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Strain engineering is an important way to control the physical properties of manganite thin films. Here, the effect of strain mode on the transverse thermoelectric (TTE) effect of inclined La1xCaxMnO3 (LCMO) thin films is investigated. The compressive strain enhances the electrical conductivity of the LCMO thin film, resulting in larger laser-induced voltage and faster response speed, which is suitable for high-energy pulse laser detection. Compared to that, the LCMO thin film on the STO substrate is ideal for heat-flux detection due to higher heat-flux sensitivity originating from lower conductivity. Still, it also has to withstand the loss of response speed. Moreover, it is first observed that the TTE voltage polarity of the LCMO thin film changes under different strain states. The measured results of LCMO thin films deposited LaAlO3 (LAO) substrate buffered with the SrTiO3 (STO) thin film and STO substrate buffered with the LAO thin film strongly support that the above results are indeed caused by the lattice strain. This work may be suitable for other material systems to modulate thermoelectric transport anisotropy and the TTE effect by strain. [ABSTRACT FROM AUTHOR]

We present a theoretical investigation of thermoelectric transport properties of bismuth-based ternary chalcogenides Pt3Bi4X9 (X = S, Se), which has low thermal conductivity and promising zT as discovered in a recent experiment [Wang et al., J. Am. Chem. Soc. 146, 7352 (2024)], using density functional theory combined with the Boltzmann transport equation within rigid band approximation. We find that the high density of states of valence bands near the Fermi level yields high p-type Seebeck coefficient. The lower effective mass of electron in Pt3Bi4S9 leads to high mobility and long relaxation time, and hence the high n-type electrical conductivity. In contrast, the effective mass of electron is much higher than that of hole in Pt3Bi4Se9 due to the flatted conduction band, which in turn gives rise to higher p-type electrical conductivity. As a result, the p-type zT is much higher than n-type in Pt3Bi4Se9, with an optimal value of 0.5 at 300 K. Considering the experimental carrier concentration for Pt3Bi4S9 (−1.4 × 1019 cm−3) and Pt3Bi4Se9 (−0.898 × 1019 cm−3), calculated n-type zT at 773 K are 0.52 and 0.04, respectively, which are consistent well with the experimental values. Our calculations uncover the upper limit thermoelectric zT of Pt3Bi4X9 and also highlight them as promising thermoelectric materials. [ABSTRACT FROM AUTHOR]

This paper presents a mean field theory of electrolyte solutions, extending the classical Debye–Hückel–Onsager theory to provide a detailed description of the electrical conductivity in strong electrolyte solutions. The theory systematically incorporates the effects of ion specificity, such as steric interactions, hydration of ions, and their spatial charge distributions, into the mean-field framework. This allows for the calculation of ion mobility and electrical conductivity, while accounting for relaxation and hydrodynamic phenomena. At low concentrations, the model reproduces the well-known Kohlrausch's limiting law. Using the exponential (Slater-type) charge distribution function for solvated ions, we demonstrate that experimental data on the electrical conductivity of aqueous 1:1, 2:1, and 3:1 electrolyte solutions can be approximated over a broad concentration range by adjusting a single free parameter representing the spatial scale of the nonlocal ion charge distribution. Using the fitted value of this parameter at 298.15 K, we obtain good agreement with the available experimental data when calculating electrical conductivity across different temperatures. We also analyze the effects of temperature and electrolyte concentration on the relaxation and electrophoretic contributions to total electrical conductivity, explaining the underlying physical mechanisms responsible for the observed behavior. [ABSTRACT FROM AUTHOR]

Graph neural networks (GNNs) have evolved many variants for predicting the properties of crystal materials. While most networks within this family focus on improving model structures, the significance of atomistic features has not received adequate attention. In this study, we constructed an atomistic line GNN model using compositionally restricted atomistic representations which are more elaborate set of descriptors compared to previous GNN models, and employing unit graph representations that account for all symmetries. The developed model, named as CraLiGNN, outperforms previous representative GNN models in predicting the Seebeck coefficient, electrical conductivity, and electronic thermal conductivity that are recorded in a widely used thermoelectric properties database, confirming the importance of atomistic representations. The CraLiGNN model allows optional inclusion of additional features. The supplement of bandgap significantly enhances the model performance, for example, more than 35% reduction of mean absolute error in the case of 600 K and 10 19 cm − 3 concentration. We applied CraLiGNN to predict the unrecorded thermoelectric transport properties of 14 half-Heusler and 52 perovskite compounds, and compared the results with first-principles calculations, showing that the model has extrapolation ability to identify the thermoelectric potential of materials. [ABSTRACT FROM AUTHOR]

Thermoelectric materials are best known for their prowess to transform the environment's waste heat into electricity. In an endeavor to explore new thermoelectric prospects, in the present study, we investigate K 2 AuBi using density functional theory-based first-principles simulations. From our simulations, we find an intrinsically low lattice thermal conductivity of 0.43 W m − 1 K − 1 at 300 K in K 2 AuBi. Based on our detailed analysis, we find the reasons for such a low value of lattice thermal conductivity as, low phonon group velocities, short phonon lifetimes, anharmonicity in the lattice vibrations, and significant mean square displacements of K and Au atoms. The large mean square displacements hint at weak bonding and anharmonicity in the lattice vibrations, favoring more phonons scattering. We also find that the vibrations of K-atoms can be related to rattlers, conducive to low lattice thermal conductivity. Our simulations predict a high value, ∼ 784 μ V K − 1 , of Seebeck coefficient at 700 K on account of the large density of states in the vicinity of Fermi level. Combining our computed lattice thermal conductivity with electrical transport properties, we obtain a high figure of merit, Z T ∼ 1.04, at 700 K in K 2 AuBi. [ABSTRACT FROM AUTHOR]

Fluorographene, a fluorinated graphene-derivative, is expected to feature both high thermal conductivity and electrical insulation simultaneously, making it an emerging material for thermal management in electronic devices. In this paper, we investigated the lattice thermal conductivity and phonon transport properties of monolayer fluorographene using first-principles calculation. The solution of the fully linearized phonon Boltzmann transport equation gives the lattice thermal conductivity of monolayer fluorographene as 145.2 W m−1 K−1 at 300 K, which is about 20 times smaller than that of monolayer graphene. We systematically compared the phonon transport properties of all phonon modes in graphene and fluorographene in terms of phonon polarization. The significantly reduced thermal conductivity of fluorographene can be attributed to the lowering of both the lifetime of the flexural acoustic phonons and the group velocities of all acoustic phonons. We concluded that the broken in-plane mirror symmetry and the weaker in-plane chemical bonds induced by fluorination led to the suppression of the lattice thermal conductivity of fluorographene. Finally, we investigated the anomalously large contribution of optical phonons to the thermal transport process in fluorographene, where the large group velocities of selected optical phonons were derived from the in-plane acoustic modes of graphene. Our work provides a new approach to studying the influence of chemical functionalization on the phonon structure and exploring graphene-derived thermal management materials. [ABSTRACT FROM AUTHOR]

