# Why does FCC crystalline forms form hexagonal crystalline structures during CVD?

During the CVD process, Copper and Nickel which are both Face Centered Cubic crystalline structures are used as substrates for shaping hexagonal atomic structures such as graphene and hexagonal Boron-Nitride. Why is it that these form hexagonal atomic structures when they themselves aren't hexagonal?

• But they are hexagonal, if you look at them sideways. Dec 29, 2022 at 14:54
• Sorry I dont quite grasp what you mean. Do you have a visual representation? Dec 29, 2022 at 15:01
• Fcc and hcp structures are similar stacking (fcc you need to look along the 111 body diagonal - a classic issue with the cubic conventional cell). Dec 29, 2022 at 15:14
• @AndiIacob for that check my answer to Silver (111) surface structure, and is bulk structure body-center or face-center cubic? Basically the "centered" lattices (fcc, bcc in 3D, centered rectangular in 2D) are contrived to be human friendly; the actual primitive unit cells are much smaller and oblique, and the 3D ones result in horizontal hexagonal planes when the "cubes" are stood up on their corners.
– uhoh
Dec 30, 2022 at 5:03
• @uhoh so this means there are no modifications needed to the substrate correct? Om effect, any FCC could theoretically be used to make hexagonal shapes? And BCC as well? Jan 5, 2023 at 9:54

[Ivan Neretin] But they are hexagonal, if you look at them sideways. –

[OP] Sorry I dont quite grasp what you mean. Do you have a visual representation?

Here is the visual.

[Jon Custer] Fcc and hcp structures are similar stacking (fcc you need to look along the 111 body diagonal - a classic issue with the cubic conventional cell).

Yes, both may be constructed by stacking hexagonal layers, either in an ABABA.. (hexagonal close packing hcp) or an ABCABCA.. (face-centered cubic fcc) fashion.

• Nice visual there! Dec 29, 2022 at 23:53