Ar Gas Flow Rate Research Articles

INFLUENCE OF THE RATIO OF GASE CONSUMPTION N<sub>2</sub>/Ar AND MAGNETRON POWER ON THE DENSITY AND STOICHIOMETRIC COMPOSITION OF TIN<sub>X</sub> FILMS SYNTHESIZED BY MAGNETRON SPUTTERING METHOD

The films of titanium nitride were deposited by direct current magnetron sputtering on the surface of singlecrystalline silicon samples in an Ar-N2 atmosphere for use as a diffusion barrier. The thickness and density of films were measured by X-ray reflectometry. The design of the MAGNA TM-200-01 installation has been changed to increase the supply of nitrogen into the chamber. The influences of sputtering conditions, including the flow rate of nitrogen and argon gases and their N2 /Ar ratios in the range of 1–60 in the chamber, magnetron power of 690–1400 W on the formation of TiNx films, their density and stoichiometric composition, were studied. It is shown that the value of x is affected not only by the N2 /Ar gas flow rate ratio, but also by the magnetron power. At the sputtering parameters 1200 W, N2 /Ar = 30, 0.8 Pa, 320 s and 100°C, a maximum density of 5.247 g/cm3 of a film was achieved, which corresponds to the composition TiN0.786 = Ti56N44. The presence of nanocrystalline film of titanium nitride and the absence of a nanocrystalline titanium phase were confirmed by photographic X-ray diffraction. It was found that for the synthesis of titanium nitride as close as possible to the stoichiometric composition TiN0.770 - TiN0.786, it is necessary to use magnetron power in the range of 900–1200 W, nitrogen rate of 30 cm3 /min with low argon flows of 1–5 cm3 /min.

Optimizing plasma-activated water for enhanced microbial control in agricultural produce processing

The study utilized a pinhole plasma jet discharge system to generate plasma-activated water (PAW) for the removal of microbes on bird's eye chili. Optimal conditions for PAW generation were determined using response surface methodology, achieving maximum microbial inactivation. The novelty of this study lies in designing a PAW system model for agricultural cooperatives using the Quality Function Deployment (QFD) methodology, which integrates customer and engineer/designer perspectives. The results demonstrate a maximum 82.54% microbial removal rate on bird's eye chili under optimal conditions (e.g., exposure time = 20 min, Ar gas flow rate = 5 L/min, and O2 mixture = 2% Ar gas), indicating effective antimicrobial activity of plasma-activated water. Furthermore, a model of the PAW system for agricultural cooperatives, including cost and electrical power usage estimates, is proposed based on the correlation matrix of QFD. This conceptual PAW model for agricultural cooperatives warrants further investigation to assess its consistency in sterilization efficiency and long-term effects on treated agricultural products.

Synthesis of nano-silicon carbide by SiO–C reaction

Carbon black has been successfully converted into silicon carbide by reacting it with SiO vapor at 1500 °C under Ar gas environment. The influence of reaction temperature, duration and Ar gas flow rate on the final product was examined. The structural and microstructural property of synthesized SiC was characterized using X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Micrographs of synthesized SiC showed that the final product was an agglomeration of SiC nano-powder of 50–500 nm size and nano-whiskers/fibres having a diameter of 50–500 nm and lengths in 0.1–10 μm depending on Ar gas flow rate. The higher conversion of C into SiC was observed at 1500 °C with Ar gas flow rate ∼250 ml/min.

