نتایج جستجو برای: rietveld method
تعداد نتایج: 1630988 فیلتر نتایج به سال:
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...
Nanostructured Ni2As2O7 semiconductor samples were synthesized by a solid state method among As2O3 and Ni(NO3)2.6H2O raw materials at 650 °C (S1) and 750 °C (S2) as reaction temperatures. The synthesized nanomaterials were characterized by powder X-ray diffraction (PXRD) technique and F...
— α-NaCaAlF6 is prepared by solid state reaction as poor quality crystals. The structure is determined ab initio from conventional X-ray powder data. The cell is monoclinic, space group P21/c, Z = 8, with a = 8.7423(3) Å, b = 5.1927(2) Å, c = 20.3514(9) Å and β = 91.499(2)°. The final Rietveld refinement leads to RP = 10.6 % and RB = 5.2 %. The structure is built up from isolated AlF6 octahedra...
We propose two improvements to the microstructural modeling in Rietveld refinement. The first is the model that yields the complete texture-weighted strain and stress tensors as a function of crystallite orientations, as well as the average values of macroscopic strain and stress tensors for all Laue classes. Implementation in the Rietveld refinement program can be made through the set of refin...
The procedure for the quantitative phase analysis using the whole-powder-pattern decomposition method has been applied to ten-component mixtures of synthesized ceramic materials and a five-component mixture of natural products. Average deviations of the calculated weight fractions of respective phases from those prepared in mixing were within 1 weight percent (wt.%), and they were smaller than ...
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...
We report on the residual stresses in amorphous shape memory polymers reinforced with SiC particles. After 50% compression of the composite material at 25 °C, the SiC particles exhibit a compressive stress, which is almost completely released during heated recovery at 120 °C. The residual stresses in SiC hexagonal (6H) phase were estimated through the average change of the unit-cell volume. Lat...
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...
We have prepared polycrystalline samples of the trimer Ir oxide BaIrO3 with face-shared Ir3O12 trimers, and have investigated the origin of the phase transition at 182 K by measuring resistivity, thermopower, magnetization and synchrotron X-ray diffraction. We propose a possible electronic model and transition mechanism, starting from a localized electron picture on the basis of the Rietveld re...
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