Question
Download Solution PDFThe unit cell of a certain type of crystal is defined by three vectors a, b and c. The vectors are mutually perpendicular, but a ≠ b ≠ c. The crystal structure is
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
If the atoms or atom groups in the solid are represented by points and the points are connected, the resulting lattice will consist of an orderly stacking of blocks or unit cells.
- The orthorhombic unit cell is distinguished by three lines called axes of twofold symmetry about which the cell can be rotated by 180° without changing its appearance.
- This characteristic requires that the angles between any two edges of the unit cell be right angles but the edges may be any length.
Important Points
There are 7 types of crystal systems:
|
Crystal System |
Angles between Axis |
Unit Cell Dimensions |
|
Cubic |
α = β = γ = 90° |
a = b = c |
|
Tetragonal |
α = β = γ=90° |
a = b ≠ c |
|
Orthorhombic |
α = β = γ= 90° |
a ≠ b ≠ c |
|
Rhombohedral |
α = β = γ ≠ 90° |
a = b = c |
|
Hexagonal |
α = β = 90°, γ = 120° |
a = b ≠ c |
|
Monoclinic |
α = γ = 90°, β ≠ 90° |
a ≠ b ≠ c |
|
Triclinic |
α ≠ β ≠ γ |
a ≠ b ≠ c |
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