Close packed structures with bases

by hokhani
Tags: bases, packed, structures
hokhani is offline
Feb16-13, 05:31 AM
P: 241
Could we have close-packed structures with bases? Or, is it possible in close-packed structures that atoms of bases have arbitrary sizes? For example could we have a fcc close-packed structure with a two-atomic base (of any types of atoms)? If yes, what would happen if sizes of the bases be larger than Octahedral or tetrahedral sites' volumes?
Phys.Org News Partner Physics news on
Chameleon crystals could enable active camouflage (w/ video)
Atomic switcheroo explains origins of thin-film solar cell mystery
X-ray laser experiment explores how specially shocked material gets stronger
M Quack
M Quack is offline
Feb16-13, 08:06 AM
P: 640
FCC is a close-packed structure. Rock salt NaCl crystallizes in a FCC crystal structure with a 2-atom basis.

I guess, though, that the ionic radii are such that the Na ions do not "touch" each other, so the structure is not really close-packed.

A better example may be binary colloidal crystals. The colloidal particels can behave very much like hard spheres. When you mix two different sizes, interesting structures can form, depending on the ratio of the diameters.
DrDu is offline
Feb16-13, 08:50 AM
Sci Advisor
P: 3,376
hexagonal close packing has a two atom base.

Register to reply

Related Discussions
Proof that c/a=RootOf(8/3) for Hexigonal Close Packed (HCP) Atomic, Solid State, Comp. Physics 0
Materials Science: Close packed vs closest packed Chemistry 0
Close Packed Planes and Slip Systems Engineering, Comp Sci, & Technology Homework 1
One-dimensional monatomic chain; square lattice; hcp close packed 2D lattice Advanced Physics Homework 0
Linus Pauling Close-Packed Spheron Model High Energy, Nuclear, Particle Physics 4