Today we test the clickers again

We now venture into the world of Metals Metals

Metallic xl Structures 1) Face-Centered Cubic (FCC) 2) Body-Centered Cubic (BCC) 3)Hexagonal Close-Packed (HCP)

FCC Atoms at 8 corners & 6 faces Equivalent of ? whole atoms. Atomic Packing Factor (APF)=.74 Fig. 3.1

FCC Cubic structure STM of Platinum Dept. Kings.edu/chemlab, Property of IBM

A scanning tunneling microscope (STM) is an instrument for imaging surfaces at the atomic level. What’s an STM image?

Atoms…. You are under our control!

1990: IBM scientist Don Eigler used an STM to move single xenon atoms on a nickel surface The engineers moved 35 atoms to spell out "IBM" in a 10 micrometer logo.

FCC examples Lab-grown copper (SEM) 0.3 mm Etched Aluminum (SEM) GoldGalena (Pb ore)

A scanning electron microscope (SEM) produces images by scanning a sample with a focused beam of electrons. Yields topography and composition. What’s an SEM image?

BCC Atoms at 8 corners & 1 in center of cube Equivalent of ? whole atoms APF =.68 Fig. 3.2

BCC Cubic structure STM of Aluminum (100) surface

BCC examples MolybdenumIron

Hexagonal System a 1 = a 2 = a 3 ≠ z  º  º Fig. 3.7

HCP Atoms at 12 corners, 3 in interior, 2 centered on basal planes Equivalent of ? whole atoms (APF)=.74 Fig. 3.3

Hexagonal structure STM of Nickel surface structure. Dept. Kings.edu/chemlab, Property of IBM

Zinc hand sample Hexagonal structure

SEM of Fine Cadmium powder SEM of ZnO nanowires photonik-lac/projekte/zinc-oxide-nanowires-for-photonic- applications/ Hexagonal structure

HCP Examples Titanium crystals Cadmium crystal bar Magnesium (SEM)

Atomic Packing Factors BCC = 0.68 FCC = 0.74 HCP = 0.74

Metallic xl Structures Body-Centered Cubic (BCC) APF = 0.68 Na, Fe, Cr, Mo, W Face-Centered Cubic (FCC) APF = 0.74 Cu, Al, Ag, Au, Pb, Ni, Pt Hexagonal Close-Packed (HCP) APF = 0.74 Ti, Zn, Cd, Co, Mg

Crystallographic Directions Section 3.9

Crystallographic direction A vector between two points in a crystal. Example: y x z Unit cube

And I should know this because….

Helps us communicate about crystals no matter where we are in the world…

A systematic study of symmetric tilt-boundaries in hard-sphere f.c.c. crystals Abstract A new method is developed for the search of mechanically stable configurations of symmetric tilt boundaries in hard sphere f.c.c. crystals. The problem of finding out relative displacements which minimize the total volume of two crystal blocks forming a boundary, is simplified to a problem of positioning a single atom sphere relative to a block which consists of real and “image” atoms; the latter are placed in such a way to reflect the arrangement in the other crystal block. The method (the image atom method) has been applied to the analysis of symmetric coincidence boundaries with [100], [110] and [111] tilt axes with ∑- values 3–103. For the [100] (013)∑5 boundary, the procedure of the analysis is described in detail; the derived structures are compared with those by computer simulation. Numerical data are given in tabulated forms for some boundaries.

Steps for finding Crystallographic Directions

Examples y x z Unit cube x z y y x z y x z

Family of Directions In the same family: Vector 1 Vector 2 y x z Unit cube

Family of Directions: y x z Unit cube 1= [1 1 0] 2 = 3= [1 1 0] 4 = [1 1 0] 5 = [1 1 0]

Structurally equivalent Atomic packing is equivalent Family of Directions:

Structurally equivalent Atomic packing is equivalent Family of Directions:

[a 1 a 2 a 3 z] Vector: [ ] Hexagonal Crystallographic directions

Other Directions [ 1 1 0][ 1 0 2] [ 1 1 1] [ 2 1 1] [ 0 0 1] [ 1 0 1]

Wednesday: Clicker Questions will include finding Crystallographic Planes and Crystallographic Directions Solved Examples posted on Canvas

Section 3.10 Crystallographic Planes: Miller Indices

Steps for finding Crystallographic Planes

Examples z x y

Families of Planes (100) (010) (001) {100}{010} {001}

Family of Planes MI: (X Y Z) Structurally equivalent planes: {X Y Z}

Hexagonal Crystallographic planes: The basal plane

Other Planes: ( 1 2 3) (0 0 1)(0 1 1) (1 1 2) (2 0 1) (1 0 1)

Notation Summary

Solved Examples posted on Canvas: Files>Assignments, Homework, Extra Credit