Diffraction and the X-Ray Powder Diffractometer

Abstract

Materials are made of atoms. Knowledge of how atoms are arranged into crystal structures and microstructures is the foundation on which we build our understanding of the synthesis, structure and properties of materials. There are many techniques for measuring chemical compositions of materials, and methods based on inner-shell electron spectroscopies are covered in this book. The larger emphasis of the book is on measuring spatial arrangements of atoms in the range from 10⁻⁸ to 10⁻⁴ cm, bridging from the unit cell of the crystal to the microstructure of the material. There are many different methods for for measuring structure across this wide range of distances, but the more powerful experimental techniques involve diffraction. To date, most of our knowledge about the spatial arrangements of atoms in materials has been gained from diffraction experiments. In a diffraction experiment, an incident wave is directed into a material and a detector is typically moved about to record the directions and intensities of the outgoing diffracted waves.