Surface and Defect Properties of Solids, Volume 1

274 Pages·1972·23.303 MB·English

by  Meirion Wyn Roberts, J M Thomas

A Specialist Periodical Report
Surface and Defect Properties
of Solids
Volume 1
A Review of the Literature Published
between January 1970 and April 1971
Senior Reporters
M. W. Roberts, School of Chemistry, University of Bradford
J. M. Thomas, Edward Davies Chemical Laboratories, University
College of Wales, A beryst wyth
Reporters
J. S. Anderson, F.R.S., University of Oxford
C. H. Bamfard, F.R.S., University of Liverpool
L. L. Ban, Cities Service Co., Cranbury, New Jersey, U.S.A
C. R. Brundle, University of Bradford
G. C. Eastmond, University of Liverpool
R. P. H. Gasser, University of Oxford
J. Pritchard, Queen Mary College, University of London
P. B. Wells, University of Hull
J. 0. Williams, University College of Wales, Aberystwyfh
ISBN: 0 85186 250 0
@ Copyright 1972
The Chemical Society
Burlington House, London, W1V OBN
Printed in Great Britain by Billing & Sons Limited
Guildford and London
Preface
A few aspects of this Report merit elaboration. The first involves editorial
policy, and is concerned with the question of what one should expect from a
volume devoted to current trends in a given area of scientific enquiry. Rather
than call for one or other of the two extreme types of report, that is, a factual
account of recent experiments, or, alternatively, a general interpretative essay
setting out to review recent progress, we have deliberately adopted an ambi-
valent approach. Some of the articles in this first volume are distinctly
phenomenological and seek to be comprehensive; others are of a more
general nature.
Through the sections dealing with defective solids runs one noticeable
thread of coherence, namely the necessity to invoke extended defects in
order to rationalize the properties of these solids. It is now absolutely
clear that point defects alone fail to account for a wide range of solid-state
phenomena and properties, and that both line defects (dislocations) and
planar defects are demonstrably real. Surface Chemistry and Catalysis are
considered on a broad front, keeping very much in mind that catalysis is
concerned with molecular events involving a solid surface whose nature
changes during reaction. In this volume, emphasis is laid on the identity
and reactions of chemisorbed species on metal surfaces, as studied by ex-
change and infrared techniques, catalytic selectivity, and the nature of surfaces
as deduced from stimulated electron emission.
M. W. R.
J. M. T.

Cont ents
Chapter 1 Shear Structures and Non-stoicheiometry
By J. S. Anderson
1 Crystallographic Shear 5
2 The Mechanism and Kinetics of Crystallographic Shear 10
3 The Characterization of Compounds with Planar Defects
or Superstructures 12
4 Crystallographic Stiear in Specific Systems 13
Derivatives of the ReO, Structure 13
Tungsten (and Molybdenum) Oxides 13
Niobium Oxyfluoride 18
Derivatives of the MOO, Structure 18
Derivatives of the Rutile Structure 21
5 Thermodynamics of Rutile CS Phases 26
6 Ternary Defect Rutile Oxides 32
7 Double Shear and Block Structures 36
Symbolism 37
Ordered Block Structures 39
8 Stoicheiometric Faults, Intergrowths, and Non-stoicheio-
metric Faults 44
9 Related Types of Non-stoicheiometry 51
Chapter 2 Direct Study of Structural Imperfections by High-
resolution Electron Microscopy
By L. L. Ban
1 Introduction 54
2 Electron Optical Considerations 57
3 Instrumentation 65
vi Contents
4 Materials Studied 66
Carbons 66
Carbon Blacks 67
Distribution of graphitic layer spacings 71
Different types of images in heat-treated carbon
blacks 76
Carbon Films 80
Pyroly~edP olymers - Glassy Carbon 84
Coal and Char Samples 86
Po I y mers 89
Amorphous Polymers 89
Macromolecules - DNA 90
5 Summary and Conclusions 94
Chapter 3 The Role of Defects in Solid-phase Polymerization
By C.H . Bamford and G. C. Eastmond
1 Introduction 95
2 Some General Considerations 96
3 Vinyl Polymerization 97
Reaction Kinetics 99
Nature of Reaction Sites 100
Molecular Mobility 102
U.V.I nitiation 105
E,S.R. Studies 106
Polymerization at Low Temperatures 112
Topotactic Polymerization 114
The Influence of Additives 117
Effects of Pressure 119
4 Polymerization of Cyclic Monomers 120
5 Co-polymerization 127
6 Concluding Remarks 127
Chapter 4 Structural Imperfections in Organic Molecular Crystals
By J. M. Thomas and J. 0. Williams
1 Point Defects 130
2 Dislocations 132
Contents
3 Stacking Faults
4 Long-range Disorder and Short-range Order
Chapter 5 Surface Studies by Photoemission
By M.W . Roberts
1 Introduction
Formal Description of the Photoemission Process
Photoemission near the Threshold
Escape Depth of Photoelectrons
2 Experimental Approaches in Photoemission
3 Information from Photoemission Studies
Alloy Surfaces
Studies of Silicon
Nickel + Oxygen and Copper + Oxygen Systems
Yield
Energy Distribution
The Aluminium-Oxygen and Aluminium-Water
Interfaces
Density of States
Chapter 6 The Application of Electron Spectroscopy to Suf
Studies
By C. R. Brundle
1 Introduction
2 Principles of Electron Spectroscopy
Summary of the Techniques Involved
Chemical Information from Electron Spectroscopy
Photoelectron Spectroscopy
Energy Loss Electron Spectroscopy
Electron Impact Auger Spectroscopy
Ion Neutralization (I.N.) Spectroscopy
3 Application to Surface Studies
Mean Free Path Lengths of Electrons
Electron Impact Auger Spectroscopy
Ion Neutralization Spectroscopy
Photoelectron Spectroscopy
Molecular Photoelectron Spectroscopy: P hotoemissior
Studies
X-Ray Photoelectron Spectroscopy, ESCA
Energy Loss Spectroscopy
...
Vlll Contents
Chapter 7 Exchange and Equilibration Reactions on Metal
Surfaces
By R. P. H. Gasser
1 The Hydrogen-Deuterium Reaction 205
2 Nitrogen Isotope Reactions 21 1
3 Carbon Monoxide Isotope Reactions 21 5
4 Oxygen Isotope Reactions 217
5 Exchange of Hydrogen Isotopes in Organic Molecules 218
Chapter 8 Infrared Spectra of Adsorbed Species on Metals
By J. Pritchard
1 Carbon Monoxide 223
2 Reflection Spectroscopy of Chemisorbed Carbon Monoxide 228
3 Other Reflection Spectra 230
4 Hydrogen, Nitrogen, and Nitric Oxide 23 1
5 Hydrocarbons and other Compounds 233
Chapter 9 Some Aspects of the Selective Action of Metal
Catalysts
By P. B. Wells
1 Introduction 236
2 Selectivity and Catalyst Structure 237
3 Selectivity and Reaction Mechanism 244
Consecutive Reactions 245
The Thermodynamic Factor 245
The Kinetic Factor 246
A Selectivity Pattern and its Interpretation 246
The Role of Occluded Hydrogen 249
Unresolved Problems 250
Parallel React ions 25 1
Substituent Effects in Selectivity 254
Isomerization of Product before Desorption 254
Reduction of Selectivity by Polymerization 255
4 Selective Poisoning and Shape-selective Catalysts 255
5 Summary 258
Author Index 259