Numerical Modelling and Simulation for Sliding Wear Effect with Microstructural Evolution of Sputtered Titanium Carbide Thin Film on Metallic Materials

Titanium carbide materials are introduced into manufacturing industries for the reinforcement and surface protection of base materials due to their substantial ability to withstand severe environments, which include sliding wear, corrosion, and mechanical failures. A thin film of titanium carbide (TiC) is coated onto brass and copper substrates using the radio frequency magnetron sputtering (RFMS) deposition method. The coating process is carried out at constant processing parameters, which include a sputtering power of 200 W, a temperature of 80 °C, a deposition time of 180 min, and an argon (Ar) gas flow rate at 10 standard cubic centimetres per minute (SCCM). The coating, together with the base materials, is modelled and its behaviours are simulated using ANSYS Workbench R19.2 Academic, supported by Mechanical APDL solver for nonlinear finite element analysis (FEA). The deformation, equivalent stress–strain characteristics, and elastic–plastic properties of the coating are determined at applied loads of 60 N and 25 N and coefficients of friction (CoF) of 0.25 and 0.38 for the thin film deposition on brass and copper substrates. The sliding distance and the speed of the alloy steel ball used during the sliding wear operation are found to be 3 mm and 4 mm/s, respectively. The sliding wear modelling and simulation process are, however, designed for the ball-on-flat (BoF) wear technique with a dry sliding approach. Therefore, BoF wear simulations are also performed on titanium carbide–brass (TiC-Br) and titanium carbide–copper (TiC-Cu) conjugates for the evaluation of surface engineering applications such as cutting tools and in automotive, aerospace, thermomechanical, and biomedical fields. The ball used for the FEA wear simulation is made from alloy steel material (AISI 52100) with a radius of 3.175 mm.

Influence of the Gas Flow Rate on the Crack Formation of AlCoCrNi High-Entropy Metallic Film Fabricated Using Magnetron Sputtering

In the present study, the AlCoCrNi high-entropy metallic film was deposited on a Si wafer using a magnetron sputtering system. To capture the effects of the sputtering parameters on the microstructure and mechanical properties of the film, the flow rate of Ar gas injected into the chamber (5, 7, and 8 sccm) was controlled. All films were identified as being of BCC phase with compositions of near equiatomic proportions, regardless of the gas flow rates. Nano-scale clusters were observed on the surfaces of all films, and nano-cracks were found in the film deposited at the Ar gas flow rate of 8 sccm, unlike the films deposited at the gas flow rates of 5 and 7 sccm. Detailed microstructural analysis of film deposition at an Ar gas flow rate of 8 sccm indicated that the void boundaries contribute to the formation of nano-cracks. The nano-indentation results indicated that the Ar gas flow rate 5 sccm specimen, with the smallest cluster size at the topmost surface, showed the highest hardness (12.21 ± 1.05 GPa) and Young’s modulus (188.1 ± 11 GPa) values.

Growth and characterization of germanium telluride nanowires via vapor–liquid–solid mechanism

Phase-change materials (PCMs), which can transition reversibly between crystalline and amorphous phases, have shown great promise for next-generation memory devices due to their nonvolatility, rapid switching periods, and random-access capability. Several groups have investigated phase-change nanowires for memory applications in recent years. The ability to regulate the scale of nanostructures remains one of the most significant obstacles in nanoscience. Herein, we describe the growth and characterization of germanium telluride (GeTe) nanowires, which are essential for phase-change memory devices. GeTe nanowires were produced by combining thermal evaporation and vapor–liquid–solid (VLS) techniques, using 8 nm Au nanoparticles as the metal catalyst. The influence of various growth parameters, including inert gas flow rate, working pressure, growth temperature, growth duration, and growth substrate, was examined. Ar gas flow rate of 30 sccm and working pressure of 75 Torr produced the narrowest GeTe nanowires horizontally grown on a Si substrate. Using scanning electron microscopy, the dimensions, and morphology of GeTe nanowires were analyzed. Transmission electron microscopy and energy-dispersive x-ray spectroscopy were utilized to conduct structural and chemical analyses. Using a SiO2/Si substrate produced GeTe nanowires that were thicker and lengthier. The current–voltage characteristics of GeTe nanowires were investigated, confirming the amorphous nature of GeTe nanowires using conductive atomic force microscopy. In addition, the effects of the VLS mechanism and the Gibbs–Thomson effect were analyzed, which enables the optimization of nanowires for numerous applications, such as memory and reservoir computing.

