清华大学：《材料科学基础》课程教学资源（PPT课件讲稿）Chapter 2.1 Space Lattice

Chapter Fundamentals of Crystallography §2.1 Space Lattice I Crystals ver sus non-crystals 1. Classification of functional materials Lesson three

§2.1 Space Lattice ◆ Ⅰ.Crystals versus non-crystals 1. Classification of functional materials Chapter Ⅱ Fundamentals of Crystallography Lesson three

Aer C-C composites. SiO2, Amorphous Structural silicon, Al-alloys, Biomedical Superalloys, Steel Zerodur Hydroxyapati Aluminum alloys Titanium alloys, Concrete Stainless steels Fiberglass Shape-memory Plastics, Wood alloys, Plastics, PZT Smart Materials Electronic Materials Ni-Ti shape Classification of Si GaAs, Ge BaTiO3, PZT memory alloys. MR nuids Materials YBa2Cu3O7.r, AL. Cu, W, Conductin Polymer gels polymers Optical E nergy Materials Technology and SiO, GaAs. Environmental UO,, Ni-Cd Zro Glasses, AlO3 Magnet YAG. ITO LiCoO2, Amorphous Si: H Fe. Fe-Si NiZn and MnZn ferrites Co-Pt-Ta-Cr y-Fez0

2 Classification of materials based on structure Regularity in atom arrangement periodic or not (amorphous) H( H (a) 入足 O (c)

2. Classification of materials based on structure Regularity in atom arrangement —— periodic or not (amorphous)

Crystalline: The materials atoms are arranged in a periodic fashion Single crystal: in the form of one crystal grains y Polycrystalline grain boundaries Amorphous: The material's atoms do not have a long-range order (0.1~1nm)

➢ Crystalline: The materials atoms are arranged in a periodic fashion. ➢ Amorphous: The material’s atoms do not have a long-range order (0.1～1nm). ✓ Single crystal: in the form of one crystal grains ✓ Polycrystalline: grain boundaries

8 do P

Hydrogen Dangling atom bond Silicon atom (a) (b) silicon.(b)Crystalline silicon. Note the variation in the inter-atomic distance for amorphous u Figure 3-10 Atomic arrangements in crystalline silicon and amorphous silicon (a)amorpho silicon

◆1. Space attice 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. Two basic features of lattice points O Periodicity: Arranged in a periodic pattern 2 Identity: The surroundings of each point in the lattice are identical

◆ 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. Two basic features of lattice points ① Periodicity: Arranged in a periodic pattern. ② Identity: The surroundings of each point in the lattice are identical

a lattice may be one two, or three dimensional two dimensions b (1) (2) (3) Space lattice is a point array which represents the regularity of atom arrangements

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

Three dimensions Each lattice point has identical surrounding environment

Three dimensions Each lattice point has identical surrounding environment