Compact Film Research Articles

Energy-dependent film growth of Cu and NiTi from a tilted DC magnetron sputtering source determined by calorimetric probe analysis

Plasma-based processes are key applications in microsystems technology and are mainly used for the deposition and modification of thin films. A strong dependence on used equipment and materials can easily affect plasma processes and results in many differences of process characteristics like energy flow and deposition rates. For a deeper understanding of inclined magnetron-deposited thin films, a passive thermal probe was used to investigate the correlation between the film growth of two commonly used metallic target materials (Cu and Ni 46.8/Ti 53.2) and the energy flow from the plasma to the substrate. The special design of the sputtering system with a fixed angle of 45° between targets and substrate allows homogeneous coating of 200mm wafers with 100mm targets. The passive thermal probe measurements were performed radially across the substrate area for two different magnetron positions. Complementary surface and cross-sectional analysis of the deposited layers by atomic force microscopy, focused ion beam technique, and fracture edge analysis by scanning electron microscopy were performed on thin film samples on silicon substrate to investigate the growth rate and structure of the films. The films deposited in these experiments exhibit randomly oriented crystalline grains and heavily position-dependent change in surface topography and morphology from compact films to columnar growth, for Cu and NiTi respectively.

Thiourea-Assisted Facile Fabrication of High-Quality CsPbBr3 Perovskite Films for High-Performance Solar Cells.

Inorganic CsPbBr3 perovskite solar cells have attracted widespread attention recently because of their decent efficiency and good ambient stability. Nevertheless, the fabrication of high-quality CsPbBr3 perovskite via the conventional solution-processing strategy still faces great challenges because the solubility of CsBr in the conventional solvent is poor. Here, we develop a facile thiourea-assisted two-step spin-coating process to fabricate a CsPbBr3 perovskite film with high phase purity and crystallinity and enlarged crystal grains. Thiourea is introduced into the PbBr2 layer during the first-step spin-coating process, which promotes the wettability of the PbBr2 layer and produces the space for growing large perovskite grains. The green high-concentration CsBr/H2O solution is adopted at the second-step spin-coating process, enabling enough CsBr to be deposited by a facile one-step process. By optimizing the content of thiourea, a compact CsPbBr3 perovskite film with a smooth surface, large grains, and high phase purity and crystallinity is formed. Consequently, the fabricated perovskite solar cell with the architecture of FTO/TiO2/CsPbBr3 film/carbon exhibits a superior performance with a high efficiency of 9.11%. In addition, the unencapsulated device preserves over 90% of its initial efficiency after storage at ambient conditions for 45 days.

Reverse V-shaped wear rate vs. friction velocity curve of hard chromium coating and its inspiration for anti-wear coating design

In this research, the friction and wear behaviors of hard chromium (Cr) coating under harsh accelerated friction test conditions (unlubricated reciprocating friction with hard Al2O3 ceramic ball as counterpart) were investigated. The results show that hard Cr coating exhibits comparatively consistent tribological performance through the combination of oxidation wear, abrasive wear and plastic deformation mechanisms in general; it shows relatively low rate of wear in a wide range of friction frequency, and even at higher sliding frequencies its wear rate decreases with increasing frequency; its wear rate-friction velocity (or frequency) curve is in reverse V shape. It has been revealed that these surprising features of hard Cr coating are closely associated with its relatively high micro-hardness and compact frictional oxide thin film. This study enlightens a desirable direction for anti-wear coating design.

Electrospinning of Microstructures Incorporated with Vitamin B9 for Food Application: Characteristics and Bioactivities.

