Effect Of Formation Conditions Research Articles

Effect of Formation Conditions on the Functional Composition of the Surface of High-Silica Porous Glass

The possibility of controlling the content and ratio of Bronsted acid to Lewis base centers on the surface of high-silica porous glass (PG) with various compositions based on two-phase alkali-borosilicate glass by varying the conditions of the preparation of PG during the acid work-up of the initial glass is shown. The results demonstrate the possibility to control the features of the surface of the PG, and in particular, the ratio of silanol to siloxane structures.

Effect Of Formation Conditions of Thick Granular Films Based on Dispersed Co3b On Their Phase Composition and Magnetoresistance

An important scientific and technical problem on developing thick resistive granular films used in microelectronics and tool manufacturing is solved. Magnetoresistive Co-containing granular films are obtained by screen printing the pastes consisting of fine-grained cobalt boride Co3B and organic binder on a dielectric substrate. Then, the deposited films are heat treated in air with no protection at all. Differential thermal analysis and thermogravimetric analysis reveal that only ferromagnetic Co (FCC) and amorphous B2O3 are present in the structure of the films at T = 650–850°C. On this basis, the modes for the heat treatment of films are developed. The effect of magnetic field on the electrical resistance of films is studied.

Formation of polycrystalline-silicon films with hemispherical grains for capacitor structures with increased capacitance

The effect of formation conditions on the morphology of silicon films with hemispherical grains (HSG-Si) obtained by the method of low-pressure chemical vapor deposition (LPCVD) is investigated by atomic-force microscopy. The formation conditions for HSG-Si films with a large surface area are found. The obtained HSG-Si films make it possible to fabricate capacitor structures, the electric capacitance of which is twice as large in comparison to that of capacitors with “smooth” electrodes from polycrystalline silicon.

Effect of Formation Conditions on the Size, Shape and Spectral Properties of EuS and Pr2S3 Nanoparticles

A solvothermal method is proposed for the preparation of EuS and Pr2S3 nanoparticles by the reaction of Eu(Stear)3 (Stear = stearate) and NH2Et2[Pr(Ddtc)4] (Ddtc = diethyldithiocarbamate) with excess carbon disulfide. Raising the temperature of this reaction leads to enhanced monodispersity of the EuS nanoparticles, while a decrease in the concentration of the starting reagents leads to a change in the shape of the nanoparticles from cubic to spherical. The band gaps were determined for the EuS and Pr2S3 nanoparticles. No quantum-size effects were found in the optical properties of the EuS and Pr2S3 materials obtained.

Direct synthesis of thermochromic VO2 through hydrothermal reaction

Thermochromic VO2 was directly synthesized using hydrothermal techniques. The effects of formation conditions on the structure and morphology of the final product were studied through X-ray diffraction (XRD), and scanning electron microscopy (SEM). Unique hollow sphere morphology was observed for the synthesized VO2 powders. Ex-situ XRD studies after heat treatment confirmed the thermal stability of the VO2 structure. Thermochromic properties, as a consequence of the reversible structural transformation between monoclinic VO2 and tetragonal phases, were observed by Fourier transform infrared spectroscopy (FTIR).

Ta-containing oxide coatings on titanium for biomedical application

Bioinert, biocompatible, chemical-resistant oxide coatings containing Ta2O5, which are promising to be applied to titanium implants, were produced on titanium by plasma electrolytic oxidation in an aqueous electrolyte. An effect of formation conditions on the elemental and phase composition, thickness, and roughness of the coatings was researched. It was found that an addition of polyethylene glycol to electrolyte without affecting the elemental composition and the thickness causes a change in the porosity and an increase in the roughness of the formed oxide layer. Changing the surface arrangement may allow affecting an adhesion of biotissues to titanium implants with coatings and accumulating drugs by the coatings.

