Sage-Tips

What percentage of octahedral voids is occupied by Aluminium ions?

In corundum oxide, ions are arranged in HCP array and the aluminum ions occupy two-thirds of octahedral voids.

How many octahedral voids are there in HCP?

So there are 4 tetrahedral voids and two octahedral voids per primitive unit cell of the HCP structure.

What percentage of octahedral voids are occupied?

It is quite clear from the above explanation that all the octahedral voids are occupied by Na+ ions in the rock salt structure. Therefore, the percentage of the octahedral voids occupied by cations in the rock salt structure would be 100\%.

How many octahedral voids are present in HCP hexagonal cubic close packing?

A.In a one-unit cell there are 12 octahedral voids and all are completely inside the unit cell.

How many Aluminium ions are present per unit cell of corundum?

Corundum crystallises with trigonal symmetry and each unit cell contains 6 formula units. each formula unit has 2 Al3+ ions. Hence, each unit cell has 12 Al3+ ions.

How many aluminum ions are present per unit cell of corundum Al2O3?

12 Al ions
Thus in such structure there are 6 formula units of Al2O3 and thus in one unit cell there are 12 Al ions and 18 oxide ions.

How many voids are occupied in nacl?

four times the number of tetrahedral voids.

How many tetrahedral voids are occupied by Zn ion in ZNS zinc blende structure?

In zinc blende structure, zinc ions occupy half of the tetrahedral sites. Each of the ions is 4 – coordinate and has local geometry. 1/2 of the tetrahedral sites that are four of the eight octants of the cube occupied by $Z{n^{2 + }}$ so therefore option A and option D both are the correct ones.

How many octahedral voids are occupied in diamond?

So, the correct option is B. And coordination number on octahedral void is 8.

How many octahedral and tetrahedral voids are there in HCP?

Total number of tetrahedral and octahedral voids in hcp arrangment are 12/18.

How many octahedral voids are there in a BCC cell?

The voids at the edge centres are shared by 4 cubes. There are 12 edges. So the effective number of voids (at the edges) per cube is 12 / 4 = 3. So the number of irregular octahedral voids per cell is 3 (at faces)+3 (at edges) = 6 per cell. Since a BCC unit cell has 2 atoms per cell, the number of octahedral voids per atom is 6/2=3 per atom.

How many octahedral and tetrahedral voids are present in 4 oxide ions?

If there are 4 oxide ions, there will be 1 Mg2+ ions and 2 Al3+. But if the 4 O2– ions are ccp in arrangement, there will be 4 octahedral and 8 tetrahedral voids. Please log in or register to add a comment.

What is the whole number ratio of oxide and aluminium in corundum?

In a close packing (hcp) or (ccp) there is one octahedral void corresponding to each atom constituting the close packing. In corrundum only two thirds of octahedral voids are occupied. It means that corresponding to each oxide ion there are 2 ∕3 aluminium ions. The whole number ratio of oxide and aluminium ion in corundum is, therefore 3:2.

What is the formula of corundum in CCP?

In ccp or hcp packing there is one octahedral void corresponding to each atom constituting the close packing. In corundum only 2/3 rd of the octahedral voids are occupied. It means corresponding to each oxide are 2/3 aluminium ions. The whole number ratio of oxide and aluminium ion in corundum is therefore 3:2 Hence formula of corundum is Al 2 O 3