Papers by Keyword: SAXS

Abstract: Aerogels are porous materials with potential applications in fields ranging from thermal insulation, catalyst support, filters, electrical storage, components in optical devices, mechanical damping all the way to drug release. However, careful reliable characterization is the base for both, understanding of fundamental structure - property relationships as well as a directed development of materials and composites for specific applications. The review therefore addressed severe problem upon aerogel characterization that have been identified in the past and presents reliable non-destructive alternatives and novel methods that can be applied for the characterization of aerogels as well as their gel precursors.

Abstract: In this report, the micro structure of PI/ TiO₂ films with different components prepared by in-situ polymerization method is researched by XRD, TEM, synchrotron radiation SAXS. Its micro structure characteristics include nano-particles distribution, PI molecule chains spacing and interface layer thickness. The experimental result shows that after doping, particle radius is almost 10nm, and cluster of nano-particles became more serious with increase of components, however, the spacing of PI molecule chains decreases 5.238 Å-4.625 Å. The scattering curves occurs negative deflection in Debye theory, it shows that there are interface layers with thicknesses in the range 0.7nm-2.1nm between nano-particles and composite matrix. Through analyzing the three kinds of micro structure change, it shows that when the component is 15 wt.%, the micro-structure of composite film is the optimal.

Abstract: Al-Cu-Li alloys are extensively used for aerospace applications. The main hardening phase is the T₁ phase that precipitates as thin platelets on {111}_Al planes. To facilitate its nucleation, different minor alloying elements are added and dislocations are introduced by cold deformation before the ageing treatment. The impact of these additions in combination with the presence of dislocations on precipitate nucleation and growth needs a deeper understanding. In this work, we investigated the precipitation kinetics of the T₁ phase in alloys containing a common content of Cu and Li and different contents of minor solutes (Mg, Ag) where these elements are present either together or independently. A general overview on the precipitation kinetics was achieved by in-situ small-angle X-ray scattering and hardness measurements. The evaluation of precipitation kinetics reveals that magnesium plays an important role during precipitation by enhancing nucleation kinetics. Additionally, a smaller yet measureable effect of Ag, both in the presence and absence of Mg has been evidenced.

Abstract: Dynamic interactions between plastic deformation and precipitation processes in Aluminium alloys can lead to large changes in precipitation kinetics as compared to conventional heat treatments. This can be due to a number of different mechanisms such as changes in vacancy concentrations or movement of structural defects. Understanding the underlying mechanisms requires a quantitative measurement of the precipitate evolution as a function of deformation conditions, temperature and time. The present contribution will review experimental results obtained by Small-Angle X-ray Scattering in three different configurations, all concerning Al-Zn-Mg-Cu alloys: first, dynamic precipitate evolution during plastic deformation at ageing temperature; second, dynamic precipitation during low cycle fatigue at room temperature; and third, precipitation during ageing of a material processed by room temperature high pressure torsion. The experimental evidence will be used to discuss the role of the different mechanisms of interaction with plasticity on the precipitate microstructure evolution.

Abstract: This work has a focus on the self-emulsifying drug delivery system (SEDDS), which can be used in pharmaceutical field for increasing bioavailability of poorly water-soluble drugs. The model drug resveratrol was used because of its poor water-solubility and is of interest because of its wide range of pharmacological effects. It is beneficial to understand the mechanism of SEDDS formation in the human body, therefore, the determination of nanoscale structure was carried out. For this purpose, small angle X-ray scattering (SAXS), photon correlation spectroscopy (PCS), and transmission electron microscopy (TEM) techniques were applied. We have found that the size and size distribution of particles were in nanometers. The inner structure of SEDDS was ordered with the lamellar distances (d-spacing) of < 20 nm. It seems that the prepared SEDDS in water form large oil drops (200-400 nm) in water as well as small micelles with the droplet size of 10-20 nm.

Abstract: Radial electron densities within 63-67 μm long ion damage trails, latent ion tracks, created in {001} muscovite by irradiation with 11.1-28.7 MeV/A U and Pb ions, have been derived by small-angle X-ray scattering. Track diameters are 8.0-10.2 nm. The tracks exhibit continuous and uniform electron density decrease of ~4%. Complementary microscopy has revealed loss of atomic order in the tracks. These ion-induced effects undoubtedly accelerate preferential through track permeability of inert and corrosive agents, a property that is important for track applications.

Abstract: The effects of processing conditions on the structure of polypropylene fibrillated fibres were studied using a combination of wide- and small-angle X-ray scattering methods. In particular the impact of selected stages of processing on the crystalline and lamellar structure of PP were analyzed. It was stated that crystalline phase is built from α crystals. The crystallinity index as well as the Herman orientation factor of the crystalline phase is found to have a correlation only with the draw ratio of the PP film. The lamellar structure also changes with the draw ratio.

Abstract: There is an ongoing interest in nanoparticles for the unique properties that have applications in a range of fields including catalysis, semi-conductors, gas storage amongst many others. In this study a variety of distinct techniques were applied on the same in-house X-Ray diffractometer. In particular, SAXS, conventional XRD and Total Scattering of nano-sized TiO2 powders were performed, together with in-situ heating experiments. The combination of the results from each technique proves to be a powerful tool for a more complete description of the material.

Abstract: The most important structural parameters of semicrystalline polymers can be determined by modeling of their structure and best fitting of a theoretical intensity distribution calculated for the assumed model to the experimental SAXS curve. This paper presents a module of a computer program SAXSDAT dedicated to such calculations.

Abstract: Magnetic fluid is a special class of materials which possesses the advantages of a liquid state of the carrier and a magnetic state of the particles. In addition to the conventional uses in mechanical engineering, magnetic fluids containing magnetite (Fe₃O₄) superparamagnetic nanoparticles are under research and development for drug delivery, hyperthermia and MRI contrast agents. On the other hand, iron-platinum (FePt) is investigated as materials for ultrahigh density recording. Before their assembly into patterned media, the as-synthesized FePt nanoparticles in superparamagnetic state are commonly stored in forms of magnetic fluids. In this work, iron-platinum (FePt) nanoparticles with their surface modified by oleic acid and oleyleamine were synthesized from the polyol process. The starting material was an environmental friendly iron(III) acetylacetonate and the products were dispersed in n-hexane. In small-angle X-ray scattering (SAXS) measurements at the Synchrotron Light Research Institute, Thailand, each magnetic fluid was injected into a sample cell with aluminum foil windows and the X-ray of wavelength 1.55 Å from BL2.2 was used. The measured SAXS intensity profiles as a function of the scattering vector from 0.27 to 2.30 nm^-1 were fitted and compared between two different reactions. Nanoparticles synthesized by using a higher amount of Fe(acac)₃ were matched with monodisperse spheres of radius 2.4±0.3 nm. The other reaction with a reducing agent gave rise to smaller nanoparticles of two size distributions. From this work, the potential of synchrotron radiation to complement conventional characterization techniques in the investigation of nanoparticles for high density recording and biomedical applications is underlined.