Optimized APCVD method for synthesis of monolayer H-Phase VS2 crystals

Abstract Monolayer transition metal dichalcogenides, specifically H-phase vanadium disulfide (VS2), hold great significance as fundamental components for next-generation low-dimensional spintronic, optoelectronic, and future electronic devices. They also offer an opportunity to explore the intrinsic magnetic properties associated with monolayer H-phase VS2 crystals at room temperature. However, there have been limited experimental studies on synthesizing pure monolayer H-phase VS2 crystals using sodium metavanadate (NaVO3) and sulfur (S) as precursors for vanadium (V) and S, respectively. In this study, we present a facile atmospheric pressure chemical vapor deposition (APCVD) approach for the synthesizing monolayer H-phase VS2 crystals with a thickness of ∼0.7 nm. The lateral dimensions of monolayer VS2 crystals extends up to ∼26 µm. Additionally, we have modulated the growth parameters, such as the temperature of NaVO3 and the Ar gas flow rate, to obtain VS2 flakes with different sizes and morphologies. This significant advancement paves the way for the synthesis of monolayer H-phase VS2 crystals on SiO2/Si substrates using the APCVD technique.

Machine Learning-Assisted Synthesis of Two-Dimensional Materials.

Two-dimensional (2D) materials have intriguing physical and chemical properties, which exhibit promising applications in the fields of electronics, optoelectronics, as well as energy storage. However, the controllable synthesis of 2D materials is highly desirable but remains challenging. Machine learning (ML) facilitates the development of insights and discoveries from a large amount of data in a short time for the materials synthesis, which can significantly reduce the computational costs and shorten the development cycles. Based on this, taking the 2D material MoS2 as an example, the parameters of successfully synthesized materials by chemical vapor deposition (CVD) were explored through four ML algorithms: XGBoost, Support Vector Machine (SVM), Naïve Bayes (NB), and Multilayer Perceptron (MLP). Recall, specificity, accuracy, and other metrics were used to assess the performance of these four models. By comparison, XGBoost was the best performing model among all the models, with an average prediction accuracy of over 88% and a high area under the receiver operating characteristic (AUROC) reaching 0.91. And these findings showed that the reaction temperature (T) had a crucial influence on the growth of MoS2. Furthermore, the importance of the features in the growth mechanism of MoS2 was optimized, such as the reaction temperature (T), Ar gas flow rate (Rf), reaction time (t), and so on. The results demonstrated that ML assisted materials preparation can significantly minimize the time spent on exploration and trial-and-error, which provided perspectives in the preparation of 2D materials.

Controlled growth, characterization and field emission properties of high-quality WS2 nanowires by chemical vapor deposition

The controlled synthesis of high-quality WS2 nanowires exhibiting good physical and chemical properties is urgent and remains challenging. In this work, the WS2 nanowires are deposited on SiO2/Si substrates by chemical vapor deposition method using sulfides and halides with transition metal oxides as precursors. The effects of various experimental parameters, such as reaction temperature, Ar gas flow rate, holding time and substrate position, on the growth of WS2 nanowires are investigated. The detailed structural analyses indicate that the deposited WS2 nanowires with high crystalline quality possess the hexagonal 2H phase structure, and exhibit a smooth surface, uniform size and density distribution with a diameter of about 200 nm. Raman spectrum exhibits empirical characteristic peaks of in-plane vibration E12g(Г) and out-of-plane vibration A1g(Г) for the deposited WS2 nanowires. The formation mechanism of deposited 2H-WS2 nanowires is due to the preferential formation of WO3 nanowires during the reaction process, which is caused by further vulcanization to form the 2H-WS2 nanowires. Field emission property measurements are carried out based on the deposited WS2 nanowires, showing good turn-on field Eto of 2.4 V and threshold field Ethr of 6.8 V as well as excellent stability, which are attributed to their unique geometrical features.

