Diffraction and the X-Ray Powder Diffractometer
This chapter begins with a general description of diffraction and the structure of materials, starting with Bragg’s law. It discusses how diffraction is used to determine crystal structure, but is also sensitive to disorder in the structure. The creation of x-rays by electron accelerations or ionizations of atoms is presented. Some features of x-ray diffractometers are described, especially x-ray detectors, x-ray tubes, and synchrotrons for generating intense x-ray beams. The angular dependence of x-ray diffraction intensities is derived from geometric considerations of a typical laboratory diffractometer. Finally, some aspects of determining the fractions of different crystallographic phases in a material are presented, and the modern method of Rietveld refinement is discussed.