Effects Of Fabrication Conditions Research Articles

Molecular dynamics study of the effect of composition on elastic properties of silicon oxynitride films

Understanding the mechanical properties of silicon oxynitride (a-SiON), a key insulating material, is vital for electronic device design and reliability. Though the effects of fabrication conditions on a-SiON have been studied, the underlying relationship between its atomic-scale structure and mechanical properties remains unclear. This study investigates the relationship between elasticity and atomic-scale structures in a-SiON by molecular dynamics simulations with a universal graph neural network interatomic potential. The bulk modulus increases from 49 to 150 GPa with higher N content. N atoms form N2 molecules under O-rich conditions, hindering bulk modulus increase, and form an Si3N4-like network under O-poor conditions, enhancing bulk modulus. Formation energy calculations indicate N2 formation is preferable under O-rich conditions. Meanwhile, under O-poor conditions, Si–N bond formation is preferable, which reinforces a-SiON by increasing bond density. The findings suggest realizing O-poor conditions is crucial for highly elastic insulating films.

Effects of Fabrication Conditions on the Partial Discharge Mitigation Performance of Electrets for Power Electronic Driven Systems

In our previous studies, we have shown that electrets can be designed to mitigate partial discharge (PD) in power electronic converter (PEC)-driven systems by neutralizing locally-enhanced harmful electric fields. Surface charge density is one of the main factors that determines the PD mitigation performance of electrets. In this study, we fabricate electrets from polyvinylidene fluoride (PVDF) films under various charging conditions including voltage magnitude, charging duration, voltage polarity, and temperature using triode-corona discharge method. The surface charge density and PD mitigation performance of the fabricated electret films are assessed by surface potential measurements and PD experiments. <styled-content style="color:black">The effects of fabrication temperature on electret surface charge stability, and the impacts of atmospheric conditions on electret surface charge density and PD magnitude are discussed.</styled-content> This study provides knowledge that is essential for establishing the fabrication conditions of electrets that can effectively mitigate PD in PEC-driven systems.

Controllable preparation of novel “ridge-valley shaped” poly(p-phenylene terephthamide) (PPTA) hollow fiber nanofiltration membrane for thermal dye/salt wastewater separation

In this study, two novel poly(p-phenylene terephthamide) (PPTA) hollow fiber composite nanofiltration (NF) membranes with excellent thermal stability and antifouling performance were synthesized on the homogeneous reinforced PPTA hollow fiber membranes by interfacial polymerization and the robust chemical vapor deposition separately. The effect of fabrication conditions, substrate properties on the NF performance was systematically investigated and optimized. Interestingly, SEM images presented that the two different composite membranes had relatively rough surfaces containing globular or striped structures, which was the same as the reported Turing-type structures. Meanwhile, the formation mechanism of the rough globular and striped morphologies on the surface of the membranes was also discussed. Moreover, both membranes were compared through filtration experiments such as permeate flux, solute rejection, heat stability, and anti-fouling property. The results presented that both membranes displayed high removal capacity for low molecular weight dyes (200–1000 Da), meanwhile, they exhibited high rejections (98.4 %) for negative dyes. However, they possessed complicated and diverse rejective behaviors for dye removal in different aqueous environments, such as diverse solute concentrations and diverse operating conditions. It was worth noting that PPTA/PA composite membrane showed higher separation efficiency, thermal stability, and antifouling performance compared to PPTA/PPy composite membrane, due to the significantly increased negative charge density and hydrophilicity on the membrane surface. Besides, this study offered new insights and strategies for exploring next-generation NF membranes for high temperature dye wastewater treatment.