CVD controlled preparation and growth mechanism of 2H-WS2 nanosheets

In this work, tungsten disulfide (WS2) nanosheets with good morphology are prepared by improved chemical vapor deposition (CVD) using a mixture of transition metal oxides and chalcogenide as precursors. By optimizing the growth conditions, the high-quality WS2 nanosheets with different morphologies, including large triangular, hexagonal, small triangular, terraced and spiral structures are obtained as the growth temperature of 850 °C, Ar gas flow rate of 50 sccm and holding time for 15 min. The detailed structural analyses by XRD, XPS, TEM and Raman measurements suggest that that the deposited WS2 nanosheets exhibit the 2H phase structure with high crystallization quality and uniform distribution of W and S elements. The formation of large triangular, hexagonal, and small triangular structures is related to the growth rate of different crystal planes of S atoms or W atoms. In addition, the formation of terraced and spiral stacking structures originates from the difference of supersaturation of precursors, which can be explained by the layer-by-layer stacking (LBL) growth and the spiral-dislocation-driven (SDD) mechanisms, respectively.

A chip-based supersonic microfluidic nebulizer for efficient sample introduction into inductively coupled plasma – Mass spectrometry

As the use of microfluidic chips for handling biological samples is increasing, so is the need for combining them with powerful analytical techniques for metal determination such as inductively-coupled plasma mass spectrometry (ICP-MS). So far, coupling a microfluidic chip to an ICP-MS has been demonstrated mainly through the use of conventional pneumatic micro-flow nebulizers. However, disadvantages associated with the use of such nebulizers entail dead volume issues and liquid suction exerted on the outlet channel of the chip. Herein, we propose that a microfluidic chip, bearing a pneumatic nozzle for liquid nebulization, has the potential to advance metal determination in chip-based ICP-MS. More specifically, we demonstrate for the first time that the coupling of a chip-based supersonic microfluidic nebulizer (chip-μf-Neb) to an ICP-MS can be conveniently achieved through the use of a spray chamber with a laminar flow makeup gas. Operation of the combined system was evaluated at low liquid flow rates across 0.5–20 μL min−1, while nebulization and makeup argon (Ar) gas flow rates were optimized with respect to maximizing indium (In) sensitivity and minimizing oxide formation; a maximum sensitivity of 40000 cps (μg L−1)−1 was achieved at 10 μL min−1. The system was further evaluated for its performance in single-particle analysis, featuring a transport efficiency of 46% for Ag nanoparticles. Finally, the capabilities for conducting single-cell analysis were demonstrated with the detection of 80Se and 75As in individual Chlamydomas reinhardtii cells, which were previously incubated in 20 μM of selenate and 300 μM of arsenate, respectively. Efficient operation at low liquid flow rates along with the absence of self-aspiration render this nebulizer a promising tool for combining the powerful field of microfluidics with metal quantitation by means of ICP-MS.

Effects of Electron Irradiation on the Properties of ZnO/Au/ZnO Films Deposited on Poly-Imide Substrates

Transparent and conductive ZnO 50 nm/Au 8 nm/ZnO 50 nm tri-layer films were deposited on poly-imide films by radio frequency (RF) and direct current (DC) magnetron sputtering at room temperature, and then the effect of electron irradiation on the crystallization, electrical resistivity and optical properties of the films was considered with X-ray diffraction, UV-visible spectrometer, Atomic force microscope and Hall measurement system. All the films were deposited at a fixed sputtering power, Ar gas flow rate, and distance between target and substrate, while the post-deposition electron irradiation energy was varied from 300 to 900 eV. The electron irradiated films exhibited a flatter surface than the as deposited films that were not electron irradiated, and the XRD patterns also revealed that the electron irradiated films had larger grain sizes than that of as deposited films. The films electron irradiated at 900 eV also showed a higher visible transmittance of 79.8% and a lower sheet resistance of 56.0 Ω/□. Post-deposition films electron irradiated at 900 eV showed a higher figure of merit of 1.86×10-3 Ω-1 than that of the as deposited film of 1.29×10-3 Ω-1. The optical band gap was also enhanced by electron irradiation. The films electron irradiated at 900 eV showed a higher optical band gap of 4.07 eV.

