1. The cause of rotation: Due to constraints, or boundary conditions imposed on the crystal. ll. The rule of rotation:

1. Deformation process of polycrystalline materials Deformation process of industrial material consists of three stages Elastic. which is reversible

Paulings three rules governing the structure of ionic compounds 1. Anion Coordination polyhedron rule Each cation is surrounded by an anion polyhedron, the distance between anion and cation is r=rt tr, while the cn depends on rt/r

1. Sing le crystal ver sus po l crystal 1. For single crystals there is only one type of structure with same orientation Single crystals is characterized by anisotropy 2. Polycrystal consists of a lot of grain, small single crystals, With same structure but different orientations. These small single crystals are called grains. The boundaries between them are called grain boundaries

2.7 Some Important Crystallographic Formulas 1. Zone and zone equation All Planes parellel to common axis [uvw] constitute a (crystal) zone, the [u v w] zone. If (h k l) belongs to zone [u v w], then hukv+=0 2.ifhuk+hw=0,then[uvw] lies in(hk) 3. For cubic crystals, [h (h k)

4. Rule for elongation or reduction of R D All R.D. in the region where K1 and K2 makes an obtuse(acute) angle will increase (reduce) its length after twinning

2.5 Indices of crystal planes and directions I What's crystal planes anddirect ions? The atomic planes anddirections passing through the crystal arecalled(crystal) planes and directionsrespectively

1.2 Atomic bonding Bonding forces and energies FF net force attractive force repulsive force

开环聚合是从本世纪50年代发展起来的。近30年来对它进行 了大量的研究,找到了多种用于开环聚合的引发剂和催化剂,探 索了各种杂环单体的聚合能力和聚合反应机理,并开发了一些新 的高分子材料。目前已经工业化的产品有聚环氧乙烷、聚环氧丙 烷、聚四氢呋喃、聚甲醛、聚己内酰胺等

黄山学院：《草坪科学与管理》第五章 草坪建植（5.2-5.3）营养繁殖种植材料、场地准备