The food industry has been expanding, and new vectors to entrap vitamins have been constantly investigated, aiming at versatile systems with good physico-chemical characteristics, low-cost production, high stability and the efficient release of active ingredients. The vitamin B9 (folic acid or folate) is essential for the healthy functioning of a variety of physiological processes in humans and is beneficial in preventing a range of disorders. In this study, two approaches were developed to encapsulate vitamin B9. Zein and the combination of modified starch with two plasticizers were the selected encapsulating agents to produce microstructures via the electrospinning technique. The objective was to improve the stability and the B9 antioxidant capacity in the final formulations. The work strategy was to avoid limitations such as low bioavailability, stability and thermosensitivity. The microstructures were fabricated and the morphology and shape were assessed by scanning electron microscopy. The B9 release profiles of modified starch and zein microstructures were analyzed in simulated gastric fluid at 37 °C, and in deionized water and ethanol at room temperature. The B9 encapsulation efficiency and the stability of the systems were also studied. The ABTS assay was assessed and the antioxidant activity of the produced microstructures was evaluated. The physico-chemical characterization of loaded B9 in the microstructures was achieved. High encapsulation efficiency values were achieved for the 1% B9 loaded in 12% w/w modified starch film; 5% B9 vitamin encapsulated by the 15% w/w modified starch with 4% w/w tween 80; and 4% w/w glycerol film with heterogeneous microstructures, 5% w/w zein compact film and 10% w/w zein film. In conclusion, the combinations of 7 wt.% of modified starch with 4 wt.% tween 80 and 4 wt.% glycerol; 15 wt.% of modified starch with 4 wt.% tween 80 and 4 wt.% glycerol; and 12 wt.% modified starch and 5 wt.% zein can be used as delivery structures in order to enhance the vitamin B9 antioxidant activity in the food and nutraceutical fields.

Characterizations of the biomineralization film caused by marine Pseudomonas stutzeri and its mechanistic effects on X80 pipeline steel corrosion

• Marine pseudomonas stutzeri is isolated and identified. • P. stutzeri can promote the formation of a protective biomineralization film. • The biomineralization film has a good inhibition effect against steel corrosion. • The inhibition effect is related to the initial cell concentrations of P. stutzeri . • A novel strategy of preparing nano iron oxides by steel corrosion is put forward. Microbiologically influenced corrosion (MIC) of steel generates a corrosion product film, which can also be called biomineralization film. It is critical to understand the structure of biomineralization film since it dominates the corrosion behavior of metal. In this work, Pseudomonas stutzeri ( P. stutzeri ) was isolated from seawater, and the biomineralization film caused by marine P. stutzeri was characterized by Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), etc. The mechanistic effects of the biomineralization film on X80 pipeline steel corrosion were also investigated. The results indicate that the minerals are mainly composed of nano Fe 3 O 4 and FeOOH, according to TEM and XRD results. The particle sizes of biominerals are below 10 nm. This work also provides an insight strategy to prepare nanomaterials by MIC caused by P. stutzeri . In addition, P. stutzeri can grow well with CO 2 as a carbon source and iron as an electron donor. The corrosion rates (CRs) of specimens are closely related to the structure of biomineralization film. The CRs increase with the decrease of initial cell concentration. P. stutzeri with an initial concentration of 10 7 cells/mL can promote the formation of a compact biomineralization film with a thickness of 145.8 ± 4.8 μm, leading to corrosion inhibition with a CR of 0.058±0.008 mm/y. But some corrosion pits can be observed due to the formation of small anodes. Electrochemical impedance spectroscopy (EIS) data show higher impedance values and two time-constants, which imply the formation of a compact biomineralization film.

Single Step Electrosynthesis of Co-Ferrite Thin Films from Alkaline Non-Aqueous Bath

Electrosynthesis in a single step was used to obtain high-quality Co-ferrite thin films from an alkaline non-aqueous bath at room temperature. Several preparative parameters were optimized to obtain smooth and adherent Co-ferrite thin films. From XRD studies, cubic crystal formation was confirmed. IR studies confirmed spinel structure formation in Co-ferrite thin films. From SEM and AFM studies, smooth, uniform, and compact film formation was observed. From magnetic measurements, the value of saturation magnetization was (304 emu/cm3) obtained it is in good agreement with that of bulk value.

