Optimum Fabrication Conditions Research Articles

Effect of fabrication conditions on crystalline of SmBCO films fabricated by TFA-MOD method

Metal organic deposition using trifluoroacetates is expected as a method for YBCO coated conductors since this method can provide high superconducting properties and is a cost-effective process with non-vacuum system. Recently, REBCO coated conductors, which has high critical properties, have attracted considerable attention. However, there are some problems to optimize fabrication conditions of REBCO films with this method. In this study, we fabricated SmBCO films by TFA-MOD method and investigated the effect of fabrication conditions on crystalline. We focused especially on a starting temperature ( T 1) of inlet moisture in calcination step and O 2 gas concentration in crystallization step. Flat surfaces were obtained for the calcined films at both T 1 = 300 °C and 350 °C compared with that at 200 °C. One possible reason for this worse morphology at T 1 = 200 °C might be a length of a reaction time between moisture and coated film. When moisture is supplied from low temperature for long time, water could react easily to the fluoride which is contained a lot in the coated film; as a result, more HF gas is generated from the film. The crystalline was also improved for the SmBCO films calcined at over T 1 = 300 °C. Furthermore, the film calcined at T 1 = 350 °C was crystallized under the condition that O 2 gas concentration was varied between 0.2 ppm and 1000 ppm. The degree of c-axis orientation depends on oxygen partial pressure and the highest c-axis oriented SmBCO film was obtained in the case of 10 ppm.

Fabrication and optical properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 thin films on Si substrates using the PLD method

Epitaxial 0.67Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3)-0.33PbTiO(3) (PMN-PT) thin films with electro-optic effects were fabricated on (PMN-PT) thin films with electro-optic effects were fabricated on (La0(0.5)Sr0(0.5))CoO(3) (LSCO)/CeO(2)/YSZ-buffered Si(001) substrates using double-pulse excitation pulsed laser deposition (PLD) method with a mask placed between the target and the substrate. Epitaxial growth of PMN-PT thin films was undertaken using the two-step growth method of PMN-PT film. The PMN-PT seed layer was deposited at 500 degrees C on the LSCO/CeO(2)/YSZ/Si, which temperature was the same as that used for LSCO deposition. The PMN-PT thin films were deposited on the PMN-PT seed layer at 600 degrees C, which enables growth of high-crystallinity PMN-PT films with smooth surfaces. We obtained optimum fabrication conditions of PMNPT film with micrometer-order thickness. Resultant films showed high crystallinity with full width at half maximum (FWHM) = 0.73 deg and 1.6 mum thickness. Electro-optic properties and the refractive index value were measured at 633 nm wavelength using the prism coupling method. The obtained refractive index was 2.59. The electro-optic coefficients r(13) and r(33) were determined by applying the electrical field between a semitransparent, thin top electrode of Pt and a bottom LSCO electrode. The electro-optic coefficient was r(13) = 17 pm/V at transverse electric field (TE) mode and r(33) = 55 pm/V at transverse magnetic field (TM) mode.

Inter-substrate microstructure formation by electroplating bonding technology

This paper explores the technological capabilities as well as theoretical limitations of electroplating bonding technology (EBT). EBT is of particular interest for the fabrication of complex three-dimensional electrical components (e.g. inductors, high frequency antennae, etc) as well as high aspect ratio mechanical structures with exotic geometrical features. Two separate substrates, each containing identical arrays of 150 µm tall copper microstructures, are aligned and then joined together using electrodeposition of copper under forced convection conditions to form 300 µm long structures that mechanically and electrically link the two substrates. Theoretical and experimental approaches are used to develop this bonding system. Mass transfer calculations of diffusion and convection are performed to predict optimal fabrication conditions. To demonstrate the ability to predict optimal plating conditions, a test coupon mimicking a chip-scaled interconnect system with 256 chip interconnects is designed, fabricated and characterized. The mechanical and electrical connectivity are verified by formation of daisy-chained test beds. The electrical testing of the bonded system shows an excellent conductivity of 0.097 Ohm/test row. Thermal-cycling-accelerated aging tests are performed over a temperature range from −55 to +125 °C. Electroplating bonded structures show excellent mechanical stability as well as electrical performance.

