Orthorhombic crystal system

Orthorhombic crystal system is one of the seven crystal systems in crystallography. It is characterized by three mutually perpendicular vectors of unequal lengths. The orthorhombic lattice is distinguished by its orthogonality and differing axis lengths, making it unique among the crystal systems.

Characteristics

In the orthorhombic crystal system, the crystallographic axes are of unequal lengths (a ≠ b ≠ c), and each axis is perpendicular to the other two. This system is described by three vectors, a, b, and c, which define the lattice points in three-dimensional space. The angles between these vectors are all 90 degrees, indicating the orthogonality of the system.

Bravais Lattices

The orthorhombic system is represented by four Bravais lattice types:

• Simple orthorhombic (P)
• Base-centered orthorhombic (C)
• Body-centered orthorhombic (I)
• Face-centered orthorhombic (F)

Each type differs in the distribution of lattice points, affecting the symmetry and physical properties of the crystals formed.

Symmetry

Orthorhombic crystals exhibit less symmetry than cubic or hexagonal crystals but more than monoclinic or triclinic crystals. The symmetry elements present in orthorhombic crystals include a center of symmetry, three mutually perpendicular twofold rotation axes, and mirror planes parallel to each of the crystallographic axes.

Physical Properties

Crystals in the orthorhombic system often display anisotropic properties, meaning their physical properties vary depending on the direction in which they are measured. This anisotropy can affect optical, mechanical, and electrical properties, making orthorhombic crystals important in various applications, including materials science and mineralogy.

Examples

Common minerals that crystallize in the orthorhombic system include olivine, sulfur, and aragonite. These minerals have diverse applications, from gemstones to industrial materials.

Applications

Orthorhombic crystals are utilized in many fields, including electronics, where their anisotropic properties can be advantageous. For example, certain orthorhombic materials are used in piezoelectric devices, which convert mechanical stress into electrical signals.

See Also

• Crystallography
• Mineralogy
• Bravais lattice
• Crystal structure