Chapter 4: Imperfections In Solids Flashcards
A deviation from perfection; normally applied to crystalline materials in which there is a deviation from atomic/molecular order and/or continuity
Imperfections
A crystalline defect associated with one or at most, several atomic sites.
Point defect
A one-dimensional defect along a line of atoms/molecules
Linear defects
A two-dimensional defect along a plane or face.
Interfacial defect/boundary
An atom of foreign element present in the structure of a material
Impurity
A normally occupied lattice site from which an atom or ion is missing
Vacancy
A thermal energy constant having the value of 1.38x10^-23 J/atomK (8.62x10^-5 eV/atomK)
Boltzmann’s constant (k)
A host atom or ion positioned on an interstitial lattice site
Self-interstitial
A linear crystalline defect associated with the lattice distortion produced in the vicinity of the end of an extra half-plane of atoms within a crystal. The Burgers vector is perpendicular to the dislocation line.
Edge Dislocation
The line that extends along the end of the extra half-plane of atoms for an edge dislocation and along the center of the spiral of a screw dislocation.
Dislocation Line
A linear crystalline defect associated with the lattice distortion created when normally parallel planes are joined together to form a helical ramp.mThe Burgers vector is parallel to the dislocation line.
Screw Dislocation
A dislocation that has both edge and screw components
Mixed dislocation
A vector that denotes the magnitude and direction of lattice distortion associated with a dislocation.
Burgers vector (b)
CONCEPT CHECK: The surface energy of a single crystal depends on crystallographic orientation. Does this surface energy increase or decrease with an increase in planer density? Why?
A boundary on the surface of a material where surface atoms are not bonded to the maximum number of nearest neighbors
External surface
