Conductivity Performance Research Articles

Thermal performance optimization for a tapered heat sink of bus bar conductor using definitive screening design

This study examines and optimizes four design parameters of a bus duct conductor's heat sink: fin pitch, fin height, fin thickness, and the number of fin valleys. Average surface temperature and Nusselt number are chosen as the thermal performance criterion of the heat sink. A Definitive Screening Design is employed as a statistical method to reduce the number of optimization runs required while minimizing the aliasing. The regression analysis, analysis of variance, main effect analysis and optimization are conducted to optimize the heat sink design parameter and its thermal performance. The current results provide an ideal heat sink design for the casing of bus duct conductors. A fin pitch of 4 mm, fin height of 6.5 mm, fin thickness of 1 mm, and six fin valleys are determined to be the most optimal combination of design parameters. The optimized responses' average surface temperature and Nusselt numbers are 72.05 °C and 21.59, respectively, with 2.97 % and 6.25 % deviation from the predicted values of the empirical equation. The experimental results are benchmarked against the IEC 60439-1 and IEC 60439-2 standards. The current analysis is expected to provide more insight into the impact of design factors on the thermal performance of a bus duct conductor.

The effect of lattice incorporation of Cu2+ in BaCe0.6Zr0.2-xY0.15Gd0.05CuxO3-δ proton conductor on its transport properties

In this paper, the introduction of Cu2+ into BaCe0.6Zr0.2-xY0.15Gd0.05CuxO3-δ (x = 0, 0.02, 0.04, 0.06; denoted as BCZYG, BCZYGCu0.02, BCZYGCu0.04 and BCZYGCu0.06, respectively)proton conductor materials. The effects of Cu doping strategy on the crystal structure, morphology and electrical properties of BCZYGCux proton conductor materials were systematically studied. The X-ray diffraction (XRD) results demonstrate that the synthesis of the BCZYGCux proton conductor material were successfully achieved through the solid-state reaction method. The scanning electron microscopy (SEM) analysis and relative density results indicate that an appropriate amount of Cu additions was conducive to lowering the sintering temperature and promoting the density of materials. A comprehensive analysis based on EIS and DRT was conducted to investigate the effects of temperature, testing atmosphere, and doping amount on the influence of conductivity on BCZYGCux proton conductor material. BCZYGCu0.02 has the largest total conductivity of 1.11×10-2 S·cm-1 at 700 ºC in the atmospheres of pO2=0.20 atm and pH2O=0.018 atm. The transference number of the BCZYGCux proton conductor material was calculated using a defect equilibrium model. The proton transference number of BCZYGCu0.02 is 0.97 at 500 °C. The BCZYGCu0.02 proton conductor has higher proton concentration and proton transference number in comparison to BCZYG. In conclusion, the Cu doping strategy has been demonstrated to be an effective method of improving the conductivity and proton transference number of BCZYGCux proton conductor materials. This provides a valuable insight into the optimisation of perovskite proton conductor performance.

Local plastic deformation effects on the critical current of high-Jc Nb3Sn strands under uniaxial strain

Abstract In order to meet the target operating parameters of the toroidal field coils (TFC) for the next-generation Chinese compact burning plasma tokamak, high critical current density (Jc) Nb3Sn strand will be applied to the high-field winding-package (WP) of the TFC. To improve the transverse stiffness of the cable in withstanding the huge Lorentz force and avoiding conductor performance degradation, the Short-Twist-Pitch (STP) and Copper-Wound-Strand (CWS) cable patterns were taken into consideration. In the processes of cabling and compaction of the conductor, the tight cable configurations lead to severe local plastic deformation (LPD) within the strands. The strands in the conductor are subjected to strain caused by thermal contraction and Lorentz force during conductor cooling down and operation. So far it is unknown, whether the LPD could impact the critical current (Ic) versus uniaxial applied strain behaviour of high-Jc Nb3Sn strand. Aiming to investigate the effect of LPD on the Ic of strands under uniaxial strain, three types of high Jc Nb3Sn strand with different indentation depths were tested on a U-shaped bending spring. The axial strain ranges from -0.9% to +0.4% at 14 T and 4.2 K. The three types of strands showed more strain sensitivity and lower tensile irreversible strain limit with increasing LPD, while even irreversible degradation of the Ic could be observed in the compressive strain region. The sample preparation, test process, test results and analysis are reported.

