文档介绍:材料科学基础 Fundamental of Materials § Space Lattice ?Ⅰ.Crystals versus non-crystals 1. Classification of functional materials Chapter Chapter ⅡⅡ Fundamentals of Crystallography Fundamentals of Crystallography Lesson three Lesson three 2 2 . Classification of materials based on structure . Classification of materials based on structure Regularity in atom arrangement —— periodic or not (amorphous) ? Crystalline: The materials atoms are arranged in a periodic fashion. ? Amorphous: The material ’ s atoms do not have a long-range order ( ~ 1nm). ?? Single crystal: Single crystal: in the form of one crystal grains ?? Polycrystalline: Polycrystalline: grain boundaries ?Ⅱ.Space lattice 1. Definition: Space lattice consists of an array of regularly arranged geometrical points, called lattice points. The (periodic) arrangement of these points describes the regularity of the arrangement of atoms in crystals. 2. 2. Two basic features of lattice points Two basic features of lattice points ①① Periodicity Periodicity : Arranged in a periodic pattern. : Arranged in a periodic pattern. ②② Identity Identity : The surroundings of each point in : The surroundings of each point in the lattice are identical. the lattice are identical. A lattice may be one , two, or three dimensional two dimensions Space lattice is a point array which represents the regularity of atom arrangements (1) (2) (3) a b