Chp 3: Structure of Crystalline Solids

20 flashcards · Other · by Rob House

  1. Location of dense and random packing in the energy well graph (r_o, E_0)

  2. Name the three structures

    Crystalline , Noncrystalline ( also called Amorphous)

  3. The most common metallic crystal structures are

    FCC, BCC, and HCP

  4. Coordination number and atomic packing factor are the same for both ____ & _____ crystal structures

    FCC and HCP

  5. Noncrystalline

    • atoms have no periodic packing occurs for: - complex structures , - rapid cooling

  6. isotropic vs anisotropic

    hank green video

  7. unit cell

    the basic structural unit of a crystal structure Generally defined in terms of positions of atom within a parallel piped volume shape

  8. lattice

    the regular geometric arrangement of points in crystal space

  9. Metallic Crystal Structures how packed are they & why

    Tend to be densely packed. Reasons for dense packing: - Typically, only one element is present, so all atomic radii are the same. -Metallic bonding is not directional. - Nearest neighbor distances tend to be small in order to lower bond energy. - Electron cloud shields cores from each other. • Metals have the simplest crystal structures.

  10. 3 cubic crystal structures

    SC , BCC , FCC

  11. Atoms per unit cell

    SC =1 BCC =2 FCC=4

  12. Single crystal

    monocrystalline a crystalline solid for which the periodic and repeated atomic pattern extends throughout the entry without interruption

  13. Polycrystal

    crystalline material composed of >_ 2 *something*

  14. What causes density in material classes

    packing density

  15. what structures have the highest packing factor

    TCC and BCC

  16. Select true or false: Low-angle grain boundaries have higher grain boundary energy when compared to that of high-angle grain boundaries.

    false

  17. Polymorphism (or allotropy)

    Two or more distinct crystal structures for the same material

  18. Crystalline

    atoms pack in periodic, 3D arrays typical of -metals, many ceramics, some polymers

  19. Densities of Material Classes

    Metals have... • close-packing (metallic bonding) • often large atomic masses Ceramics have... • less dense packing • often lighter elements Polymers have... • low packing density (often amorphous) • lighter elements (C,H,O)

  20. single crystal vs polycrystal