Film Formation Conditions Research Articles

Zr-based conversion film fabricated on cold rolled steel by separately providing zirconium and fluorine ions: Performance and mechanism study

Controlling the concentrations of Zr4+ and F− in traditional Zirconium (Zr)-based film-formation solution is challenging due to their dependence on the hydrolytic equilibrium of H2ZrF6. In this study, Zr-based films were prepared on cold rolled steel surface through the film-formation solution prepared by mixing Zr(NO3)4 and different amount of HF. The electrochemical results demonstrated that the Zr-based film prepared by Zr(NO3)4 and HF exhibited superior corrosion resistance compared to H2ZrF6. Under optimal film formation conditions, the protective efficiency of the prepared film reached 74.4 % which was higher than that of film fabricated in H2ZrF6. The electrochemical results concurrently demonstrated the self-reinforcing anti-corrosion performance of the prepared films. Scanning electron microscopy revealed that the Zr film, prepared in Zr(NO3)4 and HF, exhibited excellent corrosion resistance attributed to its high film density. The X-ray photoelectron spectroscopy and energy dispersive spectroscopic results indicated the presence of a fluoride layer on the surface of the Zr film. The F− ions can chelate with the corrosion products and selectively deposit onto the damaged areas of the film, thereby effectively contributing to the repair of the film layer. The results of density functional theory calculations demonstrated that Zr4+ readily forms Zr(OH)4 rather than ZrF62−. The present study offers an enhanced approach for regulating the properties of films prepared via H2ZrF6 by separately providing zirconium and fluorine ions.

Conditions for Cuprous Chloride Ultrathin Film Formation on Silicon Substrate by Molecular Beam Epitaxy

Conditions for Cuprous Chloride Ultrathin Film Formation on Silicon Substrate by Molecular Beam Epitaxy

Structural, morphological, compositional and optical properties of CoS2 thin films synthesized by adsorption-diffusion method

CoS2 thin films on PA 6 sheets were successfully formed by a two-step adsorption-diffusion method. A solution of pentathionate acid and a solution of Co(II) in complex form were used as a source for the formation of cobalt sulfide films. It has been established that increasing the duration of the first stage of the process, as well as increasing the temperature of the Co(II) precursor solution, plays a decisive role on the surface quality and positive physical properties of the resulting CoS2 films. The surface morphology, physical properties and elemental composition of the obtained CoS2 films have been investigated by means of XRD, SEM/EDS, ICP-OES and AFM. The formed CoS2 thin films exhibit a broad absorption edge with a high absorption coefficient (α ≈ 104 cm−1). UV–Vis studies of films have revealed a significant influence of film formation conditions on the values of their optical band gap.

The Incorporation of Sulfonated PAF Enhances the Proton Conductivity of Nafion Membranes at High Temperatures.

Nafion membranes are widely used as proton exchange membranes, but their proton conductivity deteriorates in high-temperature environments due to the loss of water molecules. To address this challenge, we propose the utilization of porous aromatic frameworks (PAFs) as a potential solution. PAFs exhibit remarkable characteristics, such as a high specific surface area and porosity, and their porous channels can be post-synthesized. Here, a novel approach was employed to synthesize a PAF material, designated as PAF-45D, which exhibits a specific surface area of 1571.9 m2·g-1 and possesses the added benefits of facile synthesis and a low cost. Subsequently, sulfonation treatment was applied to PAF-45D in order to introduce sulfonic acid groups into its pores, resulting in the formation of PAF-45DS. The successful incorporation of sulfonic groups was confirmed through TG, IR, and EDS analyses. Furthermore, a novel Nafion composite membrane was prepared by incorporating PAF-45DS. The Nyquist plot of the composite membranes demonstrates that the sulfonated PAF-45DS material can enhance the proton conductivity of Nafion membranes at high temperatures. Specifically, under identical film formation conditions, doping with a 4% mass fraction of PAF-45DS, the conductivity of the Nafion composite membrane increased remarkably from 2.25 × 10-3 S·cm-1 to 5.67 × 10-3 S·cm-1, nearly 2.5 times higher. Such promising and cost-effective materials could be envisioned for application in the field of Nafion composite membranes.