Effect of Fabrication Conditions on Tensile Strength of Porous SUS630 Using Selective Laser Melting

Effect of Fabrication Conditions on Tensile Strength of Porous SUS630 Using Selective Laser Melting

Synthesis of biodegradable liquid-core microcapsules composed of isocyanate functionalized poly(ε-caprolactone)-containing copolymers

• Biodegradable isocyanate-containing polymers were synthesized via Cu(0)-mediated controlled radical polymerization. • Good stability and well-defined morphology of powder-form biodegradable liquid-core microcapsules were obtained. • The effect of fabrication conditions on microcapsule properties was investigated. A combination of reversible deactivation radical polymerization (RDRP), isocyanate chemistry, and a convenient drying process via spray drying is employed to fabricate powder-form biodegradable liquid-core microcapsules. Two different molecular weight α,ω-poly(ε caprolactone) RDRP macroinitiators were first prepared through esterification to obtain the degradable α-halo ester initiators. Subsequently, poly(benzyl methacrylate- co -isocyanatoethyl methacrylate) (P(BnMA a - co -IEM b )) copolymers were synthesized from the RDRP macroinitiators using a copper(0)-mediated polymerization system at ambient temperature. By controlling the macroinitiator to monomer feeding ratio from 1:50 to 1:100, the resultant copolymers had number average molecular weights ( M n ) in the range of 7900–17800 g mol −1 with dispersities ( Đ ) of 1.42-1.52. Afterward, the isocyanate-containing copolymers were employed in the fabrication of particles via interfacial polymerization, followed by a water removal process using spray drying. All polymers and particles were thoroughly characterized using a range of spectroscopic, chromatographic and microscopy analyses.

Effects of Fabrication Conditions on Structure and Properties of Mechanically Prepared Natural Silk Web and Non-Woven Fabrics.

In this study, natural silk web and natural silk non-woven fabric were prepared mechanically using the binding character of the sericin in silk. The effect of process variables on the preparation, structure, and properties of the silk web and the non-woven fabric was examined. The reeling velocity affected the morphology and mechanical properties of the web but had almost no influence on the crystalline structure of the silk. From the viewpoint of reel-ability and the mechanical properties (work of rupture) of silk web, a reeling velocity of 39.2 m/min represented the optimal processing velocity. The porosity and swelling ratio of the silk web decreased slightly with increasing reeling velocity. Furthermore, the reeling bath temperature had a significant effect on the reel-ability of silk filaments from a silkworm cocoon. Bath temperatures ≥50 °C yielded good reel-ability (>900 m reeling length). The porosity, swelling ratio in water, and mechanical properties of the silk web and silk non-woven fabric changed only slightly with the reeling bath temperature but changed significantly with the hot press treatment. The hot-pressed silk web (i.e., silk non-woven fabric) exhibited higher tensile strength as well as lower elongation at break, porosity, and swelling ratio than the silk web.

Effects of fabrication conditions on the microstructure, pore characteristics and gas retention of pure tungsten prepared by laser powder bed fusion

In this study, the effects of fabrication conditions on the microstructure, pore characteristics and gas retention of pure tungsten specimens prepared by laser powder bed fusion (LPBF) were investigated. The LPBF specimens contained micro- and nano- sized pores as internal defects. By optimizing the laser irradiation conditions, the formation of micropores was suppressed. The densest LPBF specimen was obtained when the input energy density was adjusted to be 411 J/mm3, and the relative density of the specimen measured by utilizing Archimedes' principle reached 98.58 ± 0.25% (19.03 ± 0.05 g/cm3). Heat treatment at a high temperature (1900 °C) was effective to reduce the number density of nanopores. The compositions and amounts of internal gas in the specimens were examined using a quadrupole mass spectrometer. The results indicated that the specimens contained the argon (Ar), which was used as the shielding gas. The Ar retention was correlated with the number density of nanopores in the specimens and not with the density of micropores. The Ar retention decreased to almost half that in the as-fabricated specimen after the heat treatment at 1900 °C. These observations suggest that Ar gas was trapped in nanopores in the LPBF material. It was demonstrated that a part of the trapped Ar dissolved and diffused in grains during the heat treatment and was released to the outside.

