Deposition Procedure Research Articles

Structure and strain of CdS nanofilms on Au(111) during electrochemical atomic layer deposition growth

X-ray scattering is used to characterise the initial stages of the growth of CdS on Au(111) surfaces via electrochemical atomic layer deposition (E-ALD). This work characterises E-ALD films using a unique in-situ setup, allowing for X-ray reflectivity and diffraction data to be obtained to characterise the growth process of the CdS film. Structural information, as well as information concerning growth rates, roughness and strain as a function of the stage in the growth process, are obtained to provide a unique perspective of the early stages of deposition for this methodology. The results show the self-limiting, linear growth rate of CdS films that are wurtzite in structure, are highly epitaxial with the underlying Au substrate, and exhibit little to no chemical impurities during the deposition procedure.

A single-sensor multi-scale quality monitoring methodology for laser-directed energy deposition: Example with height instability and porosity monitoring in additive manufacturing of ceramic thin-walled parts

Laser Additive Manufacturing (LAM) faces various technical challenges, encompassing issues with dimensional accuracy, mechanical properties, and processing-related defects, such as surface roughness, cracking, and residual porosity. Currently, the quality of safety-critical parts produced by LAM processes, which is still improved through trial-and-error adjustments of multiple process variables, have limited real-time monitoring capabilities. This study introduces an innovative method for real-time quality assessment of laser-directed energy deposition (LDED) procedures across multiple scales (macroscale, mesoscale, and microscale) utilizing a single sensor. This approach is founded on two fundamental components: the single-sensor system for data acquisition and the algorithm for simultaneous multi-scale quality monitoring. For the data acquisition system aspect, a single-sensor, high dynamic range (HDR), multi-scale information acquisition system has been developed to mitigate intense radiation, eliminate plume disturbances, and rectifies backlight shadows, facilitating clearer images of deposition contours and the molten pool region. In the realm of data monitoring algorithms, a physics model-driven supervisory algorithm is employed to enable monitoring of contour height instability, while a convolutional neural network (CNN), driven by image data, is utilized for porosity prediction. Then, this algorithm adeptly tackles the challenge of simultaneously monitoring macroscopic contour and mesoscale porosity. Regarding the validation of the method, the outcomes of single-sensor multi-scale quality monitoring in additive manufacturing of ceramic thin-wall parts indicate a 100% recognition rate for deposition contour and molten pools, contour feature recognition with a relative error of under 0.05%, porosity prediction accuracy surpassing 99%, and a monitoring time of 80.4 ms per frame. Single-sensor multi-scale real-time quality monitoring can serve as a methodological support for future real-time quality control in LDED.

Laser-Induced Backward Transfer of Light Reflecting Zinc Patterns on Glass for High Performance Photovoltaic Modules.

Commercially available photovoltaic (PV) modules typically consist of individual silicon half-cut cells that are electrically interconnected. This interconnection method results in gaps between the cells, which do not contribute to the overall PV output power. One approach to enhance the cell-to-module power ratio is the placement of white, diffuse reflecting plastic material within these gaps. Conventionally, the process of generating reflective patterns involves several discrete steps, including film deposition, resist patterning, etching, and resist stripping. This study presents an innovative single-step procedure for the direct deposition of zinc reflective patterns onto glass substrates using laser-induced backward transfer (LIBT) and a nanosecond pulsed laser system. The process successfully produced lines and squares, demonstrating its versatility in achieving diverse geometric patterns under ambient atmospheric pressure and room temperature conditions. The evaluation of the transferred patterns included an examination of geometric dimensions and surface morphology using a 3D microscope and scanning electron microscopy (SEM) analysis at the air/Zn interface. Additionally, the thickness of the zinc film and its adhesion to the glass substrate were quantified. The angular reflectance at a wavelength of 660 nm for both the glass/Zn and air/Zn interfaces was measured.

