نتایج جستجو برای: rietveld method
تعداد نتایج: 1630988 فیلتر نتایج به سال:
This work presents a structural investigation of La2-xNdxCe2O7 (x = 0.0, 0.5, 1.0, 1.5, 2.0) using X-ray powder diffraction and total scattering neutron powder diffraction, analysed using Rietveld and the reverse Monte Carlo method (RMC). Ab initio molecular dynamics (MD) modelling is also performed for further investigations of the local order. The main intensities in the neutron diffraction d...
Sodium dicyanamide NaC2N3 was found to undergo two phase transitions. According to thermal analysis and temperature-dependent X-ray powder diffractometry, the transition of alpha-NaC2N3 (1a) to beta-NaC2N3 (1b) occurs at 33 degrees C and is displacive. 1a crystallizes in the monoclinic system, space group P21/n (no. 14), with a = 647.7(1), b = 1494.8(3), c = 357.25(7) pm, beta = 93.496(1) degre...
Global optimisation methods of structure determination from powder diffraction data have risen to prominence in a relatively short space of time and they now constitute a key approach in the examination of polycrystalline molecular organic materials. A correctly formulated global optimisation approach may be regarded as a "global Rietveld refinement" that is capable of delivering accurate cryst...
Y(2)GeO(5) (yttrium germanium penta-oxide) was synthesized by solid-state reaction at 1443 K. The arrangement, which has monoclinic symmetry, is isostructural with Dy(2)GeO(5) and presents two independent sites for the Y atoms. Around these atoms there are distorted six-coordinated YO(6) octa-hedra and seven-coordinated YO(7) penta-gonal bipyramids. The YO(7) polyhedra are linked together, shar...
Current study represents the effect of the size and synthesis method on the cation distribution of cobalt ferrite nanoparticles and on the magnetic properties. The nanoferrites have been synthesized through sol-gel auto-combustion method using metal nitrates as precursor and citrate as fuel. In order to obtain the fine and agglomerated-free particles, we have used salt-assisted combustion react...
Fitting of full X-ray diffraction patterns is an effective method for quantifying abundances during X-ray diffraction (XRD) analyses. The method is based on the principal that the observed diffraction pattern is the sum of the individual phases that compose the sample. By adding an internal standard (usually corundum) to both the observed patterns and to those for individual pure phases (standa...
Simulations of 29Si and 23Na MAS NMR spectra indicate the presence of differing proportions of two polytypes and a third phase in three samples of penkvilksite, Na4Ti2Si8O22•5H2O. The most abundant peaks are assigned to the 2O and 1M polytypes, and a third set of peaks are provisionally assigned to a proposed 2M polytype. The quadrupolar interaction parameters for 23Na, Cq and , were calculated...
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