Iterative Phase Elimination for Powder X-Ray Diffraction Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for quantitative analysis of powder samples require a precise known qualitative composition, which is limiting in samples with variable phase compositions, such as those from quarries, and can result in inaccurate phase component calculations due to parameter correlations and noise artifacts.
Innovation Solution
A method that specifies a list of phases present and possibly not present in the sample with user-definable threshold values, iteratively eliminates phases below the threshold, and repeats the refinement process until all phase components are above the threshold, enabling accurate quantitative analysis of variable phase compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a list of phases is specified including phases possibly not contained in the sample, then the quantitative analysis can be performed with generalized refinement models, but phase fractions of non-existent phases are still found due to parameter correlations and noise artifacts
Solution Approach 1:
The patent applies preliminary action by performing a qualitative phase analysis (pre-scan) before the quantitative analysis. This preliminary step identifies which phases are actually present in the sample, allowing the subsequent quantitative analysis to exclude phases that are not present. The method calculates correlation factors for each phase in the list and eliminates phases below a threshold value, thereby preventing false phase fraction determinations for non-existent phases.
2Measurement precision
If a pre-scan is performed to identify actual sample composition, then accurate quantitative analysis can be achieved, but the analysis time and process complexity increase
Solution Approach 1:
The patent merges the qualitative and quantitative phase analysis into a single integrated automated process. The method combines correlation factor calculation for phase identification with phase fraction determination in one unified refinement procedure. By using a list of phases with associated threshold values and automatically eliminating phases below the threshold during the refinement process, the patent eliminates the need for separate pre-scan and quantitative analysis steps, thereby reducing total analysis time while maintaining accuracy.
3Loss of information
If phases with low phase fractions are included in the analysis, then complete sample composition is captured, but parameter correlations lead to inaccurate results
Solution Approach 1:
The patent applies local quality by introducing phase-specific threshold values that allow different phases to be treated differently based on their actual presence in the sample. Each phase in the list can have its own threshold value, enabling the method to retain phases with low but genuine concentrations while eliminating phases that are not present. This selective approach maintains completeness for truly present phases while improving accuracy by excluding false phases.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate parallel qualitative and quantitative phase analysis, reducing parameter correlations and measurement errors, and is suitable for automated evaluation of samples with variable compositions, particularly in Industrial Minerals and Mining applications.
Implementation Method 1
X-ray diffraction is used in a variety of ways to analyze crystalline (and with certain limitations also amorphous) components of samples. X-rays are diffracted at crystal planes in the sample. From the spatial intensity distribution of the diffracted X-ray radiation, in particular the position of intensity maxima ('reflections'), conclusions can be drawn, for example, about lattice plane spacing and thus the crystal lattice (lattice symmetry)
Implementation Method 2
neutron diffractometry... From the spatial intensity distribution of the diffracted neutron radiation, in particular the position of intensity maxima ('reflections'), conclusions can be drawn, for example, about nuclear plane spacing and thus the crystal lattice (lattice symmetry)
Implementation Method 3
electron diffractometry... From the spatial intensity distribution of the diffracted electron radiation, in particular the position of intensity maxima ('reflections'), conclusions can be drawn, for example, about atomic plane spacing and thus the crystal lattice (lattice symmetry)
Data Source
Figure 1
AI summary
The method involves calculating theoretical diffraction diagram or theoretical energy-dispersive spectrum based on phases to be allocated to phase contents in a powder sample. The diagram/spectrum is fitted to a recorded powder sample by varying the contents of the diagram/spectrum. A new list of phases is generated by eliminating phases with phase contents below a threshold value from a predetermined list of phases. The above steps are repeated until all phase contents are above the threshold value. A composition of the sample is output with remaining phases and associated phase contents. A profile adjustment method based on individual reflexes, a Pawley method, a LeBail method and a Rietveld method are used in fitting the theoretical diffraction diagram or theoretical energy-dispersive spectrum to the recorded powder sample.