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Showing 1 to 20 of 30 for “"Rietveld Refinement"”.
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Aerosol synthesis and Rietveld refinement of Pd2Zn
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 500oC. Through the course of …
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Advances in the modelling of in-situ powder diffraction data
… were studied using the approach of parametric Rietveld refinement. In parametric Rietveld refinement a set of powder diffraction pattern is refined simultaneously, constraining the evolution of some parameters using mathematical models, so that only the variables of the model need to be …
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Diffraction investigations of cement clinker and tricalcium silicate using Rietveld analysis
… There has been an increase in the use of Rietveld refinement of powder diffraction data for the analysis of cement in recent years. The method has emerged as a valuable tool for the quantitative determination of the composition of cement. A further advantage of the method is its ability to …
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High throughput optical materials
… characterised by powder neutron diffraction and Rietveld refinement. Structural refinements show that substitutions at non-framework sites alter the framework bond distances of the sodalite and the observed optical property. Different colours of reversible photochromism have been observed and …
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Building Metal-Anion Layers within a Preovskite Host
… the general formula, (A2Cl)LaNb2O7 (A = Rb, Cs). Rietveld refinement of X-ray powder diffraction data shows that an alkali metal halide layer is formed between the perovskite blocks. The alkali metal cation is eight-coordinate with 4 oxygens from the perovskite layer and 4 chlorides from the new …
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Structural studies of layered transition metal oxides
… Their<br/>structures were determined through Rietveld refinement against X-ray and neutron powder<br/>diffraction, supported by vibrating sample magnetometry and thermal analysis.<br/><br/>The structure of the double layered phase Gd2SrCo2O7 was determined in the temperature<br/>range 300 – …
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Development and Scale-Up of ‘The Bradford Process’ for the Production of Titanium and Titanium Alloys
… (IGF), powdered X-ray diffraction (P-XRD) with Rietveld refinement, and particle size analysis (PSA). The research identified that the foundational works results (>99% purity titanium), could not be reproduced (highest obtained ~98.5%), and is unsuited for scaling due to calcium vaporisation, …
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Analysis of Factors Controlling the Distribution of Trace Elements in Surface Sediments of Coastal Alabama
… Ti, Tl, V, and Zn). The main minerals found via Rietveld refinement of XRD patterns in these samples were quartz, illite, kaolinite, chlorite, microcline, albite, pyrite, and mixed high CEC (cation exchange capacity) clays. Sediment extractable element concentrations and mineral percentages were …
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Synthesis and properties of some doped lithium transition-metal phosphates
… was performed using powder XRD with Rietveld refinement and Raman spectroscopy. Results showed that the pure forms of LiNiPO₄, LiCoPO₄ and Li₃Fe₂(PO₄)₃ could be synthesised in air at various temperatures. Li₃V₂(PO₄)₃ required a reducing atmosphere of 2%H₂/98%N₂ to achieve phase …
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Multi-component boron coatings on low carbon steel AISI 1018
… temperature range of 400-800 C for 24 hours. The Rietveld refinement method was used to examine the quantitative phase analysis, crystalline size, microstrain and lattice parameters of the multi-component boron coatings. The results have shown that adding transition metals into the B-Fe system …
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Synthesis and characterisation of materials with potential multiferroic behaviour
… of the constituent atoms has been calculated by Rietveld refinement. A range of materials of general formula Bi\(_5\)Fe\(_1\)\(_+\)\(_x\)Ti\(_3-x)\O\(_1\)\(_5\) was produced with a value of x ranging from 0 to 2.5, which is higher than reported. Attempts to produce Bi\(_5\)Fe\(_4\)O\(_1\)\(_5\), …
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Enhancing the study of battery degradation using machine learning to get more out of data
… In some cases, the CNN outperforms traditional Rietveld refinement on the real PXRD data. In the third chapter, non-negative matrix factorisation (NNMF) is used to model *in situ* UV-Vis data from an RFB. The models can track the different molecules in solution during cycling and are able to …
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Synthesis And Characterization Of Transition Metal Arsenide Nanocrystals And The Metastability And Magneto-Structural Phase Transition Behavior Of Mnas Nanocrystals
… method. Atomic pair distribution and Rietveld refinement were employed on synchrotron data to explore the structural transitions of the bulk and nanoparticle samples, and these results were compared to AC magnetic susceptibility measurements of the samples. The results confirm that the …
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Development of Li0.33La0.56TiO3 based Solid Electrolyte Materials
… biggest crystallite size from XRD patterns and Rietveld refinement compared with LLTO synthesized by citric acid and a mix of citric acid and glucose. According to the XRD patterns, Ag doping of LLTO (Li0.33-xLa0.56AgxTiO3) was positively proved by shifting away from the original target …
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Thermal expansion behavior of Mo-Si-B system intermetallics
… Source (CHESS) of Cornell University. The Rietveld refinement of diffraction pattern is performed through using General Structure Analysis System (GSAS) program. All the Mo-Si-B intermetallics in this research show approximate linear thermal expansion behavior from room temperature up to …
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Experimental and numerical study of the reduction of silica in a thermal plasma reactor
… internal standard methods based on whole pattern Rietveld refinement. SiC is the major product in this study. Higher power input and higher CH4/SiO2 ratio gives higher SiC yield. Maximum SiC yield of 69% was achieved at 20kW with CH4/SiO2 = 7.5. Reaction kinetics model was developed based on the …
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Structural studies using synchrotron X-ray powder diffraction and other techniques
… for crystal structure determination and refinement. The Rietveld structure refinement method is described and examples of different methods of structure determination from powder diffraction data are given. The techniques of EXAFS and Mossbauer spectroscopy, which were used to provide …
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Study of growing incongruent antiferromagnetic single crystals and characterization
… revealed the magnetic ordering of Cr2Al. The Rietveld refinement, together with thermal analysis and resistivity, indicates a likely in-plane magnetic ordering instead of a canted angle to the c-axis as published in a previous study. The magnetometry measurements carried out on an aligned …
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Computational Modeling Of High-Performance Nickel-Metal Hydride Battery Materials
… of nickel hydroxide materials, and through Rietveld refinement and DIFFaX modeling of the different types of stacking faults, the evolution of the stacking faults was tracked over precipitation time for different compositions. We determined which types of stacking faults have a stronger …
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Syntheses, Characterizations, and Properties of Suboxides and Layered Titanium-based Pnictide Oxide Superconductors
… determined using X-ray powder diffraction and Rietveld refinement. BaTi2Sb2O crystallizes in a layered variant of the CeCr2Si2C structure type (space group P4/mmm (No.123)), and features [Ti2Sb2O]2- layers separated by layers of Ba atoms. The [Ti2Sb2O]2- layers can be described as being formed …
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