SectionDStructureandBondinginSolids精编.ppt

Section D Structure and Bonding in Solids D1 Introduction to solids Words crystalline solids [5kristElain, 5sClid] 结晶固体 unit cell 晶胞 non-crystalline solids 非晶态固体 long-range order 长程有序 short-range order 短程有序 Metastable [7metE5steibl] 亚稳的 Rocksalt [`rCksC:lt] 岩盐 Polymorphism [7pCli5mC:fizEm]同质多晶 brookite [5brukait] 板钛矿 rutile [`rU:tail, -ti:l] 金红石 anatase [7AnE5teiz] 锐钛矿 perspective view [pE5spektiv] 透视图 clinographic projection [klainE5^rAfik, prE5dVekFEn] 斜射投影图 stoichiometry [7stCiki5Cmitri] 化学计量比 defect [di5fekt] 缺陷 vacancy [5veikEnsi] 空位 interstitial [7intE(:)5stiFEl] 间隙 nonstoichometry 非化学计量比 Crystals and glasses Anatase crystals——Tetragonal Rutile structure——Tetragonal Brookite——orthorhombic Unit cell Determining the Number of Lattice Points in Cubic Crystal Systems Determining the Relationship between Atomic Radius and Lattice Parameters Determine the relationship between the atomic radius and the lattice parameter in SC, BCC, and FCC structures when one atom is located at each lattice point. Calculating the Packing Factor Calculating the Packing Factor Determining the Density of BCC Iron Determine the density of BCC iron, which has a lattice parameter of 0.2866 nm. Example 3.4 SOLUTION Atoms/cell = 2, a0 = 0.2866 nm = 2.866 ? 10-8 cm Atomic mass = 55.847 g/mol Volume of unit cell = = (2.866 ? 10-8 cm)3 = 23.54 ? 10-24 cm3/cell Avogadro’s number NA = 6.02 ? 1023 atoms/mol Defects Vacanies: atoms missing from their expected sites Interstitials: extra atoms in sites normally vacant in the unit cell Substitution: partial replacement of one element by another in a crystal Nonstoichiometry A nearby pair of a vacancy and an interstitial is often called a Frenkel defect or Frenkel pair. This is caused when an ion moves into an interstitial site and creates a vacancy A vacancy (or pair of vacancies in an ionic solid) is sometimes called a Schottky defect. D2 Element strucutre Words close-packed structure 最紧密堆积 hexagonal close packing (hcp)