Formation of <I>In Situ</I> Composite Layer on Magnesium Alloy Surface by Casting Process

In order to develop a process to obtain a functional layer on the surface of a magnesium alloy, the composite layer including in situ Mg 2 Si was formed on the surface by a gravity die-casting. The optimum fabrication condition to form the composite layer and the formation mechanism of the layer were clarified by observing the microstructure, and then the wear properties of the composite layer were also investigated. By casting the magnesium alloy melt into the permanent mold on which the slurry mainly consisting of Si particles was coated, the magnesium alloy composite layer in which the in situ Mg 2 Si particles were dispersed was formed. The melt temperature and mold temperature required to form the composite layer, which perfectly covers the casting, were above 1073 K and above 673 K, respectively. The composite layer was a magnesium alloy in which the fine Mg 2 Si particles of approximately 40 vol% were dispersed. The thickness and hardness of the layer was about 600 μm and 180 HV, respectively. Under the dry sliding wear, the weight loss of the composite layer was lower than that of the magnesium alloy. These results lead to the conclusion that the wear resistant magnesium alloy composite layer in which the in situ Mg 2 Si particles were dispersed can be formed in the present process.

Thermally Responsive Reversed Micelles for Immobilization of Enzymes

AbstractIn this study, thermally responsive alkyl end‐capped poly(N‐isopropylacrylamide‐co‐acrylic acid) amphiphilic copolymers were synthesized, and successfully utilized to fabricate reversed micelles and immobilize enzymes. Transmission electron microscopy (TEM) study showed that the reversed micelles were spherical in nature. The activity of Candida rugosa lipase immobilized in the reversed micelles towards catalyzing the esterification of lauric acid and 1‐propanol was analyzed in comparison with naked enzyme. Immobilized lipase provided much greater catalytic activity. In addition, the effects of pH, water content, polymer and enzyme concentration on the catalytic activity were investigated. The optimized fabrication conditions of lipase‐loaded reversed micelles, under which lipase gave the highest activity, were as follows: polymer concentration, 12 mg mL–1; enzyme concentration, 25 mg mL–1 phosphate buffered saline (PBS); pH, 7.4; W0 ([water]/[surfactant]), 83.3. Lipase immobilized in these micelles was much more stable than that in conventional sodium bis(2‐ethylhexyl) sulfosuccinate micelles. More importantly, the size of lipase‐immobilized micelles decreased, and the enzyme solution precipitated from the reaction mixture when the temperature increased to a value slightly higher than the lower critical solution temperature (LCST) of the polymer. The recovery rate of enzyme was about 75 %. The α‐helix structure of the recovered lipase remained intact. In addition, the enzymatic reaction was terminated after raising the environmental temperature slightly above the LCST. These thermally responsive micelles may make a promising system for enzyme immobilization.

Effects of heat treatments on the properties of Cu(In,Ga)Se 2 nanoparticles

Effects of heat treatment in nitrogen or Se atmosphere on the properties of Cu(In,Ga)Se 2 (CIGS) nanoparticles were investigated to extract optimum sintering conditions for fabrication of solar cell applicable CIGS absorber films. In nitrogen atmosphere, as the temperature increases from 100 to 400 °C the intensity of X-ray diffraction (XRD) peaks corresponding to the (1 1 2), (2 2 0) and (3 1 2) planes of the chalcopyrite CIGS increases, and the peak positions shift to lower angle regions without any particle growth in scanning electron microscopy (SEM) analysis, which is in consistent with the significant In and Ga loss in the EDS data. When the temperature further goes up to 500 °C, parts of CIGS are decomposed and Cu and CuSe 2 phases are observed. From these results, the heat treatment in nitrogen atmosphere is found to have no beneficial effect on the sintering of the particles and only induces loss of In and Ga. On the other hand, heat treatment in Se atmosphere at a substrate temperature of 550 °C with Se vapor evaporated at 250 and 450 °C provided much enhanced growth of the particles, specially up to 500 nm at 450 °C, and increased crystallinity without In or Ga loss, reflecting that Se supply played a critical role in the growth of the CIGS nanoparticles.

FABRICATION OF SILICON NANOARRAYS BY DIRECT NANOSPHERE LITHOGRAPHY

We present the fabrication of large-scale two-dimensional periodic silicon nanoarrays using nanosphere lithography. The techniques start from a monolayer of self-assembled polystyrene (PS) spheres of 220 nm in diameter on water surface, which works as a mask to fabricate large-scale periodic silicon nanoarrays by direct plasmatherm reactive ion (RIE) etching. AFM images of the nanoarrays show that the patterns of PS templates are well transferred to the Si surface. The tips stand 50–80 nm high and the lateral size is around 150 nm. The optimum fabrication conditions can be chosen via the analysis of the experimental data.

