According to the Rietveld refinements and X-ray absorption studies at the Ru K-edge, it is found that three compounds La2BRuOg (B=Li, Mg, and Zn) are monoclinic with space group of P21/n, and that the mthenium ions with two oxidation states +IV (d4) and +~(d3) are stabilized in an octahedral site of oxide lattices. A correlation is obtained between absorption edge position and the oxidation sta...

The Rietveld method is the most straightforward and statistically correct approach for the re®nement of crystal structure parameters from powder diffraction data. The equivalent two-stage approach, involving the re®nement of structural parameters based on integrated intensities extracted using the Pawley method, is extremely useful in circumstances such as the global optimization methods of str...

This paper shows a simple procedure for the quantification of industrial and laboratory samples of Ammonium Sulphate-Nitrate fertilizers (ASN) based on a Rietveld fit from X-ray powder diffraction profiles. The Rietveld fit is performed by means of the structural models of the double salts 2NH4NO3·(NH4)2SO4 and 3NH4NO3·(NH4)2SO4, previously reported by the authors. The proposed method demonstra...

— The crystal structure of K2TiSi3O9•H2O has been solved ab initio from X-ray powder data. The unit cell is orthorhombic (space group P212121, Z = 4) with cell dimensions a = 7.1362(2) Å, b = 9.9084(3) Å, c = 12.9414(4) Å, V = 915.07 Å. The structural model was obtained from direct methods using 455 integrated intensities. The Rietveld refinement converged to final Bragg and profile indicators ...

Symmetry modes provide an alternative method to describe crystal structures. Using the fact that many crystal structures can be described as a distorted version of a higher symmetric parent structure, the traditional atomic positions, occupancies or lattice parameters are no longer used. Instead, all structural features are described applying symmetry modes. This can be of particular interest i...

Department of Physics, Shanghai University, Shanghai 200444, People’s Republic of China, Shanghai Key Laboratory of High-Temperature Superconductors, Shanghai 200444, People’s Republic of China, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s...

A Bayesian inference method for refining crystallographic structures is presented. The distribution of model parameters is stochastically sampled using Markov chain Monte Carlo. Posterior probability distributions are constructed for all model parameters to properly quantify uncertainty by appropriately modeling the heteroskedasticity and correlation of the error structure. The proposed method ...

SrRietveld is a highly automated software toolkit for Rietveld refinement. Compared to traditional refinement programs, it is more efficient to use and easier to learn. It is designed for modern high-throughput diffractometers and is capable of processing large numbers of data sets with minimal effort. The software currently uses conventional Rietveld refinement engines, automating GSAS and Ful...