Burger’s vector:

It gives the magnitude and direction of dislocation line.

Construction of Burgers vector:

Starting from a point „p‟ move same number of steps left, right, up and down in the clockwise direction.

If the starting point „p‟ and ending point „pl‟ coincide, then the region enclosed in the Burger’s circuit is free from imperfection.

If the starting point and ending point do not coincide i.e. pp l = b. b is the quantity indicating magnitude.

Burgers‟ vector is perpendicular to edge dislocation plane and parallel to screw dislocation plane.

 Surface defects: (two dimensional defects) ,grain, twin, twilt and stacking defects come under surface defects

Volume defects: (three dimensional defects) when group of atoms are missing and cracks arise in the crystal.

Expression for the number of vacancies at any temperature. Or energy of formation of vacancy.