Diamond and Related Materials最新文献

The paper overviews experimental findings of the direct laser processing and surface microstructuring (texturing) of various diamond-like carbon films (a-C:H, ta-C, DLN, metal-doped DLN), aimed at improvements of their tribological and nanotribological properties. The nanosecond UV and femtosecond IR/visible pulsed lasers were applied in microprocessing of the films, focusing on high precision surface structuring with fs-laser pulses. The studies were concentrated on the following tasks: (i) surface graphitization in laser microstructuring of the films under different irradiation conditions, (ii) lubricated friction performance of DLN films micropatterned with UV ns and visible fs pulsed lasers, and (iii) nanoscale friction of laser-structured DLN and metal-doped DLN films examined with contact-mode atomic force microscopy. The important findings of our studies are related to fabrication of highly-precise microgroove/microcrater patterns on DLN films and improvements of frictional properties of the laser-structured films at the macro, micro and nanoscale. The surface microstructures improved the film properties under oil-lubricated sliding in dependence on their geometrical parameters (size, depth, period) and ambient temperature. The nanoscale friction behavior of laser-structured films was shown to be controlled by the surface graphitization, nanoscale roughness, capillary forces and wear of AFM tips during friction force imaging.

The adsorption behavior of fluoroquinolone (FQ) antibiotics, including ciprofloxacin (C₁₇H₁₈FN₃O₃), levofloxacin (C₁₈H₂₀FN₃O₄), moxifloxacin (C₂₁H₂₄FN₃O₄), delafloxacin (C₁₈H₁₂ClF₃N₄O₄) and ofloxacin (C₁₈H₂₀FN₃O₄) onto the surface of pristine and M-encapsulated B₁₂N₁₂ (M = Li, Na and K) nanocages are studied using dispersion corrected density functional theory (DFTD) calculations. The potential use of these nanomaterials for effective removal of FQ was systematically investigated in this study. Metal-encapsulated cages exhibit higher adsorption energies, making them favorable candidates for the removal of FQs from water. Results reveal that the desorption mechanism facilitated the efficient release of FQ from Li-B₁₂N₁₂ and Na-B₁₂N₁₂ nanocages in acidic medium. The outcomes provide a novel insight for future research on the adsorption mechanisms of pharmaceuticals on boron nitride-based nanomaterials.

Location of doping atoms in C₆₀ fullerene influences the desired fullerene applications. Doped C₆₀ fullerene with Beryllium and Lithium atoms is used in variable energy applications such as Lithium batteries, hydrogen storage and solar cells as well as they are produced in the interstellar medium. So far, the infrared (IR) spectra and vibrational modes of Li- and Be-doped fullerenes are still unknown, although IR spectroscopy can gather information about geometrical structure and assess the purity of a compound. Therefore, the IR spectra and vibrational modes of C₅₉X and C₆₀X fullerenes (X = Li, Be) are performed using density functional theory (DFT) and implementing 6-311G++(d) basis set within G09W program. The results show that IR spectroscopy exhibits a remarkable dependence on types of dopant atoms (Li, Be), types of doping (substituted doping, endohedral doping, exohedral doping) and types of bonds (C_P-C_h and C_h-C_h bonds). Remarkably, the endohedral and exohedral fullerenes C₆₀X can be distinguished by IR spectra which are found to be mainly attributed to the range of 1400–1600 cm⁻¹ and 500 cm⁻¹-1000 cm⁻¹, respectively. Whereas the substituted C₆₀X fullerene is attributed to range of 0–500 cm⁻¹ and 1000–1400 cm⁻¹ for the dopant Li and Be atoms, respectively. Therefore, infrared spectroscopy technology can be effectively adopted to identify the types of bonds and dopant atoms as well as the location of dopant atoms. Finally, the obtained infrared spectroscopic data can be also applied to correlate unidentified infrared bands with interstellar spectroscopic data.

