PREPARATION AND CRYSTAL GROWTH OF MATERIALS WITH LAYERED STRUCTURES

Transcription

1 PREPARATION AND CRYSTAL GROWTH OF MATERIALS WITH LAYERED STRUCTURES

2 PHYSICS AND CHEMISTRY OF MATERIALS WITH LAYERED STRUCTURES Managing Editor E. MoosER, Laboratoire de Physique Appliquee, CH-1003, Lausanne, Switzerland Advisory Board E. J. ARLMAN, Bussum, The Netherlands F. BASSANI, Physics Institute of the University of Rome, Italy J. L. BREBNER, Department of Physics, University of Montreal, Montreal, Canada F. JELLINEK, Chemische Laboratoria der Rijksuniversiteit, Groningen, The Netherlands R. NITSCHE, Kristallographisches lnstitut der Universitiit Freiburg, West Germany A. D. YoFFE, Department of Physics, University of Cambridge, Cambridge, U.K. VOLUME I

3 PREPARATION AND CRYSTAL GROWTH OF MATERIALS WITH LAYERED STRUCTURES Edited by R. M.A. LIETH Technische Hoyeschoo/, Eindhoven. The Netherlands SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

4 Library of Congress Cataloging in Publication Data Main entry under title: Preparation and crystal growth of materials with layered structures. (Physics and chemistry of materials with layered structures; v. I) Includes bibliographical references and index. I. Layer structure (Solids}-Addresses, essays, lectures. 2. Crystals-Growth-Addresses, essays, lectures. I. Lieth, R. M.A., II. Series. ISBN ISBN (ebook) DOI / All Rights Reserved Copyright 1977 by Springer Science+Business Media Dordrecht Originally published by D. Reidel Publishing Company, Dordrecht, Holland in 1977 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner

5 TABLE OF CONTENTS PREFACE VII FOREWORD IX J. G. HOOLEY I Elements J. SCHOONMAN and R. M.A. LIETH I Metal Halides 35 H. R. OSWALD and R. ASPER I Bivalent Metal Hydroxides 71 R. M.A. LIETH and J. c. J. M. TERHELL I Transition Metal Dichalcogenides 141 R. M.A. LIETH 1 III-VI Compounds 225 P. BUCK I IV-VI Compounds 255 INDEX OF SUBJECTS 275

6 PREFACE The goal of the series Physics and Chemistry of Materials with Layered Structures is to give a critical survey of our present knowledge on a large family of materials which can be described as solids containing molecules which in two dimensions extend to infinity and which are loosely stacked on top of each other to form threedimensional crystals. Of course, the physics and chemistry of these crystals are specific chapters in ordinary solid state science, and many a scientist hunting for new phenomena has in the past been disappointed to find that materials with layered structures are not entirely exotic. Their electron and phonon states are not twodimensional, and the high hopes held by some for spectacular dimensionality effects in superconductivity were shattered. Nevertheless, the structural features and their physical and chemical consequences singularize layered structures sufficiently to make them a fascinating subject of research. This is all the more true since they are met in insulators and semiconductors as well as in normal and superconducting metals. Although for the time being the series is intentionally limited to cover inorganic materials only, the many known organic layered structures may well be the subject of future volumes. Among the noteworthy peculiarities of layered structures, we mention specific growth mechanisms and crystal habits. Polytypism is very common and it is fascinating indeed to find up to 240 different polytypes in the same chemical substance. In view of this abundance, it is not surprising that the exact determination of the properties of any one polytype and its structural characterization are often difficult and sometimes impossible. Connected with polytypism is the occurrence of stacking faults, which at high densities introduce one-dimensional disorder into layered structures. The low dimensionality and hence the relative simplicity of the phenomenon may well prove useful in coming to a better understanding of amorphous materials. Easy cleavage and glide along the layer planes have permitted highly interesting and esthetically pleasing electron microscopic studies of the dislocation networks in layered structures. Similar studies in connection with the hitherto not fully understood phase transitions involving charge density waves are still in progress. The anisotropy of the selection rules governing optical transitions in layered semiconductors often permits absorption measurements well beyond the fundamental absorption edge. Because of this, some of the most spectacular magneto-absorption spectra have been obtained in layered materials. As far as phonons are concerned, perhaps the most conspicuous feature is the quadratic dispersion observed in some of the acoustic branches. The free charge ::arriers in layered semiconductors interact strongly with homopolar optical phonons

