuO2 electrocatalyst. On the other, it exhibited significant photothermal effect and used into CO2 cycloaddition, delivering 95 % selectivity for styrene carbonate at a styrene oxide conversion of 95 %. As a result, a coupled photo-electro-heterogeneous catalytic system was proposed to yield styrene carbonate over ZFO based catalysts, including OER, styrene epoxidation and CO2 cycloaddition. This study provided an effective avenue for designing and fabricating ZFO based catalysts by crystal plane and support control.

Gallium-Based Liquid Metals in Rechargeable Batteries: From Properties to Applications.

Gallium-based (Ga-based) liquid metals have attracted considerable interest due to their low melting points, enabling them to feature both liquid properties and metallic properties at room temperature. In light of this, Ga-based liquid metals also possess excellent deformability, high electrical and thermal conductivity, superior metal affinity, and unique self-limited surface oxide, making them popular functional materials in energy storage. This provides a possibility to construct high-performance rechargeable batteries that are deformable, free of dendrite growth, and so on. This review primarily starts with the property of Ga-based liquid metal, and then focuses on the potential applications in rechargeable batteries by exploiting these advantages, aiming to construct the correlation between properties and structures. The glorious applications contain interface protection, self-healing electrode construction, thermal management, and flexible batteries. Finally, the opportunities and obstacles for the applications of liquid metal in batteries are presented.

Performance Improvement for the CuCrZr Alloy Produced by Laser Powder Bed Fusion Using the Remelting Process.

Owing to the high optical reflectivity of copper powder, the high-performance fabrication of copper alloys in the laser additive manufacturing (AM) field is problematic. To tackle this issue, this study employs the remelting process during laser powder bed fusion AM to fabricate defect-free and high-performance CuCrZr alloy. Compared to the non-remelting process, the remelting process yields finer grains, smaller precipitates, denser dislocations, and smaller dislocation cells. It realizes not only the dense molding of high laser reflectivity powders but also excellent mechanical properties and electrical conductivity (with an ultimate tensile strength of 329 MPa and conductivity of 96% IACS) without post-heat treatment. Furthermore, this study elucidates the influence of complex thermal gradients and multiple thermal cycles on the manufacturing process under the remelting process, as well as the internal mechanisms of microstructure evolution and performance improvement.

Comprehensive studies for evaluating promising properties of Cu/graphene/fly ash nanocomposites

Copper (Cu)'s electrical conductivity makes it attractive for industrial usage. Due to its inferior mechanical characteristics, thermal expansion, and wear resistance, its applications are limited. This manuscript solves these issues while retaining its major feature, excellent electrical conductivity. In this regard, different quantities of graphene (Gr) and fly ash (FA) nanoparticles were combined with Cu in a planetary ball mill at 440 rpm for 20 h using powder metallurgy (PM). The microstructure of the generated powders was characterized using X-ray diffraction technique and transmission electron microscopy. The powders underwent compression and were then subjected to firing at three distinct temperature levels, reaching a maximum of 850 °C. In addition, an analysis was conducted on the microstructure, mechanical properties, wear resistance, thermal expansion behaviour, and electrical conductivity of the sintered samples. Based on the findings, the inclusion of a hybrid of Gr and FA ceramics effectively led to a reduction in particle sizes. The bulk density slightly decreases with the addition of hybrid ceramic while increasing with the rise in sintering temperature. The hybrid composited Cu/0.8 vol.% Gr/8 vol.% FA recorded an increase in the microhardness, ultimate stress, and Young’s modulus of 25, 20, and 50%, respectively, relative to the Cu matrix. Furthermore, the wear rate and coefficient of thermal expansion for the same sample decreased by 67 and 30%, respectively. Finally, increasing the sintering temperature showed a clear improvement in the mechanical, electrical, and corrosion properties. Based on the results obtained, it can be concluded that the prepared hybrid nanocomposites can be used in power generation, power transmission, electronic circuits, and other applications.

