Crystal structure

seminar on crystal structure

1. DR. HARI SINGH GOUR VISHWAVIDYALAYA SAGAR,M.P. ( A CENTRAL UNIVERSITY) SEMINAR ON – CRYSTAL STRUCTURE UNDER SUPERVISION OF PROF. R.K. TRIVEDI PRESENTED BY- MADHUSMITA SETHY REG- Y18251015 1 ST SEMESTER

2. CONTENTS INTRODUCTION UNIT CELL LATTICE BASIS CRYSTAL STRUCTURE CRYSTAL SYSTEM X- RAY DIFFERACTION PAULINGS RULES POLYMORPHISM SIGNIFICANCE REFERANCE

3. INTRODUCTION Crystal are solid composed of atoms, ions , or molecules that periodic in three dimension. It has regular geometry form- physio -chemical condition , slow cooling. These are polyhedral bodies. Crystals are made of small basic building block. All crystal system are classified into six major crystal system, namely Isometric, Tetragonal, Hexagonal, Orthorhombic, Monoclinic , and Triclinic system.

4. Unit cell The basic building block of crystal. It repeat itself by translation through the crystal. The most common type of unit cell are Face centered cube (FCC) Body centered cube (BCC) Hexagonal close packing(HCP)

5. LATTICE An infinite periodic array of points in a space. A lattice may be one,two , or three dimensional. The arrangement of points defines the lattice symmetry. Auguste Bravais demonstrated 3-dimensional system there are fourteen possible lattice.

6. BRAVAIS LATTICE

7. MOTIFS A Group of one or more atoms, located in a particular way with respect to each other and associated with each point, is known as the Motifs or basis.

8. CRYSTAL STRUCTURE Crystal structure =Crystal lattice + Basis So we can say that, When an atom or identical group of atoms is attached to every lattice point, we obtain a crystal structure.

9. Crystals are classified into two types Poly crystal- Periodicity is not maintained throughout the body. Single crystal- Periodicity is maintained throughout the body.

10. STRUCTURE OF NaCl

11. METALLIC CRYSTAL STRUCTURE AND POLYCRYSTALS

12. THE MOST IMPORTANT CRYSTAL STRUCTURES Cesium Chloride structure Hexagonal closed packed structure Diamond structure Zinc Blend

13. DIAMOND STRUCTURE ZINC BLENDE STRUCTURE HEXAGONAL CLOSE PACKING STRUCTURE

14. PAULINGS RULE First rule-Radius Ratio Principle Second rule-Electrostatic Valency Principle Third rule-Sharing polyhedra Fourth rule-Small cation with high charge do not share anion easily with other cation . Fifth rule-Principle of parsimony.

15. POLYMORPHISM It is the ability of a solid material to exist in more than one form or crystal structure. Different type of polymorphism are Packing polymorphism Conformational polymorphism Pseudo polymorphism

16. SIGNIFICANCE OF CRYSTAL STRUCTURE Difference between two mineral. It has a great importance in Biology. It also helpful determining the element in a mineral. It tells about the bonding between atoms.

17. Reference Askeland R. Donald, The science and engineering of materials, Publisher : Bill Stenquist , fourth edition Nesse D. William, Introduction to Mineralogy, Publication: Oxford University Press, 2 nd edition Perkins Dexter, Mineralogy, Publication: Pearson, 3 rd edition Google images