X-Ray Diffraction by Polycrystalline Materials E-Book

René Guinebretière

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 462

Veröffentlichungsjahr: 2013

Beschreibung

This book presents a physical approach to the diffraction phenomenon and its applications in materials science. An historical background to the discovery of X-ray diffraction is first outlined. Next, Part 1 gives a description of the physical phenomenon of X-ray diffraction on perfect and imperfect crystals. Part 2 then provides a detailed analysis of the instruments used for the characterization of powdered materials or thin films. The description of the processing of measured signals and their results is also covered, as are recent developments relating to quantitative microstructural analysis of powders or epitaxial thin films on the basis of X-ray diffraction. Given the comprehensive coverage offered by this title, anyone involved in the field of X-ray diffraction and its applications will find this of great use.

Leseprobe

Table of Contents

Preface

Acknowledgements

An Historical Introduction: The Discovery of X-rays and the First Studies in X-ray Diffraction

Part 1. Basic Theoretical Elements, Instrumentation and Classical Interpretations of the Results

Chapter 1. Kinematic and Geometric Theories of X-ray Diffraction

1.1. Scattering by an atom

1.2. Diffraction by an ideal crystal

1.3. Diffraction by an ideally imperfect crystal

1.4. Diffraction by a polycrystalline sample

Chapter 2. Instrumentation used for X-ray Diffraction

2.1. The different elements of a diffractometer

2.2. Diffractometers designed for the study of powdered or bulk polycrystalline samples

2.3. Diffractometers designed for the study of thin films

2.4. An introduction to surface diffractometry

Chapter 3. Data Processing, Extracting Information

3.1. Peak profile: instrumental aberrations

3.2. Instrumental resolution function

3.3. Fitting diffraction patterns

3.4. The resulting characteristic values

Chapter 4. Interpreting the Results

4.1. Phase identification

4.2. Quantitative phase analysis

4.3. Identification of the crystal system and refinement of the cell parameters

4.4. Introduction to structural analysis

Part 2. Microstructural Analysis

Chapter 5. Scattering and Diffraction on Imperfect Crystals

5.1. Punctual defects

5.2. Linear defects, dislocations

5.3. Planar defects

5.4. Volume defects

Chapter 6. Microstructural Study of Randomly Oriented Polycrystalline Samples

6.1. Extracting the pure profile

6.2. Microstructural study using the integral breadth method

6.3. Microstructural study by Fourier series analysis of the peak profiles

6.4. Microstructural study based on the modeling of the diffraction peak profiles

Chapter 7. Microstructural Study of Thin Films

7.1. Positioning and orienting the sample

7.2. Study of disoriented or textured polycrystalline films

7.3. Studying epitaxial films

Bibliography

Index

First published in France in 2002 and 2006 by Hermès Science/Lavoisier entitled “Diffraction des rayons X sur échantillons polycristallins” First published in Great Britain and the United States in 2007 by ISTE Ltd

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

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© ISTE Ltd, 2007

© LAVOISIER, 2002, 2006

The rights of René Guinebretière to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Cataloging-in-Publication Data

Guinebretière, René.

[Diffraction des rayons X sur échantillons polycristallins. English]

X-ray diffraction by polycrystalline materials/René Guinebretière.

p. cm.

Includes bibliographical references and index.

ISBN-13: 978-1-905209-21-7

1. X-rays--Diffraction. 2. Crystallography. I. Title.

QC482.D5G85 2007

548′.83--dc22

2006037726

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

ISBN 13: 978-1-905209-21-7

Preface

In 1912, when M. Laue suggested to W. Friedrich and P. Knipping the irradiation of a crystal with an X-ray beam in order to see if the interaction between this beam and the internal atomic arrangement of the crystal could lead to interferences, it was mainly meant to prove the undulatory character of this X-ray discovered by W.C. Röntgen 17 years earlier. The experiment was a success, and in 1914 M. Laue received the Nobel Prize for Physics for the discovery of X-ray diffraction by crystals. In 1916, this phenomenon was used for the first time to study the structure of polycrystalline samples. Throughout the 20th century, X-ray diffraction was, on the one hand, studied as a physical phenomenon and explained in its kinematic approximation or in the more general context of the dynamic theory, and on the other, implemented to study material that is mainly solid.