Room temperature synthesis and hydrophobic surface protection of silver dendrites for hydrogel stretchable sensors

Hydrogel stretchable sensors have gained increasing popularity as essential components for next-generation flexible electronics. Stringent standards have been placed on the cost, conductivity, stability, and sensitivity of composites. In this work, highly conductive silver dendrites with uniform morphology were successfully synthesized by galvanic displacement reaction. Due to the more complex three-dimensional structure of the silver dendrites, the percolation threshold of the conductive composites was reduced to approximately 45 wt%. By decorating the as-prepared silver dendrites with a dense and hydrophobic dodecanethiol layer, the issue of hygrothermal stability in the hydrogel matrix has been successfully addressed. Silver dendrites conductive composites exhibited excellent electrical conductivity (8.57×10−4Ω∙cm for 65 wt% silver dendrites) and sensing properties. The stretchable conductors exhibited high sensitivity and linearity with F= 9.48 and R2= 0.9967. Therefore, human-computer interaction was successfully carried out by monitoring the movement of fingers, wrists, elbows, and knees of the human body.

Hierarchically core-shell structured nanocellulose/carbon nanotube hybrid aerogels for patternable, self-healing and flexible supercapacitors

The flexible and self-healing supercapacitors (SCs) are considered to be promising smart energy storage devices. Nevertheless, the SCs integrated with flexibility, lightweight, pattern editability, self-healing capabilities and desirable electrochemical properties remain a challenge. Herein, an all-in-one self-healing SC fabricated with the free-standing hybrid film (TCMP) composed of the 2,2,6,6-tetramethylpiperidin-1-yloxy-oxidized cellulose nanofibers (TOCNs) carried carbon nanotubes (CNTs), manganese dioxide (MnO2) and polyaniline (PANI) as the electrode, polyvinyl alcohol/sulfuric acid (PVA/H2SO4) gel as the electrolyte and dynamically cross-linked cellulose nanofibers/PVA/sodium tetraborate decahydrate (CNF/PB) hydrogel as the self-healing electrode matrix is developed. The TCMP film electrodes are fabricated through a facile in-situ polymerization of MnO2 and PANI in TOCNs-dispersed CNTs composite networks, exhibiting lightweight, high electrical conductivity, flexibility, pattern editability and excellent electrochemical properties. Benefited from the hierarchically porous structure and high mechanical properties of TOCNs, excellent electrical conductivity of CNTs and the desirable synergistic effect of pseudocapacitance induced by MnO2 and PANI, the assembled SC with an interdigital structure demonstrated a high areal capacitance of 1108 mF cm−2 at 2 mA cm−2, large areal energy density of 153.7 μWh cm−2 at 1101.7 μW cm−2. A satisfactory bending cycle performance (capacitance retention up to 95 % after 200 bending deformations) and self-healing characteristics (∼90 % capacitance retention after 10 cut/repair cycles) are demonstrated for the TCMP-based symmetric SC, delivering a feasible strategy for electrochemical energy storage devices with excellent performance, designable patterns and desirable safe lifespan.

High strength and electrical conductivity of nanostructured Cu–1Cr–0.1Zr alloy processed by multi–stage deformation and aging

The effects of equal channel angular pressing (ECAP), multiple cryogenic rolling and aging treatment on the microstructure, mechanical properties, and electrical conductivity of Cu–1Cr–0.1Zr alloy were investigated. The results showed that multi-stage deformation and aging (ECAP at ambient temperature + primary cryogenic rolling 50 % + 450 °C aging for 1h + secondary cryogenic rolling 80 % + 150 °C aging for 1h) can lead to the rational comprehensive performance of Cu–1Cr–0.1Zr alloy with tensile strength of 730 MPa and electrical conductivity of 75.5 % IACS. The microstructure characterization revealed that in the Cu–1Cr–0.1Zr alloy a subject to the multistage deformation and aging, there ultrafine grains, nanotwins, nanoprecipitates and micrometer precipitates constituted the nanostructured state. The increase in tensile strength was mainly attributed to fine grain strengthening and precipitation strengthening, followed by dislocation strengthening due to low temperature deformation. The ECAP resulted in the refinement of grain, and the increased dislocation density. The following primary cryogenic rolling refined the grains up to ultrafine-grained (UFG) size and created nanotwins. The introduction of nano-precipitated phases by intermediate aging pinned dislocations and impeded the motion of dislocation entanglements, allowing the alloy to achieve higher strength. Multi-stage deformation and aging resulted in a higher density of twin boundaries in the nanostructure and dilute solid solution in comparison with one stage treatment. These microstructural features were responsible for the excellent electrical conductivity.