The high hardness and wear resistance of polycrystalline diamond (PCD) micro tool make it widely used in precision machining of small parts of difficult-to-machine materials. The laser and grinding combined machining is an effective method to fabricate PCD micro tools, but the machining damage is difficult to control, which will reduce the cutting performance and tool life. Therefore, this paper aims to deeply study the damage forms and damage formation mechanisms during the fabrication process of PCD micro end mills, so as to improve the quality of the PCD micro mills. The laser and grinding combined machining experiments of PCD micro end mill are carried out, and the surface morphology characteristics and cutting edge of the mill are observed and analyzed. The influence of process parameters on the fabrication quality of PCD micro mill is investigated. The experimental results show that the high temperature of the laser is the main factor causing damage, which causes the melting and oxidation of the surface material, and further forms micro cracks, pits and oxidized attachments on the PCD mill. In addition, diamond phase transformation and excessive removal of cobalt-rich layer will also lead to graphitization and micro-grooves on the mill surface. For the grinding process, the cutting edge is fractured by the impact of the wheel, resulting in micro notches, micro pits and micro cracks. The intergranular crack expansion of PCD material and cleavage breakage of diamond particles are the main causes of micro cracks and micro pits on the mill surface. In addition, the chips will also scratch the tool surface to produce micro nicks and cause the chips coating on the rake face. The research results are helpful to further understand the damage mechanism of laser and grinding combined machining PCD mill, so as to improve the fabrication quality of micro tools.

Silicon complementary metal oxide semiconductor (CMOS) technology drives the integrated circuit industry due to its energy efficiency. The narrow bandgap of silicon has led to the development of wide bandgap semiconductor materials, such as diamond, favored in power electronics, radiofrequency and extreme environment applications. Here we have established a model of the diamond CMOS logic inverter for the first time and successfully simulated the static and dynamic characteristics. The simulated physical model and relevant model parameters are well calibrated with experimental data of diamond p-FET in the literature. The simulation results demonstrate that the all-diamond CMOS inverters possess rail-to-rail operation and excellent inversion characteristics, with the peak gain of 83 V/V, the transition region of 0.25 V, and the noise margins for low and high level of 2.44 V and 2.26 V under V_DD = 5 V. Particularly, all-diamond CMOS inverters have improved performance compared to the diamond-GaN inverters, operating at 500 °C with well-preserved inversion characteristics. This thermal reliability indicates that diamond CMOS inverters can be better monolithically integrated for applications in high-temperature environments in the future.

We study the electronic, phonon vibration, thermal, and optical properties of an orthorhombic BC₂N structure with two different space groups, PMM2 and P2221. The two phases are identified as BC₂N-1 and BC₂N-2, respectively. The calculations of the phonon band structure and the molecular dynamic simulations confirm that both phases of BC₂N are dynamically and thermally stable. BC₂N-2 has a higher symmetry than BC₂N-1 causing more degenerate energy levels around the Fermi energy leading a larger band gap of BC₂N-2. The BC₂N-2 has also more phonon bands as it has more atoms per unit-cell leading to a higher phonon density of states and heat capacity. However, the group velocity of both phases is similar, but the lattice thermal conductivity of BC₂N-2 is higher due to its high heat capacity. Furthermore, both phases of BC₂N have optical response in the visible light region with different refractive indices and reflectivities. Finally, most of the physical properties of the orthorhombic BC₂N are compared to other phases of the structure such as the hexagonal monolayer, the nanoribbon, the nanotube, and the porous tetragonal shape.

The MXenes-based two-dimensional (2D) materials have become a hotspot of recent research due to their exciting physical behavior. In this first-principles study, we investigate the Sc₂TlC MAX phase and its 2D derivatives, focusing on the transformation of Sc₂TlC into a Sc₂C 2D sheet and the subsequent surface functionalization of Sc₂C with oxygen (O) and fluorine (F). Investigations of the electronic structures reveal that the Sc₂TlC MAX phase is metallic and nonmagnetic, while the conversion to the Sc₂C pristine monolayer and surface functionalized Sc₂CO₂ induces significant changes in its electronic structure but retains its metallic behavior. On the other hand, functionalization of the Sc₂C monolayer with F₂ (such as Sc₂CF₂) evolves semiconductor-like behavior with an energy gap of magnitude 1.325 eV for the up-spin state and 1.227 eV for the down-spin state. The optimal optical absorption of ultraviolet (UV) for Sc₂TlC MAX phase and Sc₂C, Sc₂CO₂, and Sc₂CF₂ MXenes have been found as 13.8 × 10⁵ cm⁻¹, 49.17 × 10⁴ cm⁻¹, 81.39 × 10⁴ cm⁻¹, and 69. ×10⁴ cm⁻¹, respectively. Investigations of the optical properties reveal considerable reflection and absorption capabilities, particularly upon exposure to low-energy light photons, suggesting their potential for optoelectronic and energy harvesting applications.

