Portail documentaire Université Mohamed Khider Biskra

Atomic diffusion in glasses studied with coherent x-rays

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Titre :	Atomic diffusion in glasses studied with coherent x-rays
Auteurs :	Manuel Ross ; SpringerLink (Service en ligne
Support:	Livre
ISBN/ISSN/EAN :	978-3-319-28646-4
Format :	1 ressource en ligne (xviii, 111 pages) / illustrations en partie en couleur, fichiers PDF
Note générale :	In SpringerLink Titre de l'écran-titre (visionné le 16 août 2016) "Doctoral thesis accepted by University of Vienna, Austria."
Résumé :	This thesis provides the first successful study of jump diffusion processes in glasses on the atomic scale, utilizing a novel coherent technique. This new method, called atomic-scale X-ray Photon Correlation Spectroscopy or aXPCS, has only recently been proven to be able to capture diffusion processes with atomic resolution in crystal systems. With this new toolkit for studying atomic diffusion in amorphous systems, new insight into basic processes in a wide range of technically relevant materials, like fast ionic conductors, can be obtained.
Sommaire :	Parts of this thesis have been published in the following journal article: Supervisor’s Foreword Abstract Acknowledgements Contents Abbreviations 1 Introduction 1.1 A Long-Standing Challenge: Gaining Insight into Glass Fundamentals 1.1.1 Glass Structure 1.1.2 Glassy Dynamics 1.2 A New Method for Studying Dynamics: aXPCS 1.2.1 Methods for Studying Diffusion 1.2.2 The Development of aXPCS References 2 Theory 2.1 Achieving Coherent Scattering 2.1.1 Scattering Intensity and Speckle Patterns 2.1.2 Optimal Scattering Thickness 2.1.3 Coherence Properties 2.2 Deducing Real-Space Time-Correlations from Intensity Pattern Series 2.2.1 Van Hove Pair Correlation Function 2.2.2 Autocorrelation Functions 2.2.3 Link Between Autocorrelation Functions of Measured Intensities and Those of Real-Space Informa 2.3 Unravelling Atomic Dynamics 2.3.1 Continuous Diffusion 2.3.2 Jump Diffusion: Chudley--Elliott Model 2.3.3 Extensions of the Chudley--Elliott Model 2.4 Applying aXPCS to Diffusion in Glasses 2.4.1 Influence of Different Scattering Species 2.4.2 Kohlrausch Exponent 2.4.3 Short-Range Order Correction References 3 Experimental 3.1 Preparing Glass Samples for Coherent Experiments 3.1.1 Glass Melting 3.1.2 Creating Thin But Stable Samples: Dimpling Grinder 3.2 Creating a Stable Sample Environment for Atomic-Resolution Measurements 3.2.1 Vacuum Sample Cell 3.2.2 Helium Cryostat 3.3 Obtaining Scattering Data for Atomic-Diffusion Studies 3.3.1 Generating Coherent X-Rays 3.3.2 Conducting Synchrotron Experiments 3.3.3 Gaining Complementary X-Ray Scattering Information References 4 Data Analysis 4.1 Converting Scattered X-Rays to Intensity Data 4.1.1 Detecting Single Photons 4.1.2 Disposing of the Dark Current 4.2 Obtaining Correlation Times from Intensity Data 4.2.1 Histogram 4.2.2 Droplet Algorithm 4.2.3 Autocorrelation 4.2.4 Two-Time Correlation 4.3 Extracting Dynamics from Correlation Times 4.4 Evaluating in Real-Time During Experiments References 5 Proof of Concept: Direct Observation of Atomic Diffusion in Glasses 5.1 Previous Studies of Lead Silicate Glasses 5.1.1 Structure 5.1.2 Dynamics 5.2 New Insight into Lead Silicate Glasses 5.2.1 Scattering Intensities 5.2.2 Glass Temperatures 5.2.3 Atomic Dynamics References 6 Practical Application: Tailoring Fast Ionic Diffusion 6.1 Previous Studies on Amorphous Fast Ionic Conductors 6.1.1 Structure of Alkali Borate Glasses 6.1.2 Atomic Dynamics 6.2 Tailoring Atomic Diffusion in Glasses 6.2.1 Fluorescence: Caesium Borate Glasses 6.2.2 Influence of Thermal History: Rubidium Borate Glasses 6.2.3 Path to Light Alkali: Potassium Borate Glasses 6.2.4 First Measurement of Light-Alkali Diffusion: Sodium Borate Glasses References 7 Conclusion References Appendix A