Structural, morphological and functional properties of films polymer analogues of (co)polyvinylsuccinates

The results of a study of the structural features and associated physicochemical characteristics of films based on copolymers of n-butyl acrylate with N-vinylsuccinamic acid (sodium salt), including those containing bioactive substances (BAS), and their influence on the duration of BAS release depending on chemical structure and composition of the copolymer, film formation conditions, the nature of the introduced BAS, contact medium and release of BAS are presented.

A wafer scale thin film of ultra-small Sc2O3 nanocrystals on a 2D COF with high rigidity.

Scandium oxide (Sc2O3) has a wide range of applications in metallurgy, chemical industry, electronics and many other high-tech fields. However, most Sc2O3 materials exist in the powder or bulk form, while nanostructured Sc2O3 has rarely been reported as there is a lack of a common method to control its dimensionality, hindering the understanding of new properties and potential applications of nano-Sc2O3 materials. In this paper, we establish a procedure to synthesize a two-dimensional (2D) Sc2O3-covalent organic framework (COF) composite film where the crystal size of Sc2O3 domains is as small as ∼3 nm. The composite film is prepared by a Schiff base condensation reaction at the sharp n-pentane/water interface using a combination of surfactant-monolayer-assisted interfacial synthesis and laminar assembly polymerization methods. Then the conditions of nucleation and uniform film formation of the 2D Sc2O3/COF are explored further. Meanwhile, an atomic force microscopy indentation test shows that the material has a high Young's modulus of 89.1 ± 3.8 GPa, which is much higher than those of the majority of reported 2D polymer materials. We further extended this synthesis method to the preparation of Yb2O3 (ytterbium oxide) and/or Er2O3 (erbium oxide)-incorporated 2D COF composite films, verifying the universality of this strategy. This work provides an opportunity to vary the dimensionality of many kinds of metal oxides and explore the potential applications of low-dimensional Sc2O3 materials.

Revealing cation and metal gradients in and underneath passive films of the stainless steel 1.4652 in acidic and alkaline electrolytes with angular resolved dual energy X‐ray photo‐electron spectroscopy

AbstractPassive films on the superaustenitic stainless steel 1.4652 were studied using angular resolved hard X‐ray photo‐electron spectroscopy (HAXPES), which provides an increased information depth compared to conventional X‐ray photo‐electron spectroscopy (XPS). Elemental depth profiles in the oxide as well as gradients in the underlying metal were established using a dedicated algorithm. The utility was exemplified for three different conditions of film formation: (i) as polished and as polarized to the high passive end in (ii) 1 M H2SO4 and (iii) 1 M NaOH. The use of a superaustenitic material ascertained that metal signals from the main contributors to film formation: Fe, Cr, Ni, and Mo remained above the detection limit throughout the data set. With the dual‐source technique (XPS, HAXPES), it was possible to investigate metal gradients underneath the passive film. For polarizations in an acidic environment, a metallic nickel enrichment of the order of 5 Å was found. For a corresponding polarization in an alkaline environment, the metal region closest to the oxide/metal interface was enriched in iron, followed by concentration gradients down to about 50 Å into the metal.

Tracking Mechanical Stress and Cell Migration with Inexpensive Polymer Thin-Film Sensors.

Polydiacetylene (PDA) Langmuir films are well known for their blue to red chromatic transitions in response to a variety of stimuli, including UV light, heat, bio-molecule bindings and mechanical stress. In this work, we detail the ability to tune PDA Langmuir films to exhibit discrete chromatic transitions in response to applied mechanical stress. Normal and shear-induced transitions were quantified using the Surface Forces Apparatus and established to be binary and tunable as a function of film formation conditions. Both monomer alkyl tail length and metal cations were used to manipulate the chromatic transition force threshold to enable discrete force sensing from ~50 to ~500 nN μm-2 for normal loading and ~2 to ~40 nN μm-2 for shear-induced transitions, which are appropriate for biological cells. The utility of PDA thin-film sensors was demonstrated with the slime mold Physarum polycephalum. The fluorescence readout of the films enabled: the area explored by Physarum to be visualized, the forces involved in locomotion to be quantified, and revealed novel puncta formation potentially associated with Physarum sampling its environment.

