My sample shows bright spots and thereby crystalline nature as per the SAED (Selected Area Electron Diffraction) Pattern. However, it is not showing any sharp peaks in the XRD pattern to comment on its crystallinity (only a broad peak is present around 2theta=24 degree). Is it possible to happen like this? Anyone of you came across the same kind of problem? What can be the main reason for this? (Both XRD and SAED patterns are attached)
If we perform powder XRD test, which is a macroanalysis, then we expect to get a result of analysing millions of particles. Thus, the result will be a representative value for the common features in the structure of the sample.
This is unlike the analysis using electron diffraction under the electron microscopes, which is a microanalysis, where very small area in the sample is tested. Thus, the result will not be representative. Actually, it will be biased test and it will be affected by very small errors from the operators and the heterogeneity of the sample if any.
Keeping this in mind, your sample is either have hetrogenety as @ Alan F Rawle Sir mentioned or it is a homogeneous sample with short range order that causes a broadening in the XRD pattern, while, it is detected by SAED crystalline material. In other words, the short rang order, i.e. very small crystallite size, has two different impact on the XRD and SAED patterns. It causes broadening of the former and shifting in the positions of the spots in the later.
Dear Arya J S ,
in addition to the answers of Alan F Rawle and Imad Disher you should consider that the information/penetration depths of both techniques are quite different:
SAED is via electrons and is smaller than 1µm (and even much less);
XRD is via x-rays and is about some µm.
So for example if the net mass coverage of your sample is very small (such as it is in the case of TEM), you mainly see your substrate (or sample holder) via XRD.
You may share your mass coverage (or estimated net sample thickness) and type of substrate....(as well as type of sample and electron energy)
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