Automated parametric Rietveld refinement and its application to two dimensional X-ray powder diffraction experiments [Elektronische Ressource] / Rajiv Paneerselvam. Betreuer: Manfred Joswig

Rajiv

Sujets

• Physik

Informations

• Publié par: universitat_stuttgart
• Publié le: 01 janvier 2011
• Nombre de lectures: 37
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

Automated parametric Rietveld
refinement and its application to two-
dimensional X-ray powder diffraction
experiments








Rajiv Paneerselvam
















Institut für Geophysik Max-Planck-Institut für Universität Stuttgart Festkörperforschung
Stuttgart


Dissertation an der Universität Stuttgart
Stuttgart, 2011




























































































Automated parametric Rietveld
refinement and its application to two-
dimensional X-ray powder diffraction
experiments







Von der Fakultät für Bau- und Umweltingenieurwissenschaften der Universität
Stuttgart zur Erlangung der Würde eines Doktor-Ingenieurs (Dr.-Ing.)
genehmigte Abhandlung



Vorgelegt von
Rajiv Paneerselvam
geboren in Madurai (Indien)





Hauptberichter: Prof. Dr. M. Joswig
Mitberichter: Prof. Dr. R.E. Dinnebier
Mitberichter: Prof. Dr. H-W. Reinhardt



Tag der Einreichung: 01.03.2011
Tag der mündlichen Prüfung: 25.05.2011




Institut für Geophysik, Max-Planck-Institut für
Universität Stuttgart Festkörperforschung, Stuttgart



2011
















































Contents

1 Introduction.........................................................................................1
1.1 Introduction ............................................................................................................. 1
1.2 Thesis outline........................................................................................................... 8

2 Theory...................................................................................................9
2.1 Basics of X-ray diffraction...................................................................................... 9
2.2 Powder diffraction................................................................................................ 10
2.3 Pattern decomposition methods......................................................................... 12
2.4 Rietveld method.................................................................................................... 14
2.5 Basic math in the Rietveld method..................................................................... 15
2.6 Parametric Rietveld method................................................................................ 18

3 A program for sequential and parametric Rietveld
refinements using Topas ........................................................................21
3.1 Introduction ........................................................................................................... 21
3.2 Topas launch mode and 'Powder 3D Parametric' interface............................ 21
3.3 Description of 'Powder 3D Parametric' ............................................................. 22
3.3.1 Graphics interface ..................................................................................... 23
3.3.2 Text editor interface.................................................................................. 23
3.3.3 Test refinement.......................................................................................... 26
3.3.4 Parameters spread sheet .......................................................................... 27
3.4 Operation modes................................................................................................... 27
3.5 Technical details.................................................................................................... 28
3.6 Summary ................................................................................................................ 28

4 Automatic determination of phase transition points..................29
4.1 Introduction ........................................................................................................... 29
4.2 Preprocessing......................................................................................................... 30
4.3 Statistical analysis ................................................................................................. 32
4.4 Correlation coefficients ........................................................................................ 35
4.5 Parametric and non-parametric correlation coefficients................................. 37
4.6 Improvements in the determination of correlation coefficients..................... 39
4.6.1 Image segmentation.................................................................................. 39
4.6.2 Robustness of standard normalization procedure............................... 42
4.6.3 Enhancement of correlations matrix elemens by the application of
standard normalization procedure...................................................... 44
4.7 Other methods used for the determination of phase transition points......... 46
4.8 Summary ................................................................................................................ 48

5 Applications of the algorithm that determines the phase
transition points .......................................................................................49 5.1 Sample data............................................................................................................ 49
5.1.1 Polymorphism of silver vanadate........................................................... 49
5.1.2 Phase transitions and decomposition products of rubidium
oxalate......................................................................................................50
5.1.3 Decomposition products of Bischofite................................................... 52
5.1.4 Thermal behavior of silver isocyanate................................................... 52
5.2 Some intrepretations about the position, width and multiplicity of the
correlations peaks .................................................................................................... 53
5.3 Implementation ..................................................................................................... 55
5.4 Summary ................................................................................................................ 56

6 Parametric Rietveld analysis of the kinetics of copper
phthalocyanine.........................................................................................57
6.1 Introduction ........................................................................................................... 57
6.2 Experimental details and parameterization...................................................... 58
6.3 Program.................................................................................................................. 59
6.4 A case study........................................................................................................... 60
6.4.1 A single refinement................................................................................... 60
6.4.2 Sequential refinements............................................................................. 61
6.4.3 Parametric refinement.............................................................................. 62
6.5 Analysis .................................................................................................................. 63
6.6 Comparison of results and intrepretation ......................................................... 65
6.6.1 Pure -CuPC.............................................................................................. 66
6.6.2 -CuPC and -CuPC ................................................................................ 69
6.6.3 - CuPC -CuPC and additives .............................................................. 70
6.6.3.1 -CuPC and -CuPC.................................................................. 70 6.3.2-CuPC -CuPC with NU......................................................... 71
6.6.3.3 -CuPC -CuPC with DMAM.................................................. 72
6.6.4 - CuPC and additives.............................................................................. 73
6.6.4.1 -CuPC........