EMS162_2011_Lecture6

EMS162_2011_Lecture6 - Close Packed Structures Within the...

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1 1/20/2011 EMS 162 - Winter 2010 1 Yayoi Takamura Close Packed Structures Within the same plane – nearest neighbors : 6 Plane above – nearest neighbors : 3 Plane below – nearest neighbors : 3 1/20/2011 EMS 162 - Winter 2010 2 Yayoi Takamura Close Packed Structures A A B B Stacking order: ABABAB C ABCABC
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2 1/20/2011 EMS 162 - Winter 2010 3 Yayoi Takamura Hexagonal Close Packed (HCP) r A layer a a • Close packed planes with ABAB stacking sequence • Coordination #: 12 a=2r • Atomic packing factor = 0.74 1/20/2011 EMS 162 - Winter 2010 4 Yayoi Takamura Hexagonal Close Packed (HCP) • Many metals – Mg, Zn, Ti, Ru, Re, Be, Cd, Zr, Os, Sm c=1.633a for ideal HCP but many materials have c > 1.633 a • Bravais Lattice: Primitive Hexagonal • # atoms/unit cell = 2 (basis) Principles of Electronic Materials and Devices, Kasap, McGraw Hill A: {0001} B: {0002} A: {0001} Close packed directions 2 atom basis (2/3, 1/3, ½) or (1/3, 2/3, ½)
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3 1/20/2011 EMS 162 - Winter 2010 5 Yayoi Takamura Face Centered Cubic (FCC) Principles of Electronic Materials and Devices, Kasap, McGraw Hill • {111} planes are close packed planes with ABCABC stacking sequence Close packed directions 1/20/2011 EMS 162 - Winter 2010 6 Yayoi Takamura Face Centered Cubic (FCC) • Many metals – Cu, Ni, Ag, Pd, Au, Pt, Al, Pb • Coordination #: 12 • # atoms/unit cell: 4 • Atomic packing factor – 0.74 • Bravais Lattice: FCC 2 4 r a = Structure of Materials, De Graef and McHenry, Cambridge University Press
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This note was uploaded on 04/04/2011 for the course EMS 162 taught by Professor Howitt during the Spring '08 term at UC Davis.

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EMS162_2011_Lecture6 - Close Packed Structures Within the...

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