In crystallography, a disclination is a line defect in which there is compensation of an angular gap. They were first discussed by Vito Volterra in 1907,[1] who provided an analysis of the elastic strains of a wedge disclination. By analogy to dislocations in crystals, the term, disinclination, was first used by Frederick Charles Frank and since then has been modified to its current usage, disclination.[2] They have since been analyzed in some detail particularly by Roland deWit.[3][4]
Disclinations are characterized by an angular vector (called a Frank vector), and the line of the disclination. When the vector and the line are the same they are sometimes called wedge disclinations which are common in fiveling nanoparticles.[5][6] When the Frank vector and the line of the disclination are at right angles they are called twist disclinations. As pointed out by John D. Eshelby there is an intricate connection between disclinations and dislocations,[3][4] with dislocation motion moving the position of a disclination.[7]