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CSIRO Division of Minerals, Clayton, Melbourne, Victoria, Australia - Friday 8th March 2002 - 11:00am - "Using the latest powder diffraction methods and software to solve the problems of the world - can the Earth’s outer core contain Oxygen?"

by Lachlan M. D. Cranswick (CCP14 Project

[CSIRO Division of Minerals Webpage]

This page is located at http://www.ccp14.ac.uk/poster-talks/csiro2002/


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Table of Contents

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

Author: Lachlan M. D. Cranswick (CCP14 Project Secretary)

Email: l.m.d.cranswick@dl.ac.uk

Home Page: http://www.ccp14.ac.uk

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