Obviously, the theoretical studies were initially conducted on single crystal diffraction, but the needs for investigation methods from physicists, chemists, material scientists and more recently from biologists have led to the development of numerous works on X-ray diffraction with polycrystalline samples. Most of the actual crystallized solid objects that we encounter every day are in fact polycrystalline; each crystal is the size of a few microns or even just a few nanometers. Polycrystalline diffraction sampling, which we will address here, is actually one of the most widely used techniques to characterize the state of the “hard” condensed matter, inorganic material, or “soft”, organic material, and sometimes biological material. Polycrystalline samples can take different forms. They can be single-phased or made up of the assembling of crystals of different crystalline phases. The orientation of these crystals can be random or highly textured, and can even be unique, in the case for example of epitactic layers. The crystals can be almost perfect or on the contrary can contain a large number of defects. X-ray diffraction on polycrystalline samples enables us to comprehend and even to quantify these characteristics. However, the methods of measure must be adapted. The quality of the quantitative result obtained greatly depends on the care taken over this measure and in particular on the right choice of equipment and of the data processing methods used.

This book is designed for graduate students, as well as engineers or active researchers studying or working in a sector related to material sciences and who are concerned with mastering the implementation of X-ray diffraction for the study of polycrystalline materials.

The introduction recounts the history of the emphasis on X-ray diffraction by crystals since the discovery of X-rays. The book is then divided into two parts. The first part focuses on the description of the basic theoretical concepts, the instrumentation and the presentation of traditional methods for data processing and the interpretation of the results. The second part is devoted to a more specific domain which is the quantitative study of the microstructure by X-ray diffraction.

The first part of the book is divided into four chapters. Chapter 1 focuses on the description of the theoretical aspects of X-ray diffraction mainly presented as a phenomenon of interference of scattered waves. The intensity diffracted by a crystal is measured in the approximations of the kinematic theory. The result obtained is then extended to polycrystalline samples. Chapter 2 is entirely dedicated to the instrumental considerations. Several types of diffractometers are presently available; they generally come from the imagined concepts from the first half of the 20th century and are explained in different ways based on the development of the sources, the detectors and the different optical elements such as for example the monochromators. This chapter is particularly detailed; it takes the latest studies into account, such as the current development of large dimension plan detectors. Modern operation of the diffraction signal is done by a large use of calculation methods relying on the computer development. In Chapter 3, we will present the different methods of extracting from the signal the characteristic strength of the diffraction peaks including the position of these peaks, their integrated intensity and the shape or the width of the distribution of intensity. The traditional applications of X-ray diffraction over polycrystalline samples are described in Chapter 4. The study of the nature of the phases as well as the determination of the rate of each phase present in the multiphased samples are presented in the first sections of this chapter. The structural analysis is then addressed in a relatively condensed way as this technique is explained in several other international books.

The second part of the book focuses on the quantitative study of the microstructure. Although the studies in this area are very old, this quantitative analysis method of microstructure by X-ray diffraction has continued to develop in an important way during the last 20 years. The methods used depend on the form of the sample. We will distinguish the study of polycrystalline samples as pulverulent or massive for thin layers and in particular the thin epitactic layers. Chapter 5 is dedicated to the theoretical description of the influence of structural flaws over the diffusion and diffraction signal. The actual crystals contain a density of varying punctual, linear, plan or three-dimensional defects. The presence of these defects modifies the diffraction line form in particular and the distribution of the diffused or diffracted intensity in general. The influence of these defects is explained in the kinematic theory. These theoretical considerations are then applied in Chapter 6 to the study of the microstructure of polycrystalline pulverulent or massive samples. The different methods based on the analysis of the integral breadth of the lines or of the Fourier series decomposition of the line profile are described in detail. Finally, Chapter 7 focuses on the study of thin layers. Following the presentation of methods of measuring the diffraction signal in random or textured polycrystalline layers, a large part is dedicated to the study of the microstructure of epitactic layers. These studies are based on bidimensional and sometimes three-dimensional, reciprocal space mapping. This consists of measuring the distribution of the diffracted intensity within the reciprocal lattice node that corresponds to the family of plans studied. The links between this intensity distribution and the microstructure of epitactic layers are presented in detail. The methods for measuring and treating data are then explained

The book contains a large number of figures and results taken from international literature. The most recent developments in the views discussed are presented. More than 400 references will enable the interested reader to find out more about the domains that concern them.