Mechanical and anti-icing performance of superhydrophobic aluminum conductor by anodized oxide technique

Abstract Anodized oxide technology is a traditional surface treatment method used in the material engineering field to enhance the friction, anti-icing, anti-corrosion, and insulation properties of Al-based samples. Considering the anti-icing and insulation performance, anodized oxide technology has great application prospects in overhead transmission lines. In this study, the preparation process of Aluminum (Al) flat plates and Aluminum Cable Steel-Reinforce (ACSR) was explored by using anodizing technology to obtain superhydrophobic properties. Moreover, as the significant performance in the application of transmission lines, the mechanical performance (tensile strength) of Al conductors was evaluated to study the impact of anodized oxidation technology. The results show that anodized oxide technology can improve the tensile strength of aluminum clad steel bars and aluminum-stranded wires in ACSRs. In addition, the hydrophobicity and anti-icing performance of anodized wires can demonstrate potential application prospects in the field of anti-icing.

Exploring the Elastomer Influence on the Electromechanical Performance of Stretchable Conductors.

Stretchable electronics has received major attention in recent years due to the prospects of integrating electronics onto and into the human body. While many studies investigate how different conductive fillers perform in stretchable composites, the effect of different elastomers on composite performance, and the related fundamental understanding of what is causing the performance differences, is poorly understood. Here, we perform a systematic investigation of the elastomer influence on the electromechanical performance of gold nanowire-based stretchable conductors based on five chemically different elastomers of similar Young's modulus. The choice of elastomer has a huge impact on the electromechanical performance of the conductors under cyclic strain, as some composites perform well, while others fail rapidly at 100% strain cycling. The lack of macroscopic crack formation in the failing composites indicates that the key aspect for good electromechanical performance is not homogeneous films on the macroscale but rather beneficial interactions on the nanoscale. Based on the comprehensive characterization, we propose a failure mechanism related to the mechanical properties of the elastomers. By improving our understanding of elastomer influence on the mechanisms of electrical failure, we can move toward rational material design, which could greatly benefit the field of stretchable electronics.

Effect of sintering temperature on microstructure and electrical properties of Na0.5Bi0.47Sr0.02TiO3-δ ceramics

In this investigation, a series of Na0.5Bi0.47Sr0.02TiO3-δ samples, sintered from 1000 to 1100 °C, were synthesized utilizing the solid-state method. The XRD results indicate that all samples exhibit a perovskite phase, with the exception of those sintered at 1100 °C, which display no discernible impurity peaks. The SEM results indicate that the average grain size exhibits an increase proportionate to the sintering temperature, which attributes to the variations in the actual Na/Bi ratio. From the study of grain conductivity we can obtain that the dominant factor affecting grain conductivity is the activation energy. At 1100 °C, the oxygen vacancy concentration emerges as the primary determinant of grain conductivity. It should be noticed that the phase transition temperature of the sample increases (350 °C→400 °C) with the increase of sintering temperature, which is due to the local A-site disorder aggravated by high temperature sintering. Therefore, reducing the sintering temperature is beneficial to improve the grain conductivity. The grain boundary conductivity initially rises, then diminishes with increasing sintering temperature. It is evident that the enhanced macroscopic grain boundary conductivity stems from a marked reduction in space charge potential within the 1000–1025 °C temperature range. Within the 1050 °C−1100 °C temperature range, the space charge potential barely changed, the significant decrease of intrinsic grain boundary conductivity can be attributed to the surge in the coverage ratio of grain boundary impurities and the number of grain boundary impurities increased caused by the rapid reduction of grain boundary area and thermal evaporation. The research on electrical performance of NBT-based oxygen-ion conductors will promote the application of NBT-based oxygen ion conductors in solid oxide fuel cells, oxygen sensors and other fields.

Efficient ionic transport over wide temperature range in oxide enabled by interfacial reaction of molten carbonate

The development of solid oxide fuel cell (SOFC) operated at low and intermediate temperatures is limited by the poor performance of inorganic ionic conductors. Oxide-based ion conductors have attracted much attention due to their excellent stability and tunable ion conduction behavior. In this study, we propose a new approach for the construction of regulated ionic transport pathways in a composite oxide ionic conductor made of WO3/ZrO2 (WZ) and (Li0.68K0.32)2CO3. The interfacial reaction between WO3/ZrO2 and (Li0.68K0.32)2CO3 is used to enhance the interaction between the oxide and carbonate interfaces and introduce hydrophilic phases for water retention, thus achieving ultra-high ionic conductivity of the oxide/carbonate composites at low and intermediate temperatures. The optimal ionic conductor, 13WZ-30(Li0.68K0.32)2CO3 (13WZ-30C), has a superior ionic conductivity of 25.8-6.28 mS cm−1 from room temperature to 250 °C. The ion conduction mechanism of the composite is investigated. This study emphasizes the significance of interfacial chemistry regulation between oxides and carbonates for achieving superior ion conduction performance.

