Mackinawite,tetragonal FeS, has been synthesised by reacting iron with Na2S solutions. A Rietveld structure refinement of X-ray powder diffractipn data, recorded using X-rays monochromated from synchrotron radiationwith a wavelength of 0.6023 A, has been performed. The structure has been refined in the tetragonal sJ'.!lcegroup, P4/nmm, and has the following cell parameters: a = 3.6735(4), c = 5...

ReO2 presents two crystalline variants, with monoclinic and orthorhombic structures. The former is metastable and irreversibly transforms to an orthorhombic structure above 460oC. The structure of the latter was determined from studies on monocrystalline samples, whereas for the monoclinic variant there are no single crystals available so far. It was found only one monoclinic variant and the st...

We discuss the impact of strong absorption for thermal neutrons on data analysis and compare absorption corrections in the GSAS and MAUD Rietveld codes for texture and structural parameter refinement. Diffraction data were collected on the neutron powder diffractometer HIPPO at LANSCE from dysprosium and erbium, which are moderate to strong absorbers for thermal neutrons with absorption cross-s...

Rietveld refinement of the crystal and magnetic structures of LixMnO2 (x 1⁄4 0.98, 1.00, 1.02) are performed using neutron and X-ray measurements. A significant structural disorder due to the presence of manganese ions in lithium positions (MnLi) and lithium ions in manganese ones (LiMn) is found to be a common feature of Li0.98MnO2, Li1.00MnO2, and Li1.02MnO2. An essential anisotropy of the th...

A search for superconductivity in systems of CuCl/Si and CuCl2/Si leads to the observation of ferromagnetism with a Tc of 18 K in powder samples. The magnetism emerges when pure CuCl is exposed to humid air, while the observed magnetic moment depends on the exposure level. We used magnetic field modulated microwave spectroscopy, as well as SQUID magnetometry, to identify magnetic phase transiti...

X-ray powder diffraction and chemical analyses show that mammalian dental enamel apatite is an impure form of hydroxylapatite, Ca10(PO4)6(OH)2 (structure described in Elliott 1994). The major difference of enamel apatite from hydroxylapatite is in the presence of about 3 wt% CO3. Details of the crystallographic structures of carbonate-containing apatites (including minerals) are important becau...

Abstraet.The crystal structure of the new zeolite mineral gobbinsite, Cao.6Na2.6K2.2Al6Si¡o032 . 12H20, has been determined in the space groupPmn2¡ with a = 10.108(1), b = 9.766(1) and e = 10.171(1) Á. The topology of the framework is the same as that of gismondine and can be describedas a stacking of2-dimensional arrays of double crankshaft chains. The structure was refined by the Rietveld tec...

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...