Krystalaksene

Krystalaksene, or the crystal axes, are the set of three lattice vectors that define the geometry and orientation of a crystal's unit cell in crystallography. They are labeled a, b, and c and determine both the cell dimensions and the angles between the vectors, denoted α, β, and γ. Together, these axes provide a reference frame for describing directions and planes in the lattice.

In a crystalline lattice, many properties and measurements are described with respect to these axes. Planes are indexed by Miller indices (hkl), while directions are specified by vectors such as [uvw], with intercepts and projections measured along the axes. The axes are chosen to reflect the crystal's symmetry, and the angles between them define the cell's geometry.

Common crystal systems illustrate the variety of krystalaksene: cubic systems have a = b = c and α = β = γ = 90°, while hexagonal systems have a = b ≠ c with γ = 120° and α = β = 90°. Other systems—tetragonal, orthorhombic, monoclinic, and triclinic—have distinct relationships among a, b, c and α, β, γ. The conventional cell and the primitive cell are defined using these axes.

In practice, knowing the crystal axes is essential for X-ray diffraction analysis, materials modeling, and understanding directional properties such as conductivity and refractive indices, which can vary along different crystal directions. The Norwegian term krystalaksene is used in Nordic languages to refer to these axes, reflecting their role as the fundamental coordinate framework in crystallography.