Hybrid organic–inorganic octyl monolithic column for in-tube solid-phase microextraction coupled to capillary high-performance liquid chromatography

An octyl-functionalized hybrid silica monolithic column was developed for in-tube solid-phase microextraction (SPME) to perform on-line preconcentration coupled to capillary high-performance liquid chromatography (μHPLC) analysis. A hybrid silica monolithic column functionalized with octyl groups was conveniently synthesized by a two-step acid/base-catalyzed hydrolysis/co-condensation of tetraethoxysilane (TEOS) and n-octyltriethoxysilane (C8-TEOS). The size of through-pores as well as the carbon content can be adjusted by changing the ratio of TEOS to C8-TEOS in the polymerization mixture. The extraction characteristics of the monolithic column prepared under optimized fabrication conditions were studied by using polycyclic aromatic hydrocarbons (PAHs) as the analytes. The sample volume that could be injected into the system was increased up to 1 mL with simultaneous increase of column efficiency, when hybrid silica monolithic column was used as a precolumn. Good linear calibration curves ( R > 0.999) were obtained, and the limits of detection (signal-to-noise ratio, S/N = 3) for the analytes were found to be between 2.4 and 8.1 ng/mL with a UV absorbance detector, which are 299–456 times lower than those obtained without preconcentration. The column-to-column RSD values were 1.3–8.0% for recoveries of PAHs investigated.

Optimization of the operational controlling parameters in indirect photocatalytic oxidation of water dissolved pollutants on nanostructured TiO2 thin film electrodes

Analytical expressions are derived to theoretically analyse the effect of different operational parameters on the electron concentration at the back contact and the quantum efficiency of the nanostructured TiO2 photocatalytic electrodes in contact with aqueous electrolytes. The influence of film thickness, light absorption coefficient and electron diffusion coefficient is considered cumulatively to find the optimal fabrication conditions. Light intensity, concentration of the dissolved pollutant and the recombination rate constants are also analysed as the main affective parameters during the operation of the photocatalytic device. Finally, the competitive behaviour of generation and recombination rates of photogenerated charge carriers is considered along with the quantum efficiency. The results indicate that for any given condition, there is always an optimal film thickness at which the system has the highest quantum yield. It is also found out that the light intensity is the most important operational factor, for which the optimal amount should also be determined for any specific films and operational conditions.

Rapid prototyping of poly(methyl methacrylate) microfluidic systems using solvent imprinting and bonding

We have developed a method for rapid prototyping of hard polymer microfluidic systems using solvent imprinting and bonding. We investigated the applicability of patterned SU-8 photoresist on glass as an easily fabricated template for solvent imprinting. Poly(methyl methacrylate) (PMMA) exposed to acetonitrile for 2 min then had an SU-8 template pressed into the surface for 10 min, which provided appropriately imprinted channels and a suitable surface for bonding. After a PMMA cover plate had also been exposed to acetonitrile for 2 min, the imprinted and top PMMA pieces could be bonded together at room temperature with appropriate pressure. The total fabrication time was less than 15 min. Under the optimized fabrication conditions, nearly 30 PMMA chips could be replicated using a single patterned SU-8 master with high chip-to-chip reproducibility. Relative standard deviations were 2.3% and 5.4% for the widths and depths of the replicated channels, respectively. Fluorescently labeled amino acid and peptide mixtures were baseline separated using these PMMA microchips in <15 s. Theoretical plate numbers in excess of 5000 were obtained for a ∼3 cm separation distance, and the migration time relative standard deviation for an amino acid peak was 1.5% for intra-day and 2.2% for inter-day analysis. This new solvent imprinting and bonding approach significantly simplifies the process for fabricating microfluidic structures in hard polymers such as PMMA.

Signal Enhancement of Surface Plasmon Resonance Based on Gold Nanoparticle-Antibody Complex for Immunoassay

In the immunoassay based on surface plasmon resonance (SPR) system, the signal enhancement was done by means of the conjugate of gold (Au) nanoparticle-antibody fragment. Antibody fragment was prepared for the improved immobilization based on Au-thiol interaction. Through the ellipsometric analysis on surface, the conjugation between Au and antibody fragment was performed in the oriented manner. The optimal fabrication conditions such as concentration and incubation time were determined for the constant size of the fabricated nanoparticle-antibody conjugate. Through the plot of SPR angle difference versus antigen concentration, the linear correlation was achieved, of which the detection limit was 100 fg/ml.

