External Standards

The attached file should be self-explaining. It does two refinements at the same time.

The first one determines the K factor (B.H. O'Connor & M.D. Raven, Application of the Rietveld Refinement Procedure in Assaying Powdered Mixtures, Powder Diffraction (1988), 3, 2-6) from an external standard, in this case a diffraction pattern of NIST SRM676a.

In the second one, the K factor determined above is used to quantify the phases in the mixture according to this method. In this example, another corundum was used.

The nice thing about doing all in one .inp file is that computation of the MAC's is energy independent and all errors, starting from e.g. XRF uncertainties are properly propagated throughout all calculations.

Requires TOPAS 6. for older versions, change all “prm_with_error” to “prm” but errors will not be propagated.

The files can be down loaded here.

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