How and from where the standard XRD patterns were obtained/ derived ? Either experimentally or theoretically ?
Thank you
You should invest a bit more time in reading some overview literature.
Since a simulation is based on a theory which is quite satisfying standard XRD data are simulated, or at least added to experimental data. Before, all data cold only be measured experimentally which also means that there are uncertainties in peak intensities caused by e.g. texture effects implemented during sample preparation. Therefore, full-pattern refinement software uses simulations since they might have some limitations as well but in fact they are in general more trustful. However, as long as you do not have any crystal structure description, there is no simulation. This means, for a wide range of materials no theoretical data (simulation) are available. Fortunately, these are often very exotic phases so that it does not really affect the practical application.
You should invest a bit more time in reading some overview literature.
Since a simulation is based on a theory which is quite satisfying standard XRD data are simulated, or at least added to experimental data. Before, all data cold only be measured experimentally which also means that there are uncertainties in peak intensities caused by e.g. texture effects implemented during sample preparation. Therefore, full-pattern refinement software uses simulations since they might have some limitations as well but in fact they are in general more trustful. However, as long as you do not have any crystal structure description, there is no simulation. This means, for a wide range of materials no theoretical data (simulation) are available. Fortunately, these are often very exotic phases so that it does not really affect the practical application.
Thank you sir for the nice explaination. Please provide some relevent literature.
I think you can find this information in standard PDF cards contained in databases.
It should be stated in the PDF card if the standard pattern was obtained experimentally or theoretically, and in most cases, a reference to the literature (where you can source further information) is provided.
Thank you so much sir for the information. I will try to find solution in the way you have suggested.
"standard XRD patterns" - Are diffractograms that are invarient no matter when and where they are obtained provided the data acquisition conditions are identical. Generally, these contain only relative peak positions (angles or d-spacings) and relative peak intensities. No other information regarding the profile are used for such purposes. Such patterns originated from the need to standardize measurements from various make/models of diffractometers.
Typical standard materials are provided by reputable institutions like NIST, National Institue for Standards and Testing. Standard powders include LaB6, corundum, Si etc. Stable materials with high diffracting power and low hygroscopicity are desired characteristics for standard powders.
Some have even used locally available salt (NaCl) as a potential standard. However, its moistrue absorption is notorious and not helpful. Its purity is dubious as well.
Both numerical simulation and experimental observations may be used to create "standard XRD patterns".
Thank you so much Dr Ravi Ananth for the detail explaination.
With best regards
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