7 VIII PREFACE and, unlike in cubic semiconductors, it is this interaction which limits their mobility. Layered structures may contain many atoms per unit cell, which renders electron band calculations difficult. The preoccupation with layered structures has therefore brought about a considerable development of techniques for such calculations, which was further enhanced by the discovery in some dichalcogenides of charge density waves. In order to come to an understanding of this phenomenon, efficient methods had to be developed to carry out band calculations in compounds containing transition element atoms. At the time of this writing, the theoretical and experimental investigations on the formation of charge density waves and on the associated phase transitions in layered materials are multiplying. Many interesting results may be expected in the near future, results that will find a rightful place in the present series. Another rapidly developing field of interest is that of photo-electron-emission spectroscopy. Because the cleavage faces of layered crystals do not contain broken bands, photoemission spectra yield a nearly undistorted picture of their electron density of states. Layered materials have thus become model substances for testing and exploring the photoemission method. The above survey does not do justice to the many highly interesting aspects of layered materials and is at best only an indication of the numerous subjects which will be treated by specialists in this series. Each volume of the series will cover a particular area of interest, i.e. : Volume I : Preparation and Crystal Growth Volume 2: Crystallography and Crystal Chemistry Volume 3 : Electrons and Phonons in Layered Materials Volume 4: Electrical and Optical Properties Volume 5: Structural Chemistry of Layer-Type Phases Two more volumes are in an advanced state of planning, one on intercalated layer materials and one on photo-electron-emission spectroscopy. The articles in the different volumes are essentially of two types. On the one hand there are broad surveys of fields of advanced research which aim at informing and stimulating the experienced scientist, and on the other hand there are specialized articles describing new theoretical and experimental techniques. This distinction is not very strict, however, and the character of any one article depends largely on the personality of its author. Once an author has been chosen, he is free to organize his subject at will. This freedom leads to a certain inhomogeneity in the text but assures its spontaneity, which hopefully will make the series the stimulating research tool which I would like it to become. If this goal should be reached, it is above all due to the unfailing efforts of the authors and editors, to whom I extend my sincere thanks. Lausanne, October 1976 E. MOOSER

8 FOREWORD The study of materials with layered structures-their interesting anisotropic behaviour attracts ever increasing attention - has made considerable progress in the past years. Successful growth of single crystals of most of these substances has miade it possible to apply new investigation techniques to old problems and to attack :new ones. Our knowledge of both the physics and chemistry of these materials has thus rapidly advanced. Although the large family of layered materials also include silicates (mica, clays), organic compounds, ternary inorganic compounds and the rapidly growing group of intercalation compounds, we have limited ourselves in this volume specifically to binary inorganic compounds and to some elements. Some of the other materials mentioned will be treated in future volumes. Here we include the elements carbon, phosphorus, arsenic, antimony and bismuth, and compounds like the di- and trihalides, the hydroxides, the transition metal dichalcogenides and the compounds of the III-VI- and IV-VI families. The object of volume 1 is to present a review of the current application of preparative methods and crystal growth techniques to the investigation of the abovementioned compounds and elements. Various aspects of the growth of single crystals are discussed and reference is made to the importance of single crystal X-ray work in connection with the occurrence of polytypism, the influence of phase relations on growth experiments, and attention is given to the problem of purity and purification. In Chapter I the elements and some of the intercalates in graphitic carbon are discussed. Chapter 2 presents the vast group of the di- and trihalides, while in Chapter 3 attention is focused on the less known group of bivalent metal hydroxides. In Chapter 4 another large group is presented, that of the dichalcogenides of the transition metals. Chapter 5 contains the sulfides, selenides and tellurides of gallium and indium and in Chapter 6 the chalcogenides of silicon, germanium, tin and lead are discussed. By compiling a considerable amount of otherwise widely dispersed data in one single volume, it is hoped that the present book will facilitate the access to this information. If, in addition to this, the book helps to establish better contact among different investigators in the field of layered materials, we shall feel that our efforts have been well worthwhile. As editor I wish to express my gratitude to the authors for their fruitful collaboration. Thanks are due also to au those who have contributed by allowing us to use unpublished results and have critically read and commented on the different chapters. Eindhoven, The Netherlands 1977 R. M.A. LIETH