The (electro)chemical stability of undoped and Zn-doped 0.94Na1/2Bi1/2TiO3–0.06BaTiO3 lead-free piezoceramics (NBT–6BT) was studied. For this purpose, the Fermi level at the interface between NBT–6BT and Sn-doped In2O3 (ITO) electrode is varied by gradually reducing the ITO film either by annealing in vacuum or by applying a voltage across a Pt/NBT–6BT/ITO. The chemical and electronic changes are monitored in situ by x-ray photoelectron spectroscopy. The experiments reveal the formation of metallic Bi when the Fermi level is reaching a value of 2.23 ± 0.10 eV above the valence band maximum, while no reduction of Ti is observed. The electrochemical reduction of Bi constitutes an upper limit of the Fermi level at ≈1 eV below the conduction band minimum. High electron concentrations in the conduction band and a contribution of free electrons to the electrical conductivity of NBT–6BT can, therefore, be excluded. The reduction occurs for an ITO work function of 4.2–4.3 eV. As typical electrode materials such as Ag, Cu, Ni, or Pt have higher work functions, an electrochemical instability of the electrode interfaces in ceramic capacitors is not expected. Under the given experimental conditions (350 °C, electric fields <40 V/mm), no degradation of resistance and no enrichment of Na at the interface are observed. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) reduced graphene oxide (rGO)/Ti2CTx MXene hybrid aerogels were effectively prepared by a two-step method involving hydrothermal reaction and freeze-drying. The intimately coupled rGO/Ti2CTx hybrid aerogel combined high electrical conductivity, large interlayer spacing, and excellent mechanical stability of Ti2CTx, which not only effectively prevents the self-restacking of Ti2CTx nanosheets, exposes more active sites exposed, and improves the volume change during the charge/discharge process but also increases the accessibility of ions and promotes the rapid transfer of ions/electrons. As a result, rGO/Ti2CTx 17.5–2.5 as the working electrode of electric double layer capacitors delivers a large specific capacity (107.05 F g−1 at 0.5 A g−1 in a 1M Na2SO4 electrolyte), a high rate capability (maintains 30% of its initial capacitance at 10 A g−1, which is much better than rGO and Ti2CTx), and excellent long-term large-current cycle stability (the initial capacitance remains above 71.1% after 10 000 cycles at 1 A g−1). In addition to providing a high-performance electrode for supercapacitors, this study proposes an efficient and time-saving strategy for constructing 3D structures from 2D materials. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have received significant attention in various fields due to their remarkable ability to undergo phase transitions and induce substantial changes in their physical properties. One such material, vanadium dioxide (VO2), has emerged as a prominent PCM that exhibits a reversible metal–insulator transition near room temperature. These transitions are accompanied by rapid modifications in electrical conductivity and surface properties. Efforts have been made recently to enhance the performance and expand the utility of VO2 by combining it with other materials and structures. One effective approach is the use of plasmonic hybridization with vanadium dioxide (VO2), which enhances the optical and functional properties of VO2-based materials. This study offers a comprehensive review of previous research, with a specific focus on investigating the plasmonic hybridization in VO2@Au nanoshells. To analyze the plasmonic modes in this innovative core–shell structure, a combined theoretical and simulation-based approach is employed. The investigation encompasses both the semiconductor and metallic phases of the VO2 core, revealing the presence of sphere and cavity plasmonic modes. Remarkably, the results highlight that the cavity frequency becomes the dominant mode beyond wavelengths of 778 nm, particularly in the metallic phase. Furthermore, this study presents valuable insights into the charge distribution resulting from symmetric and asymmetric plasmon oscillations at specific wavelengths, particularly in the optimized scenario of the VO2@Au nanoshell. [ABSTRACT FROM AUTHOR]

2D Janus Rashba semiconductors, which break both the mirror symmetry in the crystal structure and the spin degeneracy in the energy band, provide a promising platform to optimize thermoelectric performance. Herein, we use first-principles and Boltzmann transport theory to investigate the electron and phonon transport properties for Janus semiconductors of monolayer Si2AsSb and Si2SbBi. The strong Rashba spin-splitting is found in both Janus monolayers especially for Si2SbBi, which decreases the bandgaps and makes the valence bands more dispersive, resulting in decreased p-type Seebeck coefficient and increased p-type electrical conductivity. The lattice thermal conductivities of both monolayers are not low due to the weak phonon anharmonicity, strong chemical bonding, and long phonon relaxation time. The low lattice thermal conductivity of Si2SbBi than Si2AsSb mainly originates from the low phonon group velocity. Both monolayers exhibit better thermoelectric performance in n-type than in p-type. The competition among Seebeck coefficient, electrical conductivity, and electronic thermal conductivity makes the difference of optimal thermoelectric figure of merits in n-type without and with Rashba spin–orbit coupling slight for Si2AsSb, but it is significant for Si2SbBi. Within Rashba spin–orbit coupling, the optimal figure of merits at 700 K reach 0.65 and 0.59 for Si2AsSb and Si2SbBi, respectively, which indicate the potential thermoelectric applications, and will stimulate the broad study on thermoelectric properties of 2D Janus Rashba semiconductors. [ABSTRACT FROM AUTHOR]

Pulsed secondary electron multipacting (SEM) cathodes with channel-type structures have been developed. The electron emission performance of these cathodes was investigated using theoretical and particle-in-cell simulation methods. The results revealed that the electrical conductivity of the channel wall material is crucial to the performance of the cathodes. Materials with low conductivity cause the SEM process in the multipacting channel to stop quickly due to the positive charges deposited on the channel wall. These positive space charges, generated by the SEM process, create a space-charge field that reduces the impact energy of electrons on the channel wall, thereby decreasing the secondary electron emission yield. Consequently, materials with high electrical conductivity and high secondary electron emission yield, such as SnO 2 , are advantageous for the SEM process, leading to stable current output from the cathodes with high current density. For a SnO 2 cathode with three multipacting channels, an output current density of 242 A/cm 2 was achieved. [ABSTRACT FROM AUTHOR]

Zeolitic Imidazolate Frameworks-8 (ZIF-8) is commonly used as an ideal precursor for non-noble metal catalysts because of its high specific surface area, ultra-high porosity, and N-rich content. Upon pyrolyzing ZIF-8 at 900 °C in Ar, the resulting material, referred to as Z8, displayed good activity toward the oxygen reduction reaction (ORR). Then the ZIF-8 was mixed with various conductive carbon materials, such as multiwall carbon nanotubes (MWCNTs), Acetylene black (ACET), Vulcan XC-72R (XC-72R), and Ketjenblack EC-600JD (EC-600JD), to form Z8 composites. The Z8/MWCNTs composite exhibited enhanced ORR activity owing to its network structure, meso-/microporous hierarchical porous structure, improved electrical conductivity, and graphitization. Subsequently, iron and nitrogen co-doping is achieved through the pyrolysis of a mixture comprising Fe, N precursor, and ZIF-8/MWCNTs, which is denoted as FeN-Z8/MWCNTs. The intrinsically high electrical conductivity of MWCNTs facilitated efficient electron transfer during the ORR, while the meso-/microporous hierarchical porous structure and network structure of Fe, N co-doped ZIF-8/MWCNTs promoted oxygen transport. The presence of Fe-containing species in the catalyst acted as activity centers for ORR. This strategy of preparing Z8 composites and modifying them with Fe, N co-doping offers an insightful approach to designing cost-effective electrocatalysts. [ABSTRACT FROM AUTHOR]

