Characterization Methods of Lattice Defects

The lattice defects in nanomaterials can be characterized experimentally using different direct and indirect methods. In the direct methods, such as transmission or scanning electron microscopy (TEM or SEM), the lattice defects are visualized directly on images. The evaluation of electron backscatter diffraction (EBSD) images provides the density and misorientation distribution of grain boundaries, while high resolution TEM may yield the density and Burgers vector of dislocations. In the indirect methods, such as X-ray line profile analysis (XLPA), electrical resistometry (ER) or positron annihilation spectroscopy (PAS), first only a fingerprint of the defect structure—a data series—is obtained and then the parameters of the lattice defects are extracted by analyzing these data. These analyses are usually based on a model of the microstructure. In this chapter, some direct (EBSD and TEM) and indirect (XLPA, ER, and PAS) methods developed for the experimental characterization of the defect structure are overviewed. Special attention is paid to XLPA since the majority of the results presented in this book are obtained by this technique. The most important advantages of this method are (1) the easy sample preparation, (2) its nondestructivity, and (3) the good statistics of the resulted microstructural parameters compared with microscopic methods. A comparison of the different methods is also presented.