Using the latest powder diffraction methods and software to solve the problems of the world - can the Earth’s outer core contain Oxygen?
Talk Aims
Notes Free Zone - they are on the web - http://www.ccp14.ac.uk/poster-talks/csiro2002/
Is there 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))
Energy Dispersive Diffraction - Schematic Diagram
Energy Dispersive Diffraction : Advantages
Energy Dispersive Diffraction - Schematic of following reactions inside reaction vessels
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)
How can you detect if the beamline you are using suffers from 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
Software to help Analyse the Data - XFIT, Crysfire, Chekcell and Rietica
Background to XFIT by Cheary and Coehlo
Peak Profiling - XFIT
Background to Crysfire by Robin Shirley
Powder Indexing - the Crysfire Suite
Chekcell - Jean Laugier and Bernard Bochu - http://www.ccp14.ac.uk/tutorial/lmgp/
Routine operation of Chekcell (1 of 5)
Routine operation of Chekcell (2 of 5)
Routine operation of Chekcell (3 of 5)
Routine operation of Chekcell (4 of 5)
Routine operation of Chekcell (5 of 5)
Chekcell: Major new feature of Chekcell Porting and "integration" of Ton Spek and A. Meetsma’s Le Page
Chekcell: GUI Cell transformation
Chekcell: Density / Z / Molecular Volume Explorer
Chekcell: result of using Le Page
1. Chekcell: indexing unknown cells from unexpected phase transitions in high pressure experiments
2. Chekcell: re-indexing lost cells (maybe transformed) from big pressure jumps in high pressure experiments due to racing a synchrotron beam-dump.
3. Chekcell: re-index again (big jumps due to trying to beat a synchrotron beam dump)
XFIT / Chekcell / LePage Summary:
Background to Rietica by Brett Hunter
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 : - Rietica Database of Structures
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 the results
Rietica Macro Language - RIET BASIC
1. Rietica and Le Bailing : problems with stability and calibration of the Energy Dispersive Detector(?)
2. Rietica and Le Bailing : problems with stability and calibration of the Energy Dispersive Detector(?)
Using XFIT and UNITCELL for traditional Unit-cell refinement and EOS to obtained unit weighting of HKLs - http://www.esc.cam.ac.uk/astaff/holland/
Using XFIT and UNITCELL for EOS of NaCl and KCl : - But:Rietica can make sure the 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
Chekcell and Rietica: results of the volume of Oxygen and the earth’s other core
Summary
Email: l.m.d.cranswick@dl.ac.uk
Home Page: http://www.ccp14.ac.uk
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