Diamond and Related Materials最新文献

Among the array of strategies deployed to combat corrosion, coating protection stands out as a method both simple and cost-effective. In this paper, paraphenylenediamine (PPDA) was used to modify graphene oxide (GO) to obtain a nano-filler with excellent dispersibility and barrier properties. Integration of this PPDA modified reduced graphene oxide (FRGO) into the epoxy resin matrix yields a composite coating boasting remarkable resistance against corrosion. Through a comprehensive analysis involving FT-IR, Raman, XPS, and XRD, the optimal reduction temperature for GO was discerned to be 500 °C. The optimal modified addition amount of PPDA to GO is 1:1. Subsequent to the preparation of PPDA modified reduced graphene oxide composite coating composite coatings featuring varied concentrations, an assessment of the coatings' corrosion resistance ensued through electrochemical workstation analysis and salt spray testing. After immersed in a 3.5 wt% NaCl solution for 120 h, the low frequency impedance modulus value (|Z|_{0.01 Hz}) of composite coating with 0.1 wt% FRGO reached a peak value of 1.94 × 10⁹ Ω·cm². Even after immersion for 240 h, the |Z|_{0.01 Hz} remained significantly high at 4.01 × 10⁸ Ω·cm², indicating a significant improvement in corrosion resistance.

Polycrystalline diamond is mostly pressed at high temperature in actual production. Thus, circumferential strain data of powder moulding are difficult to collect at high temperatures. As a result, the parameters of DPC constitutive model cannot be obtained using conventional testing methods. Moreover, the use of conventional equipment to test the mechanical properties becomes challenging because of the extremely high hardness and compressive strength of polycrystalline diamond. Sintering tests of polycrystalline diamond were carried out at 1360 °C and 223 Mpa using the spark plasma sintering (SPS) method, and displacement–load data were obtained. The spark plasma sintering experiment of polycrystalline diamond under high temperature and pressure was carried out using the Drucker Prager/Cap (DPC) model with relative density to obtain accurate displacement and load numbers. Combined with USDFLD subroutine, the experiment of polycrystalline diamond sintering was simulated on ABAQUS. Based on the complex method, ABAQUS-MATLAB platform is used for the reverse identification of constitutive parameters. The constitutive model parameters of polycrystalline diamond sintering process are obtained. This approach can describe the mechanical behaviour of polycrystalline diamond powder in the sintering process. In addition, the inverse identification method of the constitutive model in the sintering process of polycrystalline diamond based on ABAQUS and MATLAB solves the problem on the difficulty to observe the sintering of polycrystalline diamond under high temperature and high-pressure environment. Moreover, the constitutive model parameters of the sintering process are obtained, thereby reducing the cost and condition constraints in the actual experiment. A novel technique involves obtaining powder constitutive parameters at high temperature from the sintering point of view. This approach is important to simulate sintering of polycrystalline diamond and its composite products.

Foundation item

National Natural Science Foundation of China (Grant No. 52075438), the Key Research and Development Program of Shanxi Province of China (Grant No. 2020GY-106), the Open Project of State Key Laboratory for Manufacturing Systems Engineering (Grant No. sklms2020010), and the Open Research Fund of Key Laboratory of Oil & Gas Equipment of Ministry of Education (Grant No. OGE201702-110).

Utilizing classical molecular dynamics with the precise machine-learning interatomic potential MTP, we investigated the high-temperature (3000–3500 K) dynamics of NV and N₂V centers in the presence of additional free vacancies. We propose a novel mechanism for nitrogen diffusion in diamond, which involves the intermediate step of additional vacancies being absorbed by a NV center. The simulation results align with the experimentally observed transformations of NV centers into H1b and H1c in IaAB-diamond under 4.7-μm femtosecond-laser irradiation.

A set of 28 uncommon pink diamonds with yellow color zones are identified among thousands of natural pink diamonds examined. The pink color in these diamonds is caused by the 550 nm absorption band associated with plastic deformation, and is concentrated along straight lamellae (also known as deformation lines). These pink diamonds are type Ia with nitrogen concentrations ranging from 118 to 313 ppma, predominantly as A-centers, i.e., type IaA ≫ B (proportion of B-center < 10 %) to IaA > B (proportion of B-center = 11–26 %).

