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A Specialist Periodical Report Surface and Defect Properties of Solids Volume 4 A Review of the Recent Literature published up to April 1974 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. E. Chisholm, British Museum (Natural History) P. S. Dobson, University of Birmingham I.. W. Hobbs, Materials Development Division, AERE, Harwell R. W. Joyner, University of Bradford R. Kellerman, Xerox Corporation ,Joseph C. Wilson Centre for Technology, Rochester, NewYork K. Klier, Lehigh University, Bethlehem, Pennsylvania J. R. H. Ross, University of Bradford R. E. Smallman, University of Birmingham @ Copyright 1975 The Chemical Society Burlington House, London, W1V OBN ISBN :0 85186 280 2 IS S N :03053873 Library of Congress Catalog Card No.: 72-78528 Printed in Great Britain by Billing & Sons Limited, Guildford and London Preface We have continued with the philosophy adopted in earlier Volumes of giving a broad perspective of Surface Chemistry. The impact of Electron Spectroscopy on thinking in the field has already been significant and very clear indications are already emerging of new paths to follow. In heterogeneous catalysis per se the impact has to date been less marked but this is understandable at such an early stage in the application of Electron Spectroxopy. Auger Electron Spectroscopy is considered in some detail covering examples of its usefulness in metallurgy, corrosion, surface physics, and catalysis. Zeolites are for the first time reviewed in the series, and the authors (Klier and Kellerman) have attempted to give a detailed critical account of spectroscopic aspects of the field. In particular the authors have demonstrated the fascinating chemistry associated with transition-metal ions ex changed into zeolites and the precision by which these ‘active sites’ can be characterized both structurally and electronically. Ross has treated the subject of Steam Reforming from both the fundamental and applied viewpoints, drawing widely on the recent literature and highlighting some of the mechanistic problems inherent in this area of heterogeneous catalysis. The three topics covered in the sections of this Report devoted to defects all involve the application of electron microscopy, a technique now universally recognized as the most versatile of tools for the general elucidation of structural imperfections in solids. In the hands of the metallurgists, transmission electron microscopy has, until very recently, been utilized almost exclusively on the basis of diffraction- and stacking-fault-contrast coupled with selected area diffraction and the judicious use of dark-field illumination. Smallman and Dobson’s summarizing report of the role of vacancies in the oxidation of metals concentrates on the remarkably effective way in which the ‘punching of holes’, on the atomic level, proceeds in metallic solids under the driving force of interfacial oxidation. Hobbs’ comprehensive chapter encompasses a vast field relating to alkali halides. It should be regarded as a sequel to the synoptic account presented in Volume 2 by Jacobs and Corish. For a long time alkali halides were deemed to be unsuitable for study by electron microscopy, but Hobbs and others show that, once the decay and loss mechanisms are first understood, the normal pathways of degradation may be averted and the direct study of defects - again by contrast, rather than latticeimaging techniques - made possible. Chisholm’s brief account of crystallographic shear in minerals extends the domains which have already been charted and fully discussed by Anderson in Volume 1 and by Anderson and Tilley in Volume 3. The identification of extended defects and the characterization chiefly by lattice-imaging (and cautious