Testing and Analysis of Ar Plasma Processed LED at Different Ar Gas Flow Rate and Process Time: Thermal and Surface Verification

Testing and Analysis of Ar Plasma Processed LED at Different Ar Gas Flow Rate and Process Time: Thermal and Surface Verification

Determination and speciation of selenium in water samples collected from Muğla (Turkey) province by hydride generation atomic absorption spectrometry

In this work, determination of selenium in various water samples was done by using hydride generation atomic absorption spectrometry. The most appropriate values of HCl concentration, NaBH4 concentration, NaOH concentration, flow rate of argon and flow rate of waste solution were determined. The optimum concentration of the HCl, NaBH4 and NaOH solutions were found to be 7.0 mol L−1, 1.0% and 0.75%, respectively. The optimum flow rate of Ar gas and waste solution were also found to be 100.9 mL min−1 and 4.0 mL min−1, respectively. Values of LOD and LOQ were calculated separately for total Se and Se(IV). LOD and LOQ values were calculated 0.56 μg L−1, 1.87 μg L−1 for total Se and 0.72 μg L−1, 2.40 μg L−1 for Se(IV), respectively. The precision was evaluated by relative standard deviation (RSD%) was found to be 3.5% for total Se and 3.1% for Se(IV) (n = 11). A standard reference material (NIST 1643e) was used in order to check the accuracy of the proposed method. There was a good agreement between certified and found values for standard reference material. The method was applied to the analysis of total Se and Se(IV) concentrations in tap water samples collected from the various regions of Muğla. Proposed method showed spike recovery ranges from 92% to 116% in water samples.

Optimization of Atmospheric Pressure Plasma Jet with Single-Pin Electrode Configuration and Its Application in Polyaniline Thin Film Growth.

This study systematically investigated an atmospheric pressure plasma reactor with a centered single pin electrode inside a dielectric tube for depositing the polyaniline (PANI) thin film based on the experimental case studies relative to variations in pin electrode configurations (cases I, II, and III), bluff-body heights, and argon (Ar) gas flow rates. In these cases, the intensified charge-coupled device and optical emission spectroscopy were analyzed to investigate the factors affecting intensive glow-like plasma generation for deposition with a large area. Compared to case I, the intense glow-like plasma of the cases II and III generated abundant reactive nitrogen species (RNSs) and excited argon radical species for fragmentation and recombination of PANI. In case III, the film thickness and deposition rate of the PANI thin film were about 450 nm and 7.5 nm/min, respectively. This increase may imply that the increase in the excited radical species contributes to the fragmentation and recombination due to the increase in RNSs and excited argon radicals during the atmospheric pressure (AP) plasma polymerization to obtain the PANI thin film. This intense glow-like plasma generated broadly by the AP plasma reactor can uniformly deposit the PANI thin film, which is confirmed by field emission-scanning electron microscopy and Fourier transform infrared spectroscopy.

Effect of CVD parameters on large area growth of highly crystalline MoS2 thin flakes

In this study, we presented a report on effect of growth parameters (seeding promoter, growth temperature, Ar gas flow rate) on the formation of MoS2 monolayer. The morphology and structure of as-grown MoS2 were investigated in detail by optical microscopy, atomic force microscopy, Raman and photoluminesence spectroscopy techniques. The results showed that a highly reproducible growth of dense MoS2 triangular flakes with the size of ~35 µm over large area (~1.5x1 cm2) can be obtained by using a optimized parameters. The MoS2 field effect transistors based on the as-grown MoS2 exhibited carrier mobility of 0.5–2 cm2V−1s−1 and On/Off ratio of ~104. Our results can provide a useful information to realize large area, high quality of MoS2 for real electronic applications.

Impact of Ar Flow Rates on Micro-Structural Properties of WS2 Thin Film by RF Magnetron Sputtering.