On the Choice of Monitoring Procedure of Optical Coating Deposition

On the Choice of Monitoring Procedure of Optical Coating Deposition

Data-driven design for enhanced efficiency of Sn-based perovskite solar cells using machine learning

In this study, a novel three-step learning-based machine learning (ML) methodology is developed utilizing 26 000 experimental records from The Perovskite Database Project. A comprehensive set of 29 features encompassing both categorical and numerical data was utilized to train various ML models for various solar cell performance metrics, including open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE). The model accuracy was assessed using four key metrics: mean absolute error, mean square error, root mean square error, and R2 score. Among the constructed models, random forest (RF) emerged as the standout performer, boasting an R2 score of 0.70 for PCE. This RF model was then used for prediction on the large, optimized design pool of Sn-based perovskite data with intent to probe a viable non-toxic substitute to the standard Pb-based absorber. A three-step algorithm was tailored, which led to the discovery of a new set of feature combinations, showcasing a PCE improvement over the existing peak performance of Sn-based devices. The key aspects identified were device architecture, dimensionality, and deposition procedures for essential layers, including the electron transport layer, the hole transport layer, the perovskite absorber layer, and the back-contact. Through consideration of these features, an impressive increase in PCE was achieved. There was a 28.35% increase in PCE from 12.24% to 15.71% for architecture optimization and a 24.6% increase in PCE from 12.24% to 15.25% for deposition method optimization. This study additionally addresses the effective implementation of target encoding applied to a diverse set of categorical feature labels. The data-driven methodology proposed in this study allows scientists to efficiently identify an optimal architecture and deposition parameters for non-toxic Sn-based perovskite materials with a much higher anticipated device PCE compared to traditional trial-and-error analyses. Further exploration and exploitation of the current investigation is expected to lead to successful and sustainable development of highly efficient Sn-based perovskite solar cells.

INVESTIGATION OF CORROSION BEHAVIOR OF AISI 304 AND AISI 316L STAINLESS STEELS COATED WITH FeAL AND NiAL INTERMETALLICS USING ELECTRO-SPARK DEPOSITION METHOD

Due to their superior corrosion resistance at high temperatures, stainless steels have a wide range of applications in numerous industries (including chemistry, the petrochemical industry, the paper industry, and nuclear engineering), it is also utilized in the medical industry as an implant material. To enhance the outstanding qualities of stainless steel such as high temperature corrosion, surface coating methods are also used. Boronizing, nitriding, thermal spray coating, physical vapor deposition, chemical vapor deposition, and electro-spark deposition procedures are used to apply these coating processes to steel surfaces. The electro-spark deposition (ESD) coating technology is one of the most promising approaches in this area. Using high-frequency and high-current electric pulses, the ESD micro-welding procedure bonds electrode material to the surface of a metallic substrate. In this study, AISI 304 and AISI 316L stainless steels were coated with FeAl and NiAl intermetallics using the ESD method. First, suitable experimental parameters for ESD coating were established. Second, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the microstructures and phases that formed on the coated surfaces. Then, the surface hardness of the resulting layers was determined. Finally, the corrosion properties of intermetallic-coated stainless steels were determined using electrochemical methods and compared with each other. As a result, both the hardness values and corrosion resistances of both stainless steel sheets have increased with intermetallic coatings.

Unidirectional Current in Layered Metal Hexacyanometallate Thin Films: Implication for Alternative Wet-Processed Electronic Materials.

Rectifying behavior of alternative electronic materials is demonstrated with layered structures of a crystalline coordination network whose mixed ionic and electronic conductivity can be manipulated by switching the redox state of coordinated transition-metal ions. The coordinated transition-metal ions can convey additional functionality such as (redox)catalysis or electrochromism. In order to obtain rectifying behavior and charge trapping, layered films of such materials are explored. Specifically, layered films of iron hexacyanoruthenate (Fe-HCR) and nickel hexacyanoferrate (Ni-HCF) were formed by the combination of different deposition procedures. They comprise electrodeposition during voltammetric cycles for Fe-HCR and Ni-HCF, layer-by-layer deposition of Ni-HCF without redox chemistry, and drop casting of presynthesized Ni-HCF nanoparticles. The obtained materials were structurally characterized by X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy for nanoparticles, and scanning force microscopy (SFM). Voltammetry in 1 mol L-1 KCl and current-voltage curves (I-V curves) recorded between a conductive SFM tip and the back electrode outside of an electrolyte solution demonstrated charge trapping and rectifying behavior based on the different formal potentials of the redox centers in the films.