Acknowledgements

X-ray diffraction is a physical phenomenon as well as an experimental method for the characterization of materials. This last point is at the heart of this book and requires illustration with concrete examples from real experiments. The illustrations found throughout this book are taken from international literature and are named accordingly. Many of these examples are actually the result of studies conducted in the last 15 years in Limoges in the Laboratoire de Science des Procédés Céramiques et de Traitements de Surface. My profound thanks to the students, sometimes becoming colleagues, who by the achievement of their studies have helped make this book a reality. I would like to particularly acknowledge O. Masson and A. Boulle in Limoges for their strong contribution to the development X-ray diffraction on polycrystalline samples and epitactic layers respectively.

One of the goals of this book is to continually emphasize the link between the measuring device, the way in which it is used and the interpretation of the measures achieved. I am deeply convinced that in experimental science only a profound knowledge of the equipment used and the underlying theories of the methods implemented can result in an accurate interpretation of the experimental results obtained. We must then consider the equipment that has helped us conduct the experimental study as the centerpiece. Because of this conviction, I have put a lot of emphasis on the part of this book that describes the measuring instruments. I learned this approach from the experience of A. Dauger who has directed my thesis as well as during the years following my research studies. He is the one who introduced in Limoges the development of X-ray diffusion and diffraction instruments, and I thank him for his continued encouragement in this methodology.

Ever since the first edition written in French and published in 2002, several colleagues have commented on the book. These critiques led me to completely redo the structure of the book, in particular separating the conventional techniques from the more advanced techniques linked to the study of microstructure. I would once more like to thank A. Boulle, now a researcher at the CNRS and also M. Anne, director of the Laboratoire de Cristallographie in Grenoble, whose comments and encouragement have been very helpful.

An Historical Introduction: The Discovery of X-rays and the First Studies in X-ray Diffraction

X-rays and “cathode rays”: a very close pair

On November 8th, 1895, Röntgen discovered by accident a new kind of radiation. While he was using a Crookes tube, he noticed a glow on a plate, covered with barium platinocyanide, and rather far away from the tube. Röntgen, who was working at the time on the cathode rays produced by Crookes tubes, immediately understood that the glow he was observing could not be caused by this radiation. Realizing the importance of his discovery, and before making it known to the scientific community, he tried for seven weeks to determine the nature of this new kind of radiation, which he named himself X-Strahlen. On December 28th, 1895, Röntgen presented his observations before the Würzburg Royal Academy of Physics and Medicine [RON 95]. His discovery was illustrated by the photographic observation of the bones in his wife’s hand (see Figure 1). Röntgen inferred from his experiments that the Crookes tube produced beams that propagated in straight lines and could pass through solid matter [RON 95, RON 96a, RON 96b, RON 96c]. Very quickly, these “Röntgen rays” were used in the medical world to produce radiographies [SWI 96].

Immediately after this discovery, a large number of studies were launched to find out the nature of this radiation. Röntgen tried to find analogies between this kind of radiation and visible light, which lead him to conduct unsuccessful experiments that consisted of reflecting X-rays on quartz, or lime. He believed he was observing this reflection on platinum, lead and zinc [RON 95, RON 96b]. He noticed that X-rays, unlike electronic radiation, are not affected by magnetic fields. Röntgen even tried, to no avail, to produce interference effects in X-rays by making the X-ray beam pass through holes [RON 95]. The analogy between X-rays and visible light prompted researchers to study how X-rays behave with regard to the well-known laws of optics. Thus, Thomson [THO 96], Imbert and Bertin-Sans [IMB 96], as well as Battelli and Garbasso [BAT 96], showed in 1896 that specular reflection was not possible with X-rays, hence confirming the studies of Röntgen. They also found, in agreement with the works of Sagnac [SAG 97a], that the deviation of X-rays by refraction is either non-existent or extremely small.

Figure 1.The first radiographic observation

In November 1896, Stokes gave a short presentation before the Cambridge Philosophical Society, explaining some of the fundamental properties of X-rays [STO 96]. He claimed that X-rays, like γ-rays, are polarizable. This comment, made in November, did not take into account several studies, even though they had been published in February of the same year by Thompson [THO 96a], who established the absence of polarization in X-rays by having them pass through oriented crystal plates. The polarizable nature of X-rays was conclusively demonstrated in 1905 by Barkla [BAR 05, BAR 06a]. Based on the absence of refraction for X-rays, Stokes described this radiation as vibrations propagating through solid material between the molecules of this material. Finally, by analyzing the absence of interference effects for this radiation, he concluded that either the wavelength of this propagation was too small or the phenomenon was not periodical. The author, who mistakenly believed that the latter hypothesis was the right one, assumed that each “charged molecule” that hit the anode emitted a radiation, the pulsation of which was independent of the pulsations of the radiations emitted by the other molecules.