СТРУКТУРА ТА ВЛАСТИВОСТІ МОДИФІКОВАНИХ ГЛІЦЕРИНОМ ПОЛІЛАКТИДНИХ ПЛІВОК

The structure and properties of modified poly(lactiс acid) films suitable for use as packaging materials and paper lamination were studied. Modification of poly(lactiс acid) of different degrees of crystallinity with glycerol was performed. The influence of film formation conditions, the amount of glycerin plasticizer, the nature of poly(lactiс acid) on the structure, surface morphology and physical and mechanical properties of modified poly(lactiс acid) materials was studied. Modified film materials can be recommended for use in the packaging industry and paper lamination.

Evaluation of Preferential Orientation in the Film Depth Direction by Two-Dimensional Grazing Incident Wide-Angle X-ray Diffraction of CeO2 Film on Sapphire Single Crystal Substrate with Different Film Formation Conditions

Evaluation of Preferential Orientation in the Film Depth Direction by Two-Dimensional Grazing Incident Wide-Angle X-ray Diffraction of CeO₂ Film on Sapphire Single Crystal Substrate with Different Film Formation Conditions

Construction of a Novel Substrate of Unfigured Islands-in-Sea Microfiber Synthetic Leather Based on Waste Collagen.

This study is to introduce waste collagen into an unfigured islands-in-sea microfiber nonwoven material, replacing the polyurethane impregnation section of the traditional manufacturing process with the collagen impregnation process. The modified collagen was first impregnated in polyamide/low-density polyethylene (PA/LDPE) fiber nonwoven to form a film. Then the low-density polyethylene component was extracted and dissolved in toluene, resulting in a collagen-based microfiber nonwoven substrate. Waste collagen was first modified to introduce C=C into the molecular chain to obtain vinyl collagen (CMA), and then the following film formation conditions for CMA were studied: 73% degree of substitution (DS), 3 h cross-linking time, and 0.005–0.01 wt % initiator concentration. Then, the preparation of CMA-PA/LDPE and toluene extraction processes were investigated. The optimum toluene extraction conditions were obtained as an extraction temperature of 85 °C and an extraction time of 110 min. The properties of the nonwoven materials were compared before (CMA-PA/LDPE) and after (PA-CMA) extraction. It was found that the homogeneity, tensile strength, and static moisture permeability of the PA-CMA materials prepared by CMA with 50 and 73% DS were all superior to those of PA/LDPE. In particular, the static moisture permeability of PA-CMA (691.6 mg/10 cm2·24 h) increased by 36.2% compared to the microfiber synthetic leather substrate currently in the market. Using scanning electron microscopy (SEM), the continuity of a film of PA-CMA with 73% DS was observed to be better and the fibers were differentiated and relatively tighter fiber-to-fiber gap. The studied novel green process can eliminate the large amount of dimethylformamide (DMF) pollution caused by the current solvent-based polyurethane impregnation process.

Elaboration of weatherproof steel 06гн3мд for structures of bridges exploited in coastal zone