Depositing Layers of Nano Graphene on P-Type Silicon Substrate and Studying the Structural and Optical Properties

The present study involved the deposition of graphene films onto a silicon substrate of p-type using the Pulsed Laser Deposition (PLD) technique by varying the number of laser pulses (700, 600, and 500 pulses) at a fixed energy of 800 mj and a frequency of 6 Hz. The thickness of the prepared samples was calculated, revealing a significant increase in thickness (from 282 to 223 nm) attributed to the accumulation of material with increasing number of pulses. X-ray diffraction (XRD) patterns of graphene samples showed an increase in both the degree of crystallinity and the intensity of the graphene peak with increasing number of pulses leading to an initial boost in crystalline growth. The utilization of (SEM) images, particularly in samples created with 700 pulses, they appear to be more extended and smoother, forming wavy surfaces. Furthermore, a discernible augmentation in the quantity of graphene atomic layers was seen from 80 to 116 in samples that underwent an increase in the number of pulses from 500 to 700. The observation revealed a distinct arrangement of the surface, where, these layers effectively covered the surface with a thickness measuring 115 nm. Furthermore, a noticeable variation in the surface morphology of the deposited samples was also observed with increasing number of pulses. FTIR spectra exhibited a conspicuous augmentation in the intensity of bands, particularly for the asymmetric and symmetric vibrations of the CH2 group, which manifest at wavenumbers of 2940 and 2890 cm-1, respectively, concomitant with an escalation in the number of laser pulses employed during the deposition procedure.

Decoration of spherical Sb2S3 over CuO nanoflakes for efficient photoelectrochemical hydrogen generation

Developing an efficient photocathode system from earth abundant materials is essential for effectual Photoelectrochemical (PEC) water splitting. Charge transfer between heterojunctions is important in fabricating a novel photocathode, keeping cost-effectiveness, abundance, and PEC performance in mind. The p-type narrow band gap photocathode, CuO (Eg = 1.5 eV) synthesized by hydrothermal method, was decorated with Sb2S3 Nanospheres (NSs) by adopting a facile chemical bath deposition (CBD) procedure to fabricate CuO/Sb2S3 NSs heterojunction. Fabricated heterojunction showed better PEC performance contrary to bare CuO, improvement in photocurrent density CuO/Sb2S3 NSs (J = −1 mA cm−2) than CuO (J = −0.3 mA cm−2) photoelectrode at 0 VRHE in 0.5 M Na2SO4 (pH 6.85) is due to enhanced charge carrier generation/separation. The photostability of CuO/Sb2S3 remains intact for 2.5 h with no degradation in photocurrent density. Sb2S3 works as a sensitizer, diminishing the recombination rate of the e−/h+ in CuO/Sb2S3 NSs. UV–Visible and photoluminescence(PL) emission spectra results suggested CuO/Sb2S3 enhanced absorption spectrum and reduced rate of recombination. Electrochemical impedance spectroscopy studies show less charge transfer resistance for CuO/Sb2S3 NSs than CuO. This finding will pave new path in developing novel photocathodic material configurations and heterojunction with Cu-based binary oxides/chalcogenides for solar harvesting.

