Experimental: Sample and Experimental Details

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Experimental: Sample and Experimental Details

Listed below are points which should be included in the descriptions of the material the data is collected on, its preparation for data collection and the data collection itself. Some of the information may be given in tabular form; various common options are outlined for guidance.

1. Sample Details
   1. the material itself - whether synthesised in the laboratory, purchased from a company or extracted from the earth;
   2. preparation of the powder - how it was ground; if it was sieved or mixed with a support material to reduce preferred orientation.
   3. sample holder and collection geometry - flat plate for reflection, capillary tube for transmission.
   4. sample details - dimensions of specimen; if the sample was open to the atmosphere during collection or not.
   5. sample environment - whether the sample was studied at non-ambient temperature (cryostat, furnace) or pressure (diamond anvil).
2. Diffractometer and Data Collection Details
1. radiation source - options include sealed X-ray tube (specifying target metal), a synchrotron for X rays, or a neutron reactor or spallation source for neutrons.
2. radiation - the wavelength (with an error on the value if it was calibrated) if it was monochromatic, or whether a white beam was used.
3. diffractometer - the type of instrument; the geometry (Bragg-Brentano, Debye-Scherrer) in which it was operated.
4. pre-sample devices - monochromator (give the material and diffraction plane used) or filters.
5. pre-detector devices - monochromator or Soller slits.
6. detector - type (scintillation, position sensitive detector, image plate) and specific details.
7. scan details - including the type of scan (step or continuous); 2q range; step size; detector counting time at each step.
8. the software used to operate the diffractometer.

Interpretation

When reading these sections in an article you should be looking for the points described above in the text or tables. If the information is presented well you should be able to visualize the type of experiment that was performed, and this should start you thinking about problems that may have arisen. You should remember to look for discussion of such problems later in the article. For example, if the sample is prepared so as to avoid preferred orientation, you should look to see if this preparation overcame the problem or whether corrections were applied in the refinement procedure, if values of related parameters occur in any of the tables or if there are any traces of preferred orientation in the final plots.

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