Surface tension and interfacial tension are crucial to the study of nanomaterials. Herein, we report a solubility method using magnesium oxide nanoparticles of different radii (1.8–105.0 nm, MgO NPs) dissolved in pure water as a targeted model; the surface tension and interfacial tension (and their temperature coefficients) were determined by measuring electrical conductivity and combined with the principle of the electrochemical equilibrium method, and the problem of particle size dependence is discussed. Encouragingly, this method can also be used to determine the ionic (atomic or molecular) radius and Tolman length of nanomaterials. This research results disclose that surface/interfacial tension and their temperature coefficients have a significant relationship with particle size. Surface/interfacial tension decreases rapidly with a radius <10 nm (while the temperature coefficients are opposite), while for a radius >10 nm, the effect is minimal. Especially, it is proven that the value of Tolman length is positive, the effect of particle size on Tolman length is consistent with the surface/interfacial tension, and the Tolman length of the bulk does not change much in the temperature range. This work initiates a new era for reliable determination of surface/interfacial tension, their temperature coefficients, ionic radius, and Tolman length of nanomaterials and provides an important theoretical basis for the development and application of various nanomaterials. [ABSTRACT FROM AUTHOR]

Transparent conducting oxides with p-type conductivity hold immense potential for various electronic applications. The role of native point defects in delafossite CuMO 2 (M = Al, Ga, In) as the source of p-type conductivity has been widely acknowledged. However, understanding the primary defects governing the electrical properties and devising strategies for improvement remains a critical challenge. In this study, we employ range-separated hybrid density functional calculations to elucidate the impact of acceptor defects and their interactions with hydrogen on electrical conductivity. Our findings demonstrate that hydrogen plays a pivotal role in controlling p-type conductivity in these oxides. Our investigation reveals that the interactions between hydrogen interstitial H i and copper vacancy V C u lead to the formation of stable complexes that are electrically inactive. Considerable binding energies are observed for H i – V C u complexes, indicating that they are highly bound complexes with low formation energy and, thus, high concentrations under both O-rich and O-poor conditions. A second hydrogen can be bound to V C u to form 2H i – V C u complexes, which are thermodynamically stable and function as a single donor. Furthermore, hydrogen can bind with the antisite acceptor defects, Cu M , forming H i – Cu M complexes. However, the lower binding energies associated with these complexes suggest likely dissociation into isolated H i and Cu M at relatively low temperatures. By shedding light on the strong influence of hydrogen passivation of acceptor defects, this study offers valuable insights into p-type conductivity in delafossite CuMO 2. [ABSTRACT FROM AUTHOR]

Boron carbonitride (BCN) films containing hybridized bonds involving B, C, and N over wide compositional ranges enable an abundant variety of new materials, properties, and applications; however, their electronic performance is still limited by the presence of structural and electronic defects, yielding sluggish mobility and electrical conductivity. This work reports on mechanically stable BCN films and their corresponding optical and electronic properties. The ternary BCN films consisting of hybridized B–C–N bonds have been achieved by varying N2 flow by the radio frequency magnetron sputtering method. The BCN films show a bandgap value ranging from 3.32 to 3.82 eV. Hall effect measurements reveal an n-type conductivity with an improved hall mobility of 226 cm2/V s at room temperature for the optimal film. The n-BCN/p-Si heterojunctions exhibit a nonlinear rectifying characteristic, where the tunneling behavior dominates the injection regimes due to the density of defects, i.e., structural disorder and impurities. Our work demonstrates the tunable electrical properties of BCN/Si p–n diodes and, thus, is beneficial for the potential application in the fields of optics, optoelectronics, and electrics. [ABSTRACT FROM AUTHOR]

MXenes exhibit significant potential in thermoelectric materials owing to their exceptional electrical conductivity; however, their limited number of semiconductors restricts their application. Thus, it is highly desirable to expand the MXene family beyond carbides and nitrides to broaden their applications in thermoelectricity. In this work, we systematically investigate the thermoelectric transport of Ti2OX2 (X = F, Cl) MOene through comprehensively evaluating the electron–phonon coupling (EPC) from first principles. Our findings first emphasize the limitations of the deformation potential theory method and stress the importance of considering EPC. Ti2OF2 (Ti2OCl2) monolayer exhibits exceptional electronic transport, with Seebeck coefficients reaching 1483.87 (1206.22) μV/K and electrical conductivity reaching 9.5 × 105 (7.6 × 105) Ω−1 m−1 at room temperature for its N-type counterpart. Additionally, the presence of degenerate multiple valleys and peaks significantly enhances their electronic transport. For phonon transport, EPC results in a significant reduction in lattice thermal conductivity (kL) [e.g., at 300 K with 1.44 × 1015 (1.68 × 1015) cm−2 of hole, the reduction is 86.3% (73.3%) for Ti2OF2 (Ti2OCl2)]. Additionally, their kL demonstrates a strong correlation with the density of states at corresponding Fermi levels. Moreover, the kL and total thermal conductivity of P-type Ti2OF2 show T-independence, making it suitable for applications in aviation and thermal insulation materials. Finally, N-type Ti2OF2 and Ti2OCl2 demonstrate superior zT values of 0.63 and 0.9 at 900 K, respectively. This study provides in-depth insights into the superior thermoelectric properties of Ti2OX2 (X = F, Cl) MOene with considering EPC, providing a novel platform for the next-generation thermoelectric field. [ABSTRACT FROM AUTHOR]

A novel interfacial resistance-free (IRF) bifunctional camouflage (transparent and invisible) device is proposed in this paper. The thermal and electric conductivities of the shell and background are the same to eliminate the interfacial resistance. The IRF bifunctional camouflage device can operate in thermal–electric fields based on the neutral inclusion method. The distribution of isotherm and equipotential lines are studied quantitatively by the simulations. It is confirmed that the IRF bifunctional camouflage device with arbitrary natural materials can effectively achieve not only the invisible function but also the transparent function in thermal–electric fields. This method provides a window to the realization of bifunctions and the development of multi-physics fields. [ABSTRACT FROM AUTHOR]

The addition of molecular dopants into organic semiconductors (OSCs) is a ubiquitous augmentation strategy to enhance the electrical conductivity of OSCs. Although the importance of optimizing OSC–dopant interactions is well-recognized, chemically generalizable structure–function relationships are difficult to extract due to the sensitivity and dependence of doping efficiency on chemistry, processing conditions, and morphology. Computational modeling for an integrated OSC–dopant design is an attractive approach to systematically isolate fundamental relationships, but requires the challenging simultaneous treatment of molecular reactivity and morphology evolution. We present the first computational study to couple molecular reactivity with morphology evolution in a molecularly doped OSC. Reactive Monte Carlo is employed to examine the evolution of OSC–dopant morphologies and doping efficiency with respect to dielectric, the thermodynamic driving for the doping reaction, and dopant aggregation. We observe that for well-mixed systems with experimentally relevant dielectric constants, doping efficiency is near unity with a very weak dependence on the ionization potential and electron affinity of OSC and dopant, respectively. At experimental dielectric constants, reaction-induced aggregation is observed, corresponding to the well-known insolubility of solution-doped materials. Simulations are qualitatively consistent with a number of experimental studies showing a decrease of doping efficiency with increasing dopant concentration. Finally, we observe that the aggregation of dopants lowers doping efficiency and thus presents a rational design strategy for maximizing doping efficiency in molecularly doped OSCs. This work represents an important first step toward the systematic integration of molecular reactivity and morphology evolution into the characterization of multi-scale structure–function relationships in molecularly doped OSCs. [ABSTRACT FROM AUTHOR]

