Ahmad S. Masadeh

Quantitative size-dependent structure and strain determination of CdSe nanoparticles using atomic pair distribution function analysis

The size-dependent structure of CdSe nanoparticles, with diameters ranging from

PDF from X-ray powder diffraction for nanometer-scale atomic structure analysis of quasicrystalline alloys

2\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}4\phantom{\rule{0.3em}{0ex}}\mathrm{nm}

The local atomic quasicrystal structure of the icosahedral Mg25Y11Zn64 alloy

, has been studied using the atomic pair distribution function (PDF) method. The core structure of the measured CdSe nanoparticles can be described in terms of the wurtzite atomic structure with extensive stacking faults. The density of faults in the nanoparticles is

The real structure of Na3BiO4 by electron microscopy, HR-XRD and PDF analysis

\ensuremath{\sim}50%

Square net distortion engineering in the ternary variants of titanium antimonide, Ti2−δMδSb (M = Zr, Hf)

. The diameter of the core region was extracted directly from the PDF data and is in good agreement with the diameter obtained from standard characterization methods, suggesting that there is little surface amorphous region. A compressive strain was measured in the Cd--Se bond length that increases with decreasing particle size being 0.5% with respect to bulk CdSe for the

The total scattering atomic pair distribution function: New methodology for nanostructure analysis.

2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}

Structure investigation of ultra-small CdSe nanoparticles using the atomic PDF

diameter particles. This study demonstrates the size-dependent quantitative structural information that can be obtained even from very small nanoparticles using the PDF approach.

Local structural aspects of the metal-insulator transition in CuIr

Abstract For three icosahedral alloys in the Mg—Zn-RE(RE = Ho, Y) systems, the atomic pair distribution functions (PDFs) have been obtained from sealed X-ray tube (in-house) and synchrotron (ESRF and APS) powder diffraction experiments. The PDFs are at least qualitatively comparable and are suitable for least squares r ≈ 2 nm local structure refinements. A recent local model for si-Ho—Mg—Zn from in-house data can be confirmed using the synchrotron data. Acquisition and the quality of the data from the different sources are discussed. The better resolved synchrotron data open perspectives for larger scale and thus more detailed models.

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Al ocal and medium range atomic structure model for the face centred icosahedral (fci) Mg25Y11Zn64 alloy has been established in a sphere of r = 27 A. The model was refined by least squares techniques using the atomic pair distribution (PDF) function obtained from synchrotron powder diffraction. Three hierarchies of the atomic arrangement can be found: (i) five types of local coordination polyhedra for the single atoms, four of which are of Frank–Kasper type. In turn, they (ii) form a three-shell (Bergman) cluster containing 104 atoms, which is condensed sharing its outer shell with its neighbouring clusters, and (iii) a cluster connectin gs cheme corresponding to a three-dimensional tiling leaving space for a few glue atoms. Inside adjacent clusters, Y8 cubes are tilted with respect to each other and thus allow for overall icosahedral symmetry. It is shown that the title compound is essentially isomorphic to its holmium analogue. Therefore, fci-Mg–Y–Zn can be seen as the representative structure type for the other rare earth analogues fci-Mg–Zn–RE (RE = Dy, Er, Ho, Tb) reported in the literature. (Some figures in this article are in colour only in the electronic version)

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Abstract The real stucture of a new crystalline high temperature phase, metastable at room temperature, in the system sodium – bismuth – oxygen, β-Na3BiO4, was determinated using high resolution X-ray powder diffraction, pair distribution function analysis, and high resolution transmission electron microscopy. β-Na3BiO4 was synthesized by anodic oxidation of bismuth(III)-oxide in a sodium hydroxide – lithium hydroxide melt. The average crystal structure of β-Na3BiO4 at ambient conditions (R3m, a = 3.32141(9) Å, c = 16.4852(5) Å) is structurally related to α-NaFeO2 with metal layers almost statistically occupied in a Na:Bi ratio of 3:1. Analysis of the long-range order on the bulk material by Rietveld refinement led to approximately Na:Bi ratios of 2:1 and 4:1, in consecutive metal layers, while a detailed analysis of the local order by means of the pair distribution function revealed the existence of almost pure sodium layers and mixed 1:1 – sodium:bismuth layers. Complementary studies on single crystallites using high resolution transmission electron miscroscopy exhibited a complex domain structure with short-range ordered, partially ordered, and long-range ordered domains.