Review of Crystallography 1 Crystal basics m 1 Crvstal basic 1. Crystal ■2 Symmetry 2. Fundamental Characteristics of Crystals 3 Crystal Structure Analysis n 4 Crystal Chemistry E 5 Some Important Crystal Structures Why Solids? Early Ideas 6 ALL Compounds are solids under suitable nditions of temperature and pressure. Many exist o Crystals are solid -but solids are not necessarily crystalline o Crystals have symmetry(Kepler, 1611) and long o atoms in -fixed position range order I"simple"case- crystalline solid= Crystal Structure apes can be pa ked produce regular shapes (Hooke; Hauy, 1812) Why study crystal structures o description of solid n with other similar materials- 费 o correlation with physical properties Crystallinity Definition-Crvstal aA crystal may be defined as a collection of ator arranged in a pattern that is periodie in 3D. Crystals- A homogenous solid formed by a rily solids, but not all solids ar repeating, threedimensional pattern of crystalline(amorphous solids lack long range periodic atoms, Ions, or 1 molecules and having fixed order distances between constituent parts In a perfect single crystal, all atoms in the crystal are related either through translational symmetry or point symmetry POlycrystalline materials are made up of a great number of tiny ( m to nm) single crystals &Crystalline solids can be divided into two categorie extended and molecular1 Review of Crystallography 1 Crystal Basics 2 Symmetry 3 Crystal Structure Analysis 4 Crystal Chemistry 5 Some Important Crystal Structures 1 Crystal Basics 1.Crystal 2.Fundamental Characteristics of Crystals Why Solids? µ ALL Compounds are solids under suitable conditions of temperature and pressure. Many exist only as solids. µ atoms in ~fixed position “simple”case ¾ crystalline solid Þ Crystal Structure Why study crystal structures? µ description of solid µ comparison with other similar materials ¾ classification µ correlation with physical properties Early Ideas Crystals are solid ¾ but solids are not necessarily crystalline Crystals have symmetry (Kepler, 1611) and long range order Spheres and small shapes can be packed to produce regular shapes (Hooke; Hauy,1812) ? Definition ¾ Crystal Crystals ¾ A homogenous solid formed by a repeating, three-dimensional pattern of atoms, ions, or molecules and having fixed distances between constituent parts. Crystallinity A crystal may be defined as a collection of atoms arranged in a pattern that is periodic in 3D. Crystals are necessarily solids, but not all solids are crystalline (amorphous solids lack long range periodic order). In a perfect single crystal, all atoms in the crystal are related either through translational symmetry or point symmetry. Polycrystalline materials are made up of a great number of tiny (mm to nm) single crystals Crystalline solids can be divided into two categories extended and molecular