In view of the inherent pseudocapacitance, rich redox pairs (Nb5+/Nb4+ and Nb4+/Nb3+), and high lithiation potential (1.0–3.0 V vs Li/Li+), Nb2O5 is considered a promising anode material. However, the inherent low electronic conductivity of Nb2O5 limits its lithium storage performance, and the rate performance after carbon modification is still unsatisfactory because the intrinsic conductivity of Nb2O5 has not been substantially improved. In this experiment, taking the improvement of the intrinsic electrical conductivity of Nb2O5 as the guiding ideology, we prepared F-doped Nb2O5@fluorocarbon composites (F–Nb2O5@FC) with a large number of oxygen vacancies by one-step annealing. As the anode electrode of lithium-ion batteries, the reversible specific capacity of F–Nb2O5@FC reaches 150 mA g−1 at 5 A g−1 after 1100 cycles, and the rate performance is particularly outstanding, with a capacity up to 130 mA g−1 at 16 A g−1, which is far superior to other Nb2O5@carbon-based anode electrodes. Compared with other single conductivity sources of Nb2O5@carbon-based composites, the electrical conductivity of F–Nb2O5@FC composites is greatly improved in many aspects, including the introduction of free electrons by F− doping, the generation of oxygen vacancies, and the provision of a three-dimensional conductive network by FC. Through analytical chemistry (work function, UV–Vis diffuse reflectance spectroscopy, and EIS) and theoretical calculations, it is proved that F–Nb2O5@FC has high electrical conductivity and realizes rapid electron transfer. [ABSTRACT FROM AUTHOR]

Roughly, 50% of primary energy worldwide is rejected as waste heat over a wide range of temperatures. Waste heat above 573 K has the highest Carnot potential (> --> 50 %) to be converted to electricity due to higher Carnot efficiency. Thermoelectric (TE) materials have gained significant attention as potential candidates for efficient thermal energy conversion devices. Silicon nanowires (SiNWs) are promising materials for TE devices due to their unique electrical and thermal properties. In this study, we report the successful fabrication of high-quality double-sided SiNW arrays using advanced techniques. We engineered the double-sided structure to increase the surface area and the number of TE junctions, enhancing TE energy conversion efficiency. We also employed non-agglomeration wire tip engineering to ensure uniformity of the SiNWs and designed effective Ohmic contacts to improve overall TE efficiency. Additionally, we post-doped the double-sided SiNW arrays to achieve high electrical conductivity. Our results showed a significant improvement in the TE performance of the SiNW array devices, with a maximum figure-of-merit (ZT) value of 0.24 at 700 K, fabricated from the single SiNW with ZT of 0.71 at 700 K in our previous work [Yang et al., Nat. Commun. 12(1), 3926(2021)]. [ABSTRACT FROM AUTHOR]

Glutaronitrile (GN) doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at concentrations below and above the room-temperature conductivity optimum near 1M of Li salt is investigated using dielectric spectroscopy and shear rheology. The experiments are carried out from ambient down to the glass transition temperature Tg, which increases considerably as LiTFSI is admixed to GN. As the temperature is lowered, the conductivity optimum shifts to lower salt concentrations, while the power-law exponents connecting resistivity and molecular reorientation time remain smallest for the 1M composition. By contrast, the rheologically detected time constants, as well as those obtained using dielectric spectroscopy, increase monotonically with increasing Li salt concentration for all temperatures. It is demonstrated that the shear mechanical measurements are, nevertheless, sensitive to the 1M conductivity optimum, thus elucidating the interplay of the dinitrile matrix with the mobile species. The data for the Li doped GN and other nitrile solvents all follow about the same Walden line, in harmony with their highly conductive character. The composition dependent relation between the ionic and the reorientational dynamics is also elucidated. [ABSTRACT FROM AUTHOR]

In this report, the high-temperature transport properties of (Dy1−xCax)(Zr0.2Hf0.2Sn0.2Ti0.2Ge0.2)O7 pyrochlore oxides with x = 0, 0.05, and 0.1 are studied in dry and humid air. The phase composition and crystal structure were determined by using x-ray and neutron diffraction. The addition of calcium to the structure caused an increase in the concentration of oxygen vacancies, indicating an ionic charge compensation mechanism. Electrical studies allowed us to determine the total electrical conductivity as a function of the synthesis atmosphere and pH2O. The electrical conductivity turned out to be at the level of ∼10−3 S/cm at 800 °C, and only a slight effect of the presence of protonic defects in the structure on the total electrical conductivity was observed. In general, the samples had a low electrical conductivity with a relatively high activation energy of conduction. [ABSTRACT FROM AUTHOR]

In this study, the basic properties of Ba2AgSi3 were investigated in detail from both experimental and computational viewpoints. Polycrystalline Ba2AgSi3 formed by an arc-melting apparatus under an argon atmosphere was ground into powders, and then powder samples were sintered using the spark plasma sintering method. Both n-type and p-type samples were obtained. This may be due to a slight deviation from the stoichiometric composition. The energy bandgap of Ba2AgSi3 was measured to be around 0.17 eV from the temperature dependence of electrical conductivity and was in agreement with that by first-principles calculations. Sintered samples exhibited a high Seebeck coefficient of −273 μV K−1 and a high power factor of 0.38 mW m−1 K−2 at 307 K for n-type samples. They were 217 μV K−1 and 0.23 mW m−1 K−2, respectively, at 320 K for p-type samples. The electronic structures of impurity-doped Ba2AgSi3 were also discussed using first-principles calculations to investigate the insertion site of impurity atoms. The calculations suggest that the substitution of B (P) at any Si site shifts the Fermi level and transforms it into p-type (n-type) semiconductors. On the other hand, substitution of Ba or Ag sites with B or P is unlikely to occur in terms of formation energy. [ABSTRACT FROM AUTHOR]

The intrinsically low electrical conductivity and poor structural fragility of MnO2 have significantly hampered the zinc storage performance. In this work, Ba2+-implanted δ-MnO2 nanosheets have been hydrothermally grown on a carbon cloth (Ba–MnO2@CC) as an extremely stable and efficient cathode material of aqueous zinc-ion batteries. The three-dimensionally porous architecture composed of interwoven thin MnO2 nanosheets effectively shortens the electron/ion transport distances, enlarges the electrode/electrolyte contact area, and increases the active sites for the electrochemical reaction. Meanwhile, Ba2+ could function as an interlayer pillar to stabilize the crystal structure of MnO2. Consequently, the as-optimized Ba–MnO2@CC exhibits remarkable Zn2+ storage capabilities, such as a high capacity (305 mAh g−1 at 0.2 A g−1), prolonged lifespan (95% retention after a 200-cycling test), and superb rate capability. The binder-free cathode is also applicable for flexible energy storage devices with attractive properties. The present investigation provides important insights into designing advanced cathode materials toward wearable electronics. [ABSTRACT FROM AUTHOR]

