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Materials

Materials. Contributions by: John L. Falconer & Will Medlin Department of Chemical and Biological Engineering University of Colorado Boulder, CO 80309-0424.

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Materials

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  1. Materials Contributions by: John L. Falconer & Will MedlinDepartment of Chemical and Biological EngineeringUniversity of ColoradoBoulder, CO 80309-0424

  2. Sample A is an equimolar physical mixture of Si and Ge. Sample B is a Si0.5Ge0.5 solid solution. Which measurements will be different for the two samples? Elemental analysis and x-ray diffraction X-ray diffraction Absorption spectrum Absorption spectrum and x-ray diffraction Elemental analysis

  3. Below is a 2-dimensional representation of a crystal structure where each circle represents a single atom. Each lattice/unit cell contains ________ atoms. 1 2 3 4

  4. A unit cell of a simple cubic crystal is represented below. If each corner contains an atom, how many atoms are there per unit cell? 1 2 3 4 8

  5. A unit cell of a simple cubic crystal structure is represented below. If each corner contains an atom, what is the coordination number of each atom? 4 6 8 10 12

  6. In a space-filling representation, the unit cell size is limited by the close-packing of spherical atoms, where the surfaces of the atoms are in contact. For a simple cubic unit cell of this type, how are atom center distance, d, and atom radius, r, related? d = r d= 2r d= 3r d= 4r d

  7. A corner atom is part of how many unit cells in this simple cubic structure? 1 2 4 8

  8. In the face-centered cubic (FCC) crystal structure, an atom is on each corner and each side of the unit cell. How many atoms are in the unit cell? 1 2 4 14 None of the above

  9. In a face-center cubic structure, the atoms are close-packed along the face diagonal. What is the coordination number of a metal atom in this structure? 2 4 6 8 12

  10. In the body-centered cubic (BCC) crystal structure, an atom is on each corner and one atom (blue atom) is in the center of the unit cell. How many atoms are in the unit cell? 1 2 4 8 9

  11. In the body-centered cubic (BCC) crystal structure, an atom is on each corner and one atom (blue atom) is in the center of the unit cell. What is the coordination number for each atom? 4 6 8 12

  12. Which crystal structure is body center cubic? C. D.

  13. A zinc sulfide crystal structure is shown. What type of unit cell is defined by just the green sulfide ions? Simple cubic Body-centered cubic Face-centered cubic None of the above

  14. A layer sequence for an FCC metal is shown. A close-packed plane is comprised of six atoms. If atoms 2, 4, 5 are three of the six atoms, which other three atoms are need to define the plane? 11, 13, 14 6, 9, 12 7, 8, 14 6, 9, 10 Z = 0 1 6 2 9 7 5 8 3 4 Z = 1/2 Z = 1 11 10 14 12 13

  15. Which structure is the FCC (110) plane? C A B FCC unit cell

  16. Which structure is the FCC (001) plane? C A B FCC unit cell

  17. Which structure is the FCC (111) plane? C A B FCC unit cell

  18. In a zinc sulfide (ZnS) crystal structure, each zinc ion (blue) sits between four sulfide ions (white). Given a ZnS layer sequence, which sulfide ions surround the indicated zinc ion? 1, 4, 7, 8 1, 3, 4, 7 1, 3, 6, 7 1, 4, 7, 9 1 6 2 7 8 3 9 5 4 Z = 0 Z = 1/4 Z = 3/4 Z = 1/2

  19. How many sulfide ions (green) are in a zinc sulfide unit cell? 1 2 3 4

  20. Vanadium, molybdenum, and sodium all have a body-centered cubic structure. Given the following atomic radii, which two metals are most likely to form a sold solution? Vanadium, molybdenum Vanadium, sodium Molybdenum, sodium

  21. For a two-plane, octahedron arrangement of identical spheres, there will be two differently-sized gaps. One gap will be within the plane, the other gap will be between planes. Which gap will be smaller? Within the plane Between the planes The gaps are the same size Within plane Between planes