A Review on Hardfacing, Process Variables, Challenges, and Future Works

Hardfacing is an efficient and economical surfacing technique widely used by heavy industries to remediate worn components in service or to enhance the component’s wear characteristics components prior to use. Efficient hardfacing for any targeted application requires precise consideration and understanding of the deposition process, consumables, and substrates. It is also essential to understand the process variables and issues that can occur during the deposition processes, such as dilution and defects in the deposit, including residual stress-induced cracking. Significant research has been published over many years on several aspects of hardfacing, primarily focusing on abrasive wear, corrosion, and impact characterisation using different welding methods and alloy compositions. This paper primarily focuses on reviewing the prior hardfacing literature to systematically summarise the considerations and selection criteria for hardfacing processes and materials. It also presents a discussion on key process variables, such as welding parameters and number of surfacing layers, highlighting their influences during the hardfacing deposition procedure. This paper further discusses issues and challenges in hardfacing practices, such as dilution and cracking. One significant issue investigated is the thermal damage to high-strength steel substrates, with the measurement and characterisation of the damage being key elements. The focus of this investigation is to discuss the optimisation of hardfacing high-strength steel substrates and to communicate potential research areas and prospective applications in the hardfacing industry.

Investigation of factors enhancing droplets spreading on leaves with burrs.

Spread effect is one of the aspects on deposition quality evaluation of pesticide droplets. It could be affected by many factors such as the microstructure of the target plant leaf surface, physical features of the droplets, and the concentration of spray additives. In this study, using a high-speed photography system, 2.3% glyphosate ammonium salt solution with different concentration of the additive was applied to investigate the impact process of single droplet deposition on the plant leaf surface with burrs. Effect of droplet sizes and velocities on spreading area and dynamic deposition procedure was analyzed using image processing programs. The diffusion factor in the process of droplet spreading was changed over time. The occurrence of bubbles in the droplets was observed in the results. With the bubble generation, the droplet diameter expands and a better diffusion effect is obtained. As a result, better spreading effect was obtained as the droplet diameter was expanded with the generation of bubbles. The significant effects of each physical property of droplets on droplet spreading and the interaction effects between the influencing factors were analyzed. A significant correlation was found between additive concentration, droplet impact velocity, droplet diameters and droplet spreading area. All interactions of concentration:velocity, concentration:diameter, velocity:diameter, and concentration:velocity:diameter had a significant effect on the spreading area of droplets. The study of the factors influencing the process of pesticide droplet impact on the leaf surface contributes to the efficient use of pesticides. Thus, the consumption of pesticides and the resulting impact on the environment can be reduced.

Influence of the interlayer temperature on structure and properties of CMT wire arc additive manufactured NiTi structures

A potential method for producing intricate Shape Memory Alloy (SMA) structures for uses like actuators and vibration dampers is wire arc additive manufacturing (WAAM). However, excessive heat build-up during the multi-layer deposition procedure in WAAM can result in process instability and departures from the intended mechanical qualities and dimensions. To address these problems, the interlayer temperature was optimized for printing on NiTi walls in this work. Without interlayer temperature control (WITC), 200 °C, and 400 °C were used to create three samples in order to study the impacts on the porosity level, morphology, and mechanical characteristics of the NiTi walls generated by WAAM. The Shape memory behavior of the manufactured NiTi walls was further examined through shape recovery investigations utilizing hot plate actuation. The findings demonstrated that regulating the interlayer temperature below 300 °C, preferably at 200 °C, enhanced the mechanical characteristics, decreased the porosity content, and enhanced the microstructure of the NiTi walls. The development and improvement of WAAM techniques for the manufacture of premium NiTi SMA components can benefit greatly from these findings.

Charge transfer in copper oxide nanostructure

The deposition potential affects the structural, morphological, optical, and electrochemical impedance spectroscopy properties of cuprous oxide (Cu2O) thin films formed on copper (Cu) substrates adopting a three-electrode electrochemical deposition procedure. XRD data revealed that the deposited films have a cubic structure established with desired (111) growth orientation. Scanning electron microscopy (SEM) images reveal that Cu2O film has very well three-sided pyramid-shaped grains which are equally spread over the surface of the Cu substrates and change substantially when the plating potential is changed. The photo-current density of prepared Cu2O thin films was increased from -1.41×10-4 to -3.01×10-4 A/cm2 with increasing the deposition potential of -0.3 to -0.6V, respectively. Further, Cu2O thin films obtained at -0.6V have the minimum charge transfer resistance (Rct) than Cu2O thin films synthesized at -0.3 to -0.5V, suggesting that Cu2O thin films produced at -0.6V have the highest electron transfer efficiency.

