Part 1 - Crystal fundamentals Flashcards
Which seven crystal systems are there?
Trinclinic, monoclinic, orthorhombic, rhombohedral, tetragonal, hexagonal and cubic
What are the requirements of lattice vectors and shear angles for a triclinic crystal?
That none of the lattice vectors are alike, and that none of the shear angles are alike or 90 degrees.
What are the requirements of lattice vectors and shear angles for a monoclinic crystal?
That the beta and gamma shear angles are 90 degrees.
What are the requirements of lattice vectors and shear angles for a orthorhombic crystal?
That all the lattice vectors are unlike, and the shear angles are all 90 degrees.
What are the requirements of lattice vectors and shear angles for a rhombohedral crystal?
That all the lattice vectors are equal and that all the shear angles are equal, but not 90 degrees (skewed cubic).
What are the requirements of lattice vectors and shear angles for a tetragonal crystal?
That the a and b vectors are identical, with a different c vector. All shear angles are 90 degrees.
What are the requirements of lattice vectors and shear angles for a hexagonal crystal?
That the a and b lattice vectors are alike, with c different. Also, alpha and beta shear angles are 90 and gamma is 120.
What are the requirements of lattice vectors and shear angles for a cubic crystal?
That all lattice vectors are equal, and that all the shear angles are 90 degrees.
What is the difference between morphology and polymorphism?
Morphology: different shapes of the same crystal structure.
Polymorphism: same chemical compound, but different crystal structures.
What are some reasons that the morphology and size can be different for two crystals of the same compound?
- Some crystal faces are inhibited during growth.
- Different growth rates of different crystal faces.
- Twin-crystals, dendritic, spherulitic, and other complicated growth mechanisms.
- Agglomeration
