This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular...

With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom...

PdZn catalysts have been proven to be a viable option to replace current Cu catalysts for methanol steam reforming. The change in selectivity to CO2 that makes this a possibility has been attributed to the formation of tetragonal β1-PdZn at treatment temperatures of 500 o C. Through the course of studying the phase evolution of the 1:1 PdZn, it was seen that an intermediate Pd2Zn phase formed a...

The crystal structures of triethyl-1,3,5-triazine-2,4,6-tricarboxylate (I), triethyl-1,3,5-benzenetricarboxylate (II) and tris-2-hydroxyethyl isocyanurate (III) have been determined from conventional laboratory X-ray powder diffraction data using the differential evolution structure solution technique. The determination of these structures presented an unexpectedly wide variation in levels of d...

The method of angular- and wavelength-dispersive (e.g. two-dimensional) Rietveld refinement is a new and emerging tool for the analysis of neutron diffraction data measured at time-of-flight instruments with large area detectors. Following the approach for one-dimensional refinements (using either scattering angle or time of flight), the first step at each beam time cycle is the calibration of ...

Nanoscale potassium niobate (KNbO3) powders of orthorhombic structure were synthesized using the sol-gel method. The heat-treatment temperature of the gels had a pronounced effect on KNbO3 particle size and morphology. Field emission scanning electron microscopy and transmission electron microscopy were used to determine particle size and morphology. The average KNbO3 grain size was estimated t...

The new crystal structure of 5,6-dibromoacenaphthene has been successfully determined from X-ray powder diffraction data with monoclinic crystals, P21/n, a = 7.88(1) Å, b = 11.64(1) Å, c = 11.62(1) Å, β =107.09(9)°, V = 1019.9(1) Å and Z = 4. Individual reflection intensities were extracted by means of Le Bail’s method. The molecular structure of 1 was solved by direct methods and refined using...

The particle size distribution of the resultant cobalt ferrite samples was determined from Scanning Electron Microscopy (SEM) images using the granulometry image analysis method. Results showed the nanosized particles of the samples. The X-Ray Diffraction (XRD) patterns of samples were also analyzed by Rietveld refinement method. The results indicated that the precipitated sample at 95 <sup...

This study examined the local structural properties of CuI at low temperatures of 10-300 K by x-ray diffraction (XRD) and extended x-ray absorption fine structure (EXAFS) measurements at the Cu K edge. The XRD data were refined using two models, split (distorted zinc-blende structure) and non-split (zinc-blende structure), using a conventional Rietveld refinement combined with a maximum entropy...