At present decreasing of costs and increasing of efficiency are the most priority directions in any industry. Developing in this way, JSC “Ural steel” together with FGUP “CNIIchermet after I.P. Barding” had mastered production of sheet metal product with increased resistivity against atmosphere corrosion made of steel 14ХГНДЦ for construction of bridges. Because of specific chemical composition of the steel, in the process of metal structures running in the open air, a solid strong oxide film is formed on the metal of the structures which prevents further corrosion without painting. For bridge builders elimination of costly operation of painting of span structures will enable to decrease considerably the costs of bridges construction and running. Having many advantages, steel 14ХГНДЦ has some restrictions in applications for steel structures without painting, as follows: - in sea zone according to domestic norms no close than 500 m from coastline; - in case of disorderly conditions of protective film formation and/or application of salt solutions for surface cleaning (as a rule the restrictions refer to traffic area of bridge span). In view of that for JSC “Ural Steel”, as the leading producer of bridge steel in Russia, an actual task erose: to elaborate and create a weatherproof steel, which could not only operate the whole period of a bridge running without additional protection at bridges con­struction through sea areas or close to coastline, but also withstand severe climate conditions of our country, including areas of High North with temperature lower -50°С. To solve the task together with OJSC “Institute Giprostroymost” and JSC BNIIZhT, a research work was accomplished to elaborate a system of alloying new steel 06ГН3МД with nickel content ~3.0 %, as well as production modes ensuring required corrosion resistance for operation in sea zone. Results of laboratory studies of the new weatherproof steel 06ГН3МД for application in bridge structures for coastal conditions and sea areas presented. Results of mechanical, technological, corrosion as well as fatigue tests of rolling products of the elaborated steel presented. It was established by laboratory studies that the new steel is weatherproofed and ensures lower corrosion losses, higher impact toughness at negative temperatures and plasticity comparing with steels used at present. It was shown that the strength class, technology and modes of factory welding of steel 06ГН3МД meet the requirements to steel span structures of bridges. Base on the results of the studies, the chemical composition of the steel 06ГН3МД was specified, as well as modes of heat treatment, ensuring the required characteristics with significant acceding. It was established that samples of the new steel 06ГН3МД showed considerably higher corrosion resistance - in average by 20% comparing with steel 14ХГНДЦ. At that corrosion resistance tests of welded joints of the new steel showed even higher resistance of the seam comparing with the basic metal, which speaks about quality selection of welding modes and welding materials.

The chemical treatment of the AZ31-Magnesium alloy surface by a high-performance corrosion protective praseodymium (III)-based film

This study deals with the Mg-AZ31 alloy anticorrosion properties improvement via a novel surface treatment method. In this regard, the praseodymium (Pr)-based film formation on the Mg-alloy surface at different film formation conditions (i.e., pH, time, temperature) were investigated. The composition of the generated Pr-based film on the Mg-AZ31 alloy surface was characterized in depth using atomic/microscopic level techniques, i.e., X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and contact angle (CA) test. The influence of Pr film on the polyurethane (PU) coating adhesion properties and corrosion protection performance were studied by the pull-off test, neutral salt spray (NSS), and electrochemical impedance spectroscopy (EIS) analyses, respectively. FE-SEM micrographs revealed that the metal surface was covered with a Pr film, which has brought about a rough surface. Applying the Pr film to the Mg alloy surface has caused significant improvement in the corrosion resistance characteristics. A 94.84% corrosion retardation potency was recorded for the Pr-modified Mg alloy at the optimum surface chemical treatment condition. A significant improvement in the adhesion degree (about 64%) was obtained for the PU film on the Mg alloy modified by an optimized Pr film. Results have declared that the Pr-based film could improve the Mg alloy corrosion resistance by affecting the anodic/cathodic reactions through the formation of insoluble and electrically insulate inorganic film and enhancing the PU adhesion by providing a surface with high energy/wettability and micro-nano scales roughness.

A simple strategy for fabricating honeycomb patterns on commercially available polymer film under a wide humidity range

Abstract

Precise Control of Phase Separation Enables 12% Efficiency in All Small Molecule Solar Cells

AbstractCompared to conjugated polymers, small‐molecule organic semiconductors present negligible batch‐to‐batch variations, but presently provide comparatively low power conversion efficiencies (PCEs) in small‐molecular organic solar cells (SM‐OSCs), mainly due to suboptimal nanomorphology. Achieving precise control of the nanomorphology remains challenging. Here, two new small‐molecular donors H13 and H14, created by fluorine and chlorine substitution of the original donor molecule H11, are presented that exhibit a similar or higher degree of crystallinity/aggregation and improved open‐circuit voltage with IDIC‐4F as acceptor. Due to kinetic and thermodynamic reasons, H13‐based blend films possess relatively unfavorable molecular packing and morphology. In contrast, annealed H14‐based blends exhibit favorable characteristics, i.e., the highest degree of aggregation with the smallest paracrystalline π–π distortions and a nanomorphology with relatively pure domains, all of which enable generating and collecting charges more efficiently. As a result, blends with H13 give a similar PCE (10.3%) as those made with H11 (10.4%), while annealed H14‐based SM‐OSCs have a significantly higher PCE (12.1%). Presently this represents the highest efficiency for SM‐OSCs using IDIC‐4F as acceptor. The results demonstrate that precise control of phase separation can be achieved by fine‐tuning the molecular structure and film formation conditions, improving PCE and providing guidance for morphology design.

