晶体结构structure of crystal solid概要1.pptxVIP

The Structure of Crystal Solids; 3.1 Introduction CRYSTAL STRUCTURES 3.2 Fundamental Concepts 3.3 Unit Cells 3.4 Metallic Crystal Structures 3.5 Density Computations 3.6 Polymorphism and Allotropy 3.7 Crystal Systems CRYSTALLOGRAPHIC POINTS, DIRECTIONS, AND PLANES 3.8 Point Coordinates 3.9 Crystallographic Directions 3.10 Crystallographic Planes 3.11 Linear and Planar Densities 3.12 Close-Packed Crystal Structures CRYSTALLINE AND NONCRYSTALLINE MATERIALS 3.13 Single Crystals 3.14 Polycrystalline Materials 3.15 Anisotropy 3.16 X-Ray Diffraction: Determination of Crystal Structures 3.17 Noncrystalline Solids Summary;3.1 Introduction;CRYSTAL STRUCTURES 3.2 Fundamental Concepts;3.3 Unit Cells;3.4 Metallic Crystal Structures; Two other important characteristics of a crystal structure are the coordination number and the atomic packing factor (APF).;? APF for a body-centered cubic structure = p/(3?2) = 0.74 (best possible packing of identical spheres);Body–centered cubic（BCC）crystal structure; APF for a body-centered cubic structure = p?3/8 = 0.68;Hexagonal close-packed crystal structure;Close packed crystals;3.5 Density Computations;3.6 Polymorphism and Allotropy;3.7 Crystal Systems;CRYSTAL SYSTEMS;CRYSTALLOGRAPHIC POINTS, DIRECTIONS, AND PLANES; A crystallographic direction is defined as a line between two points, or a vector. The following steps are utilized in the determination of the three directional indices: A vector of convenient length is positioned such that it passes through the origin of the coordinate system. Any vector may be translated throughout the crystal lattice without alteration, if parallelism is maintained. 2. The length of the vector projection on each of the three axes is determined; these are measured in terms of the unit cell dimensions a, b, and c. 3. These three numbers are multiplied or divided by a common factor to reduce them to the smallest integer values. The three indices,