Search results for "small-angle"
showing 10 items of 258 documents
Low temperature synthesis of monodisperse nanoscaled ZrO2with a large specific surface area
2012
Thermal decomposition of Zr(C(2)O(4))(2)·4H(2)O within an autoclave or in a conventional tube furnace at temperatures below 380 °C resulted in nano- and micron-sized ZrO(2), respectively. Reactions under autogenic pressure yielded monodisperse monoclinic (m) and tetragonal (t) ZrO(2) nanoparticles with an average diameter of ~8 nm and interconnected t-ZrO(2) nanoparticles with diameters of ~4 nm, depending on the synthesis temperature. Samples were characterised by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) associated with energy dispersive X-ray spectroscopy (EDS), Raman microspectroscopy and phot…
Structure of Hybrid Materials Based on Halloysite Nanotubes Filled with Anionic Surfactants
2016
The structures of pristine halloysite nanotubes (HNTs) and ones functionalized by anionic surfactants (sodium dodecanoate and sodium dodecyl sulfate) were investigated by small angle neutron scattering (SANS). These experiments evidenced the structural organization of the surfactants adsorbed onto the HNT cavity and the importance of the surfactant headgroup. Contrast matching experiments were employed in order to mask the dominant scattering effect of the clay hollow nanotubes and to focus on the surfactant organization within the lumen. Further investigation on the mesoscopic structure of the investigated materials was carried out by electric birefringence (EBR), which allowed study of th…
1979
Fractal approach in petrology: combining ultra small angle, small angle and intermediate angle neutron scattering
2000
Ultra small angle neutron scattering (USANS) instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering (SANS) instruments on one side and optical microscopy on the other side. New fields of investigations are now open and important areas of material science (ceramics, glass fibers, natural materials) and fundamental physics (phase transition, phase separation and critical phenomena) can be studied in bulk samples with an accuracy previously unobtainable owing to a combination of favourable features of the neutron-matter interaction: high penetrability of neutrons, even cold neutr…
Laser light scattering and polydispersity of polymers
1977
The application of lasers to light scattering improves the potentials of elastic scattering, especially in the high molecular weight range and enables the technique of inelastic scattering to be used. For elastic light scattering an experimental arrangement and an evaluation method is described which allows, within appropriate molecular weight ranges, the determination of the ratio Mw/Mn from the experimental scattering function with an accuracy down to 0.02. The newer technique of inelastic light scattering yields the coefficient of translational diffusion D. Besides D, the friction coefficient f is also directly accessible. The basic equations are reported, as well as an application to mi…
Light scattering in opal heterojunctions
2006
Light propagation in photonic hetero-crystals, consisting of two opal films with different lattice constants, has been investigated in the realistic regime of weak scattering, when the main light flux is transported by ballistic photons. The light scattering at the photonic bandgap interface is studied in combination with transmission data. The spectra and directionality diagrams of scattered light of single- and hetero-opal films are compared. The rate of decrease of the scattering intensity as a function of the scattering angle has been used to quantify the scattering strength. The anisotropy of the interface scattering is identified by deducing the trajectories of single scattered photon…
Scaling in colloidal crystallization
1994
The process of colloidal crystallization has already been separately investigated by light scattering mearurements of the crystalline order (Bragg peaks) and of long-ranged density fluctuations (small-angle scattering). We present the firstsimultaneous small- and large-angle light scattering experiment. Our measurements have been performed on hard-sphere colloids of different particle densities. We show results for the temporal evolution of crystallization and find two distinct regimes: homogeneous nucleation and diffusion- or reaction-limited growth at early times, followed by ripening of the Lifshitz-Slyozov or Lifshitz-Allen-Cahn type. To our preliminary experience, we can already state …
Hiding in plain view: Colloidal self-assembly from polydisperse populations.
2016
We report small-angle x-ray scattering (SAXS) experiments on aqueous dispersions of colloidal silica with a broad monomodal size distribution (polydispersity 18%, size 8 nm). Over a range of volume fractions the silica particles segregate to build first one, then two distinct sets of colloidal crystals. These dispersions thus demonstrate fractional crystallization and multiple-phase (bcc, Laves AB$_2$, liquid) coexistence. Their remarkable ability to build complex crystal structures from a polydisperse population originates from the intermediate-range nature of interparticle forces, and suggests routes for designing self-assembling colloidal crystals from the bottom-up.
Small angle neutron scattering on periodically deformed polymers
1984
Small angle neutron scattering from periodically deformed samples is a useful extension of the methods presently available for the study of molecular dynamics of polymers. In this paper we describe apparatus that has been used to produce large cyclic deformations at frequencies upto 10 Hz and the principles by which data is collected to give spectra corresponding to different states of strain of the sample. Some data on model polydimethylsiloxane networks is given as an illustration of the value of this technique.
12C + 12C large angle elastic scattering at 240 MeV
2010
Abstract The measurement of the differential cross sections of the 12C + 12C and the 13C + 12C elastic scattering are carried out at the 12C energy 240 MeV and the 13C energy 250 MeV to solve some interpretation problem of the 12C + 12C scattering data. Is it possible that the 1st Airy minimum in 12C + 12C scattering data is missing? Our analysis shows that the positions of the 1st Airy minima obtained in former measurements are confirmed.