48.2: Formation of potential barriers at grain boundaries in multicomponent ZnO‐based transparent thin films

The article discusses the reasons for the deterioration of the electrical characteristics of ZnO‐based thin films in conditions of both high humidity and high ambient temperatures. Based on the standard damp heat test, in which thin samples subjected to temperature 85�C and relative humidity 85 % for 1000 h, it is shown that the stability of electrical performances of the transparent ZnO‐based films may be increased with an increase in the temperature of their deposition, which, in turn, leads to the formation of denser compact films. It is shown that the porous structure formed in ZnO‐based films, which leads to poor thermal stability, is due to the relatively low mobility of adatoms on the growing surface during film deposition at relatively low substrate temperatures. The analysis of the obtained data shows that the key factor determining both the composition and state of grain boundaries (GBs) in nanocrystalline ZnO‐based films, as well as the formation of potential barriers at the GBs is the possible segregation of impurity materials at the GBs, which depends on the arrangement of impurity atoms with respect to Zn in the series of metal activity. The conditions for the amorphization of complex composite oxide structures are considered.

Microstructure and mechanical property evolution of He-implanted nanochannel W film under post-annealing

Tungsten (W) has been selected as the most promising Plasma Facing materials (PMFs) due to its excellent properties. One of the most challenged problems for W is the He retention. Nowaday, a nanochannel structure film was presented to improve the He irradiation resistance of W. In this work, the microstructure and mechanical property evolution of He-implanted nanochannel W film under post-annealing from 573 to 1273 K were studied. A significant growth of He bubbles and the formation of large size holes at grain boundaries (GBs) were observed after post-annealing at 1273 K. In addition, a formation model of pores structure on surface caused by high energy He implantation was proposed. Moreover, a mitigated lattice swelling was observed at 1273 K due to the He-V clusters and He bubbles migration and coarsening. The shape of the He bubbles at 1273 K was also investigated in detail. The nanochannel film has a better resistance to the degradation of Young's modulus under the He implantation than compact film, due to the loose nanochannel. Hardness increment induced by the implantation of He was analyzed. The hardening effect of the He-implanted film annealing at 1073 K, resulting from the transition of He-V clusters or He bubbles distributions from dislocations to distributed vacancies, should be notice. Finally, the holes at GBs led to the decrease of both Young's modulus and hardness.

Microstructure and Corrosion Behavior of Selective Laser‐Melted Al–Ti–Ni Coating on 90/10 Copper–Nickel Alloy

Al–Ti–Ni composite coatings with different Ti contents (wt% = 20, 25, 30, 35) are prepared on the surface of 90/10 copper–nickel alloy using selective laser melting. The microstructure and phase composition of the coatings are characterized by scanning electron microscopy, X‐ray diffraction, and energy‐dispersive spectrometry, and the corrosion resistance of the four coatings and the 90/10 copper–nickel alloy in 3.5 wt% NaCl solution is investigated. The coatings exhibit a good metallurgical bonding with the substrate, and passive films are formed on the surfaces of the coatings after 6 h of potentiostatic polarization. The coating with a Ti content of 30% has the most compact passive film and the best corrosion protection performance due to the minimal Ti2O3 content in the passive film, which greatly improves the stability of the passive film. The immersion corrosion mechanism of the coating is pitting corrosion. Electrochemical tests show that the corrosion current density of all four coatings is one order of magnitude lower than that of the substrate, and the coating with a Ti content of 30% has the lowest corrosion current density, indicating that this coating could significantly improve the corrosion resistance of the substrate.

Poly(vinylidene fluoride-co-hexafluoropropylene) based tri-composites with zeolite and ionic liquid for electromechanical actuator and lithium-ion battery applications

