MXenes are a versatile family of two-dimensional materials whose magnetic properties can be tailored through transition-metal substitution, opening promising opportunities for spintronic and magnetic sensing applications. In this work, we investigate the effect of vanadium doping on the magnetic properties of Ti 2C MXenes by combining first-principles calculations and Monte Carlo simulations. Our results show that pristine Ti 2C exhibits ferromagnetic (FM) intralayer and antiferromagnetic (AFM) interlayer exchange interactions, leading to a compensated AFM ground state. The incorporation of vanadium locally modifies the exchange pathways by introducing FM Ti-V and V-V couplings, while preserving the global AFM ordering. Although single V substitution induces only moderate changes in the magnetic response, double-doped configurations exhibit a significantly enhanced field-induced magnetization and magnetic susceptibility, evidencing a cooperative effect between multiple V centers. Among the studied configurations, the o-Ti 6V 2C 4 arrangement shows the strongest magnetic response, highlighting the importance of the relative dopant distribution in controlling the exchange topology. The enhanced low-field susceptibility persists up to room temperature, demonstrating the robustness of the V-induced magnetic perturbations against thermal fluctuations. These findings reveal that both dopant concentration and geometric distribution provide effective tuning parameters for engineering the magnetic functionality of MXenes, establishing multi-metallic Ti 2C-based systems as promising candidates for future spintronic devices.
Two-dimensional transition metal carbides have emerged as a material class of broad scientific and technological interest, yet terminological ambiguity conflates two fundamentally distinct systems: MXenes and ultrathin carbide crystals. Here, we provide a systematic, side-by-side comparison of these two material families using molybdenum carbide (Mo2C) as a model system, chosen because it is uniquely accessible in both forms: as termination-stabilized Mo2CTx MXene obtained by selective etching of Mo2Ga2C, and as single-crystalline ultrathin films grown by chemical vapor deposition (CVD) on Cu/Mo substrates. Through parallel analysis of crystal structure, morphology, vibrational properties, and surface chemistry, we demonstrate that the two systems differ in many aspects. CVD-grown Mo2C, with lateral dimensions up to similar to 100 & micro;m, exhibits well-faceted crystal morphology, crystallizes in the thermodynamically stable orthorhombic alpha-phase, and shows sharp x-ray diffraction peaks indicative of a strong preferred orientation, with the (200) planes aligned parallel to the surface, analogous to the (00l) planes in layered MXenes. In contrast, Mo2CTx MXene consists of subnanometer-thin flakes with lateral dimensions of similar to 3 & micro;m, exhibits broad (00l) diffraction peaks, and features termination-rich surface chemistry, where electronegative T-x groups (predominantly = O) modulate both Mo 3d and C 1s core-level binding energies. By combining Raman spectroscopy with first-principles DFT calculations, we assign the vibrational modes in both systems and identify a termination-induced out-of-plane A(1g) mode at 476 cm(-1) for Mo2CTx MXene, which is absent in the pristine carbide. Based on these distinctions, we provide a synthesis-rooted comparative reference and terminology guide for distinguishing MAX-derived MXenes from CVD-grown ultrathin transition metal carbides.
We consider a (2+1)-dimensional variable-coefficient version of the Mel'nikov system and analyze soliton dynamics under time-dependent parameter modulation. Variable coefficients are of interest in physical settings involving nonuniform media or managed dispersion/nonlinearity, where the evolution of coherent structures can differ markedly from that in constant-parameter models. Within Hirota's bilinear formalism we derive the bilinear equations and obtain the associated coefficient requirement that ensures the bilinearization (including gamma 1(t) = gamma 2(t)). This enables us to construct explicit one and two-soliton solutions in closed form by means of perturbation expansions. Using these expressions, we illustrate typical spatiotemporal behaviors for representative coefficient choices and show how the coefficients tune soliton trajectories and amplitude evolution. Moreover, we derive long-time asymptotic expressions of the two-soliton solution as t -> +/- infinity, which clearly separate the incoming and outgoing states and describe the interaction outcome analytically. Our results provide a concise framework for exploring managed soliton interactions in variable environments.
The increasing demand for multifunctional materials, capable of addressing challenges in energy, environmental sustainability, and electronics, has stimulated considerable interest in double perovskite oxides. In this regard, spin-polarize density functional theory is employed to conduct a comprehensive study of Sr 2NiMo 1-xW xO 6 ( x = 0.0, 0.5, and 1.0), focusing on its structural, mechanical, thermodynamic, electronic/magnetic, photocatalytic, and thermoelectric (TE) aspects. All investigated compositions are found to crystallize in a tetragonal phase, exhibiting strong thermodynamic, dynamical, and mechanical stabilities. The calculated electronic structure reveals a semiconducting indirect band gap of 2.08/1.61/2.54 eV for x= 0.0/0.5/1.0, demonstrating effective control of electronic features via W-incorporation. Additionally, all the structures hold antiferromagnetic spin orderings due to favorable anti-alignment of Ni spin moments. The analysis of band edge alignment reveals that x= 0.0 and 1.0 compositions are capable of driving both hydrogen and oxygen evolution reactions, making them viable for water splitting, whereas x= 0.5 remains active only for oxidation. Thermoelectric analysis further reveals excellent high-temperature performance owing to a high figure of merit of 0.72/0.73/0.82 at 1000 K for x = 0.0/0.5/1.0, supported by a high Seebeck coefficient (172/180/184 mu & centerdot;V & centerdot;K -1) and reduced lattice thermal conductivity (0.22/0.18/0.15 W & centerdot;m -1 & centerdot;K -1). Thus, these findings demonstrate that W substituted at the Mo-site effectively tunes the multifunctional responses of Sr 2NiMoO 6, establishing it as a strong candidate for generating hydrogen, capturing waste heat, and producing TE power.
Ionic wind propulsion represents a quiet, low-noise thrust generation technique. This work experimentally explores how collector mesh geometry and emitter needle layout affect thrust characteristics. Test results show thrust varies non-monotonically with mesh density, resulting from the counterbalancing effects of electric field reinforcement and aerodynamic drag loss. Multiple needle layouts deliver comparably high thrust within the tested range, one layout exhibiting stable performance across all test voltages is chosen for prototype fabrication. A miniature boat fitted with two thrusters is built for preliminary proof of concept testing, which realizes controllable straight and turning motion. This study provides tentative empirical guidance for the structural design of small surface ionic wind thrusters under the present experimental configuration.
