Crystal Physics

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Crystal Physics

  1. 1. Lattice • Regular , periodical arrangements of points in three dimension. • Lattice point : The points which presents in the lattice
  2. 2. Basis • Group of atom is called as basis
  3. 3. Crystal structure • Lattice + basis = crystal structure • Crystal structure is obtained by arranging the basis in each and every lattice point
  4. 4. Unit cell • Smallest geometric figure , by the repetition of this we get complete crystal structure.
  5. 5. Crystal parameters • The three mutual perpendicular lines OX,OY and OZ. • Inter axial lengths: OA = a , OB = b and OC = c • Inter axial angles: α,β and γ
  6. 6. Crystal system Cubic Orthorhombic Monoclinic Triclinic Hexagonal Rhombohedral Tetragonal
  7. 7. Bravais lattice
  8. 8. Lattice planes
  9. 9. Miller indices
  10. 10. d spacing in cubic lattice a d h2 k2 l2
  11. 11. Calculation of number of atoms per unit cell – Atomic radius – Coordination number – Packing factor for SC , BCC ,FCC and HCP
  12. 12. Simple Cubic structure
  13. 13. Atomic radius(r) • r = a/2
  14. 14. Coordination number (N)
  15. 15. Body Centered Cubic
  16. 16. Number of atoms per unit cell
  17. 17. Coordination number • For BCC the coordination number is 8
  18. 18. Face Centered Cubic
  19. 19. • Atomic radius = a √2 / 4
  20. 20. HCP
  21. 21. Na Cl structure
  22. 22. ZnS Structure
  23. 23. diamond and graphite Structure
  24. 24. Polymorphism and allotropy • Polymorphism is a physical phenomenon where a material may have more than one crystal structure. • A material that shows polymorphism exists in more than one type of space lattice in the solid state. If the change in structure is reversible, then the polymorphic change is known as allotropy. • The prevailing crystal structure depends on both the temperature and the external pressure.
  25. 25. • Allotropes of carbon Diamond and graphite
  26. 26. Crystal defects • Point defect • line defect • surface defect • Burger vector
  27. 27. Point defect
  28. 28. Line defect
  29. 29. Burger vector
  30. 30. Dislocations

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