Local Structure from Diffraction


Book Description

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up-to-date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M.F. Thorpe, Series Editor E-mail: thorpe @ pa.msu.edu East Lansing, Michigan PREFACE One of the most challenging problems in the study of structure is to characterize the atomic short-range order in materials. Long-range order can be determined with a high degree of accuracy by analyzing Bragg peak positions and intensities in data from single crystals or powders. However, information about short-range order is contained in the diffuse scattering intensity. This is difficult to analyze because it is low in absolute intensity (though the integrated intensity may be significant) and widely spread in reciprocal space.







Underneath the Bragg Peaks


Book Description

Table of contents




EXAFS: Basic Principles and Data Analysis


Book Description

The phenomenon of Extended X-Ray Absorption Fine Structure (EXAFS) has been known for some time and was first treated theoretically by Kronig in the 1930s. Recent developments, initiated by Sayers, Stern, and Lytle in the early 1970s, have led to the recognition of the structural content of this technique. At the same time, the availability of synchrotron radiation has greatly improved both the acquisition and the quality of the EXAFS data over those obtainable from conventional X-ray sources. Such developments have established EXAFS as a powerful tool for structure studies. EXAFS has been successfully applied to a wide range of significant scientific and technological systems in many diverse fields such as inorganic chemistry, biochemistry, catalysis, material sciences, etc. It is extremely useful for systems where single-crystal diffraction techniques are not readily applicable (e.g., gas, liquid, solution, amorphous and polycrystalline solids, surfaces, polymer, etc.). Despite the fact that the EXAFS technique and applications have matured tremendously over the past decade or so, no introductory textbook exists. EXAFS: Basic Principles and Data Analysis represents my modest attempt to fill such a gap. In this book, I aim to introduce the subject matter to the novice and to help alleviate the confusion in EXAFS data analysis, which, although becoming more and more routine, is still a rather tricky endeavor and may, at times, discourage the beginners.




Charge Density and Structural Characterization of Thermoelectric Materials


Book Description

Thermoelectric materials permit the direct conversion of temperature differences into electric energy, and vice versa. They are therefore of highest technological interest in applications such as solid state coolers, waste heat recovery, sensors and detectors, and power generators including remote power generation. Thermoelectric materials are often called “environmentally green”, and for good reasons. Not only can they help generate electrical energy from waste gases as they are generated in such processes as home heating, industrial fabrication and automotive motion. In cooling applications they eliminate the use of chemical refrigerant gases. Moreover, as thermoelectric conversion devices have no moving parts, they operate silently and have a very long life expectancy. The only current drawback of these devices is their poor efficiency. Scientists all over the world are therefore studying the structural, thermoelectric, charge-density and magnetic properties of the most promising types of these materials at the atomic and electronic level. In addition to providing an introduction to the field, the main objective of this book is to present the results of the growth and structural characterization of thermoelectric materials that are of high current interest; including Mg2Si, PbTe, Bi1-xSbx, Bi2Te3, Sb2Te3, Sn1-xGexTe and InSb.




Physics of Manganites


Book Description

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involves chemistry, physics, materials science and engineering, with length scales ranging from Ångstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up to date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M. F. Thorpe, Series Editor E mail: thorpe@pa. msu. edu V PREFACE This book records invited lectures given at the workshop on Physics of Manganites, held at Michigan State University, July 26 29, 1998. Doped manganites are an interesting class of compounds that show both metal insulator and ferromagnetic to paramagnetic transitions at the same temperature. This was discovered in the early 1950s by Jonker and van Santen and basic theoretical ideas were developed by Zener (1951), Anderson and Hasegawa (1955), and deGennes (1960) to explain these transitions and related interesting observations.










Atomic Pair Distribution Function Analysis


Book Description

Since the early 1990s the atomic pair distribution function (PDF) analysis of powder diffraction data has undergone something of a revolution in its ability to do just that: yield important structural information beyond the average crystal structure of a material. With the advent of advanced sources, computing and algorithms, it is now useful for studying the structure of nanocrystals, clusters and molecules in solution or otherwise disordered in space, nanoporous materials and things intercalated into them, and to look for local distortions and defects in crystals. It can be used in a time-resolved way to study structural changes taking place during synthesis and in operating devices, and to map heterogeneous systems. Although the experiments are somewhat straightforward, there can be a gap in knowledge when trying to use PDF to extract structural information by modelling. This book addresses this gap and guides the reader through a series of real life worked examples that gradually increase in complexity so the reader can have the independence and confidence to apply PDF methods to their own research and answer their own scientific questions. The book is intended for graduate students and other research scientists who are new to PDF and want to use the methods but are unsure how to take the next steps to get started.




International Tables for Crystallography, Volume I


Book Description

X-ray absorption spectroscopy and X-ray emission spectroscopy are complementary to crystallographic methods, particularly for materials science and the study of nanostructure and systems with partial disorder and partial local order, including solutions, gases, liquids, glasses and powders. This new volume of International Tables for Crystallography has nine parts and over 150 chapters contributed by a wide range of international experts. Part 1 provides a brief overview and introduction to the background of X-ray absorption spectroscopy (XAS) and experimental facilities. Part 2 discusses the quantum theory of XAS and related approaches. Part 3 describes both standard and advanced experimental methods used in XAS, X-ray emission spectroscopy (XES) and related techniques. Part 4 covers both standard and more advanced pre-processing of data. Part 5 gives an extensive overview of the analysis of experimental data. Part 6 provides details of the major software packages for data collection, reduction and analysis. Part 7 outlines the importance in science, reporting and hypothesis testing of the exchange of input and processed output data, and data deposition. It also presents excerpts of tables of data and supplementary material for XAS, pre-edge studies, X-ray absorption near-edge spectroscopy (XANES) and X-ray absorption fine structure (XAFS) studies. These tables are also available in full as online supporting information. Part 8 explores a wide range of applications of XAS in fields including materials science, physics, chemistry, biology, earth sciences, catalysis and cultural heritage. Part 9 presents definitions of the terms and quantities used, as developed by the International Union of Crystallography's Commission on XAFS. The volume has been written for the worldwide XAS community of thousands of practitioners, beamline scientists, experts and academics, and for the novice user who wishes to know what XAS and XES can do for them and how they may use these techniques for their particular purposes. The volume is therefore intended to be a self-contained, authoritative reference work that can also be used for training, learning or teaching, providing practical guidance for readers of all levels of experience. More information on the volumes in the series International Tables for Crystallography can be found at https://it.iucr.org.