Due to its inherent electrochemical catalytic activity, molybdenum sulfide (MoS₂) is a potential electrocatalyst for hydrogen evolution reaction (HER). However, the limited exposure of its active sites resulting from the easy stacking of nanosheets and inert basal plane hampered its optimal catalytic activity. Herein, we developed a novel facile hydrothermal method to prepare phosphorus-doped MoS₂ nanosheets anchored on agar-derived 3D nitrogen-doped porous carbon (P-MoS₂/NC). The synthesized P-MoS₂/NC electrocatalyst possesses high HER catalytic activity with a low overpotential of 167 mV at 10 mA cm⁻² and a small Tafel slope of 45 mV dec⁻¹. The excellent performance is attributed to the unique 3D network carbon structure, which avoids the stacking of the MoS₂ sheets resulting in more exposed active sites. Additionally, the P atom introduced on the surface of MoS₂ sheets successfully activated the in-plane inertness. This work provides an efficient strategy for designing and preparing high-quality catalysts with enhanced electrocatalytic HER activity.

Energy is the basic need of this modern era and water splitting is the best known renewable source of energy. Designing an effective, high performing and durable electrocatalyst has become a serious endeavour to enhance water-splitting efficiency. For this purpose, a hydrothermal method was used to produce a non-toxic, environmentally friendly and cost-effective rGO/ZnSnO₃, a composite material to improve water oxidation. For this, various analytical approaches were used to investigate the structural, textural, compositional, thermal and morphological features of the reported materials. The electrochemical properties of the rGO/ZnSnO₃ nanohybrid was also analyzed by a three-electrode setup in a 1 M potassium hydroxide (KOH) and the resulting nanohybrid exhibited exceptionally small overpotential (212 mV) at an ideal current density (j) of 10 mA/cm². The larger electrochemical surface area (ECSA) value 506.25 cm², minimum charge transfer resistance (R_ct) 0.18 Ω and remarkable stability around 20 h revealed that the produced composite material exhibited excellent potential for OER. Further examination revealed a significantly low Tafel value (37 mV/dec), suggesting that the rGO/ZnSnO₃ nanohybrid possesses improved electrocatalytic efficiency and fast reaction kinetics. The nanohybrid mentioned above (rGO/ZnSnO₃) shows significant potential for electrolysis of water and other electrochemical processes attributed to its considerable surface area, various active sites, exceptional stability, rapid electron mobility, low resistivity and favourable electrical conductivity.

The focus on advancing armor systems, combining enhanced ballistic resistance properties with reduced weight, has gained considerable attention as nations recognize the need to fortify sophisticated self-defense mechanisms against prospective military confrontations and threats. The evolving landscape of protective body armor necessitates innovative materials that combine flexibility with high-strength performance. This review article delves into the advancements and potential of carbon nanotubes (CNTs) based soft body armor materials, assessing their structural, mechanical, and protective properties. Beginning with an overview of the unique characteristics of CNTs that make them promising candidates for soft armor applications, the paper scrutinizes the incorporation of CNTs via different techniques to prepare composites for ballistic protection. These methods includes dispersion of CNTs within polymer matrix to impregnate ballistic fabrics, interleaving of CNTs macroform in between the layers of fibers, growth of CNTs over the surface of fabrics, and CNTs based fabrics. Additionally, the review highlights recent experimental studies and computational models, providing insight into the initial and residual velocity, absorbed energy, ballistic limit, and back face deformation characteristics of armor materials incorporating CNTs. Moreover, a comprehensive analysis of the challenges, such as scalability, cost-effectiveness, and environmental concerns associated with CNTs integration, is presented. By consolidating insights from diverse research endeavors, this review aims to offer a comprehensive insight into CNTs-based soft body armors, elucidating their potential to redefine the future of protective materials for both defense and civilian applications.