Comparison of the fabrication methods, formation dynamics, structure, and delivery performance of solid nanoparticles and hollow layer‐by‐layer edible/biodegradable nanodelivery systems

AbstractAimThis article summarizes and reviews recent studies on nanoparticulation of solid and hollow nanoparticles using edible proteins and carbohydrates from plant and animal origin and shares new research conducted in our laboratory on fabrication of biopolymer‐based nanodelivery systems.MethodsWe compare the properties of nanoparticles fabricated using desolvation, coacervation, and layer‐by‐layer assembly. The parameters affecting the morphological and physical states of the nanodelivery systems as well as their abilities to encapsulate bioactive compounds, and the mechanisms of the nanoparticulation process are discussed in detail.ResultsThe article offers methods that need to be used with each nanoparticulation technique along with key characterization data obtained. The effect of varying a wide range of parameters on particle size, size distribution, morphology, effect of solvents and non‐solvents, effect of surface charge of polyelectrolytes, effect of fabrication conditions are presented.ConclusionsWe believe the article gives enough detail to give the reader useful information related to the performance of all the different nanoparticles studied in our laboratory over the last 6 years.Practical applicationsBiopolymer based nanodelivery systems presented in this article, have great potential to be used in the nutraceutical, food, pharmaceutical industries as well as agriculture. The biodegradable and edible nature of these nanodelivery systems make them safe for incorporating into food and nutraceutical materials, because, the biopolymers used in their fabrication are biocompatible polymers of food origin that are generally recognized as safe (GRAS) (Food and Drug Administration, The Daily Journal of the United States Government, 2016). Therefore, use of edible polymer‐based nanoparticles would be safer and less toxic and consequently better for all these industries. For example, in the food industry, antioxidant compounds can be encapsulated which would then be incorporated into packaging materials and that would help maintain freshness and good quality and would prevent oxidative deterioration of foods to increase shelf life. Pesticides and insecticides can also be encapsulated in these nanodelivery systems for agricultural applications. Because they are biodegradable and originated from natural biopolymers, their impact on the environment and the quality of the soil would be minimized compared to current applications that use some burdensome chemicals. Biopolymer based nanodelivery systems would also be of high interest for the pharmaceutical industry. Through the efficacy and extra stability gained with encapsulation, drugs and bioactives would be better protected from the acidic environment of the stomach and be released more controllably in the intestines. Further functionalization of nanodelivery systems with recognition elements, such as antibodies or aptamers, would enable more specifically targeted delivery.

One-pot fabrication of polymer micro/nano-discs via phase separation and a roll-to-roll coating process

Disc-shaped particles are one of the unique and promising shapes that can improve adhesion to interfaces and can function as the key feature in various applications; e.g. injectable drug carriers. However, most of these methods include the shape deformation process from spheres to discs using various external stimuli or require multiple processing steps, which is complicated and has limitations in terms of continuous fabrication. We herein propose a novel method combining polymer blend phase separation and a roll-to-roll coating process to continuously fabricate polymer micro/nano-discs in a one-pot manner on a large-scale. The evaporation of solvent during a roll-to-roll coating process encourages the formation of homogenous island-like domains composed of the minor component dispersed in a matrix of the major component on a water-soluble polyvinyl alcohol (PVA) film. In fact, polyvinylpyrrolidone (PVP) was chosen as the major component since it dissolves in both water and chloroform. Another polymer, polystyrene (PS), as a minor component was dissolved in chloroform with PVP. A PVP and PVA matrix film can be easily washed out by water, and micro/nano-discs of the PS minor component can be obtained in a one-pot manner. This method is shown to be capable of continuously fabricating PS micro/nano-discs at a very high rate of ∼108 particles/min. The effects of fabrication conditions, such as the blend ratio and total polymer concentration on the dimensions of the PS discs were investigated, and a maximum aspect ratio (ratio between diameter and thickness) of 6.3 (diameter ∼830 nm, thickness ∼130 nm) was demonstrated. The method proposed in this study could provide a straightforward and time-saving way to continuously fabricate micro/nano-discs via polymer phase separation and a roll-to-roll coating process.

