Estructuras Cristalinas

Crystalline Structures
A crystalline material is one in which the atoms are arranged in a repetitive three dimensional pattern.
If the atoms in a material are not packed in a periodicpattern, it is called amorphous.

Crystalline Material Amorphous

Lattice: is a three dimensional array of points coinciding with atoms.
Lattice systems are a grouping of crystal structures according to the axial system used to describe their lattice. Each lattice system consists of a set of three axes in a particulargeometrical arrangement. There are seven lattice systems. They are similar to but not quite the same as the seven crystal systems and the six crystal families.

1. Triclinic | | | | |
2.Monoclinic | Simple | Base Centered | | |
3. Orthorhombic | Simple | Base Centered | Body Centered | Face Centered |
4. Trigonal | | | | |
5.Tetragonal | Simple | Body Centered | ||
6. Hexagonal | | | | |
7. Cubic | Simple Cubic (SC) | Face Centered ( FCC) | Body Centered (BCC) | |

Crystal characteristics
1. Number of lattice points & atoms per unitcells.
2. Coordination number: number of nearest neighbor atoms.
3. Relation between atomic radius & lattice parameter.
4. APF = Volume of the atomson a unit cell
total unit cell volume

Simple Cube

Perhaps the simplest cubic system is the simple cubic structure. Theunit cell for the simple cubic structure contains one-eighth portions of eight corner atoms to make one complete atom, molecule or ion in each unit cell. Given the radius of the atom or ion theedge length is just; edge length a = 2r where r is the radius of the atom or ion.
a= 2r

*Polonium is the only known metal with simple cube structure

Body Centered Cube

a= 4r...