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31 Cards in this Set
- Front
- Back
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What is a Crystalline material?
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One in which the atoms are situated in a repeating or periodic array over large atomic distances
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What form crystalline structures under normal solidification conditions?
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ALL metals, many ceramics and some polymers form crystalline structures.
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What are materials that do not crystallize called?
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Noncrystalline or amorphous materials.
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Some of the properties of crystalline solids depend on what?
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The crystal structure of the material - manner in which atoms, ions, or molecules are spatially arranged.
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What is a Unit Cell?
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Basic structural unit of crystal structures
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What is Face-Centered Cubic?
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Crystal structure found in some metals where atoms are located at all corner and face-centered positions.
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How many atoms are in a FCC unit cell?
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4 atoms
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What is Atomic Packing Factor?
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The fraction of the volume of a unit cell that is occupied by "hard-sphere" atoms or ions.
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What is Coordination Number?
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The number of atomic or ionic nearest neighbors.
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What is the coordination number for FCC?
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12
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What is the formula for APF?
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Volume of atoms in a unit cell over total unit cell volume
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What is the normal APF for FCC?
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0.74
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What is Body-Centered Cubic?
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Crystal structure found in some metals where atoms are located at each corner and cell center positions.
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In FCC, a is equal to what?
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a = 2Rsqr(2)
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In BCC, a is equal to what?
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a = (4R)/sqr(3)
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How many atoms are in a unit cell of BCC?
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2 atoms
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What is the coordination number for BCC?
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8
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What is the APF for BCC?
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0.68
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What is the Hexagonal Close-Packed?
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Crystal structure found in some metals where unit cell is of hexagonal geometry and generated by stacking close-packed planes of atoms.
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How many atoms in HCP?
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6 atoms
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What is the Coordination number for HCP?
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12
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What is the APF for HCP?
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0.74
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List some metals that are HCP.
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Cadmium, magnesium, titanium, and zinc
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List some metals that are BCC.
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Chromium, Iron, Molybdenum, Tungsten
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List some metals that are FCC.
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Aluminum, Copper, Lead, Nickel, Silver, Platinum
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What are Cations?
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Metal ions with positive charge
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What are Anions?
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Non-metalic ions with negative charge
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What two things influence ceramic crystal structure?
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Magnitude and relative size of each component ion
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Ceramic crystals must be what in terms of charge?
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Neutral!
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In Ceramic Crystal structure, what is the most stable structure?
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When anions surrounding cation are all in contact with the cation.
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In Ceramic Crystal structure, coordination number is related to what?
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The ratio of cation to anion radii.
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