Enhanced Durability and Antireflective Performance of Ag-Based Transparent Conductors Achieved via Controlled N-Doping.

Ag-based transparent conductors (TCs) are often proposed as an alternative to ITO coatings. However, while their performance has been widely demonstrated, their environmental durability is frequently overlooked or addressed with the use of highly specific encapsulating layers. In this work, the durability and antireflective performance of Ag-based TCs are simultaneously enhanced. To do so, a transfer matrix modeling approach is used to determine the general requirements for high performance antireflective properties as a function of Ag thickness and dielectric refractive indices, offering more widely applicable insight into stack optimization. Coating durability is investigated as a function of the Ag microstructure, which is modified by altering the N2 concentration used for doping of the Ag layer and the selection of the seed layer. Increasing N2 concentration during Ag deposition was found to decrease grain size and durability of Ag coatings deposited on Si3N4 whereas all coatings on ZnO(Al) showed higher stability. Significantly higher durability is found when specifically combining intermediate N2 concentrations in the sputtering gas mixture (Ag(N):5%, compared to 0% and 50%) and a ZnO(Al) seed layer, and a mechanism accounting for this increased durability is proposed. The addition of NiCrNx protective coatings increases the system durability without altering these trends. These findings are combined to fabricate a highly performant Ag-based TC (TV = 89.2%, RVFS = 0.23%, 21.4 Ω), which shows minimal property changes following corrosion testing by immersion in a heated and highly concentrated aqueous NaCl solution (200 g/L, 50 °C).

Facile Fabrication of Transparent Conductor of Cu Nanowire-PEDOT:PSS

Facile Fabrication of Transparent Conductor of Cu Nanowire-PEDOT:PSS

Double gyroid-structured electrolyte based on an azobenzene-containing monomer and its polymer.

The self-assembled structure has a significant impact on the performance of ion conductors. We prepared a new type of electrolyte with self-assembled structures from an azobenzene-based liquid crystalline (LC) monomer and its corresponding polymer. By doping different amounts of monomers and lithium salt LiTFSI, the self-assembled nanostructure of the electrolyte was changed from lamellae to double gyroid. The ionic conductivity of the azobenzene-based electrolytes with the double gyroid structure was 1.64 × 10-4 S cm-1, higher than most PEO-based polymer electrolytes. The azobenzene-based system provides a new strategy to design solid electrolytes with self-assembled structures that may be potentially used in solid-state lithium-ion batteries.

Thermoelectric performance of organic conductors

Organic conductor Cu(DMDCNQI)2 exhibits a very large thermoelectric power factor at low temperatures.

Design of Quench Detection System for Background DC Magnet in the Conductor Performance Research Platform of CRAFT

Design of Quench Detection System for Background DC Magnet in the Conductor Performance Research Platform of CRAFT

Metallographic investigation of first full-size high-Jc Nb3Sn cable-in-conduit conductor after cyclic loading tests

In order to verify the feasibility of applying high-Jc Nb3Sn strand in fusion magnet, a full-size cable-in-conduit conductor (CICC) with short twist pitch (STP) cable pattern was manufactured and tested in SULTAN facility at SPC, Switzerland. Three levels of cyclic electromagnetic (EM) load were applied on the sample stepwise, no visible decrease of current sharing temperature (Tcs) was observed until the EM load increased to 80 kA × 10.8 T, after that the Tcs decreased dramatically with the EM cycles, which suggested that irreversible deformation, causing a change in the strain state, or even damage has occurred in the superconducting strands. For investigating the reason which caused the conductor performance degradation, the tested conductor was dissected for metallographic observation. Eight segments which subjected to different EM loads were extracted from one of the legs, the geometric feature changes of the cable cross-sections were analyzed and compared. A good correlation was found between the decrease of the Tcs and deformation of the cable cross section. A mass of cracks were found on the sub-elements of strands in the segment which subjected to highest EM load, but the amount of crack is much lower in other segments. Combining the analyses, it is speculated that the critical EM load which causes irreversible degradation is between 850 kN/m and 870 kN/m for this conductor. The results could be a reference in high-Jc Nb3Sn CICC design.

Elucidating Phase Transformation and Surface Amorphization of Li7 La3 Zr2 O12 by In Situ Heating TEM.

