What are octahedral and tetrahedral sites?
The space between four spheres having a tetrahedral arrangement is called a tetrahedral void or a tetrahedral site. The void formed by the vertices on opposite sides by two equilateral triangles is called octahedron al void or octahedral site.
What is octahedral site in FCC?
An octahedral position for an (interstitial) atom is the space in the interstices between 6 regular atoms that form an octahedra. Four regular atoms are positioned in a plane, the other two are in a symmetrical position just above or below.
How many octahedral sites are in CCP?
In CCP,there are 8 tetrahedral sites and all are present completely inside the unit cell. There are 13 octahedral sites out of which 1 is at the body centre and 12 are at edge centres. Like CCP,another packing is HCP,in which the number of tetrahedral sites that are completely inside one unit cell is x.
What are octahedral holes?
Each of the holes marked with an o touches three atoms in the plane below and three atoms in the plane above the hole. They are called octahedral holes because positive ions that occupy these holes are surrounded by six negative ions arranged toward the corners of an octahedron. Octahedral Holes.
How many octahedral holes are there?
There are 8 tetrahedral holes and 4 octahedral holes in a fcc unit cell.
What is octahedral hole?
Where are the octahedral holes in fcc?
The face-centered cubic unit cell contains a single octahedral hole within itself, but octahedral holes shared with adjacent cells exist at the centers of each edge. Each of these twelve edge-located sites is shared with four adjacent cells, and thus contributes (12 × ¼) = 3 atoms to the cell.
What is an octahedral hole?
How many octahedral holes are in a fcc?
4 octahedral holes
There are 8 tetrahedral holes and 4 octahedral holes in a fcc unit cell.
How many octahedral holes are in a unit cell?
How many octahedral holes are in bcc?
A BCC has 6 octahedral holes and 12 tetrahedral holes. At each face of the bcc, there is one octahedral hole. There is also an octahedral hole on each edge.
How many octahedral holes are in a FCC?
How many octahedral holes are in HCP?
In HCP (hexagonal closed packed structure):- the number of octahedral voids in HCP is 6. Because the total number of atoms in HCP is 6.
How many octahedral voids are in NaCl?
48Twice the number of octahedral voids.
How many tetrahedral and octahedral holes are there?
There are 8 tetrahedral holes and 4 octahedral holes in a fcc unit cell. while the quite small sodium ions occupy all the tetrahedral holes.
How many octahedral holes are in BCC?