Fabrication of highly oriented lead-free (Na, K)NbO 3 thin films at low temperature by Sol–Gel process

Lead-free piezoelectric (Na 0.5K 0.5)NbO 3 (NKN) thin films were fabricated on SiO 2/Si substrates by sol–gel process. The NKN precursor solution was prepared from Na-ethoxide, K-ethoxide, Nb-pentaethoxide, and 2-methoxyethanol. From thermogravimetry differential thermal analysis (TG-DTA) curve of the precursor dried-gel, weight loss and exothermic peaks appeared at about 300–500 °C at heating period. By using optimum fabrication conditions established from the TG-DTA, highly oriented single- phase NKN thin films were obtained at 500 °C by spin-coating technique. Average grain size and root mean square roughness obtained from atomic force microscope (AFM) image of the NKN thin film sintered at 500 °C were estimated to be about 250 and 8.35 nm, respectively. From TG curve, crystallinity and surface morphology, it is found that volatilization of alkaline elements seems to have been suppressible at temperature lower than 600 °C.

Optimisation of melting and casting conditions for Zr-fluoride based glasses

A systematic investigation was carried out on melting and casting of Zr-fluoride based glasses in order to find out the optimum fabrication conditions. Several rods were prepared with variation in compositions and melting/casting parameters. They were characterised to compare their optical homogeneity and stability. The results showed an appreciable influence of the conditions selected during different stages of melting on the glass quality. The fabrication conditions were optimised for three different compositions suitable for making optical fibre preforms.

Octyl-functionalized hybrid silica monolithic column for reversed-phase capillary electrochromatography

Hybrid silica monolithic stationary phase functionalized with octyl groups was synthesized by a two-step acid/base-catalyzed hydrolysis/co-condensation of tetraethoxysilane (TEOS) and n-octyltriethoxysilane (C 8-TEOS). The influences of determining factors in the sol–gel process such as the monomer ratio and water content on the monolith formation were systematically investigated. An increase in the TEOS/C 8-TEOS ratio in the polymerization mixture shifted the pore size distribution towards smaller pore diameter with larger pore volume. The optimal TEOS/C 8-TEOS volume ratio was found to be 90/50, under which condition the median pore diameter of the monolith was around 1.0 μm with pore volume of 3.25 cm 3/g. The chromatographic characteristics of the monolithic column prepared with the optimized fabrication condition were studied. Some aromatic compounds including alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs) and phenols were successfully separated on the octyl-functionalized silica monolithic column with high column efficiency up to 180,000 plates/m.

Energetic Surface Smoothing of Complex Metal-Oxide Thin Films

A novel energetic smoothing mechanism in the growth of complex metal-oxide thin films is reported from in situ kinetic studies of pulsed laser deposition of on , using x-ray reflectivity. Below 50% monolayer coverage, prompt insertion of energetic impinging species into small-diameter islands causes them to break up to form daughter islands. This smoothing mechanism therefore inhibits the formation of large-diameter 2D islands and the seeding of 3D growth. Above 50% coverage, islands begin to coalesce and their breakup is thereby suppressed. The energy of the incident flux is instead rechanneled into enhanced surface diffusion, which leads to an increase in the effective surface temperature of DeltaT approximately 500 K. These results have important implications on optimal conditions for nanoscale device fabrication using these materials.

Phase separation and interfacial reaction of high-k HfAlOx films prepared by pulsed-laser deposition in oxygen-deficient ambient

Ultrathin high-k HfAlOx films on silicon wafers are prepared by pulsed-laser deposition in oxygen-defective ambient. The precipitation of HfOx clusters from HfAlOx matrix is revealed by x-ray photoelectron spectroscopy. It is argued that the HfOx clusters react with silicon to form Hf-silicide interfacial layer at a temperature as low as 600°C, which evolves into Hf-silicate in the subsequent postannealing at 700°C for 30s in oxygen ambient. The optimized fabrication conditions developed to avoid the formation of interfacial layer is employed to prepare high-quality HfAlOx films of excellent electrical characteristics, such as a dielectric constant of 17.7, a small equivalent oxide thickness of 0.66nm, a flatband voltage of 0.45V, and a low leakage current density of 53.8mA∕cm2 at 1V gate voltage.

