Study of the Properties of Hydrogen and Deuterium in Beta Phase Palladium Hydride and Deuteride SIMON ANTHONY STEEL 18/04/2018 Materials and Physics Research Group School of Computing Science & Engineering This thesis is submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy Dedication This work is dedicated to the memory of Professor Donald Keith Ross. “I may not have gone where I intended to go, but I think I have ended up where I needed to be.” Douglas Adams i Contents Dedication .................................................................................................................................... i Figures ...................................................................................................................................... vii Acknowledgements .................................................................................................................... x Glossary .................................................................................................................................... xii Units, Constants, and Standard Values ................................................................................... xiii Conventions in this Document ................................................................................................ xiv Abstract .................................................................................................................................... xv 1 Introduction ......................................................................................................................... 1 1.1 History .......................................................................................................................... 1 1.1.1 In the Beginning… ................................................................................................. 1 1.1.2 Significant Pd-H/D/T System Discoveries and Firsts............................................. 3 1.2 Motivation.................................................................................................................... 6 1.2.1 Nuclear Fusion ...................................................................................................... 8 1.2.2 Isotope Separation ............................................................................................... 9 1.2.2.1 Cryogenic Distillation ...................................................................................... 10 1.2.2.2 Chromatography ............................................................................................. 10 1.2.2.3 Other Techniques ............................................................................................ 10 1.2.2.4 Current Industrial Systems .............................................................................. 10 1.2.3 Why Now? .......................................................................................................... 11 1.3 Aims and Objectives of this Work .............................................................................. 12 2 The Palladium Hydride System .......................................................................................... 14 2.1 Palladium ................................................................................................................... 14 2.2 Palladium Hydride ...................................................................................................... 15 2.2.1 Order / Disorder ................................................................................................. 20 2.2.2 Isotope Dependence........................................................................................... 22 ii 2.3 Diffusion ..................................................................................................................... 24 2.3.1 Jump Diffusion .................................................................................................... 25 2.3.2 Arrhenius Behaviour ........................................................................................... 25 2.4 Sample Materials ....................................................................................................... 26 2.4.1 Spherical Palladium Powder ............................................................................... 26 2.4.2 Palladium Foil ..................................................................................................... 27 2.5 Determining Concentration ....................................................................................... 28 2.5.1 Gravimetric Sorption .......................................................................................... 28 2.5.2 Manometric Sorption ......................................................................................... 32 3 Neutron Scattering ............................................................................................................ 37 3.1 Why Use Neutrons? ................................................................................................... 37 3.2 Neutron Scattering Basics .......................................................................................... 38 3.2.1 Properties of Neutrons ....................................................................................... 38 3.2.2 Neutron Interactions .......................................................................................... 40 3.2.2.1 Neutron Absorption ........................................................................................ 40 3.2.2.2 Geometry of Scattering ................................................................................... 41 3.2.2.3 Mechanics of Scattering.................................................................................. 43 3.2.2.4 Scattering Length and Cross Section .............................................................. 43 3.3 Coherent Vs. Incoherent Scattering........................................................................... 45 3.4 Elastic Scattering ........................................................................................................ 45 3.4.1 Neutron Diffraction ............................................................................................ 46 3.4.2 Diffuse Scattering ............................................................................................... 48 3.5 Inelastic and Quasi-Elastic Neutron Scattering .......................................................... 49 3.6 Neutron Scattering from Palladium, Hydrogen and Deuterium................................ 52 3.6.1 Diffraction from Pd-H/D ..................................................................................... 52 3.6.2 QENS from Pd-H/D ............................................................................................. 54 iii 3.6.3 The Chudley-Elliott Model .................................................................................. 54 3.6.3.1 Modifications and Considerations for the Hydride Sample ........................... 55 3.6.3.2 Modifications and Considerations for the Deuteride Sample ........................ 56 3.7 The Multiple Scattering Problem ............................................................................... 60 3.8 Facilities and Instruments .......................................................................................... 60 3.8.1 Producing Neutrons ............................................................................................ 60 3.8.1.1 Fission ............................................................................................................. 61 3.8.1.2 Spallation ........................................................................................................ 61 3.8.1.3 Other Neutron Sources ................................................................................... 61 3.8.2 Moderation ......................................................................................................... 61 3.8.3 ISIS ...................................................................................................................... 62 3.8.3.1 OSIRIS .............................................................................................................. 63 3.8.4 Institut Laue Langevin ......................................................................................... 65 3.8.4.1 IN5 ................................................................................................................... 65 3.9 Data Collection, Reduction, and Fitting ..................................................................... 66 3.9.1 Data Collection ................................................................................................... 66 3.9.2 MantidPlot .......................................................................................................... 67 3.9.3 Data Reduction ................................................................................................... 67 3.9.4 Quasilines ........................................................................................................... 67 4 Pd-H Vs. Pd-D Diffusion Rate as a Function of Temperature ............................................ 71 4.1 Introduction ............................................................................................................... 71 4.1.1 Why OSIRIS ......................................................................................................... 71 4.2 Experimental Setup ...................................................................................................