RESUMEN
We studied the Lagrangian strain-induced colossal magnetism and thermoelectric performance of platinum (Pt) and palladium (Pd) nanowires (NWs) using first-principles density functional calculations. Pt and Pd NWs were found to be dynamically stable for both strain-free and strained situations. Their cohesive energy and magnetic moment showed decrease and increase, respectively, with an increase in tensile Lagrangian strain (2% to 10%) in the (001) plane. Furthermore, we analyzed the thermodynamic properties using the quasi-harmonic approximation (QHA), heat capacity and internal energy of both NWs originating at 0 K, where their internal energy (E) remained high. For the NWs with the (100) and (010) planes, magnetism exist in the strain-free case, whereas it decreases rapidly on increasing the value of strain. Our results predict the excellent stability, colossal magnetism, and thermoelectric properties of the studied NWs; therefore, these NWs can be used as potential thermoelectric materials for device applications.
RESUMEN
We present the electronic, magnetic, thermoelectric and optical properties of ferromagnetic metal nanowires (NWs) made of iron (Fe) and cobalt (Co) atoms using a first principles approach. Each property has been investigated as a function of atomic arrangement and nanowire diameter. Magnetic anisotropy is predicted originating from the spin-orbit coupling. Significant delocalization of electronic charge density is found in Fe nanowires with the increase in nanowire diameter, while the charge distribution anisotropy manifests in all the studied nanowire configurations. The thermoelectric properties exhibit strong coupling to the nanowire configuration and diameter. Thermal conductivity shows large divergence from the bulk iron and cobalt. The optical properties show the strongest increase for nanowires with large diameters. The theoretical modeling of configuration- and diameter-dependent nanowire properties serves as a cornerstone for future utilization of nanowire films in a variety of applications.
RESUMEN
Cationic alteration related to a sodium super ion conductor (NASICON)-structured Na3V2(PO4)3 (NVP) is an effective strategy for formulating high-energy and stable cathodes for sodium-ion batteries (SIBs). In this study, we altered the structure of NVP with dual cations, namely, Cr and Fe, to develop Na3V1.5Cr0.4Fe0.1(PO4)3 cathodes for SIBs with high-rate capability (â¼71 mAh g-1 at 100 C) and an extreme cycle life output (â¼75 mAh g-1 with 95% capacity retention for 10,000 cycles). These excellent electrochemical properties can be ascribed to the synergistic effects of Cr and Fe in the NVP structure, as verified experimentally and theoretically. Therefore, the proposed cosubstitution method can enhance the performance of SIBs by improving their structural stability, electronic conductivity, and phase-change behavior.
RESUMEN
Among lithium-sulfur (Li-S) battery materials, sulfurized polyacrylonitrile (SPAN) has attracted substantial attention as a cathode material owing to its potential to bypass the problematic polysulfide formation and shuttling effect. Carbonate-based electrolytes have been eschewed compared with ether-based electrolytes because of their poor compatibility with Li metal anodes. In this work, we design and study an electrolyte comprising 0.8 M of lithium bis(trifluoromethanesulfonyl)imide, 0.2 M of lithium difluoro(oxalate)borate, and 0.05 M of lithium hexafluorophosphate in ethyl methyl carbonate/fluoroethylene carbonate = 3:1 v/v solution in the Li-S battery coupled with a Li metal anode and SPAN cathode. The well-designed carbonate-based electrolyte effectively stabilizes both electrodes, delivering high Coulombic efficiencies with stable cyclability. Studies using operando optical microscopy and atomic force microscopy demonstrate that dense, uniform Li deposition is promoted to suppress dendrite growth even at a high current density. Operando Raman spectroscopy reveals a reversible Li+ storage behavior in the SPAN structure through the cleavage of disulfide bonds and their redimerization during lithiation and delithiation. As a result, the proposed Li-S battery delivers an overall capacity retention of 73.5% over 1000 cycles, with high Coulombic efficiencies over 99.9%.
RESUMEN
Recently, the two-dimensional (2D) material beryllium diphosphide (BeP2) has attracted significant attention for potential device applications due to its Dirac semimetal state, dynamic and thermal stability, and high carrier mobility. In this work, we investigated its electronic and optical properties under biaxial Lagrangian strain using density functional theory (DFT). Electronic band gaps and effective charge carrier mass were highly sensitive to the Lagrangian strain of BeP2 monolayer. The bandgaps of BeP2 varied from 0 eV to 0.30 eV for 2% to 8% strain, where the strain range is based on the final stable condition of the system. The absorption spectra for the dielectric properties show the highest absorption peaks in the infrared (IR) region. These abundant strain-dependent studies of the BeP2 monolayer provide guidelines for its application in infrared sensors and devices.