Improving Angular Resolution in XRD
Angular resolution plays a key role in the quality and accuracy of the structural information contained within X-ray diffraction data. It is influenced by a combination of factors relating to the X ray source, optics, detector, experimental setup, and sample properties. By optimizing each factor, the combined benefit leads to enhanced resolution that produces sharper and less convoluted diffraction peaks.
Introduction
In the context of X-ray diffraction (XRD), the term “resolution” typically refers to angular resolution of the diffraction data and is described as the ability to separate two or more close-neighboring reflections. This is a key consideration when analyzing multi-phase materials with complex crystal structures where peaks of two different reflections may overlap if the resolution is insufficient. Consequently, the higher the angular resolution the better the separation of the closely spaced peaks and the easier it is to identify and quantify individual phases.
There are a number of factors that influence the resolution and understanding them can assist in optimizing the XRD measurements in such a way to obtain high-quality data. These factors include but are not limited to:
- Degree of crystallinity of the material
- Crystallite size (too small leads to broadening)
- How monochromatic (narrow the wavelength distribution) the X-ray beam is Beam divergence
- Use of optics
- Detector resolution
- Beam geometry
- Instrumental broadening
By carefully optimizing each of these factors where possible, the resolution can be improved, resulting in sharper and more distinguishable peaks.
For this report, a standard reference Portland cement sample (SRM 2688) from the National Institute of Standards and Technology (NIST) was analyzed under ambient conditions.
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