Garnet-type Li7 La3 Zr2 O12 (LLZO) solid-state electrolytes hold great promise for the next-generation all-solid-state batteries. An in-depth understanding of the phase transformation during synthetic processes is required for better control of the crystallinity and improvement of the ionic conductivity of LLZO. Herein, the phase transformation pathways and the associated surface amorphization are comparatively investigated during the sol-gel and solid-state syntheses of LLZO using in situ heating transmission electron microscopy (TEM). The combined ex situ X-ray diffraction and in situ TEM techniques are used to reveal two distinct phase transformation pathways (precursors→La2 Zr2 O7 →LLZO and precursors→LLZO) and the subsequent layer-by-layer crystal growth of LLZO on the atomic scale. It is also demonstrated that the surface amorphization surrounding the LLZO crystals is sensitive to the postsynthesis cooling rate and significantly affects the ionic conductivity of pelletized LLZO. This work brings up a critical but often overlooked issue that may greatly exacerbate the Li-ion conductivity by undesired synthetic conditions, which can be leveraged to ameliorate the overall crystallinity to improve the electrochemical performance of LLZO. These findings also shed light on the significance of optimizing surface structure to ensure superior performance of Li-ion conductors.

Influence of Timbral Sound Coloring on the Evolution of the Conductor's Gesture

An overview of the professional aspects of conducting as a process of managing a performing team was carried out. The main directions of the development of the conductor's performance skills from the noisy type to the silent type are revealed. The dynamics of changes in the forms and methods of conducting have been traced while preserving the priority of gesturing as the main type of influence on the collective during the performance of a musical piece. It was found that the conductor controls not only the logic of the development of the musical material, but implements it by using a specific complex of real physical movements (gestures) organized in time. The essence of the conductor's orchestral thinking is analyzed, which is a synthesis of his logical and procedural thinking, which ensures the development of the timbre dramaturgy of the musical work. The dependence of the timbral coloring of sound on the involvement of various types of orchestral instruments in the reproduction of musical material is substantiated. It has been established that orchestration is the basis of the conductor's timbral thinking. Composers are divided (conditionally) into two main types of timbral thinking, where the first includes those for whom orchestration is a means of expressing musical thought (L. Beethoven, R. Wagner, P. Tchaikovsky, D. Shostakovich, and others), and the second includes those for whom orchestration is a means of expressing sophisticated imagery by creating an orchestral color and multi-colored sound (H. Berlioz, M. Rimskyi Korsakov, K. Debussy and others). It has been proven that: timbral coloring and the conductor's manual technique have a reciprocal relationship; The elements of the conductor's gesture reflect not only the metro-rhythmic structure, stroke realization, dynamic shades, emotional and figurative content of the musical work, but also reflect the quality of the new timbre, its modification and development; the timbre auditory imagination of the conductor develops in classes on orchestration (instrumentation) and in the process of conducting directly with the orchestra; the conductor's gesture, which is not supported by timbral feeling, leads to a formal gesticulation that does not reflect the emotional and figurative content of the musical work.

Electrochemical properties and performance of a flexible polysiloxane-based ionic conductor as a binder for LiFePO4 cathode

Poly(methyl(2-(tris(2-H methoxyethoxy)silyl)ethyl)siloxane)) modified with Si-tripodant centers (2550EO) and integrated amide salt (LiF(SO2CF3)2 (LiTFSI)) has been used as a binding agent in the lithium-ion batteries containing LiFePO4 (LFP). The performance of the cathode produced using 2550EO/LiTFSI was evaluated using X-ray diffraction, scanning electron microscope, and electrochemical measurements. The electrochemical performance of the LFP cathode using 2550EO/LiTFSI was compared to alternative binders, such as Polyvinylidene fluoride (PVDF), Polyethylene oxide (PEO), and 2550EO, at 25 °C and 60 °C, respectively. By using 2550EO/LiTFSI as a binder in LFP/Li battery preparation, the rate capability and cycle stability of the LFP cathode is significantly enhanced. The enhanced performance is attributed to the formation of a thin, solid-electrolyte interface (SEI) on the electrodes, the uniform dispersion of active and conductive materials throughout the electrode, and the adhesion capability of 2550EO#LiTFSI/LFP to the Al current collector, which increases the electronic conductivity of the LFP cathode.