Tungsten disulfide (WS2) thin films were deposited on soda-lime glass (SLG) substrates using radio frequency (RF) magnetron sputtering at different Ar flow rates (3 to 7 sccm). The effect of Ar flow rates on the structural, morphology, and electrical properties of the WS2 thin films was investigated thoroughly. Structural analysis exhibited that all the as-grown films showed the highest peak at (101) plane corresponds to rhombohedral phase. The crystalline size of the film ranged from 11.2 to 35.6 nm, while dislocation density ranged from 7.8 × 1014 to 26.29 × 1015 lines/m2. All these findings indicate that as-grown WS2 films are induced with various degrees of defects, which were visible in the FESEM images. FESEM images also identified the distorted crystallographic structure for all the films except the film deposited at 5 sccm of Ar gas flow rate. EDX analysis found that all the films were having a sulfur deficit and suggested that WS2 thin film bears edge defects in its structure. Further, electrical analysis confirms that tailoring of structural defects in WS2 thin film can be possible by the varying Ar gas flow rates. All these findings articulate that Ar gas flow rate is one of the important process parameters in RF magnetron sputtering that could affect the morphology, electrical properties, and structural properties of WS2 thin film. Finally, the simulation study validates the experimental results and encourages the use of WS2 as a buffer layer of CdTe-based solar cells.

Effects of operating parameters on the flow field in slab continuous casting molds with narrow widths

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min−1 and casting speed of 1.7 m·min−1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.

Superior control for physical properties of sputter deposited ITO thin-films proper for some transparent solar applications

Superior control of sputtering deposition of ITO thin-films to enhance the physical properties of the ITO thin-films has been investigated. The effect of different sputter deposition conditions and the thermal post-annealing on the physical properties of the transparent-conductive indium tin oxide (ITO) thin-films deposited on a glass substrate have been studied. The power varied from 20 to 210 W with argon (Ar) gas flowing at a rate from 20 to 80 sccm. Thermal post-annealing of deposited thin-films at 200–450 °C in vacuum and air has been carried out as well. The physical properties were monitored using XRD, STM, four-point probe electrometer, and UV–Vis spectrometer. The change of the Ar flow rates influences the deposited films surface roughness, electrical sheet resistance (Rs), average optical transmittance (Tavg) with no apparent change in the morphology fractal dimension. At the Ar flow rate of 30 sccm and the critical power of 120 W, the deposited thin-films transform from amorphous to semi-crystalline structure mostly up 170 W. Optimal thin-films with fairly the highest Tavg at 97.7% and good Rs with 158.3 Ω/sq could be obtained under a residual Ar gas flow rate of 50 sccm and at 20 W. The critical post-annealing temperature at 350 ℃ (air) and 450 °C (vacuum) could initiate the semi-crystalline structure of the previously amorphous deposited thin-films. For the first time, ITO thin-films with Tavg and Tmax up to 97.7% and 99.9% respectively have been achieved. Besides, the Rs value is controlled from 6 to 3981 Ω/sq with excellent average transparency. These prove viable candidates in transparent solar applications.

Boron Removal from Metallurgical-Grade Silicon by Slag Refining and Gas Blowing Techniques: Experiments and Simulations

To enhance the removal of B from metallurgical-grade Si (MG-Si) by the CaO-SiO2-CaCl2 slag refining technique, Ar gas was injected during the refining process. The effects of the refining time, Ar gas flow rate, and the blowing-pipe immersion depth on the removal of B from MG-Si were studied. The results show that the injection of Ar gas can effectively stir and then mix the Si and slag phases, resulting in an increase in the Si/slag contact area and in an acceleration of the mass transfer rate of B. With the combined slag-refining and Ar gas-blowing approach, the reaction time for the removal of B was reduced to 5 min from 75 min required with the slag-refining approach. Correspondingly, the content of B was reduced from 23.91 to 10.42 ppmw, with a removal efficiency of 56.42%. The results were confirmed by the coupled large-eddy simulation model and the volume of fluid multiphase flow model.