Atomic structure of crystals

Solids exhibit an extremely wide range of properties, which is what makes them so useful and indispensable to mankind. While our familiarity with many different types of solids makes this fact seem unimpressive, it is indeed extraordinary when we consider its origin. The origin of all the properties of solids is nothing more than the interaction between electrons in the outer shells of the atoms, the so called valence electrons. These electrons interact among themselves and with the nuclei of the constituent atoms. In this first chapter we will give a general description of these interactions and their relation to the structure and the properties of solids. 

One example is the ability of solids to conduct electricity, which is measured by their electrical resistivity. Some typical single-element metallic solids (such as Ag, Cu, Al), have room-temperature resistivities of l-5pf2-cm, while some metallic alloys (like nichrome) have resistivities of lO p cm. All these solids are considered good conductors of electrical current. Certain single-element solids (like C, Si, Ge) have room-temperature resistivities ranging from 3.5 x lO pS -cm (for graphitic C) to 2.3 x lO V -cm (for Si), and they are considered semimetals or semiconductors. Finally, certain common solids like wood (with a rather complex structure and chemical composition) or quartz (with a rather simple structure and composed of two elements. Si and O), have room-temperature resistivities of lO -lO pS -cm (for wood) to lO p cm (for quartz). These solids are 

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Reflection contrast Reflection-imaging microscopy Field ion microscopy Quantification in gap between light and em microscopies Useful for imaging highly reflective particles such as silver grains in autoradiographs Atomic structure of crystals Immunoelectron Localization of cellular antigens... 

Even Democritus and Epicurus laying down the hypothesis of an atomic structure of bodies, associated hardness with the binding force of atoms. The first attempts at a theoretical interpretation of hardness on the basis of a mathematical analysis of the atomic structure of crystals date back to Bottone (1873), who analysing the interrelation of atomic weights, specific gravities and hardness of metal elements proposed the formula ... 

There are five main types of crystals, and these types have been arranged into seven crystallographic systems based on the crystal interfacial angles and the relative length of its axes. The treatment of the description and arrangement of the atomic structure of crystals is the science of crystallography. The material in this discussion will be limited to a treatment of the growth and production of crystals as a unit operation. 

In addition to its power of directly imaging atomic structures of crystals, H RTEM is often equipped with several other powerful devices for characterization of solids, such as electron diffraction (ED), EDX, electron energy loss spectroscopy (EELS), scanning transmission electron microscopy (STEM) and so on. In this chapter, only the most commonly used supporting techniques for HRTEM, ED and EDX, are discussed in detail. 

Atomic structure of crystals 1.1.4 Atoms with s and d valence electrons... 

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