Analyzing structure factor phases in pure and doped single crystals by synchrotron X-ray Renninger scanning

Abstract

X-ray multiple diffraction has been applied to study the substitutional incorporation of Mg 2+ ions into NSH crystals (nickel sulfate hexahydrate, NiSO 4 Á6H 2 O). Intensity profiles provide information on invariant phases, while angular positions of the multiple diffractions allow accurate determination of lattice parameters. By increasing the atomic disordering only of O 2À sites in model structures of doped NSH, the sense and magnitude of induced phase shifts match those necessary to justify the observed changes in the intensity profiles. Causes of disordering and lattice parameter variation are discussed. Although the amount of extra oxygen disordering is relatively large with respect to the small difference in the ionic radii of the metallic ions, this disordering is beyond the resolution power achievable by analyzing diffracted intensities of isolated reflections, such as in standard crystallographic techniques.

Phonon scattering mechanism in thermoelectric materials revised via resonant x-ray dynamical diffraction

“…The information extracted from the phases of the structure factors is then used to validate or select feasible model structures for the crystal. [37][38][39] The minimum crystal size for this type of experiment is, in general, ten times larger than the usual grain size found in powder samples. [40] Structure factor phases are susceptible to the differences between the vibration amplitudes of the atoms-root mean square (RMS) atomic displacements.…”

“…Reflections with phase susceptible to changes in ionic charges, resonance amplitudes, atomic positions, and occupation and DW factors have been identified by means of model structures. [37][38][39][40] For the CeFe 4 P 12 structure, the atomic planes of Ce and Fe are interleaved along [001] type directions, Fig. 1(c).…”

Effect of L-asparagine as dopant on the growth and characteristics of ammonium tetroxalate dihydrate single crystal

“…Single crystal X-ray diffraction gives information about the physical measurements of structural phases demanding a high level of instrumental expertise [6]. Also, there is not much gain in structural resolution from the accuracy level of the obtained X-ray diffraction data values and this technique is rarely utilized [7].…”

X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological moleculesviaphysical phase measurements

“…However, since the coherent scattering cross sections for X-rays by atoms have intermediate values between those for electrons and neutrons, physical measurements of structure factor phases have been feasible with X-rays only (Amirkhanyan et al, 2014). Dynamical diffraction taking place within perfect domains is another requirement for physical phase measurements via multiple diffraction (MD) experiments.…”

“…Dynamical diffraction taking place within perfect domains is another requirement for physical phase measurements via multiple diffraction (MD) experiments. In crystals with small unit cells, the dynamical diffraction regime is achieved in much smaller domains than in crystals with large cells such as protein crystals: a fact that has allowed phase measurements to reveal structural detailsinaccessible by other techniques -in magnetic materials (Shen et al, 2006) and optical crystals with dopant ions (Morelhã o et al, 2011;Amirkhanyan et al, 2014), and to resolve the chirality in crystals with no resonant atoms (Hü mmer & Weckert, 1995;Shen et al, 2000;Morelhã o et al, 2015).…”