Effect of fabrication conditions on charge transport and photo-response of n-ITO/p-Cd1−xZnxTe heterojunctions

Conditions for the production of heterostructures n-ITO/p-Cd1-хZnхTe with rectifying and photosensitive properties by the magnetron sputtering method of the thin films (ITO) on crystalline substrate p-Cd1−xZnxTe are studied. On the basis of analysis of the temperature dependence of I-V-characteristics and the frequency dependence of C-V characteristics, the dynamics of the change in heterostructure energy parameters are established, and the role of the energy states at the ITO/Cd1-хZnхTe heterojunction interface in the formation of the heterojunction potential barrier is determined. Also we investigated photoelectric properties of the ITO/Cd1хZnхTe heterostructure.

Highly Sensitive and Selective Ethanol Sensor Based on ZnO Nanorod on SnO2 Thin Film Fabricated by Spray Pyrolysis

This work reports the fabrication of mixed structure of ZnO nanorod on SnO2 thin film via spray pyrolysis followed by thermal annealing and their gas sensing properties. ZnO/SnO2 nanostructures are successfully prepared on a gold interdigitated alumina substrate by spraying varying mixed precursor concentrations of zinc acetate and tin (IV) chloride pentahydrate solutions in ethanol and thermal annealing. The morphology of the nanostructures is controlled by tailoring the Zn:Sn ratio in the precursor solution mixture. Unique ZnO crystals and ZnO nanorods are observed under a field emission scanning electron microscopy (FESEM) when the Zn/Sn ratio in the precursor solution is in between 13:7 to 17:3 after thermal annealing. The fabricated nanostructures are tested for ethanol, methane and hydrogen in air ambient for various gas concentrations ranging from 25 ppm to 400 ppm and the effect of fabrication conditions on the sensitivity and selectivity are studied. Among the nanostructure sensors studied, the film fabricated with molar ratio of Zn/Sn =3:1 shows better sensitivity and selectivity to ethanol due to high sensing surface area of nanorod. The response to 25 ppm ethanol is found to be as high as 50 at an operating temperature of 400oC.

The effect of fabrication conditions on 2DEGs transport characteristics at amorphous-LaAlO3/KTaO3 interfaces

Two-dimensional electron gases (2DEGs) formed at the interface between two oxide insulators present a promising platform for the exploration of emergent phenomena. While most of the previous works focused on SrTiO3-based 2DEGs, here we report on a systematic investigation of the 2DEGs at amorphous-LaAlO3/KTaO3 (a-LAO/KTO) interfaces, focusing on the effect of fabrication conditions on 2DEGs. We found that 2DEGs can be formed in a wide temperature range from room temperature to 750° under the oxygen pressure 1 × 10–4 Pa. Unexpectedly, its performance shows a unusual strong dependence on fabrication temperature: the Hall mobility increases rapidly with the decrease of substrate temperature. The highest extracted mobility of charge carriers coming from dXZ/dYZ subband is ∼6.6 × 103 cm2 V−1s−1, achieved under the condition of TS = 100 °C and PO2 = 3 × 10–5 Pa. This value is higher than that of the 2DEGs of a-LAO/SrTiO3 by a factor of 30, which reveals the unique character of the 2DEGs formed by 5d electrons. Two-band model is applied for the analysis of the transport behavior, from which information on carrier density and Hall mobility and their dependence on fabrication conditions are determined.

Porous morphology and mechanical properties of poly(lactide-co-glycolide) hollow fiber membranes governed by ternary-phase inversion

