X-ray Diffraction Absorption Correction via Transmission Feedback
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Solution Overview
Problem
In X-ray diffraction analysis, especially in transmission geometry, the absorption of X-rays by the sample introduces significant errors in quantitative analysis due to unknown sample thickness and variable composition, making it difficult to accurately determine the concentration of components like free lime in pressed powder samples.
Innovation Solution
A method and apparatus that corrects diffraction intensity for absorption effects by calculating the mass attenuation coefficient and using a matrix correction factor, allowing for simultaneous X-ray fluorescence and correction measurements to reduce measurement time and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmission geometry is used for X-ray diffraction measurements, then structural information from both sides of the sample can be obtained, but absorption of X-rays by the sample causes significant errors in quantitative analysis
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual transmission intensity through the sample and using this information to calculate and apply absorption corrections to the diffraction intensities. The system continuously monitors transmission and adjusts the quantitative analysis accordingly, resolving the accuracy problem while maintaining transmission geometry benefits
Solution Approach 2:
The patent changes the approach from directly using measured intensities to using corrected intensities that account for absorption effects. By introducing correction factors based on transmission measurements and theoretical models, the system transforms the raw data into accurate quantitative information while preserving the versatility of transmission geometry
2Measurement precision
If accurate mass thickness measurements are made before X-ray analysis, then quantitative accuracy improves, but measurement time and process complexity increase
Solution Approach 1:
The patent combines the mass thickness measurement with the X-ray diffraction measurement by using the same instrument and sample setup. The transmission measurement is performed simultaneously or in sequence with the diffraction measurement, eliminating the need for separate precise thickness measurements and reducing total analysis time
Solution Approach 2:
The system uses the X-ray transmission measurement itself to provide the information needed for correction, rather than requiring external thickness measurements. The transmission intensity data serves dual purposes: assessing sample quality and providing correction factors for quantitative analysis
3Strength
If pressed powder samples are made with robust thickness (>3mm), then sample strength is sufficient for handling, but absorption effects become highly non-linear and reduce measurement accuracy
Solution Approach 1:
The patent uses transmission measurements as feedback to determine the actual absorption conditions in the pressed powder sample. This feedback information allows the system to apply appropriate corrections for the non-linear absorption regime, enabling accurate quantitative analysis even with thick, robust samples
Solution Approach 2:
The patent changes from assuming linear absorption relationships to using correction factors that account for non-linear absorption in thick samples. By transforming the data processing approach rather than the sample preparation, the system maintains both sample robustness and measurement accuracy
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
Enables accurate quantitative measurements of component concentrations by accounting for sample thickness and composition variations, significantly improving the reliability of X-ray diffraction analysis in industrial settings.
Implementation Method 1
Absorption of electromagnetic waves that pass directly through a medium without diffraction may be characterised by the Beer-Lambert law Where I 0 is the original intensity, I the intensity after passing through the material, μ the mass attenuation coefficient of the material, ρ the material density and d the material thickness
Implementation Method 2
X-ray diffraction is used in these cases
Implementation Method 3
the X-rays diffracted by a diffraction angle 2θ from the same surface of the sample are detected by a detector
Implementation Method 4
A problem with making measurements in this transmission geometry is that the sample itself may be absorbing for X-rays
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Quantitative X-ray analysis is carried out by making X-ray fluorescence measurements to determine the elemental composition of a sample and a correction measurement by measuring the transmitted intensity of X-rays at an energy E transmitted directly through the sample without deviation. An X-ray diffraction measurement is made in transmission by directing X-rays from an X-ray source at the energy E onto a sample at an incident angle Ψ1 to the surface of the sample and measuring a measured intensity Id(θfl) of the diffracted X-rays at the energy E with an X-ray detector at an exit angle Ψ2 corresponding to an X-ray diffraction peak of a predetermined component. A matrix corrected X-ray intensity is obtained using the measured X-ray intensity in the X-ray diffraction measurement, the correction measurement and the mass attenuation coefficient of the sample calculated from the elemental composition and the mass attenuation coefficients of the elements.