Yellow color zones are observed on or beneath the surface of these faceted pink diamonds. Yellow fluorescence and occasionally yellow phosphorescence excited by long-wave (365 nm) or deep UV (<225 nm), corresponding to the yellow color zones, are commonly observed in yellow diamonds colored by the 480 nm absorption band. PL mapping conducted on the diamond surface and along the depth of the pink diamonds in this study reveals that the yellow color zones have features associated with the 480 nm absorption band. Some of these features are associated with nickel-related defects, and are only detected within the yellow color zones. This suggests that the yellow color zones formed in a different growth episode or from a different diamond-forming fluid than the remaining volume of the diamond with pink body color. Post-growth plastic deformation created defects giving rise to the 550 nm absorption band, producing a pink body color to diamond that was presumably colorless, and producing brown color in zones that may have had pre-existing yellow color. Three diamonds in this study contain eclogitic mineral inclusions, indicating that they formed in association with mantle eclogite, prior to plastic deformation.

Biomass is widely applied in catalysis and energy storage as an excellent carbon source for porous carbon materials due to its abundant, diverse, renewable, low-cost, and non-polluting. In this work, the low-cost Pleurotus eryngii were used as a carbon source to fabricate high-performance porous carbon materials and applied to the treatment of phosphorus-containing wastewater and the oxygen reduction electrocatalytic reaction (ORR). The adsorption of phosphorus up to 193 mg/g was achieved by loading ZnO nanoparticles onto Pleurotus eryngii-based porous carbon materials (Zn-PE). Moreover, the adsorbed Zn-PE was treated by a simple impregnation‑carbonization to obtain iron-oxide loaded P doped Pleurotus eryngii-based porous carbon materials (Fe-PE-P) and applied for ORR in fuel cells. The Fe-PE-P exhibited excellent electrocatalytic activity (J_L = 5.45 mA cm⁻², E_1/2 = 0.81 V) and the half-wave potential of the catalyst was only negatively shifted by 25 mV after 3000 cycles of CV, indicating that the catalyst also has good stability. This work not only provides a novel strategy for the preparation of highly catalytic active biomass-based electrocatalysts, but also broadens the high-value utilization of biomass in different fields.

A multifunctional terahertz (THz) metasurface for broadband absorption and wavefront manipulation based on graphene and vanadium dioxide (VO₂) is proposed in this paper. While VO₂ is in the metallic state, a broadband absorber is obtained. The bandwidth of over 90 % absorption rate is 1.11 THz. By adjusting graphene Fermi level, absorption bandwidth dynamical tunning is realized. The modulation depth for bandwidth tuning is 64 %, and the drift of center frequency is slight. Also, an equivalent circuit model is explored to explain the absorption mechanism. While VO₂ is in the insulating state, the metasurface acts as a deflected vortex beam generator. Based on the convolutional operations, the functionalities of deflector and spiral phase plate are integrated into the proposed metasurface. Through precise phase arrangement based on the rotation angle of the metal resonator, arbitrary manipulation of transmitted vortex beams can be performed in the range of 0.75–0.85 THz. We also develop a 1D focusing metalen operating at different frequencies, which exhibits remarkable subwavelength focusing capabilities. Thus, multifuncitons including broadband absorption, beam deflection, vortex beam generation, and focusing metalen are integrated into one single metasurface successfully. It holds the great potential in diverse applications, such as optical stealth, beam generation, and holographic technique in the future.