Effects of Formation Conditions on the Physicochemical Properties, Aggregation, and Phase Transformation of Iron Oxide Nanoparticles

In this work, hematite transformation from a precursor 6-line ferrihydrite phase was investigated by systematically altering the forced hydrolysis hematite synthesis. Specifically, we used a combination of in situ and ex situ characterization techniques to examine the effects of varying the Fe(III) injection rates and cooling methods on the hematite and 6-line ferrihydrite nanoparticle size, isoelectric point, mineral phase, and aggregation. Finally, As(V) adsorption experiments were performed to determine how the two iron oxide phases existed in the reaction system. Nanoparticle synthesis thermodynamics and kinetics were found to control the extent of distinct 6-line ferrihydrite phases in the iron oxide nanoparticle solutions, as well as the particle size and isoelectric point. Conversion of 6-line ferrihydrite to hematite was greatly influenced by the degree of aggregation (determined by synthesis conditions) during drying. As(V) adsorption experiments revealed that 6-line ferrihydrite and hematite exist as a linear combination of two separate phases. These results provide unique information regarding how in situ iron oxide nanoparticle properties can direct their ex situ behavior.

The Performance of Polypropylene Wood–Plastic Composites with Different Rice Straw Contents Using Two Methods of Formation

ABSTRACT To utilize agricultural and forestry wastes and to improve environmental protection, polypropylene (PP) wood–plastic composites were prepared with rice straw powder by using two methods of formation. The effects of formation conditions and rice straw powder content on the mechanical properties, water absorption, and moisture absorption performance of the composites were studied. The tensile sections of the composites were observed by using a stereo-microscope. The results showed that the mechanical properties, water absorption, and moisture absorption performance of the composites formed by mixing compression molding were better than those obtained by layer compression molding. Mixing produced more uniform blending of PP with the fiber compared with using layers of PP with powder. With a rice straw powder content of 50 percent, composites formed by mixing compression molding had good mechanical properties, water absorption, and moisture absorption performance.

Effect of formation conditions on biochars: Compositional and structural properties of cellulose, lignin, and pine biochars

The application of biochar to soil has been proposed as a long-term sink for atmospheric carbon dioxide in terrestrial ecosystems while providing improved soil fertility and increased crop production. Because biochar differs from the widely documented activated carbon, initial characterization information on effects of formation conditions on physical and chemical properties of biochar is important prior to its large-scale incorporation into soils. Plant biomass is composed primarily of cellulose and lignin. As a means of predicting biochar characteristics, samples of cellulose, lignin, and pine were charred under a nitrogen atmosphere at temperatures ranging from 250 °C to 500 °C for times ranging from 1 h to 168 h. Mass loss, elemental composition (carbon, hydrogen, and oxygen), Fourier transform infrared and 13C Nuclear Magnetic Resonance (NMR) spectra of the biochars produced were compared. Mass loss combined with NMR spectrometry showed that the initial rapid loss of material is attributed to aliphatic components, which are either lost or converted to aromatic carbon early in the charring process, and oxygen was lost more rapidly than carbon. The biomass contains a labile oxygen fraction that is quickly removed or lost upon initial heating, and a recalcitrant oxygen fraction which remains fixed in the char. If biochar is to be incorporated into agricultural soils, formation conditions should be tailored to optimize desirable characteristics, such as recalcitrance to degradation, soil fertility and pollutant sequestration, and minimize less desirable characteristics of degradability or low yield (mass loss).

Urushiol-formaldehyde polymer microporous films with acid–alkali resistance property: Effects of formation conditions on surface morphologies

Chinese lacquer, a natural polymeric material, and its processing products have been principally used to coat objects of high artistic and pleasing beauty with excellent physico-mechanical properties for centuries. The use of modified urushiol as functional materials, however, is rarely reported in the previous literature. To develop their potentially functional applications, the microporous films of urushiol-formaldehyde polymer (UFP) were fabricated on a solid substrate by using water-assisted assembly method in this paper. The resulted films were characterized by SEM and contact angle measurements. Several influencing factors were considered on the formation of the microporous films with different morphologies, including the concentration of the polymer solution, the relative humidity in the atmosphere, the speed of the moist airflow and the spread volume of the polymer solution. It was found that the pore size of microporous films increased with the increase of relative humidity, the speed of the moisture airflow, and the amount of the solution. Additionally, the ordered pores of UFP films could be formed even under the high concentrations. Furthermore, the as-prepared UFP microporous films had hydrophobic property and good acid–alkali resistance.