Revolutionizing Porous Liquids: Stabilization and Structural Engineering Achieved by a Surface Deposition Strategy.

Facile approaches capable of constructing stable and structurally diverse porous liquids (PLs) that can deliver high-performance applications are a long-standing, captivating, and challenging research area that requires significant attention. Herein, a facile surface deposition strategy is demonstrated to afford diverse type III-PLs possessing ultra-stable dispersion, external structure modification, and enhanced performance in gas storage and transformation by leveraging the expeditious and uniform precipitation of selected metal salts. The Ag(I) species-modified zeolite nanosheets are deployed as the porous host to construct type III-PLs with ionic liquids (ILs) containing bromide anion , leading to stable dispersion driven by the formation of AgBr nanoparticles. The as-afforded type-III PLs display promising performance in CO2 capture/conversion and ethylene/ethane separation. Property and performance of the as-produced PLs can be tuned by the cation structure of the ILs, which can be harnessed to achieve polarity reversal of the porous host via ionic exchange. The surface deposition procedure can be further extended to produce PLs from Ba(II)-functionalized zeolite and ILs containing [SO4 ]2- anion driven by the formation of BaSO4 salts. The as-produced PLs are featured by well-maintained crystallinity of the porous host, good fluidity and stability, enhanced gas uptake capacity, and attractive performance in small gas molecule utilization.

Low-temperature solution-processed Mg: NiOx hole transport layers for formal (n-i-p) perovskite solar cells

NiOx is one of the most promising inorganic hole transport materials for perovskite solar cells. However, lots of fabrication methods refer to NiOx are limited in n-i-p type perovskite solar cells. Because the deposition procedure of NiOx film such as polar solvents and high temperature process is seriously incompatible with perovskite light-absorption underlayers. In this work, highly crystalline NiOx nanocrystals are prepared using solvothermal method under the presence of long-chain oleylamine molecules. The resulted NiOx nanocrystals can be easily dispersed in weak-polar toluene and form films on perovskite layer without annealing procedure. The n-i-p type device with NiOx hole transport layer achieves an efficiency of 10.34%. Later, Mg2+ with different molar ratios are incorporated into the NiOx nanocrystals. It is found that introducing a certain amount of Mg2+ benefits to improve the ratio of Ni3+/Ni2+, thereby changing the work function and increasing the hole conductivity. As a result, the n-i-p type device with Mg-NiOx hole transport layer yields an improved efficiency of 12.41%.

Durable graphite oxide nanocoating for high performing flame retarded foams

Recent developments in the design of water-based coatings encompassing platelet-like nanoparticles have clearly demonstrated the flame retardant potential of this approach for open cell flexible foams. However, the relatively high number of deposition steps required and the limited reports on the durability of the deposited coatings to multiple compression cycles currently represent the main constraints to this approach. This paper addresses these limitations by exploiting a few steps deposition procedure to produce coatings with durable flame retardant properties. Graphite oxide, sodium alginate and sodium hexametaphosphate were combined in a continuous protective coating that extends to the complex three-dimensional structure of the foam. The flame retardant properties of the coatings were evaluated before and after 1000 compression cycles. Even after such multiple deformations, the coated foams showed no melt dripping and self-extinguishment during flammability tests, as well as a highly reduced heat release rates (-70%) and total smoke release (-70%) during cone calorimetry tests. Furthermore, the ability to withstand the penetration of an impinging flame focused on one side of the coated foam for more than 5 min was also maintained. These results clearly demonstrate the durability of the coated foams, opening to real life application fields such as transports seats where high levels of flame retardancy must be maintained for long time under frequent mechanical stress.

