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Solid Structures of Metals

Solid Structures of Metals. Preeti Aghalayam. Building up from basic units Sodalite - > Zeolite. Zeolite A. Sodalite. Zeolite Y. Notice how the placement and bonding between the basic sodalite cages can lead to different symmetries and properties.

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Solid Structures of Metals

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  1. Solid Structures of Metals Preeti Aghalayam

  2. Building up from basic unitsSodalite -> Zeolite Zeolite A Sodalite Zeolite Y Notice how the placement and bonding between the basic sodalite cages can lead to different symmetries and properties (Vining & Auerbach, Personal Communication, 2010)

  3. Common catalyst structures bcc fcc & hcp Do these pictures give you a clue?

  4. Structures of metal catalysts Hexagonal

  5. Catalyst properties • Different metals tend to take different solid structures – hcp, bcc, fcc are common • bcc: Ti, Cr, Fe, W, Mo, V • fcc: Ag, Au, Co, Cu, Ni, Pb, Pt • hcp: Be, Mg, Zn • Today’s task is to understand something about the symmetry in each of these structures; & identify potential catalyst active sites.

  6. Miller Indices (named for British mineralogist William Miller)

  7. Miller indices • Miller indices are a handy way of labelling the various possible intersecting surfaces • The Miller indices (hkl) refer to the (inverse of the) intercepts of the intersecting plane, on the three crystallographic axes: (110) (111) (100) (210) (100), (110) & (111) are the common ‘low-index’ planes

  8. Low index planes in bcc & fcc

  9. Summary • Low index Miller planes for bcc & fcc were identified • Potential ‘adsorption sites’ on each type of plane were examined • Properties can be expected to be different at each of these sites, as surroundings are so different • Tilted closely packed layer of fcc was identified as the fcc(111) plane • Assignment (due Sunday 26th Aug) was announced

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