44 research outputs found
Folding a 2-D powder diffraction image into a 1-D scan: a new procedure
A new procedure aiming at folding a powder diffraction 2-D into a 1-D scan is
presented. The technique consists of three steps: tracking the beam centre by
means of a Simulated Annealing (SA) of the diffraction rings along the same
axis, detector tilt and rotation determination by a Hankel Lanczos Singular
Value Decomposition (HLSVD) and intensity integration by an adaptive binning
algorithm. The X-ray powder diffraction (XRPD) intensity profile of the
standard NIST Si 640c sample is used to test the performances. Results show the
robustness of the method and its capability of efficiently tagging the pixels
in a 2-D readout system by matching the ideal geometry of the detector to the
real beam-sample-detector frame. The whole technique turns out in a versatile
and user-friendly tool for the scanning of 2-D XRPD profiles.Comment: 11 pages, 1 table, 2 figure
Testing the Debye Function Approach on a Laboratory X-ray Powder Diffraction Equipment. A Critical Study
Total Scattering Methods are nowadays widely used for the characterization of defective and nanosized materials. They commonly rely on highly accurate neutron and synchrotron diffraction data collected at dedicated beamlines. Here, we compare the results obtained on conventional laboratory equipment and synchrotron radiation when adopting the Debye Function Analysis method on a simple nanocrystalline material (a synthetic iron oxide with average particle size near to 10nm). Such comparison, which includes the cubic lattice parameter, the sample stoichiometry and the microstructural (size-distribution) analyses, highlights the limitations, but also some strengthening points, of dealing with conventional powder diffraction data collections on nanocrystalline material
The International Summer School on "Diffraction at the Nanoscale: Nanocrystals, Defective & Amorphous Materials”
Testing the Debye Function Approach on a Laboratory X-ray Powder Diffraction Equipment. A Critical Study.
Synthesis and Microstructural Investigations of Organometallic Pd(II) Thiol-Gold Nanoparticles Hybrids
In this work the synthesis and characterization of gold nanoparticles functionalized by a novel thiol-organometallic complex containing Pd(II) centers is presented. Pd(II) thiol,trans, trans-[dithiolate-dibis(tributylphosphine)dipalladium(II)-4,4′-diethynylbiphenyl] was synthesized and linked to Au nanoparticles by the chemical reduction of a metal salt precursor. The new hybrid made of organometallic Pd(II) thiol-gold nanoparticles, shows through a single S bridge a direct link between Pd(II) and Au nanoparticles. The size-control of the Au nanoparticles (diameter range 2–10 nm) was achieved by choosing the suitable AuCl4−/thiol molar ratio. The size, strain, shape, and crystalline structure of these functionalized nanoparticles were determined by a full-pattern X-ray powder diffraction analysis, high-resolution TEM, and X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements of the hybrid system show emission peaks at 418 and 440 nm. The hybrid was exposed to gaseous NOxwith the aim to evaluate the suitability for applications in sensor devices; XPS measurements permitted to ascertain and investigate the hybrid –gas interaction
Colloidal Synthesis and Characterization of Tetrapod-Shaped Magnetic Nanocrystals
Tetrapod-shaped maghemite nanocrystals are synthesized by manipulating the decomposition of iron pentacarbonyl in a ternary surfactant mixture under mild thermal conditions. Adjustment of the reaction parameters allows for the systematic tuning of both the width and the length of the tetrapod arms, which grow preferentially along the 〈111〉 easy axis direction. Such degree of control leads to modulation of the magnetic behavior of the nanocrystals, which evolves systematically as their surface magnetization phase and shape anisotropy are progressively increased