Ti-doped In 2 O 3 thin films with varying Ti contents are prepared by partial reactive co-sputtering using ceramic In 2 O 3 and metallic Ti targets and characterized by in situ x-ray photoelectron spectroscopy, electrical conductivity, and Hall-effect measurements. For a substrate temperature of 400 ° C , the carrier concentration increases faster than the Ti content and saturates at ≈ 7.4 × 10 20 c m − 3 . Based on these results, it is suggested that Ti does not directly act as donor in In 2 O 3 but is rather forming TiO 2 precipitates and that the related scavenging of oxygen generates oxygen vacancies in In 2 O 3 as origin of doping. Neutralization of oxygen vacancies is, therefore, suggested to be origin of the limitation of the carrier concentration in Ti-doped In 2 O 3 films. [ABSTRACT FROM AUTHOR]

In recent years, organic–inorganic hybrid perovskite (PVK) devices have attracted widespread attention with their high absorption coefficient and low-cost fabrication process. Formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have been reported to obtain high power conversion efficiencies (PCEs) due to the narrow bandgap. Zinc oxide (ZnO) has better electrical conductivity and high transmittance than tin (IV) dioxide (SnO2). However, the deprotonation behavior of ZnO limits its use in formamidinium (FA) or methylammonium (MA) devices, so it is mostly used in all-inorganic PSCs. In this work, to avoid the deprotonation behavior of ZnO, we prepared FAPbI3 PSCs using ZnO/SnO2 as bilayer electron transporting layers (ETLs), which improved the conductivity of the ETLs and promoted electron extraction and transfer. In addition, the decrease in the oxygen vacancy (Ov) on the bilayer ETLs contributed to the suppression of the non-radiative recombination of the device, thus enabling the achievement of a higher fill factor. As a result, the modified ETLs increased the PCE of FAPbI3 PSCs from 20.24% to 21.42% and improved the stability of the devices. The PCE of unpackaged devices increased steadily to 21.91% when stored in an N2 atmosphere for 183 days. [ABSTRACT FROM AUTHOR]

Single-turn coil (STC) is a destructive pulse magnet aiming at a 100–300 T ultra-high magnetic field. A thermal–electrical coupling model, in which the solid–liquid phase transition process is considered, is proposed. The effects of solid–liquid phase transition on pressure, temperature, and electrical conductivity are investigated. The results show that the compressed and stretched regions coexist simultaneously, and the distribution of both regions changes with time during discharging. Moreover, the region with the highest current density is inside the conductor, since the phase transition reduces the electrical conductivity of the region near the inner surface of STCs. By comparison, the simulation results are highly consistent with the measured data, and the necessity of considering the phase transition process is validated. The results obtained in this work are helpful for understanding the thermodynamic process of STCs during discharge. [ABSTRACT FROM AUTHOR]

PbTe-based compounds are excellent candidates for the different types of optical detector applications from near to far IR ranges. In the present work, a technology has been developed for the fabrication of Pb 1 − x Sn x Te compositions, doped with In, on a thin amorphous substrate (polyimide). The film preparation was performed by the electron gun evaporation method. The systematic study of structure and transport properties (Hall coefficient and electric conductivity) in the entire temperature range of 10–300 K for Pb 1 − x Sn x Te:In films (x = 0 , 0.1, 0.2) was investigated. It was studied that the photoconductivity of the films in the telecom wavelength range, including kinetics, sensitivity, and noise equivalent power, has been conducted and it discovered persistent photoconductivity for all compositions at the temperature T < 21 K. The results of the work have promising potential to use poly(nano) crystalline Pb 1 − x Sn x Te:In films on an amorphous substrate both for photodetection in the telecom wavelength range and for the creation of all-optical neuromorphic systems, cooled memory, and logic elements operating at the low energy of laser pulses. [ABSTRACT FROM AUTHOR]

Despite extensive studies of spin transport in metallic structures, it remains a challenge to achieve spin relaxation length well above 1 μm in metals even at low temperatures. We explore nonlocal spin transport in Cu channels with a cross section of 0.5 × 0.5 μm2, which exhibit superior values of electrical conductivity and residual resistivity ratio (RRR). Based on structures fabricated in a single batch, we found an average spin relaxation length of λ C u = 3.2 ± 0.7 μ m and an average spin relaxation time of τs = 120 ± 50 ps at 30 K. Substantial variations of λ C u , RRR, and resistivity ρ C u are found among the structures and the three quantities correlate well to one another. The most conductive Cu channel in the batch yields λ C u = 5.3 ± 0.8 μ m and τ s = 250 ± 80 ps. These superior values exceed expectations for metals and can be attributed to reduced spin relaxation from grain boundaries and surfaces. [ABSTRACT FROM AUTHOR]

When it comes to simulate or calculate an optoelectronic tweezer (OET) response for a microparticle suspended in a given medium, a precise electrical conductivity (later referred to as conductivity) value for the microparticle is critical. However, there are not well-established measurements or well-referenced values for microparticle conductivities in the OET realm. Thus, we report a method based on measuring the escape velocity of a microparticle with a standard OET system to calculate its conductivity. A widely used 6 μm polystyrene bead (PSB) is used for the study. The conductivity values are found to be invariant around 2×10-3 S/m across multiple different aqueous media, which helps clarify the ambiguity in the usage of PSB conductivity. Our convenient approach could principally be applied for the measurement of multiple unknown OET-relevant material properties of microparticle-medium systems with various OET responses, which can be beneficial to carry out more accurate characterization in relevant fields. [ABSTRACT FROM AUTHOR]

The electrical conductivity of Na2O substituted zinc borate glasses has been studied in the frequency range of 10 mHz to 1 MHz and in the temperature range from 313 to 573 K. The conduction mechanism has been ascertained using the values of the frequency exponent (s) extracted from the fitting of experimental data of the real part of electric conductivity in light of the Almond–West equation. Depending on the glass composition, the ac conduction in the glasses happened via correlated barrier hopping and non-overlapping small polaron tunneling conduction models. The electric modulus studies support the assertion of composition dependent conduction mechanisms. Furthermore, electronic conduction and ionic conduction have been studied from impedance investigations. Equivalent circuit models were used to fit the Nyquist and Bode plots of each sample at the temperatures under consideration. It has been found that the activation energy values calculated from conductivity, electric modulus, and impedance measurements are more or less the same. [ABSTRACT FROM AUTHOR]

Adding Fe3O4 nanoparticles to composites of [Fe(Htrz)2(trz)](BF4) spin-crossover polymer and polyaniline (PANI) drives a phase separation of both and restores the molecular structure and cooperative effects of the spin-crossover polymer without compromising the increased conductivity gained through the addition of PANI. We observe an increased on-off ratio for the DC conductivity owing to an enlarged off state resistivity and a 20 times larger AC conductivity of the on state compared with DC values. The Fe3O4 nanoparticles, primarily confined to the [Fe(Htrz)2(trz)](BF4) phase, are ferromagnetically coupled to the local moment of the spin-crossover molecule suggesting the existence of an exchange interaction between both components.

