What is meant by crystal defect?

Crystal defect, imperfection in the regular geometrical arrangement of the atoms in a crystalline solid. These imperfections result from deformation of the solid, rapid cooling from high temperature, or high-energy radiation (X-rays or neutrons) striking the solid.
A.

Why do crystals have defects?

A point defect disturbs the crystal pattern at an isolated site. It is useful to distin- guish intrinsic defects, which can appear in a pure material, from extrinsic defects, which are caused by solute or impurity atoms.
  • What is a stacking fault?

    In crystallography, a stacking fault is a type of defect which characterizes the disordering of crystallographic planes. It is thus considered a planar defect. The most common example of stacking faults is found in close-packed crystal structures.
  • What is the resolved shear stress?

    Critical resolved shear stress (CRSS) is the component of shear stress, resolved in the direction of slip, necessary to initiate slip in a grain.
  • What is a slip direction?

    The slip direction is the direction in which the dislocation moves, which is the direction of the Burgers vector for edge dislocations. During slip, the edge dislocation sweeps out the plane formed by the Burgers vector and the dislocation; this plane is called the slip plane.
B.

What is surface defects in crystals?

Surface defects are the boundaries, or planes, that separate a material into regions, each region having the same crystal structure but different orientations. There are different kinds of surface defects, some of which are described: Material Surface.
  • What is meant by Frenkel defect?

    A Frenkel defect or dislocation defect is a type of defect in crystalline solids wherein an atom is displaced from its lattice position to an interstitial site, creating a vacancy at the original site and an interstitial defect at the new location without any changes in chemical properties.
  • What is volume defects?

    The 3-dimensional defects change the crystal pattern over a finite volume. They include precipitates, which are small volumes of different crystal structure, and also include large voids or inclusions of second-phase particles. 4.2 POINT DEFECTS. A point defect disturbs the crystal pattern at an isolated site.
  • What do you mean by polycrystalline materials?

    A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Polycrystalline or multicrystalline materials, or polycrystals are solids that are composed of many crystallites of varying size and orientation.

Updated: 28th September 2018

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