. The Ca2 and F are located in CaF2 crystal, respectively at body centered cubic lattice points and in

(a)    tetrahedral voids

(b)  half of tetrahedral voids

(c)  octahedral voids

(d)  half of octahedral voids


Best Answer

Answer: (a)

Solution: In CaF2 radius ratio = 0.73

It suggested its crystal structure to be body centered cubic. In this each Ca2+ ion is surrounded by eight F- ions, i.e., co-ordination number is eight and for fluorine it is 4/ In fluorite the Ca2+ ions are too small to touch each other, hence the structure is not strictly close packed structure relative positions of Ca2+ ions are like ions in a cubic close packed structure in which all the tetrahedral holes are occupied by the F- ions.


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