Insufficient surface dynamics and severe carrier recombination limit the photoelectrochemical water splitting (PEC-WS) performance of hematite (α-Fe2O3) photoanodes. The surface/interface engineering as an effective method can improve the above-mentioned problems. In this study, the ZIF-67 and FeCoNi-LDH as cocatalysts formed via in situ hydrolysis are successfully introduced on the surface of the α-Fe2O3 photoanode to improve the photogenerated carrier transport. The Sn@α-Fe2O3/ZIF-67/FeCoNi-LDH photoanode exhibits an excellent photocurrent density of 1.72 mA cm−2 at 1.23 VRHE, which is 1.7 times that of the original α-Fe2O3 photoanode. The detailed studies demonstrate that the introduced ZIF-67/FeCoNi-LDH heterojunction cocatalyst provides more abundant surface active sites and defects and enhances the light absorbance ability and electric conductivity. The synergistic effect between ZIF-67 and FeCoNi-LDH cocatalysts can significantly enhance photogenerated carrier separation and transfer efficiency. [ABSTRACT FROM AUTHOR]

The electrocatalytic urea oxidation reaction (UOR) can serve as an alternative to the anodic oxygen evolution reaction (OER) in water splitting. Therefore, it is of great significance to develop efficient and cheap electrocatalysts to improve the kinetics of the UOR. In this study, a Ni/NiO/NiB@NC-500 composite was prepared by anchoring Ni/NiO/NiB nanoparticles on a nitrogen-doped carbon substrate through a straightforward hydrothermal-pyrolysis method. The optimal Ni/NiO/NiB@NC-500 composite exhibited remarkable activity and stability for the UOR, that is, the current density (j) of Ni/NiO/NiB@NC-500 for the UOR was 264 mA cm−2 at a potential of 1.67 V. Furthermore, the j retention rate of Ni/NiO/NiB@NC-500 was 84.6% of the initial value after 12 h of chronoamperometry (CA) test. The remarkable performance of Ni/NiO/NiB@NC-500 was ascribed to the following aspects: its hydrophilicity facilitated the adsorption of reactants and products, its porous spongy structure exposed more active sites for the UOR and promoted charge transfer and electrolyte diffusion, and the nitrogen-containing carbon matrix enhanced its electrical conductivity and stability. In addition, the density functional theory (DFT) calculations indicated that the introduction of B significantly reduced the energy barrier of the rate-determining step (RDS) during the UOR. [ABSTRACT FROM AUTHOR]

Supercapatteries combine the high-power density characteristic of supercapacitors with the high energy density typically found in batteries, offering a promising solution for advanced energy storage applications. We present an efficient two-step method to fabricate hierarchical, binder-free NiCo layered double hydroxide (LDH) nanosheet arrays supported on polyaniline layered nickel foam (NF). A PANI@NiCo-LDH/NF nanocomposite serves as the anode in the supercapattery, leveraging the high capacitance and improved conductivity of the combined materials, yielding a significantly high specific capacity of 1481 C g−1 (3703.33 F g−1). Coffee grounds derived reduced graphene oxide (rGO), providing a sustainable and environmentally friendly material with excellent electrical conductivity and high mechanical strength, serves as the cathode. The synergy between the PANI@NiCo-LDH/NF anode and the rGO cathode creates a novel and highly efficient supercapattery system. The fabricated supercapattery device offers an energy density of 54.44 W h kg−1 at a power density of 0.702 kW kg−1 and exhibits good cyclability with capacitance retention of 84.88% and Coulombic efficiency of 77.68% over 5000 charging/discharging cycles. This innovative approach addresses the limitations of traditional energy storage devices, paving the way for more versatile and sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Vanadium oxide has become a promising electrode material for supercapacitors because of its high capacitance and multiple redox states. However, low intrinsic conductivity, narrow interlayer spacing and poor structural stability limit its practical application. The study reports the construction of Co-doped V2O3 using asparagic acid-functionalized graphene quantum dots (GQD) and biomass carbon (BC). V5+ and Co2+ were combined with GQD to form the Co/V-GQD complex. Then, it was adsorbed on cotton, dried and annealed. The resulting Co–V2O3-GQD@BC shows the three-dimensional carbon framework. The formed V2O3 nanocrystals with rich edges and corners are dispersed on the carbon sheets. V5+ was partly reduced to form low-valent V2+ species. V2+ and Co2+ self-doping narrows the bandgap and creates new electron transfer pathways. Graphene modification accelerates the electron transfer from V2O3 to graphene and improves structural stability. The integration of double doping with graphene modification realizes a significant improvement in electrical conductivity and a safe voltage window (1.8 V). The specific capacitance of V2O3 in Co–V2O3-GQD@BC reaches 2182.89 F g−1, which is more than that of the other vanadium oxide electrodes. The symmetrical supercapacitor with Co–V2O3-GQD@BC electrodes provides a high capacitance (664.89 F g−1 at current density of 1 A g−1), rate capacity (366.67 F g−1 at 50 A g−1), cycling stability (97.65% capacitance retention after 10 000 cycles) and energy density (74.8 W h kg−1 at a power density of 425 W kg−1). [ABSTRACT FROM AUTHOR]

Graphene fibers (GFs) have a bright future in a variety of applications ascribing to their excellent performance. However, strict preparation conditions with extremely high graphitization temperature or toxic chemical reagents severely restrict their extensive implementation. Meanwhile, researchers are seeking easily scalable and eco-friendly GFs production methods. Here, we propose a green two-step reduction strategy involving L-ascorbic acid (LAA) chemical reduction followed by low-temperature annealing for the preparation of high-performance GFs. Benefiting from the elimination of macro-, micro- and nano-scaled defects and recombination of graphene nanosheets, the prepared GFs demonstrated amazing tensile strength of 778.49 MPa, Young's modulus of 92.61 GPa and an outstanding electrical conductivity of 3.2 × 104 S m−1, outperforming most of the chemically reduced GFs. This two-step green reduction strategy provides a new insight for constructing integrated high-performance GFs for sustainable application in many fields. [ABSTRACT FROM AUTHOR]

In this work, we report the thermoelectric behaviour of flexible fabric-based Mo doped CuAl 2 O 4. The doped Mo atom occupies the interstitial positions of the spinel lattice of CuAl 2 O 4. This results the lattice expansion and also provides the carrier electrons. Initially, the pristine CuAl 2 O 4 has the carrier concentration of 2.81 × 1014 cm−3, while doping with molybdenum, it not only increases the concentration of the carriers (about −7.65 × 1015 cm−3), but also changes the carrier type. The minimum doping (2 %) of molybdenum to spinel CuAl 2 O 4 (CuAl 2 O 4 Mo 0.02) creates the fermi level near to the conduction band, which reduces the band gap and results in the effective electrical conductivity as 0.69 Scm−1 at 340 K. The heavy doping enhances the scattering process. This leads to deduction of mobility and lower the electrical conductivity. The highest power factor of 0.0599 μWcm−1K−2 is achieved for the CuAl 2 O 4 Mo 0.06 sample at 300 K. This is due to the high Seebeck coefficient value of the sample and has an ultralow thermal conductivity value of 0.056 W/mK. The highest output voltage of 3.9 mV is achieved for parallelly connected p-type CuAl 2 O 4 -n-type CuAl 2 O 4 Mo 0.02 thermoelectric device at the temperature difference of ΔT = 4.1 K. This research findings justify, the doping of molybdenum in the spinel lattice effectively enhances the thermoelectric properties of CuAl 2 O 4 and provide the new ideas for the flexible, wearable fabric based thermoelectric research. [Display omitted] [ABSTRACT FROM AUTHOR]