MOF derived α-Fe2O3/Ti3C2Tx magnetic-dielectric composites for microwave absorption

The design and development of microwave-absorbing materials with excellent performance hold significant importance in both civil and military fields. The combination of magnetic loss materials and dielectric loss materials can achieve complementary performance effects and regulate impedance matching. In this paper, spindle-like α-Fe2O3 was synthesized using MIL-88A as a template, which was then composited with Ti3C2Tx phase possessing excellent electrical conductivity to obtain Fe2O3/Ti3C2Tx composites. Ti3C2Tx can provide good conductance loss and dipole polarization relaxation, while the incorporation of Fe2O3 between the layers of Ti3C2Tx not only triggers the interfacial polarization effect but also increases layer spacing, thereby enhancing multiple reflection effects. Furthermore, the magnetic-dielectric synergies further optimize the impedance matching. Through the combined action of multiple mechanisms, the Fe2O3/Ti3C2Tx composites (with a mass ratio of 1:3 for Fe2O3 and Ti3C2Tx) exhibit a minimum reflection loss of −34 dB and an effective absorption bandwidth of 1.53 GHz at a thickness of 3 mm, as well as an effective absorption bandwidth of 2.805 GHz at a thickness of 1.5 mm. This paper presents a reference strategy for constructing highly efficient microwave absorbers derived from Metal-organic frameworks (MOFs) and MXene based on their outstanding properties.

Electrochemical Properties of LaMO3(M=Cr, Mn, and Co) Perovskite Materials

The utilization of lanthanide perovskite oxides as electrode materials for supercapacitors has garnered significant interest owing to their excellent electrical conductivity, low cost, and excellent thermal stability. In this study, LaMO3(M=Cr, Mn, and Co) nanoparticles were prepared by the sol–gel method coupled with a calcination process. To evaluate the microstructures, morphologies, and electrochemical properties of the samples, a variety of techniques were employed, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area measurements, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) cycling, and electrochemical impedance spectroscopy (EIS). The results revealed that the LaCoO3 electrodes exhibited a maximum specific capacitance of 118.4 F/g at a current density of 1 A/g, attributed to its higher concentration of oxygen vacancy, larger specific surface area, and lower charge transfer resistance. This discovery substantiates the notion that the electrochemical efficacy is enhanced with the diminishing B-site cation radius in the perovskite LaMO3 system. The charge–discharge process was employed to investigate the anion-intercalation mechanism of LaMO3(M=Cr, Mn, and Co).

Molecular Intercalation Enables Phase Transition of MoSe2 for Durable Na-Ion Storage.

1T-MoSe2 is recognized as a promising anode material for sodium-ion batteries, thanks to its excellent electrical conductivity and large interlayer distance. However, its inherent thermodynamic instability often presents unparalleled challenges in phase control and stabilization. Here, a molecular intercalation strategy is developed to synthesize thermally stable 1T-rich MoSe2, covalently bonded to an intercalated carbon layer (1TR/2H-MoSe2@C). Density functional theory calculations uncover that the introduced ethylene glycol molecules not only serve as electron donors, inducing a reorganization of Mo 4d orbitals, but also as sacrificial guest materials that generate a conductive carbon layer. Furthermore, the C─Se/C─O─Mo bonds encourage strong interfacial electronic coupling, and the carbon layer prevents the restacking of MoSe2, regulating the maximum 1T phase to an impressive 80.3%. Consequently, the 1TR/2H-MoSe2@C exhibits an extraordinary rate capacity of 326mAhg-1 at 5Ag-1 and maintains a long-term cycle stability up to 1500 cycles, with a capacity of 365mAhg-1 at 2Ag-1. Additionally, the full cell delivers an appealing energy output of 194Whkg-1 at 208Wkg-1, with a capacity retention of 87.3% over 200 cycles. These findings contribute valuable insights toward the development of innovative transition metal dichalcogenides for next-generation energy storage technologies.

