Solid State #1 by Sanjay Sharma (a) Amorphous solids (b)
Crystalline solids 4. Solid angle 5. Interfacial angle 6. Zone
and Zone-axis (i) AB type structures The AB2 or A2B type of
ionic crystals contain the ions in the ratio 1:2 or 2 : 1
respectively. For Example : CaF2 populary called to have
fluorite structure with other examples like SrF2, BaF2, PbF2and
BaCl2 etc. The coordination number of Ca++ in CaF2 is 8 while
that of F- is 4. On the contrary Na2O have antifluorite
structure i.e., here the place of cations in occupied by anions
and vice versa. The size of the unit cell and arrangement of
atoms in a crystal is determined with the help of measurement of
differaction of x-rays by the crystal. When a beam of
monochromatic x-ray strikes two planes of atoms in a crystal at
a certain angle Q, It is reflected. The intensity of reflected
beam will be maximum if - In actual practice it is difficult to
grow a perfect crystal. Even single crystals grown with-all care
are found to contain In an ionic crystal, the e