Paracrystal
A paracrystal is a kind of partially disordered crystal; wherein some forms of short and medium-range order of the lattice is present, but where long-range ordering (in at least one direction) does not exist. Many real materials are best though of as paracrystals (and not perfect crystals). I.e. in real materials there is often a well-defined local packing, essentially a unit cell, but this packing does not persist indefinitely without some kind of distortion.
In scattering, paracrystal disorder leads to specific kinds of peak broadening and peak shapes.
See Also
- Wikipedia: Paracrystalline
- A.M. Hindeleh and R. Hosemann Paracrystals representing the physical state of matter J. Phys. C: Solid State Phys. 1988, 21, 4155 doi: 10.1088/0022-3719/21/23/004
- Buckley Crist Small-angle x-ray scattering of semicrystalline polymers. I. Review of existing models J. Poly. Sci.: Poly. Phys. 1973, 11 (4), 635-661 doi: 10.1002/pol.1973.180110403
- J. L. Eads and R. P. Millane Diffraction by the ideal paracrystal Acta. Cryst. 2001, A57, 507-517 doi: 10.1107/S0108767301006341
- Richard Welberry Discussion of: Diffraction by the ideal paracrystal
