1、2019/5/28,材料科学基础,材料科学基础 Fundamental of Materials,Lesson nine,2019/5/28,材料科学基础,3.4 Some Rules Governing the Ionic Compounds,Paulings three rules governing the structure of ionic compounds.1. Anion Coordination polyhedron ruleEach cation is surrounded by an anion polyhedron, the distance between anion
2、 and cation is ror+r-, while the CN depends on r+/r-.,2019/5/28,材料科学基础,ror+r,ror+r stable ionic compound,ror+r there is some covalent bounding,stable,unstable,2019/5/28,材料科学基础,2019/5/28,材料科学基础,2019/5/28,材料科学基础,2. Valence ruleThere is a definite relation between valence and CN.Let S be the strength o
3、f electrostatic bonding between a pair of anion and cation,2019/5/28,材料科学基础,if S1S2S, Then Z (CN)S（CN）（Z+/CN+）,2019/5/28,材料科学基础,3. The anion polyhedron prefer to share apex instead of sharing edges or faces:,2019/5/28,材料科学基础,3.5 Crystal Structure of Ceramic Materials,AB AB2 A2B3 ABO3 AB2O4,. AB type
4、1. NaClr+/r0.54 octahedron CN+6 Z1CN(Z+/CN+)CN1/6 CN6,2019/5/28,材料科学基础,2019/5/28,材料科学基础,2. CsClr+/r0.91 hexahedron CN+8Z1CN(Z+/CN+)CN1/8 CN8,2019/5/28,材料科学基础,3. Zinc blende ( ZnS ),CN 4 CN+ 4,2019/5/28,材料科学基础,2019/5/28,材料科学基础,4. Wurtzite ( ZnS, ZnO ),S(O)1/21/212Zn1/4412,2019/5/28,材料科学基础,. AB2 type1
5、. Fluorspar (CaF2)Li2O Na2O,CN+ 8 CN- 4,2019/5/28,材料科学基础,2019/5/28,材料科学基础,2. Rutile (TiO2),2019/5/28,材料科学基础,. A2B3 type ( ),2019/5/28,材料科学基础,2019/5/28,材料科学基础,. ABO3 type ( BaTiO3, CaTiO3 ),2019/5/28,材料科学基础,2019/5/28,材料科学基础,. AB2O4 type (spinel, MgAl2O4 ),2019/5/28,材料科学基础,Examples and Discussions,2019/5/28,材料科学基础,Exercise,2019/5/28,材料科学基础,Thank you !,9,
