Beyond Classical Rietveld Analysis using Le Bail fitting
Agenda
Before Le Bail analysis "was the void"
Invention of Le Bail fitting and Le Bail Extraction
What is the Le Bail method
Some more Le Bail history
The spread and impact of the Le Bail Method
The spread and impact of the Le Bail Method -2
The spread and impact of the Le Bail Method - 3 Comparison with other methods
Some of the most complex structures solved from Le Bail method data
Some organic structures solved from Le Bail method data
Recent example
A recent application involving the Le Bail method Can there be Oxygen in the Earth’s outer core
What do we need from the data?
What do we need from the diffraction experiment
Energy Dispersive Diffraction E(keV) = 6.199 / (d_space * sin(theta_angle of Energy Dispersive detector)) Schematic Diagram
Energy Dispersive Diffraction : Advantages
Energy Dispersive Diffraction Beamline 16.4 at Daresbury X-ray Synchrotron, Cheshire, UK
Energy Dispersive Diffraction : Example of High pressure/temp. sample assembly for the multi-anvil Walker Cell
Energy Dispersive Diffraction : Example datasets at high pressure and high temperature
What do we need from the data to help us determined if there can be Oxygen in the Earth’s outer core?
Synchrotron Hardware Fixation Syndrome (SHFS)
Thus the next problem : Software Analysis: Difficulties that need to be considered:
Other Problems that need to be considered
3 x Problems that need to be overcome
Le Bail fitting is a solution!
Performing the Le Bail fit
Rietica Rietveld for Mass Le Bail fitting to get cell volumes Example of 3 phase setup : KClO3; KClO4, B2-KCl
Rietica Rietveld for Mass Le Bail fitting At simplest: 3 step process after initial setup has been done
Rietica Rietveld for Mass Le Bail fitting 1 of 10
Rietica Rietveld for Mass Le Bail fitting 2 of 10
Rietica Rietveld for Mass Le Bail fitting 3 of 10
Rietica Rietveld for Mass Le Bail fitting 4 of 10
Rietica Rietveld for Mass Le Bail fitting 5 of 10
Rietica Rietveld for Mass Le Bail fitting 6 of 10
Rietica Rietveld for Mass Le Bail fitting 7 of 10
Rietica Rietveld for Mass Le Bail fitting 8 of 10
Rietica Rietveld for Mass Le Bail fitting 9 of 10
Rietica Rietveld for Mass Le Bail fitting 10 of 10
Rietica Rietveld for Mass Le Bail : Graphing up "some" results
1. Rietica and Le Bailing : problems with stability of the Energy Dispersive Detector(?)
2. Rietica and Le Bailing : problems with stability of the Energy Dispersive Detector(?)
Using XFIT and UNITCELL for traditional Unit-cell refinement and EOS using unit weighting of HKLs http://www.ccp14.ac.uk/solution/xfit-95/ and http://www.esc.cam.ac.uk/astaff/holland/
Using XFIT and UNITCELL for EOS of NaCl and KCl : But:Le Bailing can make sure correct HKLs are assigned to the correct peaks and phases - greater than 5 phases (spurious peaks can be easily identified)
Volume of Oxygen as a function of Pressure
Implications of the volume of fluid Oxygen and the earth’s other core
Warning: a new volume of fluid oxygen at high pressure that is 50% different from the established value is up for debate
For those who believe in Shockwave / Molecular Dynamics / Impulsively Stimulated Scattering Measurements over Diffraction Methods
Summary
Email: l.m.d.cranswick@dl.ac.uk
Home Page: http://www.ccp14.ac.uk
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