(1) The close packed structures have both
octahedral and tetrahedral voids. In a ccp structure, there is 1 octahedral
void in the centre of the body and 12 octahedral void on the edges. Each one of
which is common to four other unit cells. Thus, in cubic close packed
structure.
Octahedral voids in the centre of the cube =1
Effective number of octahedral voids located
at the 12 edge of = 12*1/4=3
Total number of octahedral voids = 4
(2) In ccp structure, there are 8
tetrahedral voids. In close packed structure, there are eight spheres in the corners
of the unit cell and each sphere is in contact with three groups giving rise to
eight tetrahedral voids
TETRAHEDRAL VOIDS LOCATION:
(3) Circles labelled T represent the centers of the tetrahedral interstices in the ccp
arrangement of anions. The unit cell "owns" 8 tetrahedral
sites.
OCTAHEDRAL VOIDS LOCATION:
Circles labelled O represent centers of the octahedral interstices in the ccp
arrangement of anions (FCC unit cell). The cell "owns" 4
octahedral sites.
Amazing!!!!
ReplyDeleteJust changed the way i studied solid state!
Those diagrams are really amazing 🤩