  22. When a copper wire is heated, it becomes more malleable because ___________________________. the bonds have been weakened the wire has fewer atomic level defects the wire has more atomic level defects the density is lower there is more space inside the crystal lattice

  23. Atoms in a solid _____________________________. cannot move, only electrons move may move through vacancies in a crystal lattice may move in the spaces between atoms in a crystal lattice can move through both vacancies and in the spaces between atoms in a crystal lattice none of the above

  24. Gallium(Ga) can be mixed with two other elements to form a solution. Possible elements include aluminum(Al), arsenic(As), and phosphate(P). If 0 < x < 1, which gallium alloys could be solid solutions? • GaxAl1-xAs ; GaAlxAs1-x • GaxAl1-xAs ; GaPxAs1-x • GaPxAs1-x ; GaAlxAs1-x • GaPxAs1-x ; GaxP1-xAs

  25. Buckminsterfullerene, C60, is face-centered cubic in crystalline form. If a fullerene was saturated with potassium, by placing a potassum atom in every tetrahedral hole and every octahedral hole, the chemical formula would be ____. KC60 K2C60 K3C60 K4C60 K6C60

  26. How many zinc ions (green) are in a zinc sulfide unit cell? 1 2 3 4

  27. How many atoms are in the following layer sequence of a diamond structure? 4 6 8 13 Z = 0 Z = 1/4 Z = 3/4 Z = 1/2

  28. What is the coordination number for a diamond structure? 4 6 8 10

  29. What is the coordination geometry of a diamond structure? Tetrahedral Square Octahedral Cubic

  30. In the two-dimensional square packing shown below, what is the coordination number of the central atom? 2 4 6 8

  31. Which part of a face-centered cubic crystal surface is likely to chemically etch faster? 111 plane 100 plane Grain boundary Vacancy

  32. A system contains an equimolar vapor/liquid mixture of components A and B. The saturated pressure of A is greater than that of B. If the system is an ideal gas, which plot represents the effect of raising the system pressure on the vapor/liquid fractions of component A? xA 1.0 xA 1.0 1.0 yA xA A. B. C. yA yA 0 0 0 P P P 1.0 1.0 yA xA yA xA Pasat> PBsat E. D. 0 0 P P

  33. A D Temp. E Time Time Time Time Time C B Liquid For this Cu/Ni phase diagram, which cooling curve results for a 50/50 mixture? Temperature Solid 100% Ni 100% Cu 50/50 Temp. Temp. Temp. Temp.

  34. Magnesium and silicon form Mg2Si under certain conditions. What phases and how much of each will be present for a 60 mol% Si mixture at 1000 K? 1 phase that is 57% Si 2 phases; 57% is Mg2Si 2 phases; 40% is Mg2Si 2 phases; 57% is pure Mg 2 phases; 57% is pure Si 1700 Liquid Temperature (K) 800 0 1 Mg Si xSi

  35. A Pt/Ag alloy containing 62% Ag is initially at 1600°C . As it cools, what phases are observed?L represents liquid and α and βare solids. L+α, L+α+β, L+β, β, α+β L+α, L+β, α, α+β L+α, L+α+β, L+β, α+β L+α, L+β, α+β L+α, L+β, β , α+β 1800 L L+α α Temp. (°C) L+β α+β β 0 100 Wt % Ag

  36. Cu/Pb alloys can form several combinations of phases between two liquids (L1 and L2) and alpha (α) and beta (β) solid. Given some of the phases, what phase(s) is/are present at the point indicated? L2+α L1+β L1+L2 α+β L L+ α Temperature α + β 0 100 Wt % Pb

  37. A Si-Mg mixture containing 40 mol% Si at 1000 K (the blue dot in the figure) contains ____________. a single solid phase a mixture of pure Si and pure Mg a mixture of Si and Mg2Si none of the above 1700 Liquid Temperature (K) 800 xSi 0 1 Mg2Si

  38. For the binary phase diagram for components A and B, what fraction of the mixture is liquid at point indicated by the black dot? 30% 45% 50% 55% 70% Liquid Temperature Solid 0 1 Weight frac B

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