In order to improve the multifunctionality of polymer composites for advanced applications a novel tri-composite material is presented based on the inclusion of MFI zeolite and the ionic liquid (IL) 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) in an electroactive poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. Tri-composites were produced by solvent casting with a relative overall filler content up to 40 wt.%. A compact film morphology is obtained, and the polymer degradation temperature and degree of crystallinity are independent on the filler content and type. On the other hand, the polymer crystalline phase depends on the presence of the IL but is independent of its content. Regarding the mechanical properties, it is observed that the IL has a plasticizing effect with a significant contribution to the reduction of the Young's modulus from 151 MPa for the pristine polymer to 92 MPa for the 30 wt.%/10 wt.% IL/MFI content sample. A high ionic conductivity value at room temperature of 3.9 × 10−5 S.cm−1 was obtained for the tri-composite with the highest IL content (30 wt.%/10 wt.% IL/MFI). The tri-composite system was studied as solid polymer electrolyte (SPE) for battery and bending actuator applications, demonstrating the multifunctionality of the material. The sample with the best cycling performance was observed for the highest MFI content (10 wt.%/30 wt.% IL/MFI) with a discharge capacity value of 110 mAh.g−1 and maintaining almost 80% of its initial capacity after 30 cycles at the C/10 rate. Regarding to the bending performance, the best bending actuation was detected for highest IL content (30 wt.%/10 wt.% IL/MFI), related to the ionic conductivity of the sample. Thus, it is demonstrated that the new tri-composite system, due to its tunable characteristics as a function of the relative IL and zeolite contents, is suitable for a next generation of multifunctional polymer composite materials for advanced applications.

Accelerated deterioration mechanism of 316L stainless steel in NaCl solution under the intermittent tribocorrosion process

In this research, the tribocorrosion behavior of 316L stainless steel in simulated seawater was investigated under continuous and intermittent sliding at open circuit potential. The tribocorrosion mechanism was discussed in terms of wear morphologies, mechanical property as well as chemical composition. Meanwhile, microstructure evolution inside the wear track and open circuit potential recorded after sliding were analyzed to quantify the repassivation kinetics and evaluate the impact of the regenerated passive film on wear. The results showed that the wear rate increased under intermittent sliding when the pause time is long enough to repassivate after sliding. Repeated sliding promoted the refinement of the grain inside the sliding area, which was beneficial to the generation of the thicker and more compact passive film inside the wear track. The ruptured passive film often acted as abrasives during subsequent sliding. Therefore, the accelerated material loss under intermittent sliding was attributed to the periodic mechanical removal of the thickened passive film and the enhanced abrasive wear inside the wear track.

Roll-to-roll processable MXene-rGO-PVA composite films with enhanced mechanical properties and environmental stability for electromagnetic interference shielding

MXene films promise potential electromagnetic interference (EMI) shielding materials, but poor scalable processability, environmental instability, and weak mechanical properties severely restrict their applications. Herein, we engineer the large-area, high-performance, and compact nacre-like MXene-based composite films through cooperative co-assembly of Ti 3 C 2 T X MXene and reduced graphene oxide (rGO) in the presence of polyvinyl alcohol (PVA). The resulting MXene-rGO-PVA composite films benefit from enhanced bonding strength and extra chain bridging effect of linear PVA molecules enriched with hydroxyl groups. Therefore, the composite film achieves high tensile strength (∼238 MPa) and toughness (∼1.72 MJ m −3 ) while having high conductivity of ∼32 S cm −1 . A significant EMI shielding effectiveness (41.35 dB) is also demonstrated, with an excellent absolute shielding effectiveness of ∼20,200 dB cm 2 g −1 at only 12-μm thickness. Moreover, due to the synergistic effect of multiple components, the composite films maintain a stable EMI shielding performance in harsh environments (sonication, hot/cold annealing, and acid solution) with mechanical properties that fluctuate only within 10% compared to the original film. More importantly, commercial polyethylene terephthalate release liner can be applied for the film coating, facilitating continuous roll-to-roll production of large-area films and future applications.

Synthesis and Corrosion Inhibition Performance of Mannich Bases on Mild Steel in Lactic Acid Media.

