Crystallography: statements about unit cells Evaluate standard statements about unit cells (crystal lattices) and choose the most comprehensive correct option. Which is correct?
Mechanical Engineering
Engineering Materials
Difficulty: Easy
Choose an option
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AContain the smallest number of atoms which, together, exhibit all properties of the crystal
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BHave the same orientation in a crystal and similar faces are parallel
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CCan be defined as the smallest parallelepiped that tiles space to build the lattice
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DAll of the above
Answer
Correct Answer: All of the above
Explanation
ConceptA unit cell is the smallest repeating building block of a crystal lattice. All unit cells in a given single crystal share the same orientation and parallelism of corresponding faces; repeating the unit cell along lattice vectors reconstructs the entire lattice.
Why all true
- (a) Captures the representative nature of the unit cell.
- (b) Unit cells in a single crystal are identically oriented; similar faces are parallel.
- (c) The formal definition: a smallest parallelepiped (the unit cell) that, by translation along three non-coplanar vectors, fills space.
Final AnswerAll of the above