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A compact small-angle X-ray scattering (SAXS) camera was modified in order to cover a significantly wider size range than that typically covered by conventional lab-based devices. A new housing with a larger sample-to-detector distance (230 → 1300 mm) was developed and a new focusing Göbel mirror was installed to provide a narrower beam width needed to detect scattering intensities very close to the primary beam. A new photon-counting detector was applied to probe the intensity at small scattering vectors while an imaging plate detector serves to simultaneously collect data at large scattering angles up to 90°. The relevant features of the camera are shown and discussed based on raytracing simulations and SAXS measurements, respectively. The minimum scattering vector could be decreased by a factor of 10 to a value of 0.008 nm corresponding to structures up to 780 nm in size. Structural analyses of selected particle systems demonstrate ability of the modified camera to probe various structural parameters on multiple scales, e.g., crystallite size, primary particle size, aggregate size, and fractal dimensions. The modified camera system is promising for structural studies of particle formation and growth/aggregation mechanisms since it provides information on multiple scales ranging from angstroms to several hundred nanometers. [ABSTRACT FROM AUTHOR]

Time-resolved characterization of silica-coated magnetite nanoparticles during synthesis is performed using our self-developed small-angle X-ray scattering (SAXS) instrument. The shell growth (5-20 nm) is determined quantitatively using a core-shell sphere model. SAXS analyses provide reliable information on the shell thickness despite the complex geometry of the synthesized nanocomposites. They are in good agreement with transmission electron microscope (TEM) observations. Firstly, time-resolved SAXS analyses are used to study the influence of the precursor concentration (tetraethyl orthosilicate) on growth kinetics. Time evolution of the shell thickness can be described by diffusion-limited shell growth, obeying kinetics of first order in the precursor concentration. Furthermore, SAXS measurements provide information on the standard deviation of the shell thickness as a function of the coating time. Its decrease observed with increasing coating time is explained by a self-sharpening mechanism and/or a morphology evolution to more isometric shapes. Additionally, the influence of ammonia is studied. By increasing its concentration, the growth rate is affected. However, the final shell thickness and the standard deviation do not change significantly. For low ammonia concentration, by contrast, the SAXS and TEM observations reveal superimposed silica gelation. In addition, coating reaction was conducted at elevated temperature (40 °C). SAXS patterns measured as a function of the coating time and TEM micrographs reveal simultaneous production of classic Stöber particles under these conditions. Hence, SAXS is found to have a big potential for on-line monitoring of the shell properties. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles have attracted a particular interest in scientific research and industrial applications due to their unique size-dependent physical and chemical properties. An eco-friendly and cost-effective synthesis method called electrical discharge enables large scale production of metallic nanoparticles. Systematic investigations of such synthesized metallic nanoparticles help to optimize the synthesis process and improve the product quality. In this work, for the first time we have investigated the diffuse interfacial boundary nanostructures of the metallic nanoparticles, which were synthesized under different conditions by electrical glow and arc discharges in the carrier gas, by means of a small- and wide-angle X-ray scattering (SWAXS) technique using a laboratory X-ray source. Meanwhile, this unique SWAXS technique allows simultaneous study of the primary particle size, morphology, and crystallinity. The metallic nanoparticles (copper and nickel) under investigation cover a size range of 10–80 nm, and the determined thickness of the diffuse boundary nanostructured layer of metallic nanoparticles is in the range of 1–3 nm. The experimental results obtained by SWAXS were compared to the TEM/EDX observation and the XRD reference patterns from RRUFF database, and a good agreement was found. Our SWAXS investigations indicated that the existence of a diffuse nanostructured solid layer on the synthesized metallic nanoparticle surface causes a negative deviation of the scattering intensity $$\left( {I \propto q^{ - \alpha } ,\;\alpha > 4} \right)$$ I ∝ q - α , α > 4 from Porod’s law which corresponds to the case of ideal two-phase particle systems with sharp boundaries $$\left( {I \propto q^{ - \alpha } ,\;\alpha = 4} \right)$$ I ∝ q - α , α = 4 . This implies that the electron density profile is not sharp but changes gradually between two phases, and hence the exponent α is greater than four. Two electron density profile models, sigmoidal electron-density gradient model and linear electron-density gradient model, have been taken into account in determining the thickness of the diffuse boundary nanostructured layer. Combined with the SWAXS experimental results, the possible mechanisms of the formation of the diffuse boundary nanostructured layer of the metallic nanoparticles synthesized by electrical glow and arc discharges in the gas phase have been discussed in detail. [ABSTRACT FROM AUTHOR]

A small- and wide-angle X-ray scattering (SWAXS) technique using a laboratory X-ray source is reported in this article. This non-destructive SWAXS technique allows simultaneous measurements of the primary particle or pore size, surface and mass-fractal dimensions, as well as quantitative determination of the crystallite properties, like phase identification, the co-existence of crystallite components, and their fractions. Some selected experimental results of the SWAXS study of the metallic and oxide nanostructured particles (such as pure Silver nanoparticles, commercial AEROXIDE TiO P25, Nickel and Nickel oxide nanoparticles as well as Titanium nanoparticles generated by a laboratory electric discharge generator) are presented and discussed in detail, covering a size range of 1-50 nm. The results obtained by SWAXS are compared to those observed with the transmission electron microscope and scanning electron microscope, as well as the XRD reference patterns from the RRUFF database, showing good agreement. In addition, a comparison between powder and dispersion measurements was carried out for estimating the existence and accessibility of microporous structures inside the synthesized nanoparticles, as well as the fraction of open pores. Because of many advantages, such as the high intensity of the primary beam while using a conventional laboratory X-ray source equipped with unique X-ray focusing optics, a short measurement time can be realized. By noninvasive simultaneous measurement of SAXS and WAXS spectra using a single detector; this unique technique allows for fast and extensive in-situ characterizations of metal and metal oxide nanoparticles, respectively, as well as nanostructured materials in many other potential application fields. [ABSTRACT FROM AUTHOR]