A novel electrochemical glucose biosensor was fabricated using the casting technique of multi-walled carbon nanotubes (MWCNT)/polyaniline (PANI)/carboxymethyl chitosan (CCs) as an appropriate matrix for glucose oxidase (GOx) immobilization. The differential pulse voltammetry (DPV) study results demonstrated a wide linear range of glucose concentrations from 10 nM to 10 μM, with a limit of detection (LOD) of 1.41 μM and a sensitivity of 1791 μA mM⁻¹ cm⁻². Additionally, cyclic voltammetry (CV) data analysis yielded a heterogeneous rate constant (ks) of 0.3 s⁻¹ and an apparent Michaelis-Menten constant ($k_m^{\mathrm{app}}$) of 18 nM. Over a 30-day period, the biosensor exhibited exceptional repeatability and stability, maintaining approximately 84.58 % of its initial performance for storage stability at 4 °C and 82.13 % for functional stability. Moreover, the reproducibility, interference resistance, and overall performance of the biosensor were assessed, demonstrating its capability to accurately measure glucose levels in human serum with a relative standard deviation (RSD) of <5 %.

Solid lubricating coatings which offer and maintain anti-friction and anti-wear are urging to develop in the advanced technology applications over a wide range of temperatures. The h-BN composite coatings on the Inconel X750 superalloy is prepared by spark plasma sintering (SPS) technology to obtain low friction and wear over a broad temperature ranging from room temperature (RT) to 800 °C using a high temperature rotary tribometer. The influence of the contents of h-BN and CePO₄ powders of the tribological properties of the composite coatings was studied systemically under different temperatures. The experimental results show that the composite coatings with 20 wt% h-BN show excellent high temperature anti-friction behaviors. Coefficient of friction (CoF) of the composite coatings with 20 wt% h-BN with CePO₄ powder is lowest about 0.12 among the composite coatings at 800 °C. The CePO₄ powders are helpful to improve the sintering behaviors and reduce the wear rate of the composite coatings at elevated temperature. The synergistic lubrication mechanism of h-BN and CePO₄ of the composite coatings are investigated systematically. The high temperature anti-friction and anti-wear mechanism of the composite coatings is due to the formation of a layered gradient lubrication film on the worn surface.

The adjustment of the electron distribution of 2D metal-organic frameworks (2D-MOFs), as a hot anode candidate for electrocatalytic oxidation, is crucial for its application. In this work, a new electron distribution was achieved with dual-ligand connection and graphene oxide (GO) loading and the complex of dual-ligand 2D-MOF/GO (Co-IH/GO) exhibit faster electron transfer efficiency (Rct = 62.5) and more active sites (I_D/I_G = 1.01). Co-IH/GO demonstrated excellent electrocatalytic performance and achieved 100 % electrocatalytic degradation of bisphenol A (BPA) within 10 min. In addition, superior properties of stability, temperature tolerance, and pH tolerance were achieved, after 5 cycles of degradation, the catalyst was able to maintain 100 % degradation efficiency, Capable of maintaining good degradation performance over a temperature range of 25 °C–45 °C and a wide pH range of pH = 5–11. Both experimental and electron paramagnetic resonance analysis results indicated that ¹O₂ acted as the dominant active substrate. With the involvement of Cl⁻ in marine wastewater, activated chlorine was also generated during the reaction, which contributed to fast BPA degradation. Furthermore, the established dual-ligand 2D-MOF/GO electrocatalytic system exhibited superior activity for the degradation of dyes and complex microflora, while the solar-driven degradation experiment shed light on the independence of fossil and stationary sources of energy.

The aim of this research is to fabricate plane-type devices possessing straight longer axons individually and regularly arrayed for evaluating the axon behavior of neuronal cells in vitro toward the development of brain-on-chip models, utilizing diamond-like carbon (DLC) thin film patterning deposition. The DLC thin films were deposited on a polydimethylsiloxane (PDMS) plate with a plasma CVD method under four conditions, with/without stretching of and a metal mask on the plate, and the fabricated substrates were used to culture human neuroblastoma cells, SH-SY5Y, for up to 21 days. In the case of the stretched PDMS plate with the mask covered, extremely peculiar structures were created on the DLC deposited areas of the substrate, with multiple 20 μm-thick rope-like axons aligned straight at the length of millimeter-level at intervals of about 200 μm. It was found that the rope-like axons consisted of plenty of thinner axons, and were supported by the clusters of cells at both ends. It was strongly suggested that the linear wrinkle structures created by the DLC deposition played an important role in the formation of the rope-like axons. This device can be fabricated by means of not conventional lithographic techniques, but only DLC thin film deposition.