Heterocyclic Mannich bases, N-(3-oxo-3-phenylpro-pyl)thiazol-2-aminium chloride (DTZA) and N-(3-oxo-3-phenylpropyl)-1H-pyrazol-3-aminium chloride (DPZA), were developed for the corrosion inhibition of N80 steel in a 15 wt % lactic acid solution. Weight loss measurements, electrochemical techniques, surface characterization, and theoretical calculations were combined to investigate their anticorrosion performance and mechanism. The results showed that DTZA exhibited a satisfactory inhibitor efficiency of 97.56% with a dosage of 0.15% at 363 K, while DPZA achieved only 58.3% under the same conditions. Adsorptions of both inhibitors on the metal surface followed the Langmuir model with physical and chemical adsorptions. Based on X-ray photoelectronic spectroscopy (XPS) analysis, DFT calculations, and molecular dynamics (MD) simulations, stronger interactions between DTZA and iron than those in the case of DPZA were revealed, leading to the formation of a compact protective film on the metal surface, which is attributed to the presence of a thiazole ring in the DTZA chemical structure.

In-vitro corrosion behaviors of extruded Mg–Ga alloys in alpha minimum essential medium

The in-vitro corrosion behaviors of extruded Mg–xGa (x = 1, 3, 5) alloys in alpha minimum essential medium (α-MEM) were investigated. The bilayer corrosion film was composed of an outer layer dominated by amorphous phosphates–carbonates and an inner layer dominated by MgO–Mg(OH)2. Pure Mg and Mg–1Ga exhibited low corrosion rates and homogeneous corrosion behaviors owing to the protection from the compact corrosion films. By contrast, Mg–3Ga and Mg–5Ga exhibited high corrosion rates and inhomogeneous corrosion behaviors owing to the bulky micro-galvanic corrosion caused by Mg5Ga2. Based on these results, possible corrosion models were developed.

Chitosan films with tunable droplet size of Pickering emulsions stabilized by amphiphilic konjac glucomannan network

In this work, chitosan (CS) emulsion films were prepared with grapefruit essential oil (GEO) Pickering emulsions (OGEOs) stabilized by amphiphilic octenyl succinic anhydride (OSA) konjac glucomannan (OSA-KGM) network. The droplet size of emulsion was regulated by altering oil content in OGEOs (10 %, 20 %, 30 % and 40 %, w/w). The structural and physicochemical properties of CS films with tunable emulsion droplets (OGEOs) were investigated. The droplet size of OGEOs increased with the increasing content of GEO. FT-IR revealed that the formation of CS-OGEOs films was attributed to hydrogen bonding. CS-OGEOs films with large droplets presented smoother surface, enhanced water resistance, UV-shielding property, mechanical properties, but increased water vapor permeability (WVP) compared with CS-OGEOs films with small droplets. In addition, CS-OGEOs films with large droplets also presented compact film structure, controlled release of GEO, high efficiency of DPPH free radical scavenging and antibacterial activity. To sum up, incorporation of emulsion droplets was a good strategy for improving the structural and physicochemical properties of CS films.

Tailoring the microstructure and enhancing the corrosion resistance of extruded dilute Mg-0.6Al-0.5Mn-0.25Ca alloy by adding trace Ce

The effect of trace Ce addition on the microstructure evolution and corrosion behavior of dilute Mg-0.6Al-0.5Mn-0.25Ca-xCe (x = 0.1–0.3 wt%) alloys were investigated using immersion tests and electrochemical measurements. The Ce addition caused the formation of Al8Mn4Ce and Al11Ce3, which were less noble than Al8Mn5. Strikingly, the alloy containing 0.3 wt% Ce exhibited the lowest average corrosion rate of 4.13 mm y−1, which was 6.5 times lower than that of Ce-free alloy. The outstanding anti-corrosion properties were attributed to the low potential difference between Ce-containing phases and matrix, the compact composite oxide film (MgO-CeO2-Al2O3), and the enrichment of Fe in Ce-containing phases.

Direct Tracking of Additive‐Regulated Evolution on the Lithium Anode in Quasi‐Solid‐State Lithium–Sulfur Batteries

AbstractThe complicated problems confronted by lithium (Li) anode hinder the practical application of quasi‐solid‐state lithium‐sulfur (QSSLS) batteries. However, the interfacial processes and reaction mechanisms, which are still vague, pose challenges to disclose. Herein, the insoluble sulfides stacking and Li dendrites growth on the Li anode are real‐time monitored via in‐situ atomic force microscopy inside the working QSSLS batteries. In the LiNO3‐added electrolyte, it is detected that the formation process of solid electrolyte interphase (SEI) involves two stages, forming loose nanoparticles (NPs, ≈102 nm) at the open circuit potential and dense NPs (≈74 nm) during discharging owing to the synergism of Li polysulfides (LiPSs) and LiNO3. The compact SEI film not only blocks the erosion of LiPSs but also homogenizes the Li deposition behaviors, leading to the electrochemical performance enhancement of QSSLS batteries. These straightforward insights uncover the additive‐manipulated morphological/chemical evolution and interfacial properties and thus facilitate the improvement of QSSLS batteries.