Due to the controllable biodegradability and good biocompatibility, poly(lactide-co-glycolide acid) (PLGA) hollow fiber membranes (HFMs) have been successfully used for various biomedical applications, where the morphological and mechanical characteristics of HFMs are of crucial importance. This study focused on the effects of fabrication conditions on the morphology and mechanical performance of PLGA HFMs, which were manufactured by a phase inversion-based dry-jet wet spinning process. The cross-sectional morphology of HFMs was found to be significantly influenced by PLGA concentration of dope fluid. A 5-layered microstructure with macrovoids varied to a 6-layered microstructure with sponge-like microvoids when the PLGA concentration increased from 14% to 22%. Also, Young's modulus and compressive modulus of these PLGA HFMs were found to dramatically increase with PLGA concentration. To understand the underlying mechanism of morphological formation in PLGA HFMs, a physical mass transfer model was developed to describe the mutual diffusion process of PLGA/dimethyl sulfoxide (DMSO)/water ternary system. This model was able to quantify the PLGA distribution within the HFM cross sections by considering the interaction terms of polymer/solvent/nonsolvent in the governing equations, which was validated by the overall agreement between the experimental and numerical results. The present study should be helpful for understanding the formation mechanism of porous morphology during the phase inversion-based dry-jet wet spinning process, which may guide the optimization of PLGA HFMs for their applications as tissue engineered scaffolds.

Microstructure and thermoelectric properties of Bi1.9Lu0.1Te3 compound

Effect of fabrication conditions on microstructure and thermoelectric properties of the Bi1.9Lu0.1Te3 compound was studied. Starting nanopowder with mean nanoparticle size of ~37 nm was synthesized by a microwave–solvothermal method. In order to prepare samples with various micro-grained structures, the synthesized nanopowder was compacted by two methods. The first method is cold isostatic pressing with further high-temperature annealing, while the second method is spark plasma sintering at various temperatures of process (653 and 683 K). It is found that mean grain size is equal to ~290, ~730 and ~1160 nm for cold isostatically pressed and spark plasma sintered at 653 and 683 K samples, respectively. The micro-grained sample with maximum mean grain size shows the best thermoelectric properties. This sample is structurally inhomogeneous and has the lowest thermal conductivity and the specific electrical resistivity. Maximum dimensionless figure of merit for this sample is equal to ~0.9 for temperature range of 450–500 K.

Photocurrent Enhancement by Introducing Gold Nanoparticles in Nanostructures Based Heterojunction Solar Cell Device

ABSTRACTIn this paper, we report a first hand study of plasmon-enhanced photocurrent observed in hybrid nanostructures based heterojunction solar cell. The heterojunction solar cell was fabricated, using chemically synthesized narrow gap, IV-VI group semiconductor nanoparticles (PbS) of 3∼6nm diameter, wide gap semiconductor ZnO nanowires of 500nm∼1 μm length and ∼50nm diameter, and gold nanoparticles (∼5nm to 30nm), by spin-coating (∼20cycles) onto FTO glasses, in ambient conditions (25°C, 1atm). The synthesized nanostructures were characterized by XRD, UV-VIS absorption, SEM, TEM, solar simulator, etc. Nanostructures of variant sizes were integrated in to the heterojunction devices to study the effects on photocurrent and solar cell performance. The sizes, lengths, thickness of nanostructures were optimized to have best solar cell devices. The effects of fabrication conditions (such as growth temperature, growth time, anneal temperature, ligand treatments, in air or in N2, etc.) on device performance were also studied. The architecture of film stack, i.e., the positions of Au nanoparticles and PbS nanoparticles were also studied. It was confirmed that introducing Au nanopartiles with proper size would lead to the increase of photocurrent. The key challenges were to minimize the trap states and optimize the interface of nanostructures.

One-Pot Approach to Prepare Organo-silica Hybrid Capillary Monolithic Column with Intact Mesoporous Silica Nanoparticle as Building Block.

A facile “one-pot” approach to prepare organo-silica hybrid capillary monolithic column with intact mesoporous silica nanoparticle (IMSN) as crosslinker and building block was described. An IMSN crosslinked octadecyl-silica hybrid capillary monolithic column (IMSN-C18 monolithic column) was successfully prepared, and the effects of fabrication conditions (e.g. concentration of intact mesoporous silica nanoparticle, polycondensation temperature, content of vinyltrimethoxysilane and stearyl methacrylate) on the structures of the IMSN-C18 monolithic column were studied in detail. The IMSN-C18 hybrid monolithic column possessed uniform morphology, good mechanical and pH stability (pH 1.1–11), which was applied to the separations of alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), as well as proteins. The minimum plate height of 10.5 μm (corresponding to 95000 N m−1) for butylbenzene and high reproducibility were achieved. The analysis of tryptic digest of bovine serum albumin (BSA) was carried out on the IMSN-C18 monolithic column by cLC coupled mass spectrometry (cLC-MS/MS), with the protein sequence coverage of 87.5% for BSA, demonstrating its potential application in proteomics.