Effect of formation conditions on the structure and properties of nanocomposite alginate fibers

AbstractThe conditions for producing nanocomposite fibers composed of calcium alginate, containing a hydroxyapatite nanoadditive were devised and the rheological, sorptive, and strength properties of these fibers, as well as their porous and supramolecular structure were subjected to analysis. It has been concluded that the presence of the HAp nanoadditive in the material of alginate fibers decreases their susceptibility to distortion in the drawing stage, which results in their tenacity properties being lower by 2cN/tex than of the fibers with no nanoadditive. The obtained nanocomposite fibers are characterised by a tenacity value exceeding 26 cN/tex, accompanied by high sorptive and water‐retention properties of 90% and the even distribution of the nanoadditive on the fiber surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of formation conditions on the structure, morphology and magnetic properties of nanosized MIIFe 2 III O4 ferrites (M = Mn, Co, Ni) and Fe2O3

A study was carried out on the conditions of formation of highly crystalline, superparamagnetic, nanosized oxides, MII Fe2III O4 and γ-Fe2O3 (4.9–11.7 nm) by the thermal decomposition of complexes [MFe2O(CH3CO2)6(H2O)3] (M = Mn, Fe, Co, Ni) in tetraethylene glycol. The presence of surfactants leads to a decrease in the size and size distribution of the nanoparticles formed, while the use of microwave radiation significantly reduces the time for formation of the nanocrystalline oxides. The magnetic measurements showed ferrimagnetic ordering in the nanoparticles studied and their superparamagnetic behavior.

Effect of Formation Conditions on Catalytic Properties of Self-Purifying Coatings

It is found that the technological conditions for the formation of self-purifying coating depend on the sintering interval of the vitreous phase and its dispersion. The most porous coating with the maximum effect of self-purification (96 – 98%) was obtained on introducing 12 – 14 parts by weight of sodium silicate solution into the coating slip. The optimum coating structure provides for decomposition of food fats after multiple thermal cycling.

The Very Long-Term Volume Recovery of Polycarbonate: Is Self-Retardation Finite?

The specific volume change of Bisphenol A polycarbonate was measured at room temperature for several years. The effects of formation conditions like cooling rate and pressure, the addition of low molecular additives, and injection molding and quenching were investigated. The volume shrinkage at long times was found to be much higher than extrapolated from short term measurements. A general pattern is observed in the volume recovery curves. They start with a small constant slope on the logarithmic time scale. After about 107 s a transition is observed to a much steeper slope. Whereas in the first section the characteristic increase in τeff is observed, the volume recovery during the transition can be fitted quite well with a single exponential. The sharp transition suggests that there is a long retardation time, which may represent the genuine α-relaxation. It also means that the self-retardation during physical aging is finite. The slope at long times (>107 s) scales with the distance from equilibrium, as extrapolated from measurements close to Tg. The cooling rate during vitrification affects the slope in the first zone only, while the formation pressure leads to a vertical shift of the curves. Addition of low molecular weight additives leads to a dramatic densification and accelerates the volume recovery.

Effect of Formation Conditions on Oxide Film Properties of Zirconium

Effect of Formation Conditions on Oxide Film Properties of Zirconium

The Effect of Formation Conditions on the Structural and Electrical Properties of Ultrathin Cobalt Silicide Films

ABSTRACTWe have studied the dependence of the structural and electrical properties of ultrathin cobalt silicide films on the annealing temperature and deposited Co thickness.We recently reported that coherent, electrically continuous films of CoSi2 could be grown on Si(111) with thicknesses as small as 1 nm.1 The thinnest of these films had a high density of pinholes which covered about 20% of the area of the substrate. The resistivity of the films increased dramatically with decreasing thickness in a manner which was qualitatively consistent with quantum size effects. In order to investigate the dependence of both the pinhole density and the resistivity of ultrathin CoSi2 films on Si(111), we have deposited different thicknesses of Co onto near room temperature (<100°C) Si(111) substrates and have annealed the samples at different temperatures in order to study the effect of silicide formation conditions on the structural and electrical properties of the resulting films.Co layers were deposited onto Si(111) wafers in a molecular beam epitaxy apparatus as described previously.1 In our earlier work, CoSi2 was formed by heating the sample to ∼600°C for a few seconds after Co deposition. Because higher temperature anneals are known to lead to pinhole formation in thicker films,2 annealing temperatures in the present experiments were constrained to be 600° or less. The reaction time was on the order of 5 minutes. The layers were examined using plan-view transmission electron microscopy (TEM) in order to avoid beam heating and ion beam mixing effects which might cause artefacts in cross-section TEM observation.The results of our experiments are summarized in Figure 1. The figure indicates the silicide phases found in a film as a function of deposited Co thickness and annealing temperature. The numbers in each square correspond to the residual resistivity, ρo, measured for each film. Perhaps the most striking finding of this study is the abrupt change in the structure of the films between 0.7 and 1.4 nm of deposited Co. For all temperatures investigated (including near room temperature), films formed by depositing less than 1 nm of Co form CoSi2 immediately upon deposition. (For films approaching this thickness, there is also a small amount of Co2Si which persists at all temperatures