Morphology and Defect Control of Metal Halide Perovskite Films for High-Performance Optoelectronics

Delicate morphology and defect control are crucial for high-performance optoelectronics. For metal halide perovskites, antisolvent precipitation is the most common process to realize the control and develop the state-of-art devices. However, the solute/solvent/antisolvent interactions and their influence on the film formation process are unclear. Here, we propose a novel solubility parameter δDN to measure the coordinate interaction between solvent and perovskite precursors. A combination of δDN and Hansen’s solubility parameters allows for the first comprehensive analysis of interactions between pure liquids and the perovskite precursors. The relative energy difference (RED) between antisolvent and solvent is used to quantify the supersaturation level during film deposition. Dense morphology films form in the maximum supersaturation region (0.85 < RED < 1.00). Perovskite properties are controlled by the interaction behavior difference in antisolvent/solutes. The photovoltaic performance increases by 53% when RED increases from 0.416 to 0.858. We demonstrate that detailed knowledge of the physicochemical characteristics of the solutions used to form films of perovskites is a valuable tool in the discovery of optimum film formation conditions and consequently in attaining efficient optoelectronic performance.

Evaluation of MoS2 Films Fabricated by Metal-Organic Chemical Vapor Deposition Using a Novel Mo Precursor i-Pr2DADMo(CO)3 Under Various Deposition Conditions

ABSTRACTMolybdenum disulfide (MoS2) is expected to be applied for devices in various fields owing to its unique characteristics. Establishing a high-productivity manufacturing method which yields high quality films is an important and unresolved issue for the practical applications of MoS2. Among different techniques conducted by researchers all over the world, our approach is cold-wall metal-organic chemical vapor deposition, and we previously reported the deposition of MoS2 with i-Pr2DADMo(CO)3, a novel Mo precursor [S. Ishihara, et al., MRS Advances 3, 379-384 (2018).]. In this study, with the aim of further improving the quality of the MoS2 film using this new Mo precursor, various film formation conditions were controlled and the influence on the film quality was investigated. X-ray photoelectron spectroscopy, atomic force microscopy and Raman spectroscopy were used as evaluation techniques of the samples. As a result, mm-scale uniform film was formed with the deposition time less than 30 min. at temperature as low as 400 °C to 500 °C. It was revealed that maintaining low Mo/S supply ratio (SRMo/S) is crucial in fabricating high quality films.