Effects of fabrication conditions on the microstructures and performances of smart gating membranes with in situ assembled nanogels as gates

Smart gating membranes with in situ assembled poly(N-isopropylacrylamide) (PNIPAM) nanogels as gates are successfully prepared via vapor-induced phase separation (VIPS) with different exposure time periods, temperatures and relative humidities of the water vapor. Effects of the fabrication conditions on microstructures as well as thermo-responsive and mechanical performances of the membranes are investigated. Both the membrane microstructure and the movement of blended PNIPAM nanogels in the membrane forming solution can be controlled by adjusting the fabrication conditions. With increasing the exposure time, the membrane microstructure undergoes a transition from typical liquid-induced phase separation (LIPS) structure (unsymmetrical finger-like porous structure) to typical VIPS structure (symmetric cellular-like porous structure). The critical time periods for the microstructure transition of membranes prepared with vapor temperature and relative humidity of 25°C/90%, 25°C/70% and15 °C/70% are about 1.5min, 2min and 10min respectively. The performances of membranes are heavily dependent on the microstructures. The membranes with unsymmetrical finger-like porous structures show large thermo-responsive factor (R39/20, the ratio of water flux at 39°C to that at 20°C), with the maximum R39/20 value being 43.2. All the membranes with symmetric cellular-like porous structures exhibit strong mechanical property and large water flux at 39°C, which is higher than the volume phase transition temperature (VPTT) of PNIPAM nanogels. The results provide valuable guidance for rational design and fabrication of smart gating membranes with desirable performances.

Microwave synthesis of nanosized particles of a complex oxide system with a garnet structure

The possibility of applying the method of microwave synthesis for the fabrication of nanosized particles of complex oxides has been demonstrated. The effect of fabrication conditions on the size of nanoparticles with a garnet structure has been established on the example of the Gd–Ga–Al–O system. The concentration of the organic solvent for obtaining particles of an average size of 50 nm has been determined experimentally. The phase composition of thermally treated samples has been investigated. The optimal conditions of producing nanosized powders of garnets, Gd3(Ga,Al)5O12, have been determined.

Effect of the catalytic system based on multi-walled carbon study of properties of catalysts based on cation-exchange resins for synthesis of bisphenols

Effect of fabrication conditions on the physicochemical and catalytic properties of catalysts based on cation-exchange resins was studied. It is shown that the porous structure and surface texture, mechanical and osmotic characteristics of both gel-like and macroporous ion exchangers are determined by the content of divinylbenzene in the copolymer. Effective ways to raise the activity of the catalysts were found.

Effects of fabrication conditions on mechanical properties and microstructure of duplex β″-Al2O3 solid electrolyte

Abstract Na-beta batteries are an attractive technology as a large-scale electrical energy storage for grid applications. However, additional improvements in performance and cost are needed for wide market penetration. To improve cell performance by minimizing polarizations, reduction of electrolyte thickness was attempted using a duplex structure consisting of a thin dense electrolyte layer and a porous support layer. In this paper, the effects of sintering conditions, dense electrolyte thickness, and cell orientation on the flexural strength of duplex BASEs fabricated using a vapor phase approach were investigated. It is shown that sintering at temperatures between 1500 and 1550 °C results in fine grained microstructures and the highest flexural strength after conversion. Increasing thickness of the dense electrolyte has a small impact on flexural strength, while the orientation of load such that the dense electrolyte is in tension instead of compression has major effects on strength for samples with a well-sintered dense electrolyte.