Efficient Structural Regulation Platform for the Controlled Synthesis of LiFePO4 Cathodes with Shorter Li-Ion Diffusion Paths.

The rate performance of lithium iron phosphate (LiFePO4) is mainly limited by its poor electronic conductivity and slow Li-ion diffusion rate. Graphene-based materials are often compounded with LiFePO4 (LFP) to improve their rate performance, mainly because of their excellent electrical conductivity. Unlike most past composite work focusing on the conductive network between LFP and graphene, in this work, we further developed the functionality of graphene-based materials as nanoparticle carriers, where the nitrogen-doping strategy endows graphene with properties that make it an efficient structural regulation platform during the solvothermal process. Compared to reduced graphene oxide, not only does the nitrogen-doped sites confer more nucleation growth sites for LFP on the graphene surface during the solvothermal process, but also the localized formation of an EG-enriched microenvironment helps to further inhibit the in situ growth of LFP along [010]. The efficient structural regulation platform assisted the synthesis of (010)-oriented LFP with a smaller particle size, which further shortens the Li-ion diffusion paths. The optimized LFP composite electrode materials exhibit a discharge-specific capacity of 133.1 mA·h/g at 10C, which exceeds/is comparable to that of previously reported LFP compounded with graphene-based materials. This work broadens the functionality of graphene-based carriers and provides new ideas for the controllable synthesis of nanoparticles.

Fabrication and properties of monolayer graphene reinforced Al2O3/TiN ceramic tool material

AbstractAl2O3/TiN/graphene ceramic tool materials were prepared by spark plasma sintering technology and the strengthening and toughening mechanisms were studied. The influence of monolayer graphene content on the mechanical properties and microstructure of the composite material were analyzed and the strengthening and toughening mechanisms were researched. The results showed that with an addition of .5 vol.% graphene the mechanical properties of the material reached the best. The bending strength, hardness, and fracture toughness were 624 MPa, 23.24 GPa, and 6.53 MPa·m1/2, respectively. Graphene existed in the forms of few‐layer and multilayer. The toughening mechanism of few‐layer graphene was mainly graphene breaking, and that of multilayer graphene included graphene breaking and pulling‐out. Graphene could contribute to the uniform growth of grains due to the excellent electrical conductivity and the high thermal conductivity. The addition of nano‐TiN introduced many endocrystalline structures and graphene promoted this phenomenon. Micro‐TiN grains made the crack extension show a combination of transgranular fracture, intergranular fracture, crack bridging, and crack deflection, while graphene introduced weak grain interfaces and made the crack appear more branches. The layered graphene made the material fracture change from two‐dimension to three‐dimension.

Synthesis of Titanate Nanosheets from Indigenous Indonesian Ilmenite Minerals

Titanate nanosheets are a type of 2-dimensional nanomaterial with vast applications in electronics, energy storage, and photocatalysis due to their superior properties, such as their large specific surface area and excellent electrical conductivity. Titanate nanosheets are expected to be the material precursor of TiO2 nanostructures with further treatment. The current research aims to synthesize titanate nanosheets using the natural mineral ilmenite from Indonesia through the hydrothermal method. X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunaeur-Emmett-Teller (BET) analysis were used to characterize the chemical composition, crystal structure, shape, size, and specific surface area of the prepared samples. The structure phase of the as-synthesized sample is known to be layered titanate. The as-synthesized nanosheet sample has a diameter ranging from 2.5 to 4 μm and BET surface areas of approximately 40 m2/g. This concise hydrothermal method could create 2-dimensional structured nanomaterials from Indonesian local minerals.

Piezo-Acoustic Resistive Switching Behaviors in High-Performance Organic-Inorganic Hybrid Perovskite Memristors.