Inception Characteristics of Surge Corona on Line Conductors

Knowledge on the characteristics of surge corona on overhead line conductors is of great importance for studies on attenuation and distortion of lightning overvoltage surges. Impulse corona may initiate and grow in various discharge modes, namely glow, intermittent or stable streamer corona. Its inception characteristics can be described by statistical distributions, with parameters dependent on the steepness of the electric field strength around the conductor and on the atmospheric conditions. Agreement between theory and experiment on impulse corona inception characteristics is achieved based on the critical volume theory. The impulse corona performance of line conductors may differ between laboratory and outdoor testing, due to differences in the background density of negative ions. An empirical procedure yielding probability distributions for the inception characteristics of surge corona on overhead line conductors is introduced.

Anti-Icing Mechanism for a Novel Slippery Aluminum Stranded Conductor.

The icing of transmission conductor seriously threatens the safe operation of power grids. Slippery lubricant-infused porous surface (SLIPS) has shown great potential for anti-icing applications. However, aluminum stranded conductors have complex surfaces, and the current SLIPSs are almost prepared and studied on small flat plates. Herein, the construction of SLIPS on the conductor was realized through anodic oxidation and the anti-icing mechanism of the slippery conductor was studied. Compared to the untreated conductor, the SLIPS-conductor reduces the icing weight by 77% in the glaze icing test and shows very low ice-adhesion strength (7.0 kPa). The excellent anti-icing performance of the slippery conductor is attributed to the droplet impact dynamics, icing delay, and lubricant stability. The dynamic behavior of water droplets is most affected by the complex shape of the conductor surface. Specifically, the impact of the droplet on the conductor surface is asymmetric and the droplet can slide along the depression in low-temperature and high-humidity environments. The stable lubricant of SLIPS increases both the nucleation energy barriers and the heat transfer resistance, which greatly delays the freezing time of droplets. Besides, the nanoporous substrate, the compatibility of the substrate with the lubricant, and the lubricant characteristics contribute to the lubricant stability. This work provides theoretical and experimental guidance on anti-icing strategies for transmission lines.

The Influence of Regiochemistry on the Performance of Organic Mixed Ionic and Electronic Conductors.

Thiophenes functionalised in the 3-position are ubiquitous building blocks for the design and synthesis of organic semiconductors. Their non-centrosymmetric nature has long been used as a powerful synthetic design tool exemplified by the vastly different properties of regiorandom and regioregular poly(3-hexylthiophene) owing to the repulsive head-to-head interactions between neighbouring side chains in the regiorandom polymer. The renewed interest in highly electron-rich 3-alkoxythiophene based polymers for bioelectronic applications opens up new considerations around the regiochemistry of these systems as both the head-to-tail and head-to-head couplings adopt near-planar conformations due to attractive intramolecular S-O interactions. To understand how this increased flexibility in the molecular design can be used advantageously, we explore in detail the geometrical and electronic effects that influence the optical, electrochemical, structural, and electrical properties of a series of six polythiophene derivatives with varying regiochemistry and comonomer composition. We show how the interplay between conformational disorder, backbone coplanarity and polaron distribution affects the mixed ionic-electronic conduction. Ultimately, we use these findings to identify a new conformationally restricted polythiophene derivative for p-type accumulation-mode organic electrochemical transistor applications with performance on par with state-of-the-art mixed conductors evidenced by a μC* product of 267 F V-1 cm-1 s-1 .

The Influence of Regiochemistry on the Performance of Organic Mixed Ionic and Electronic Conductors.

Thiophenes functionalised in the 3-position are ubiquitous building blocks for the design and synthesis of organic semiconductors. Their non-centrosymmetric nature has long been used as a powerful synthetic design tool exemplified by the vastly different properties of regiorandom and regioregular poly(3-hexylthiophene) owing to the repulsive head-to-head interactions between neighbouring side chains in the regiorandom polymer. The renewed interest in highly electron-rich 3-alkoxythiophene based polymers for bioelectronic applications opens up new considerations around the regiochemistry of these systems as both the head-to-tail and head-to-head couplings adopt near-planar conformations due to attractive intramolecular S-O interactions. To understand how this increased flexibility in the molecular design can be used advantageously, we explore in detail the geometrical and electronic effects that influence the optical, electrochemical, structural, and electrical properties of a series of six polythiophene derivatives with varying regiochemistry and comonomer composition. We show how the interplay between conformational disorder, backbone coplanarity and polaron distribution affects the mixed ionic-electronic conduction. Ultimately, we use these findings to identify a new conformationally restricted polythiophene derivative for p-type accumulation-mode organic electrochemical transistor applications with performance on par with state-of-the-art mixed conductors evidenced by a μC* product of 267 F V-1 cm-1 s-1.