Yttria Hydroxy‐Salt Binders

Binder phase (primarily chloride or nitrate) formation was examined in YX3‐NaOH‐H2O, Y2O3‐acid‐H2O, and Y2O3‐salt‐H2‐O systems. The cementitious phase consisted mostly of plate‐ (or needle‐) shaped hydroxy salts of the general formula Y2(OH)6‐m XmnH2O, where m and n normally equal one. These binders were examined by X‐ray diffraction and thermal analysis techniques. Nitrate binders decompose to Y2O3 by 600°C, whereas chloride binders form oxychlorides that sublime or convert to Y2O3 after oxygen replacement of chlorine (in air) at >1000°C. Although nitric and hydrochloric acid solutions form porous (< 50% dense) plasterlike bodies in 2 to 10 min of reaction with Y2O3 powder, salt solutions (i.e. NH4NO3 Mg(NO3)2, NH4Cl, and YCl3‐ ∼6H2O) slow the reaction considerably (48 h to 4 weeks), allowing 70‐ to 80%‐dense cements to form. The effects of formation conditions on physical properties of binders were studied. Examination of scandium and lanthanide oxides showed that several behave in the same way as yttria.

Effect of formation conditions on the motion of a cloud rising upward under the action of the force of buoyancy

The present article gives the results of an experimental investigation of the dependence of the angle of expansion α of an ascending cloud on the conditions of its formation. When the cloud starts from a state of rest, α≈ 0.18. The greatest expansion corresponds to the presence of perturbations at the surface of the cloud. In this case, when the cloud has an initial velocity, the angle of expansion decreases with a rise in the value of the initial modified Froude number. Starting from Fr0=1.5, at the initial moment of time the starting substance breaks away from the surface of the cloud. An experimental investigation was also made of the mechanism of the capture of the surrounding medium by the cloud.

Anodic oxide films on titanium formed in molten salt electrolytes—II. Effect of formation electrolyte on non-stoichiometry of the film

The effects of formation conditions, especially the electrolyte, on the non-stoichiometry of the anodic oxide films of titanium have been studied. The electrolytes were molten sodium nitrite, molten sodium nitrate and molten mixture of these salts and sodium peroxide, which was used to change the oxide-ion concentration in the melts. Films with the least crystal imperfections are formed in molten sodium nitrite. This result is supported by the build-up curve of formation potential, the photocurrent and the dielectric loss of the film. In other molten salts, impurity concentrations in the films are controlled by oxide-ion concentrations in the melts. At higher temperatures, oxide ion and metal cation are presumed to move easily in the growth of the film and crystallization of the film proceeds rapidly.

Effect of formation conditions on the supermolecular organization and mechanical properties of polyethylene film

Films formed by extruding medium-pressure polvethylene through a flat-slot have a spherulitic supermolecular organization whose principal parameters (size and shape of the spherulites) are determined by the extrusion conditions. Thus, as the draw-down ratio increases, the radius of the spherulites decreases, and their degree of flattening relative to the direction of extension increases. Stretching these films leads to a transition from a spherulitic to an orientational supermolecular order, whose period is genetically related to the diameter of the starting spherulites. Films containing flattened spherulites have a yield point anisotropy opposite in sign to the degree of flattening. The mechanical anisotropy, like the degree of flattening, increases with increase in the draw-down ratio. The probable cause of flattened spherulite formation is the draw-down process, whose mechanical field may retard the radial growth of the spherulites in the take-off direction.