Preparing XRD measurements

Important that the sample is flat and smooth, and all of the surfaces at the same height as the sample holder edges.
This is because of geometrical considerations when using the Bragg-Brentano geometry (see, for example [1])
Too large grains?
- Grain size should optimally be less than 10 microns, so there will be tens of thousands of grains irradiated by the X-ray beam. Please read ref. [2] below for more details
- You can find pestles and mortars in the lab to crush the samples
- Milling machines available in other labs (for example: https://www.ntnu.no/wiki/display/imtlab/Sample+preparation#Samplepreparation-Crushing,milling,sieving )
The powder should be densely packed.
The grains/crystallites should be randomly oriented.
There should not be ANY powder left on the edges of the sample holder (it will spill into the diffractometer and clog up the gears).
It is especially important that the edges are free of any particles/grains.
Use the water-soluble markers to label the sample holder with your name (first name, family name or full name – preferably not only initials).
Never use permanent markers or even whiteboard markers on the sample holders (it may look like can be washed off with ethanol, but if you leave it for weeks it will remain!)
Here is a list of all the sample holders available in the lab.

Short instruction videos for how to use different sample holders

Using the standard sample holders: Normal sample holders
Using the Si cavity holders: Preparation cavity holders
Using the flat Si holders: Preparation Si holders
- Method nr 1, suspension in ethanol (most common)
- Method nr 2, glass rod
Using the Back loaders: Preparation Back loader holders
Using Kapton tape: Preparation Kapton holders
Using the deep sample holders and clay: Deep sample holders
For using the dome holder, you need to have a short training of 10 min.

Which angles to scan. Look at previous XRD results. There is a lot of information in the website.
Which step size to use: The step size will depend on the nature of your sample. For Davinci 1 we work with three different step size which are divided in three folder.
- Highly crystalline : step size 0.01
- Crystalline : step size 0.014
- Low crystalline : 0.04
How long time to measure
- It will depend on the nature of your sample (crystalline or not, element that contain) and the amount of sample. If you see a lot of noise in your diffractogram then increase scanning time. The standard is 60 min.
Which divergence slits to use:
- Fixed vs. variable slit: coming!
- Use variable slit for Si-cavity insert.
- Do NOT use variable slit for cobalt (due to fluorescence)!
- Video showing quick scan of a flourescent screen, first using fixed slit, then variable slit (V6). Fixed vs variable (6 mm) divergence slit

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