Bridging sheet size controls densification of MXene films for robust electromagnetic interference shielding

SummaryNumerous voids among the incompact layer-structure of MXene films result in their low ambient stability and poor innate conductivity for electromagnetic interference (EMI) shielding. Herein, we report a bridging-sheet-size-controlled densification process of MXene films by applying graphene oxide (GO) as a bridging agent. Specifically, the sheet size of GO is tailored to quantify a negative correlation of sheet size with densification for directing the preparation of most compact MXene-GO films. Benefiting from the shortest electron-transport-distance in the most compact structure, the conductivity of the MXene-GO film achieves 1.7 times (∼1.6 × 105 S/m) that of MXene film. The EMI shielding performance (5.2 × 106 dB/m) reaches the record-value among reported MXene films at 10 μm-scale thickness. Moreover, the compact structure boosts the ambient stability of MXene-GO films where the conductivity and EMI shielding performance remain 88.7% and 90.0% after 15 days, respectively. The findings rationale the structure-activity relationship of compact MXene films for flexible electronics.

Antimony Selenide Thin Films by Electrodeposition: Influence of Deposition Conditions and Post‐Deposition Thermal Treatment on Physical and Photoelectrochemical Properties

Herein, Sb2Se3 thin films are obtained by the electrodeposition technique from a single bath on fluorine‐doped tin oxide (FTO) substrates. The electrodeposition conditions such as precursor concentration and applied potential, as well as the annealing temperature, and its influence on the structural, morphological, optical, and photoelectrochemical properties are analyzed. From the cyclic voltammetry measurements, the range of deposition potential is established and from the sweep rate variation, an irreversible and diffusion‐controlled process is assumed. With the chronoamperometric curves, an instantaneous nucleation is concluded. The Se/Sb ratio variation of the precursor solutions demonstrate that the 0.7 ratio is optimal to obtain Sb2Se3 stoichiometric thin films. The conductivity decreases with the increase of the deposition potential, while the highest photosensitivity is obtained with the film deposited at −0.75 V versus the saturated calomel electrode. Regarding the annealing temperature, a compact homogeneous film is obtained in the range from 325 to 425 °C. Therefore, the suitable properties of Sb2Se3 films obtained by electrodeposition and the establishment of optimized deposition conditions for its use in photoelectrochemical cells (PECs) are demonstrated.

Corrosion behaviors and mechanism of CrFeNi2 based high-entropy alloys

Herein, a novel CrFeNi2-based multi-component alloy system was designed and the corrosion behaviors were investigated in 3.5 wt% NaCl solution. The single-phase FCC solid solution was observed in CrFeNi2 and CoCrFeNi2 alloys, while the lamellar eutectic structure composed of dual-phase formed in the AlCoCrFeNi2 alloy. The electrochemical results showed that the CrFeNi2-based alloys, with higher Epit and lower Icorr, displayed better corrosion resistance, outperforming previously reported conventional alloys and some other high entropy alloys, due to the compact and stable oxide films composing of protective oxide/hydroxide. In the CrFeNi2-based alloy system, all examined specimens were suffered localized corrosion. The Co-free CrFeNi2 alloy possessed the best corrosion resistance, demonstrating the widest passivation region (approximately 1035 mVAg/AgCl), the highest pitting potential (954 mVAg/AgCl), and an outstanding repassivation ability. In addition, the corrosion mechanism was investigated and discussed. This research will sight light on the comprehending of corrosion behaviors through different phases and the effect of element on corrosion resistance.