Rietveld refinement of Sm0.55Sr0.45Mn0.4Fe0.6O3

Single crystals of Sm0.55Sr0.45Mn0.4Fe0.6O3 were grown by an optical floating zone technique in an oxygen atmosphere. The powder X-ray diffraction pattern for the grown crystal revealed single-crystalline nature. The lattice parameters and atomic structure were refined and indexed using a General Structure Analysis System (GSAS) to an orthorhombic structure with lattice parameters a = 5.4415 (32) Å, b = 7.6994 (27) Å, c = 5.43868 (28) Å, and space group Pnma.

Materials for learning use of GSAS-II

The General Structure Analysis System (GSAS-II) package provides materials and crystallographic analysis for all types of diffraction data. It was initially made available with very limited capabilities, but over much of the last decade the features have been expanded, so that GSAS-II is now a comprehensive tool for nearly all types of structural and materials characterization studies. The need to provide materials to teach use of GSAS-II, while the software has been undergoing constant revision and expansion, has required new approaches for documentation. This has included providing tutorials, as each major new capability has been added, and context-sensitive help for each section of the program. Comments in the code are also expanded into a software reference guide. Most recently, video versions of more than half of the tutorials were created and others were provided with animated graphics. All GSAS-II documentation is web-based.

Rietveld refinement of X-ray powder diffraction data of Sm0.55Sr0.45MnO3 polycrystalline material

Polycrystalline Sm0.55Sr0.45MnO3 was prepared by solid-state reaction at 1300 °C. Single phase of the compound was analysed by a powder X-ray diffraction technique. The powder pattern of Sm1−xSrxMnO3 was indexed and refined using a General Structure Analysis System (GSAS) to an orthorhombic structure with space group Pnma, a = 5.4323(7), b = 7.6585(4), and c = 5.4343(7) Å.

Parallel processing for Rietveld refinement

A method for speeding Rietveld refinements using parallel computing is presented. The method can be applied to most, if not all, Rietveld refinement programs. An example implementation for the Los AlamosGeneral Structure Analysis System(GSAS) package is described. Using a cluster with seven processors, least-squares refinements are completed 2.5 to 5 times faster than on an equivalent single-processor computer.