Materials containing the elements Y, Ba, Cu, and O that are superconductors (electrical resistance equals zero) at temperatures above that of liquid nitrogen were recently discovered. The structures of these materials are based on the perovskite structure. Were they to have the ideal perovskite structure, the superconductor would have the structure shown in pant (a) of the following figure. a. What is the formula of this ideal perovskite material? b. How is this structure related to the perovskite structure shown in Exercise 85? These materials, however, do not act as superconductors unless they are deficient in oxygen. The structure of the actual superconducting phase appears to be that shown in pan (b) of the figure. c. What is the formula of this material?

Interpretation:

The formula of given superconductor and Ideal should be determined and the superconductor structure and perovskite structure are relatively explained.

Concept Introduction:

• In packing of atoms/ions in a crystal structure, they are imagined as spheres. The two major types of close packing of the spheres in the crystal are – hexagonal close packing and cubic close packing.

• Cubic close packing has two types –Face-centered cubic close packing (FCC) and Body – centered cubic close packing (BCC).

• In edge-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 12 edges are having 12 atoms and shared by 4 unites center of the cube is occupied by one atom.

• In the In face-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 6 faces are having 6 atoms and shared by 2 unites, center of the cube is occupied by one atom.

Fig.2

The given ideal Perovskite (a) and superconductor actual structure (b) are recorded as shown above.

To calculate the empirical formula given ideal perovskite material

• One Yttrium atom present in center of the cubic unit

•  Two Barium are present in centers of cubic unite.

• The Copper atom is,

The number of Cu atoms in corners is,                  8 corners×1/8 Cucorner= 1 Cu atomThe number of Cu atoms in edges is,                     8 edges ×1/4 Cuedges= 2 Cu atoms            The total Cu  

Interpretation:

The formula of given superconductor and Ideal should be determined and the superconductor structure and perovskite structure are relatively explained.

Concept Introduction:

• In packing of atoms/ions in a crystal structure, they are imagined as spheres. The two major types of close packing of the spheres in the crystal are – hexagonal close packing and cubic close packing.

• Cubic close packing has two types –Face-centered cubic close packing (FCC) and Body – centered cubic close packing (BCC).

• In edge-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 12 edges are having 12 atoms and shared by 4 unites center of the cube is occupied by one atom.

• In the In face-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 6 faces are having 6 atoms and shared by 2 unites, center of the cube is occupied by one atom.

Interpretation:

The formula of given superconductor and Ideal should be determined and the superconductor structure and perovskite structure are relatively explained.

Concept Introduction:

• In packing of atoms/ions in a crystal structure, they are imagined as spheres. The two major types of close packing of the spheres in the crystal are – hexagonal close packing and cubic close packing.

• Cubic close packing has two types –Face-centered cubic close packing (FCC) and Body – centered cubic close packing (BCC).

• In edge-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 12 edges are having 12 atoms and shared by 4 unites center of the cube is occupied by one atom.

• In the In face-centered cubic unit cell, the eight corners is occupied by single atom and shared by 8 unite calls and the 6 faces are having 6 atoms and shared by 2 unites, center of the cube is occupied by one atom.