Unit Cells and Crystals
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How many Bravais lattices are there? Name them.
Seven bravais lattices: Triclinic Monoclinic Orthorhombic Tetragonal Cubic Rhombohedral Hexagonal
How many total systems are there?
14, and that is including things like fcc and bcc
What is BCC and FCC?
BCC: Body centered cubic FCC: Face centered cubic
What is a crystal lattice?
A reptitive layout of unit cells.
What is a unit cell?
The smallest number of atoms that make a unique cell
Can the unit cell be repeated in all three dimensions?
Yes.
What is the coordination number for a cubic unit cell?
6
What is the edge length equation for the cubic unit cell? What is its packing efficients approximately?
2r ~50% packing efficiency
What is the coordination number for a body centered cubic system?
8
What is the edge length equation for the BBC system? What is its packing efficiency approximately?
4r/sqrt(3) ~68% packing efficiency
What is the coordination number for FCC?
12
What is the edge length equation for FCC? What is the packing efficiency?
2r*sqrt(2) About a 75% packing efficiency
Define alloying
The act of mixing metals together.
What determines how “soluble” materials will be when alloying?
How similar each element is to the other.
What do we call poorly soluble materials? Describe them.
Intermetallics. They are limited to specific ratios and rely on defects or vacancies to compensate.
What are highly soluble materials called?
Solid solutions