The long-term operation of intermediate temperature-solid oxide fuel cells (IT-SOFCs) could be significantly influenced by the stability of the interconnect itself, especially, its oxidation resistance under the cathode environment. To effectively prevent Cr-volatilization and improve the interconnector performance, application of highly dense and stable protective coatings over the interconnector is indispensable. In this work, Ni-Co-based alloy protective coatings doped with Fe and Cu were applied onto the 441 interconnector via a novel high-speed laser cladding technology. The microstructure evolution, phase composition, oxidation resistance, electrical conductivity and mechanical properties of the coated steels were investigated at different oxidation stages at 800 °C. It was found that the Ni 33.8 Co 34 Fe 32.2 -coated steel shows the best oxidation resistance and electrical properties. The oxidation rate (k p) and ASR of Ni 33.8 Co 34 Fe 32.2 -coated steel is respectively 4.44 × 10−13 g2 cm−4 s−1 and 25.55 mΩ cm2, significantly lower than the uncoated steel and Ni 44.6 Co 44.7 Cu 10.7 -coated steel at the end of 1000-h test cycle. The resultant conductivity of the Ni 44.6 Co 44.7 Cu 10.7 and Ni 33.8 Co 34 Fe 32.2 -coated steels is approximately 7.8 and 4.1 S cm−1, respectively, which could meet the requirement for SOFC stacks. In addition, the nano-hardness of the Ni 33.8 Co 34 Fe 32.2 and Ni 44.6 Co 44.7 Cu 10.7 -coated steels was found to be 8.3 GPa and 8.8 GPa, respectively, through nanoindentation testing. The improved surface hardness is attributed to grain refinement and increased oxide content on the coating surface. The results indicated that the Ni-Co-based alloy coatings effectively improved the long-term stability and mechanical property of the 441 interconnector under the SOFC cathode environment. [Display omitted] [ABSTRACT FROM AUTHOR]

TiSiC/MeN (where Me represents Zr, Ti, and Cr) multilayer films were deposited onto 316LSS substrates for proton exchange membrane fuel cells via magnetron sputtering. A comparative investigation of the microstructures and corrosion resistances of the films was conducted. The results indicate that the incorporation of the MeN interlayers interrupts the continuous growth of the columnar TiSiC layer. The TiSiC/MeN multilayer coated 316LSS exhibits better resistance to corrosion and higher electrical conductivity compared to the TiSiC monolayer. The film porosity dominates the corrosion resistance while the electrical conductivity depends on both the phase structure and oxygen concentrations of the films. The multilayer structure suppresses ion diffusion in the etchant solution and decreases the film porosity. However, interfacial delamination caused by the interaction of the solution with the substrate produces the failure of the monolayer TiSiC. [ABSTRACT FROM AUTHOR]

In this study, we report the synthesis of MFe 2 O 4 @SiO 2 (M = Cu, Ni, Co) nanostructures by microwave-assisted sol-gel synthesis utilizing rice husk as a cost-effective silica precursor and polyethylene glycol (PEG) as a soft template. Structural and electrochemical properties were characterized using XRD, FTIR, FESEM, EDS, HRTEM, BET, and electrochemical techniques. The result revealed the formation of well-defined MFe 2 O 4 spherical nanoparticles decorated mesoporous silica spheres. Electrochemical studies indicate that the CoFe 2 O 4 @SiO 2 electrode performs better than the CuFe 2 O 4 @SiO 2 and NiFe 2 O 4 @SiO 2 electrodes in faradaic redox processes and supercapacitor performance, having a specific capacitance of 1263 F/g at 1 A. Asymmetric supercapacitor (ASC) with CoFe 2 O 4 @SiO 2 as positive electrode exhibits high specific capacitance of 135.66 F/g at 1 A/g with good cycle stability retention (70.83 % at 10 A/g), high energy density (50.4 Wh/kg) and power density (891.522 W/kg). CoFe 2 O 4 @SiO 2 performs better than CuFe 2 O 4 @SiO 2 and NiFe 2 O 4 @SiO 2 because cobalt ferrite (CoFe 2 O 4) has higher electrical conductivity, superior redox activity, and better electrochemical stability. This study offers cost-effective potential electrode materials for electrochemical energy storage, combining environmental sustainability with superior electrochemical performance. [ABSTRACT FROM AUTHOR]

Fly ash cenospheres serve as an inexpensive filler for various composites. Coating their surface with metal significantly alters the properties of the resulting composites. In this study, aluminosilicate cenospheres receive a copper coating using a plasma method with magnetron sputtering. Based on these copper-coated cenospheres, composites are created, and their dielectric properties are investigated in a parallel plate capacitor cell under isotropic pressures ranging from 1 to 75 atm. Composites based on pure fly ash cenospheres exhibit pressure-invariant properties, including the dielectric constant and loss factor. However, for composites based on copper-coated fly ash cenospheres, an abrupt increase in electrical conductivity is observed as the pressure increases. Interestingly, significant changes in electrodynamics characteristics are not detected under the influence of anisotropic stress. The methodology tested in this work can be utilized for creating smart materials based on cenospheres. [ABSTRACT FROM AUTHOR]

The Ag-SnO 2 contact material is widely regarded as the most promising environmental friendly electrical contact material. However, during the make and break operations, SnO 2 particles rising to the surface can cause increased contact resistance and temperature rise, which affects the service life of the contact material. In this study, a three-dimensional (3D) Ni skeleton reinforced Ag-based contact material with CuO-coated SnO 2 are successfully fabricated via powder metallurgy technology. The basic physical properties of the novel contact material were tested and the microstructures and arc erosion morphologies were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The research demonstrated that the hardness and electrical conductivity of the novel contact material are 128.9 HV and 46 %IACS, respectively. It can be observed that the SnO 2 -rich phase is uniformly distributed in the Ag matrix without significant upward after arc erosion, which indicates that the SnO 2 @CuO core-shell structure effectively enhances the wettability between Ag and SnO 2. Meanwhile, the study revealed that the Ni phase uniformly distributed at the interface of the Ag phase during the arc erosion process, indicating that the 3D Ni skeleton structure effectively impedes the expansion of the Ag molten pool and improves the anti-arc erosion performance. [ABSTRACT FROM AUTHOR]

Cu 3 SbSe 4 is recognized for its abundant elemental availability, cost-effectiveness, and non-toxic properties, making it a promising candidate for thermoelectric applications at medium temperatures. This study explored the preparation of Bi/Fe, Ag/Fe, and Ag/Bi double-doped Cu 3 SbSe 4 ceramics using vacuum melting and cold isostatic pressing techniques. The focus was on examining the influence of these dopants on the microstructural and thermoelectric performances of Cu 3 SbSe 4. The analysis revealed the presence of Cu 3 SbSe 4 and Cu 2− x Se phases in the doped samples. Double doping optimized the carrier concentration, increased the effective mass, and significantly enhanced the electrical conductivity from 12.45 to 64.01 S cm−1. Notably, the power factor of the Cu 2.85 Ag 0.15 Sb 0.985 Bi 0.015 Se 4 sample reached 649.1 μWm−1K−2 at 573 K. Furthermore, the thermal conductivity was significantly reduced to 0.73 W/mK. The maximum ZT value of the Cu 2.85 Ag 0.15 Sb 0.985 Bi 0.015 Se 4 sample was 0.47 at 573 K. These breakthrough results demonstrate that dual doping markedly enhances the thermoelectric properties of the Cu 3 SbSe 4 system. [ABSTRACT FROM AUTHOR]

