What is a tetrahedral site in a closest-packed lattice formed by?

Verified step by step guidance

1. Understand that a closest-packed lattice refers to the arrangement of atoms in a crystal structure where they are packed as closely as possible.
2. Recognize that in a closest-packed structure, there are two main types of interstitial sites: tetrahedral and octahedral.
3. A tetrahedral site is formed when four atoms are arranged in a tetrahedron, creating a small space or void in the center.
4. Visualize that in a face-centered cubic (FCC) or hexagonal close-packed (HCP) lattice, the tetrahedral sites are located between the layers of atoms.
5. Remember that these sites are important because they can be occupied by smaller atoms or ions, influencing the properties of the material.

Key Concepts

Closest-Packed Lattice

A closest-packed lattice is a type of crystal structure where atoms are packed together as closely as possible, maximizing density. The two most common arrangements are face-centered cubic (FCC) and hexagonal close-packed (HCP). In these structures, atoms occupy specific positions that minimize empty space, leading to efficient packing and stability.

Tetrahedral Coordination

Tetrahedral coordination refers to a geometric arrangement where a central atom is surrounded by four other atoms at the corners of a tetrahedron. In a closest-packed lattice, tetrahedral sites are formed when four atoms from the lattice surround a central atom, allowing for specific bonding and spatial arrangements that influence the properties of the material.

Interstices in Crystal Structures

Interstices are the small spaces or voids between atoms in a crystal lattice. In closest-packed structures, there are two main types of interstitial sites: octahedral and tetrahedral. Tetrahedral sites specifically accommodate smaller atoms or ions, which can fit into these voids without disrupting the overall lattice structure, playing a crucial role in the properties of alloys and compounds.