for NaTl, is the unit cell of it based on the repetition of body centered cubic and the holes in this unit cell are octahedral?

octahedral

To determine the unit cell of NaTl, we need to analyze its crystal structure. NaTl is an ionic compound, composed of a sodium ion (Na+) and a thallium ion (Tl-).

The crystal structure of NaTl is based on the repetition of a body-centered cubic (BCC) unit cell. In a BCC structure, each lattice point is situated at the corners and at the center of the cube.

Now, let's consider the positions of the atoms within the BCC unit cell of NaTl. The Na+ ion occupies the body-centered position, while the Tl- ions are located at the eight corners of the cube.

In addition to the atoms at the corners and body center, there are also octahedral holes within the BCC unit cell. Octahedral holes are formed by the coordination of six ions in a regular octahedral arrangement.

In the case of NaTl, the octahedral holes are located at the centers of the six faces of the unit cell. These holes are not occupied by any atoms in NaTl, as they are left empty.

So, to summarize, the unit cell of NaTl is based on the repetition of a body-centered cubic (BCC) structure, and the octahedral holes within this unit cell are left vacant.