Study of Polyoxometalates Based Films Formation with High Gas Sensitivity

Introduction Inorganic oxide films activated with different additives are the unique sensitive layers for working at room temperature sensors. The sensor behavior of nanostructured activated silica films produced by sol-gel route was examined for environment control. Polyoxometalates (POMs) of Dawson type were used as additives in the silica matrix for gas sensitivity. POMs have good electronic conductivity and chemical stability. These compounds can act as reversible reagents in the reactions of ligand exchange and redox transformations, accompanied by changes in current carrier concentration or catalyze of such transformations that can be used in chemical sensors. Their redox properties can be varied within broad limits due to changing the heteropolyanion composition [1-4]. Porous silica is a unique matrix for chemical sensors, which has a lot of excellent physical and chemical properties [5]. Method The sensor’s interdigital structure was made by microelectronic planar technology as shown in figure 1. The active area of the sensor was 4 x 4 mm. The thickness of the electrodes was 0,2 mm. The width of finger pairs of electrodes and distance between them were 20 μm. The method of hydrolythic polycondensation from tetraethyl orthosilicate solutions was used for forming complex silica films in this work. Films were deposited by a centrifugation from solutions based on tetraethyl orthosilicate and polyoxometalate. POMs with various compositions have been incorporated into the initial solution. The developed technology of multistep temperature treatment up to 413 K allowed film properties stabilizing.The conditions of film formation varied during the tests: solution composition, temperature, and application modes. Morphology and infrared spectra of the layers were studied using Solver-P47 scanning probe microscope (NT-MDT, Russia) and spectrometer Bruker EQUINOX 55 (Germany). Standard gas mixtures (MGPZ, Russia) and Environics – 4000 gas-mixture generator (Environics, USA) were used to measure the properties of sensors. Electrical parameters of the sensors have been measured in real-time mode. Environment influence on sol preparation and films forming was investigated. Results and Conclusions Films had thickness of 200-300 nm and nanoscale pores. The metrological parameters of sensors depend mainly on different parameters: synthesis conditions and chemical content of sensitive film, temperature of the environment, annealing temperature, storage conditions and duration after heat treatment. Temperature treatment and decreasing of environment humidity lead to acceleration of hydrolythic polycondensation of solutions and stabilization of sensitive films at right conditions as demonstrated in figure 2. Introduction of heteropolyanion into film resulted in film’s mass stabilization. The temperature treatment don’t disturb POM molecule in the film. The polyoxometalates didn’t display their catalytic activity at weight content less than 10 % in the film. The increase in conductivity is observed due to an increase in the concentration of charge carriers on the surface of the film, donors of which are introduced into the film POM molecules. And gas sensitivity maximum decreases at weight content more than 50-60 % in matrix what is explained apparently by the formation of crystalline aggregates POM in the volume of the film. Besides the humidity adsorption on the film’s surface contribute to the sensor response. Adding of Mn3P2Mo18O62 into silica film resulted in high sensitivity to ethanolamine (up to 10 times) more than to ammonia as shown in figure 3. Obviously, this is explained by the reaction of ethanolamine complexation with Mn ions, among the possible valence states of which the strongest complex with ethanolamine molecules is formed by Mn3+. An equilibrium shift towards Mn3+ and a decrease in the redox potential of the Mn3+/Mn2+ pair leads to an intramolecular reduction reaction of the heteropolyanion. This interaction is quick (less than 30 s) and reversible at room temperature.

Некоторые особенности анодного поведения Co2Si-электрода в растворе серной кислоты

The effect of anodic film formation conditions on the electrochemical behavior of Co2Si electrode in 0.5 M H2SO4 has been studied. It was shown that the rate of passive dissolution of Co2Si is only moderately greater than that of CoSi2 provided the Co2Si electrode passes through the active dissolution region very quickly. From the current decay curves at E = const, it was deduced that in the middle part of the passive region the oxide film on Co2Si grows according to near logarithmic law. Impedance spectra obtained in measurements at different initial electrode potentials were analyzed.

Explanation of the Electrochemical Behavior of Salt Film in Pit Growth

A unifying framework has recently been developed to describe the critical conditions for pit growth stability and salt film formation 1-3. It was shown that a salt film is not required for pit stabilization; it is just a consequence of a pit achieving diffusion-controlled growth. A salt film can form on the surface of both metastable and stable pits when the maximum pit dissolution current density, i diss,max, exceeds the diffusion-limited current density, i lim. In this work, the unifying framework is further expanded to establish a mathematical model describing the electrochemical behavior of salt film after it precipitates, i.e. the situation when i diss,max > i lim. It can be mathematically shown that the main function of a salt film during diffusion-controlled pit growth is to accommodate the extra potential of (E max - E sat) by regulating its thickness to adjust the actual potential at the pit surface to E sat and thus restricting the anodic dissolution current density at the diffusion-limited value 4. Therefore, the salt film will respond to any changes of the applied potential, temperature, pit depth, and perforation radius of the pit cover. This new model can explain the current peak observed during the downward potential scan of a 1D pit at the transition point from diffusion-controlled region to charge-transfer-controlled region. According to this new model, the current peak results from the supersaturation generated by thinning of the salt film during the downward scan. The model predicts that the amplitude of the current peak decreases with decreasing scan rate, which is in agreement with the experimental results from 1D artificial electrode, providing strong support for the validity of the new model. Acknowledgments: This work was supported as part of the Center for Performance and Design of Nuclear Waste Forms and Containers, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0016584. Reference G. S. Frankel, T. Li and J. R. Scully, Journal of the Electrochemical Society 164, C180-C181 (2017).T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society 165, C484-C491 (2018).T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society 165, C762-C770 (2018).T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society 166, C115-C124 (2019).