マグネタイト超微粒子の作製とその特性評価

Recently, the ultrafine magnetic particles are applied in many fields, such as magnetic record materials, magnetic fluid, catalysts, biologic medicine materials and so on. In order to fabricate the magnetite nanoparticle with uniform size, liquid phase precipitation method with lower cost is used in this research work. Here, Iron (II) Chloride Tetrahydrate [FeCl2·4H2O], Iron(III) Chloride Hexahydrate [FeCl3·6H2O] mixture solution and NaOH solution were added into the reaction solution by titration method step by step according to the change of pH value, and the solution was being stirred during the reaction process. In this paper, the optimum fabrication condition and the magnetism of composed nanoparticles are investigated. Through evaluation of magnetic property of the fabricated nanoparticle, at room temperature and pH value 7.0, 8nm uniform magnetic particles were synthesized with saturation magnetization value of 48 emu/g and Curie point 471°C.

Macroporous Hydroxyapatite Ceramic Coating by Using Electrophoretic Deposition and Then Heat Treatment

A macroporous hydroxyapatite ceramic coating was fabricated on a titanium substrate by an electrophoretic deposition (EPD) process followed by a heat treatment in order to obtain high performance bioactive porous hydroxyapatite. The key of this EPD process is a formation of composite particles by using a heterocoaguration reaction, consisting of hydroxyapatite ceramic nanoparticles for the ceramic frame material and monodisperse polystyrene polymer microspheres for template component, in a suspension. Microstructure of the porous ceramic coating layer depends on electrophoretic deposition parameters, and on heat treatment conditions. Under the optimized fabrication conditions, the hydroxyapatite ceramic coating layer with well-controlled macroporous structure was obtained. In vitro examination using a simulated body fluid revealed a good biocompatibility of the macroporous specimen.

Organic thin-film transistors on plastic substrates

In this paper, organic thin-film transistors (OTFTs) were fabricated on polyethersulfone (PES) and silicon (Si) substrates with top-contact geometry. Several kinds of metals with different work functions were used for source and drain electrodes, and optimum fabrication conditions were found. Photo cross-linkable polymeric gate dielectrics and thermal silicone oxide (SiO 2) were used for the plastic and Si OTFTs, respectively. From the electrical measurements, typical I– V characteristics of the thin-film transistor (TFT) were observed. The field-effect mobility, μ, was obtained to be 2.59 cm 2/(V s) from the flexible OTFT with polymeric gate dielectrics. Moreover, a possible critical work function of 4.3 eV for the electrode of pentacene OTFT with top-contact geometry.

Formation of water-resistant hyaluronic acid nanofibers by blowing-assisted electro-spinning and non-toxic post treatments

A unique blowing-assisted electro-spinning process has been demonstrated recently to fabricate hyaluronic acid (HA) nanofibers. In this article, effects of various experimental parameters, such as air-blowing rate, HA concentration, feeding rate of HA solution, applied electric field, and type of collector on the performance of blowing-assisted electro-spinning of HA solution were investigated. With the assistance of air-blowing, the solution-feeding rate could be increased to 40 μl/min/spinneret and the applied electric field could be decreased to 2.5 kV/cm. The optimum conditions for consistent fabrication of HA (with a molecular weight of ∼3.5 million) nanofibers involved the use of an air-blowing rate of around 70 ft 3/h and a concentration range between 2.5 and 2.7% (w/v) in aqueous solution. Two benign methods to fabricate water-resistant HA nanofibrous membranes without the use of reactive chemical agents were demonstrated: (a) the exposure of HA membranes in hydrochloric acid (HCl) vapor, followed by a freezing treatment at −20 °C for 20–40 days; and (b) the immersion of HA membranes in an acidic mixture of ethanol/HCl/H 2O at 4 °C for 1–2 days. Although both methods could produce hydrophilic, substantially water-resistant HA nanofibrous membranes (the treated membranes could keep their shape intact in neutral water at 25 °C for about 1 week), the immersion method (6) was shown to be more versatile and effective. IR spectroscopy was used to investigate this ‘cross-linking’ mechanism in the solid HA membrane. Viscosity studies of acidic HA solutions under varying freezing conditions were also carried out. It was found that when the freezing time exceeded 8 h, the HA solution became gel-like and exhibited a large increase in the hydrogen-bond concentration. Thus, the resistance to water solubility could be due to the high density of hydrogen bonds in the solid HA membranes that were treated by the ‘freezing’ approach.