Long-term effects of tear film component deposition on the surface and optical properties of two different orthokeratology lenses

PurposeTo understand the effects of long-term deposition of tear film components on the surface and optical properties of orthokeratology (ortho-k) lenses, two different lenses, Brighten 22 and Optimum Extra, were tested here. MethodsOrtho-k lenses were immersed in artificial tears and cleaned with a commercial care solution repeatedly for up to 90 days. Both the daily and accumulated lysozyme deposition amounts using an Enzyme-Linked ImmunoSorbent Assay were then analyzed. The base curve, central thickness, power, and transmission of visible light, ultraviolet A, and ultraviolet B were analyzed before and after repeated tear film component deposition procedures. The surface roughness using atomic force microscopy was observed and an energy dispersive spectrometer was used to analyze the composition of the deposits. ResultsThe highest levels of lysozyme were adsorbed on both lens materials during the first four days of the procedure and became saturated by day 6. For both lens materials, contamination on the lenses was easily observed by day 30, and the degree of surface roughness was higher. The transmission levels of different light spectrums were reduced showing that the optical characteristics of both lenses were also affected. ConclusionsThe results provide in vitro evidence that lysozyme could not be completely removed from orthokeratology lenses. Both surface and optical properties were affected by the deposition of tear film components. However, only one commercial multipurpose care solution was used to clean the lens in this study when the main ingredient was a surfactant, and the results might be different when other care regimens with other key ingredients are used. In addition, whether tear film component deposition might result in increased risks of infection or corneal abrasion will require further investigation.

Thermodynamic Modeling and Experimental Implementation of the Synthesis of Vanadium Oxide Films

The paper describes the thermodynamic modeling and experimental study of the synthesis of vanadium oxide films at various temperatures from the tetrakis(ethylmethylaminovanadium) V[NC3H8]4 precursor in the presence of oxygen in an argon atmosphere. The thermodynamic modeling was carried out using the calculation of chemical equilibria based on the minimization of the Gibbs energy of the system. In the experimental part of the paper, the films were synthesized by the atomic layer deposition procedure. The thermodynamic modeling and experimental results agree with each other and can be used to develop procedures for the synthesis of film coatings based on vanadium oxides.

Charge transfer in copper oxide nanostructure

The deposition potential affects the structural, morphological, optical, and electrochemical impedance spectroscopy properties of cuprous oxide (Cu2O) thin films formed on copper (Cu) substrates adopting a three-electrode electrochemical deposition procedure. XRD data revealed that the deposited films have a cubic structure established with desired (111) growth orientation. Scanning electron microscopy (SEM) images reveal that Cu2O film has very well three-sided pyramid-shaped grains which are equally spread over the surface of the Cu substrates and change substantially when the plating potential is changed. The photo-current density of prepared Cu2O thin films was increased from -1.41×10-4 to -3.01×10-4 A/cm2 with increasing the deposition potential of -0.3 to -0.6V, respectively. Further, Cu2O thin films obtained at -0.6V have the minimum charge transfer resistance (Rct) than Cu2O thin films synthesized at -0.3 to -0.5V, suggesting that Cu2O thin films produced at -0.6V have the highest electron transfer efficiency.

Charge transfer in copper oxide thin films deposited at different electrodeposition potential

The deposition potential affects the structural, morphological, optical, and electrochemical impedance spectroscopy properties of cuprous oxide (Cu2O) thin films formed on copper (Cu) substrates adopting a three-electrode electrochemical deposition procedure. XRD data revealed that the deposited films have a cubic structure established with desired (111) growth orientation. Scanning electron microscopy (SEM) images reveal that Cu2O film has very well three-sided pyramid-shaped grains which are equally spread over the surface of the Cu substrates and change substantially when the plating potential is changed. The photo-current density of prepared Cu2O thin films was increased from −1.41 × 10−4 to −3.01 × 10−4 A/cm2 with increasing the deposition potential of −0.3 to −0.6 V, respectively. Further, Cu2O thin films obtained at −0.6 V have the minimum charge transfer resistance (Rct) than Cu2O thin films synthesized at −0.3 to −0.5 V, suggesting that Cu2O thin films produced at −0.6 V have the highest electron transfer efficiency.