Burgersvektor

The Burgersvektor, commonly called the Burgers vector, is a key concept in crystallography and materials science that describes the magnitude and direction of lattice distortion produced by a dislocation in a crystal. It is defined using a closed loop, or Burgers circuit, drawn in the deformed crystal. When the circuit is mapped back to the perfect lattice, the net displacement required to close the loop is the Burgers vector.

The Burgers vector is a lattice vector of the crystal and corresponds to the smallest translation that maps the distorted region back to the undistorted lattice. Its magnitude depends on the crystal structure, and its direction relates to the underlying lattice directions. Dislocations can be categorized by the orientation of the Burgers vector relative to the dislocation line: for edge dislocations the Burgers vector is perpendicular to the line, for screw dislocations it is parallel, and for mixed dislocations it forms an angle with the line.

In practice, the Burgers vector serves to classify dislocations and governs the elastic fields around them. It influences material properties such as yield strength, work hardening, and creep. In common crystalline systems, typical Burgers vectors are fractions of the lattice parameter, for example b = a/2 in face-centered cubic crystals along the <110> directions.

The term is named after the Dutch physicist Jan Burgers, who contributed to the theoretical framework of lattice defects. The Burgers vector is fundamental in dislocation theory, continuum elasticity, and computational models of crystal plasticity.