What do you get from Rietveld refinement?
Rietveld refinement is a technique described by Hugo Rietveld for use in the characterisation of crystalline materials. The neutron and X-ray diffraction of powder samples results in a pattern characterised by reflections (peaks in intensity) at certain positions.
What is Profex software?
What is Profex? Profex is a graphical user interface for Rietveld refinement of powder X-ray diffraction (XRD) data with the program BGMN. It can be used for phase identification, phase quantification, structure refinement, and export of results and graphs to tables and figures.
Why is Rietveld refinement used?
Rietveld analysis is a program to filter your lattice parameters via d-value and the actual intensity of a particular phase or plane can be theoretically estimated. This gives you very accurate d, lattice parameters (a, b, c) and other parameter.
What is RWP in Rietveld refinement?
Rwp <10% and GOF between 1 and 2% are usually suggested to be satisfactory. But these are “just numbers”. The graphical representation of the fit of the calculated data to the obtained one is very (or rather more) important. An example: a particular sample may bear a phase at ~1 or <1 wt.
What is scale factor in Rietveld refinement?
In the Rietveld refinement, scale parameter is a fitting parameter, which scales the calculated intensity to the observed intensity. So, this value varies system to system.
What is RP and RWP in Rietveld refinement?
how good your Rietveld model has been refined. – Rp: residual of least-squares refinement. – wRp: weighted residual. – GOF: goodness of fit.
What is Rp factor?
In crystallography, the R-factor (sometimes called residual factor or reliability factor or the R-value or RWork) is a measure of the agreement between the crystallographic model and the experimental X-ray diffraction data. In other words, it is a measure of how well the refined structure predicts the observed data.
What is Bragg R factor?
Definition. The R factor measuring the agreement between the reflection intensities calculated from a crystallographic model and those measured experimentally.
What is Rietveld refinement and how does it work?
Rietveld refinement is a tool that tries to model a full powder diffraction profile based on crystal structure data, specimen and instrument effects.
What is the Rietveld method for structural analysis?
The Rietveld method fits a calculated profile (including all structural and instrumental parameters) to experimental data. It employs the non-linear least squares method, and requires the reasonable initial approximation of many free parameters, including peak shape, unit cell dimensions and coordinates of all atoms in the crystal structure.
Why run Rietveld refinements on my diffraction pattern?
In addition, running Rietveld refinements on your diffraction pattern will give you an opportunity to think and learn more about your sample, your experiment and your model. Please take a look at the chapter Some Hints, Tips and Tricks for Rietveld Refinement.
What are the limitations of the Rietveld method?
R.A. Young (ed.), “The Rietveld Method”, International Union of Crystallography, Oxford University Press, New York 1993. One of the key issues of Rietveld refinement is that the method is rather sensitive to problems and errors in the model, resulting in non-convergence and other issues.