Crystalline Structures

Bravais lattices

Bravais Lattices are the basic patterns that describe how points can be arranged in space to form a crystal lattice. Named after Auguste Bravais, who studied them in 1848, there are 14 unique Bravais lattices, each representing a distinct way to repeat a pattern in three dimensions. These lattices are grouped into seven crystal systems: cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, and triclinic. Each lattice is defined by its symmetry and how it repeats in space, forming the backbone of all crystalline materials. Understanding Bravais lattices is important because they help explain how atoms are arranged in crystals and how this arrangement affects a material's properties like strength, conductivity, and optical behavior.

The main types of configurations that a Bravais lattice can take are: Primitive, Body-Centered Cubic (BCC), and Face-Centered Cubic (FCC). These configurations describe how atoms are arranged within a unit cell and are essential for understanding the structure and properties of crystalline materials. Primitive is the weakest of the 3 followed by BCC.

Primitive (Simple Cubic):

In this configuration, atoms are located only at the corners of the unit cell. Each corner atom is shared with adjacent unit cells, resulting in one net atom per unit cell. The packing efficiency is low, making this arrangement relatively rare in nature.

Example: Polonium, Caesium Chloride

Body-Centered Cubic

In addition to the corner atoms, there is a single atom located at the center of the unit cell. This arrangement increases the packing efficiency compared to the primitive structure but still leaves some empty space within the lattice.

Example: Iron, Tungsten, Potassium (K)

Face-Centered Cubic=

Atoms are present at each corner and the centers of all the cube faces. This configuration has the highest packing efficiency among the cubic structures (74%), leading to dense and stable crystal arrangements.

Example: Aluminum, Copper, Gold, Salt