Besides excellent thermoelectric properties, composed of earth-abundant elements and featuring simple chemical compositions are more conducive to the practical fabrication and utilization of thermoelectric materials. In this study, a tellurium-free thermoelectric compound, AgSbSe 2 , was synthesized, and the impact of Ag deficiencies on its thermoelectric performance was examined. It was found that the density of charge carriers of AgSbSe 2 can be effectively modulated by introducing slight Ag deficiencies, thereby significantly optimizing its electrical transport performance. A peak power factor of 6.63 μWcm−1K−2 @623 K is achieved in the sample with a composition of Ag 0.99 SbSe 2 , which is similar to the maximum value observed in Pb doped samples prepared by the same experimental production. Meanwhile, extremely low thermal conductivity was restrained in AgSbSe 2 with Ag deficiencies due to the effect of phonon scattering caused by crystal defects, which offsets the increased electrical thermal conductivity. Finally, a maximum zT value of 0.97 @623 K is obtained for Ag 0.99 SbSe 2 , which is comparable to that of heavily doped AgSbSe 2 with the conventional divalent cations doping at the Sb site. [ABSTRACT FROM AUTHOR]

Poor machinability and limited electrical conductivity present significant challenges for silicon carbide (SiC) composites used in the semiconductor industry. In this study, Ti-Si/SiC composites were synthesized by liquid infiltration of a Ti-Si eutectic alloy, using SiC and Carbon black as raw materials. The reactive sintering mechanism and properties of Ti-Si/SiC composites were investigated using the reactive infiltration sintering process. The relative density of Ti-Si/SiC composites reached 98.43 % at 1600 °C. The results indicate that continuous infiltration of the Ti-Si eutectic alloy and dissolution-reprecipitation are critical for synthesizing Ti-Si/SiC composites. The coefficient of thermal expansion for the composites is 5.16 × 10−6 °C−1. Remarkably, the exponential increase in electrical conductivity with rising temperature strongly supports the enhanced conductive properties of this composite semiconductor. The Ti-Si/SiC composites exhibit maximum flexural strength, indentation modulus, and hardness values of 310.4 MPa, 434.1 GPa, and 29.4 GPa, respectively. This research aims to advance the application of high-performance Ti-Si/SiC materials in semiconductor technology. [ABSTRACT FROM AUTHOR]

The novel perovskite Sr 0.90 Ba 0.10 Co 0.95 Ti 0.05 O 3-δ has been designed as cathode material to be used in intermediate-temperature solid oxide fuel cells (IT-SOFC). To enlarge the unit-cell size and enhance oxygen diffusion, Sr atoms have been partially substituted by a 10 % of Ba. This new compound was characterized through X Ray Diffraction (XRD) unveiling a tetragonal phase at RT. An in situ Neutron Powder Diffraction (NPD) study between RT and 800 °C showed a transition to a cubic perovskite at 400 °C, which was also noticeable in the thermogravimetric analysis (TGA) and dilatometric analysis. Adequate chemical and mechanical compatibility were achieved with the components of the cell. Electrical conductivity peaked at 400 °C, with values over 200 S cm−1 , where it changed its behavior from semiconductor-like to insulator. Finally, polarization resistances as low as 0.062 Ω cm−2 were obtained for the working temperature of the cell in a symmetric cell, associated with the excellent power densities of 564 and 752 mW cm−2 obtained at 850 °C using pure H 2 as fuel for the conventional test fuel cell and in a Pd-infiltrated one. [ABSTRACT FROM AUTHOR]

The prime goal of this novel work is to investigate the efficacy of spinel zinc ferrite as a thermoelectric material and its performance enhancement for high temperature applications. Zn 1-x Ni x Fe 2 O 4 (0 ≤ x ≤ 0.2) were prepared by sol-gel method and their structural, morphological, and thermoelectric behaviours were examined as functions of composition and temperature. Among the studied compositions, Zn 0.8 Ni 0.2 Fe 2 O 4 exhibits the highest electrical conductivity (σ) of 49.83 S/m, the largest power factor of 6.66 μW/mK2, and the lowest thermal conductivity (κ) of 0.36 W/mK at 947 K, thus extending to an overall enhancement in the thermoelectric figure of merit (zT). Conduction through electron hopping is proven to be the main driving force for the enhancement in electrical and thus thermoelectric properties. Results reveal that thermoelectric properties of ZnFe 2 O 4 can potentially be enhanced by the doping Ni at Zn site and opens up an exciting opportunity for the utilization of this spinel ferrite as a novel thermoelectric material for applications involving elevated temperatures. [Display omitted] • Thermoelectric figure of merit of ZnFe 2 O 4 was considerably enhanced by doping Ni. • Electron hopping is found to be one of the major contributors for the enhancement of electrical conductivity. • The dopant is also effective in reducing the thermal conductivity of ZnFe 2 O 4 at higher temperatures. • The results indicate that the studied material is suitable for high temperature (>700K) thermoelectric applications. [ABSTRACT FROM AUTHOR]

High-nickel layered cathode materials for lithium-ion batteries have received widespread attention in new energy vehicles for their excellent specific energy and cost advantages, and are considered to be the most promising cathode materials for high-energy density lithium-ion batteries. Despite its many advantages, poor thermal stability and rapid capacity degradation have greatly limited its large-scale application. Ion doping is considered to be an effective way to improve its drawbacks, and in this paper, a series of W-doped LiNi 0.9 Co 0.1 O 2 cathode materials were prepared using WO 3 as a tungsten source. Among them, 1 mol% W doping was the most effective, and its reversible capacity of 204.44 mA g −1 still had 93.25 % capacity retention after 100 this cycles at 1C. Combined with DFT calculations, it is found that the introduction of W does not change the original layered structure and the material transitions from semi-metallic to metallic at lower doping concentrations, resulting in more electrons occupying the Fermi energy levels to enhance its electrical conductivity and leading to an elevated spin state and a lower oxidation state of Ni. [ABSTRACT FROM AUTHOR]

Zn2P2O7−y (referred to as ZPO) is expected to be an ideal anode material for lithium-ion batteries (LIBs) owing to its low cost, good chemical and thermal stability, and environmental friendliness. The effects of oxygen vacancies on the structure, morphology, and electrochemical performance of ZPO were systematically investigated. The sample obtained in an argon–hydrogen atmosphere (referred to as ZPO-1) exhibited an initial discharge capacity of 1178.4 mA h g−1 at 0.2 A g−1, which was superior to that of the samples obtained via calcination in argon (referred to as ZPO-2, 749.1 mA h g−1), vacuum (referred to as ZPO-3, 901.3 mA h g−1), and the air (referred to as ZPO-4, 911.2 mA h g −1). The excellent electrochemical performance of ZPO-1 could be attributed to the introduction of more defects under reducing atmospheres, which accelerated the transmission rate of lithium ions and improved discharge capacity. Appropriate amounts of oxygen vacancies not only enhance electrical conductivity, but also act as active sites for electrochemical reactions. Additionally, synthesizing ZPO with oxygen vacancies provides a reference for exploring anode materials with exceptional performances for LIBs. [ABSTRACT FROM AUTHOR]