Memristors are regarded as promising candidates for breaking the problems including high off-chip memory access delays and the hash rate cost of frequent data moving induced by algorithms for data-intensive applications of existing computational systems. Recently, organic-inorganic halide perovskites (OIHPs) have been recognized as exceptionally favorable materials for memristors due to ease of preparation, excellent electrical conductivity, and structural flexibility. However, research on OIHP-based memristors focuses on modulating resistive switching (RS) performance through electric fields, resulting in difficulties in moving away from complex external circuits and wire connections. Here, a multilayer memristor has been constructed with eutectic gallium and indium (EGaIn)/ MAPbI3 /poly(3,4-ethylenedioxythiophene): poly(4-styrenesulphonate) (PEDOT: PSS)/indium tin oxide (ITO) structure, which exhibits reproducible and reliable bipolar RS with low SET/RESET voltages, stable endurance, ultrahigh average ON/OFF ratio, and excellent retention. Importantly, based on ion migration activated by sound-driven piezoelectric effects, the device exhibits a stable acoustic response with an average ON/OFF ratio greater than 103 , thus realizing non-contact, multi-signal, and far-field control in RS modulation. This study provides a single-structure multifunctional memristor as an integrated architecture for sensing, data storage, and computing.

Enhancing the thermoelectric properties of bismuth antimony tellurides containing excess Te with respect to sintering temperature

Bi–Te-based thermoelectric materials with excellent room-temperature properties are difficult to commercialise because of their low dimensionless figure of merit ( ZT). In this study, a powder was synthesised by adding an excess amount of Te to improve its thermoelectric performance at room temperature. The synthesised powder was sintered using spark plasma sintering at various temperatures to examine the effect of temperature-dependent behaviour of Te on the electrical resistivity and Seebeck coefficient. The excess Te-containing powder exhibited excellent electrical conductivity and Seebeck coefficient at high temperatures, and the thermal conductivity was significantly reduced. Bi0.4Sb1.6Te3+ x ( x = 2) showed a maximum room-temperature ZT of 1.57 at a sintering temperature of 450°C.

Mechanochemical production of graphene/amorphous carbon/Mn3O4 nanocomposites for asymmetric supercapacitor

The practical application of graphene/manganese oxide nanocomposites in energy storage presents a significant challenge due to their environmentally unfriendly and complex synthesis, as well as weak interface interactions. Herein, a sustainable and scalable ball milling-thermal annealing method is proposed to produce a graphene/amorphous carbon/Mn3O4 (GACMO) nanocomposite. A triblock copolymer is employed as an intercalator to facilitate the formation of few-layer graphene during ball-milling, a precursor for amorphous carbon to encapsulate Mn3O4 upon thermal-annealing, and thus an intermediate layer to enhance the interface interaction between graphene and Mn3O4. Benefiting from its 3D porous structure and exceptional interface design, GACMO exhibits a large specific surface area, excellent electrical conductivity, enhanced structural stability. Consequently, the GACMO electrode presents a high capacitance of 219 F g−1 at 0.5 A g−1 with a 91.4 % retention at 10 A g−1 after 5000 cycles. Furthermore, the GACMO-based asymmetric supercapacitor shows a high capacitance of 138 F g−1 at 0.5 A g−1, superior energy/power density (62.1 W h kg−1 at 0.45 kW kg−1, 0.6 mW h cm−3 at 9.3 mW cm−3), and promising cycling stability (88.3 % retention after 10,000 cycles). This study brings new insights into the fabrication of graphene/metal oxide-based energy materials.

Development process and future trends of chemical refining agents' influence on grain refinement in aluminum alloys

Aluminum is the world's largest production of non-ferrous metals, with light weight, high specific strength, excellent electrical and thermal conductivity and other characteristics. With the continuous development of aerospace, precision electronic instruments, photovoltaic semiconductors and other emerging strategic industries, the demand for high-performance materials of aluminum alloys has become increasingly strong. This paper reviews the research progress of aluminum alloy melt refinement treatment, summarizes the development history of grain refinement, and evaluates the advantages and disadvantages of various types of refining agents, such as Al–Ti–B, Al–Ti–C, Al–Ti–B/C–Re, etc. The article points out the shortcomings of the current research on the melt refinement treatment of aluminum alloys, and looks forward to the future research direction.