Germanides, germanide-tungstate double salts and substitution effects in Zintl phases [Elektronische Ressource] / Siméon Ponou

Informations

• Publié par: technische_universitat_munchen
• Publié le: 01 janvier 2006
• Nombre de lectures: 17
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Germanides, Germanide-Tungstate Double Salts
and
Substitution Effects in Zintl Phases








Siméon Ponou






Technische Universität München
Lehrstuhl für Anorganische Chemie
mit Schwerpunkt Neue Materialien


August 2006 Technische Universität München
Lehrstuhl für Anorganische Chemie







Germanides, Germanide-Tungstate Double Salts
and
Substitution Effects in Zintl Phases






Siméon Ponou




Vollständiger Abdruck der von der Fakultät für Chemie der Technischen Universität
München zur Erlangung des akademischen Grades eines


Doktors der Naturwissenschaften


genehmigten Dissertation.



Vorsitzender: Univ.-Prof. Dr. Michael Schuster
Prüfer des Dissertation: 1. Univ.-Prof. Dr. Thomas Fässler
2. Univ.-Prof. Dr. Ulrich K. Heiz
3. Univ.-Prof. Dr. Rainer Niewa




Die Dissertation wurde am 07.07.2006 bei der Technische Universität München eingereicht
und durch die Fakultät für Chemie am 16.08.2006 angenommen.
=





To my mother Domche Jeannette,
my sisters Cathy, Fideline and Alyce













The Lord is my shepherd.
I am never in need.
Psaml 23.1


















To the memory of Bertrand Seumo Meuleye


i

Acknowledgements


To my Supervisor Prof. Thomas Fässler, my deepest gratitude for the supply of this
interesting topics as well as all support and guidance. Thank you also for accepting
me as PhD student, for your leniency and your great help, even on some rather
personal problems;
To Prof. Sven Lidin, Stockholm University, for his assistance with solving crystal
structures of the double-salts and for showing interest in my project;
Prof. Brigitte Eisenmann, TU Darmstadt, for the fruitful discussions on Zintl phases
and for providing me with various literatures;
Prof. Lars Kloo and Dr. Martin Lindsjö, Royal Institute of Technology Stockholm, for
the Raman spectroscopy;
Priv. Doz. Dr. Lorenz Kienle, Max-Planck-Institut für Festkörperforschung Stuttgart,
for the Transmission Electron Microscopy study;
Dr. Mathias Opel, Walther-Meissner-Institut TU München, for SQUID magnetic
measurements;
To Dr. Stefan Hoffmann (TU Darmstadt) for kindly introduce me to the general
experimental techniques;
Dr. Stephan D. Hoffmann, Dr. Frank Dubois and Dr. Martin Schreyer for their
valuable suggestions and assistance;
I am particularly indebted to Dipl.-Chem Sung-Jin Kim for reading my manuscript and
for his suggestions and to Anna Margareth Fredricks for correcting the English
language;
Also to all the members of the Fässler Research Group for their continuous
encouragements, friendliness, care and company and whose comments were very
helpful.
Finally, I would like to thank Mr. Henri Severin Kamgaing and Dipl.-Ing Paul René
Ngandjui for moral supports. ii

CONTENTS

1. Introduction ....................................................................................................... 1
1.1 Probing the Zintl concept – Double salts with Zintl anions .......................... 2
1.2 Beyond the Zintl concept ................................................................................. 4
1.2.1 Bonding at the Zintl border............................................................................. 5
1.2.2 Beyond Electronic Effects .............................................................................7
1.3 Scope and aims of this work............................................................................ 7
1.4 Literature ........................................................................................................... 9

2. Experimental and characterization methods................................................ 12
2.1 Starting materials and synthesis................................................................... 12
2.2 X-ray diffraction study.................................................................................... 14
2.2.1 Powder X-ray diffraction............................................................................... 14
2.2.2 Single crystal X-ray diffraction ..................................................................... 14
2.3 Energy Dispersive X-ray analysis (EDX)....................................................... 15
2.4 Differential Thermal Analysis (DTA).............................................................. 16
2.5 Magnetic measurements ...............................................................................17
2.6 Theoretical band structure calculation ........................................................17
2.7 Literature ......................................................................................................... 18

3. Alkali-metal Germanides and Germanide-Tungstate double salts ............ 19
3.1 Introduction ..................................................................................................... 19
3.2 Synthesis and characterization of the K and Rb germanide tungstates
A [Ge ] WO (A = K, Rb, Cs) ......................................................................... 21 10 9 2 4
3.2 Synthesis 21
3.2.2 EDX analysis and X-ray powder diffraction.................................................. 22
3.2.3 Characterization by Raman spectroscopy ..................................................22
3.3 Crystal structure of the K germanide tungstates K [Ge ] WO ................25 10 9 2 4
3.3.1 Crystal structure determination .................................................................... 25
3.3.2 Description of the structure of K [Ge ] WO ..............................................26 10 9 2 4
3.4 The Crystal structure of the Rb germanide tungstates Rb [Ge ] WO ..... 38 10 9 2 4
3.4.1 Crystal structure determination 38
3.4.2 Description of the structure of Rb [Ge ] WO ............................................. 38 10 9 2 4
3.5 Discussions on the double-salts ................................................................... 44 iii
3.6 The crystal structure of K Ge ....................................................................... 48 4 9
3.6.1 Synthesis and characterization .................................................................... 48
3.6.2 Crystal structure determination 48
3.6.3 Description of the structure of K Ge ........................................................... 49 4 9
3.6.4 Discussions.................................................................................................. 56
3.7 Rb Hg Ge – a Mercury substituted Germanium Clathrate-I ..................... 58 8 3 43
3.7.1 Synthesis and characterization 58
3.7.2 Crystal structure determination ................................................................... 58
3.7.3 Structural description of Rb Hg Ge ..........................................................58 8 3 43
3.7.4 Discussions ................................................................................................. 62
3.8 Literature ......................................................................................................... 65

4. Influence of atomic properties on the structure and bonding of Zintl
phases: Sb for Bi Homologous substitutions in Ba Sb ............................. 67 2 3
4.1 Introduction ..................................................................................................... 67
4.2 The Phase Ba Bi , its Coloring Variant Ba BiSb and the Solid Solutions 2 3 2 2
Ba Bi Sb (y < 2)......................................................................................... 69 2 1+y 2-y
4.2.1 Synthesis and characterization .................................................................... 69
4.2.2 Determination of the crystal structures......................................................... 70
4.2.3 Structural descriptions of Ba Bi and Ba Bi Sb (y < 2)........................... 70 2 3 2 1+y 2-y
4.2.4 Electronic Structure and Discussions........................................................... 80
4.2.5 Physical properties....................................................................................... 84
4.3 Further results – The crystal structure of BaBi .......................................... 86 2
4.3.1 Source of the material and crystal structure determination .......................... 86
4.3.2 Description of the structure of BaBi and discussions .................................. 88 2
4.4 Literature ........................................................................................................91

5. Substitution effects in Zintl phases of the Na/Sn phase system .................... 92
5.1. Introduction ..................................................................................................