X-rays produce a diffraction pattern because their wavelength is typically the same order of magnitude ( 0.1-10.0 nm ) as the spacing between the atomic planes in the crystal.
12.
The screw dislocation is more difficult to visualise, but basically comprises a structure in which a helical path is traced around the linear defect ( dislocation line ) by the atomic planes of atoms in the crystal lattice.
13.
Face-centered cubic ( fcc ) structures differ from hexagonal close packed ( hcp ) structures only in stacking order : both structures have close-packed atomic planes with sixfold symmetry the atoms form equilateral triangles.
14.
A simplistic attempt to calculate the shear stress at which neighbouring atomic planes " slip " over each other in a perfect crystal suggests that, for a material with shear modulus " G ", shear strength ? " m " is given approximately by:
15.
Geim defined " isolated or free-standing graphene " as " graphene is a single atomic plane of graphite, which and this is essential is sufficiently isolated from its environment to be considered free-standing . " This definition is narrower than the IUPAC definition and refers to cloven, transferred, and suspended graphene.
