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Unit Cell

Quick Reference
Also Known AsCrystal unit cell, lattice unit cell, repeating unit of crystal, primitive cell

What is Unit Cell?

A unit cell is the smallest repeating structural unit that defines the structure of a crystal lattice. When repeated in three dimensions, unit cells build up the entire crystal. The unit cell is defined by its lattice parameters: edge lengths (a, b, c) and angles (α, β, γ). There are seven crystal systems with different unit cell geometries and 14 Bravais lattices.

Properties & Characteristics

Seven crystal systems: cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, triclinic. Types: simple (P), body-centered (I), face-centered (F), base-centered (C). Atoms per unit cell: corner atoms count 1/8, face atoms 1/2, edge atoms 1/4, body center atom 1. Packing efficiency: FCC/HCP = 74%, BCC = 68%, SC = 52%.

Uses & Applications

Crystal structure determination by X-ray diffraction. Materials science and design. Understanding physical properties (density from unit cell). Crystallography databases. Pharmaceutical polymorphism (different unit cells for same compound). Semiconductor materials design.

Safety Information

Theoretical concept — no direct safety concerns.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Unit Cell
Synonyms Crystal unit cell, lattice unit cell, repeating unit of crystal, primitive cell

Frequently Asked Questions

A unit cell is the smallest repeating structural unit that defines the structure of a crystal lattice. When repeated in three dimensions, unit cells build up the entire crystal. The unit cell is defined by its lattice parameters: edge lengths (a, b, c) and angles (α, β, γ). There are seven crystal systems with different unit cell geometries and 14 Bravais lattices.

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