Semi-quantitative phase identification using Whole Pattern Fitting (WPF) is a sophisticated technique derived from Rietveld Refinement. It aims to determine the relative quantities of [[Crystalline phases]] in a material by comparing the measured diffraction pattern to calculated patterns of known phases. Here's a more detailed explanation: 1. Methodology: WPF takes into account variations in crystal structure, including: a) Lattice parameters, which can shift peak positions b) Orientation factors, which can alter peak intensity relations 2. Process: - The software (in this case, Smartlab Studio 2) uses known crystal structures from the ICSD (Inorganic Crystal Structure Database) to generate theoretical diffraction patterns for each identified phase. - It then attempts to minimize the difference between the measured diffraction pattern and a weighted sum of these theoretical patterns. - The weightings of these theoretical patterns correspond to the relative abundances of each phase. 3. Quality of Fit: - The quality of this fitting is quantified by the Rwp value (weighted profile R-factor). - In this analysis, an Rwp of 13.15% was achieved, indicating a moderate agreement between observed and calculated patterns. 4. Limitations: - The report notes a critical limitation: differences in X-ray absorptivity between phases. - Iron silicon, being less likely to absorb X-rays than the other phases, is probably overestimated in quantity. - This overestimation consequently affects the reported percentages of other phases. 5. Accuracy: - The concentrations are reported with an uncertainty of ±5 wt%. - This uncertainty reflects both the inherent limitations of the technique and the specific challenges of this sample. 6. Interpretation: - Despite the limitations, WPF provides valuable insights into the relative abundances of crystalline phases. - It's particularly useful for comparing similar samples or tracking changes in phase composition. In this specific analysis, the semi-quantitative results suggest a predominance of iron silicon $(\text{Fe}_4\text{Si})_{0.4}$ at 75%, followed by silicon oxide $\text{SiO}_2$ at 18.7%, biotite at 5.3%, and a complex potassium-sodium-barium-magnesium-iron-aluminum-titanium-silicon oxide hydroxide compound at 1%. However, these percentages should be interpreted cautiously due to the noted absorptivity issues. This semi-quantitative approach, while not providing absolute quantification, offers a robust method for characterizing the crystalline composition of complex materials like the "golden mica ore" analyzed in this report. <hr/> <!-- Your main content goes here --> <div class="footer"> Carbonatik © 2024 </div>