Calculation of d -spacing and lattice parameters:

For the cubic systems as shown in Figure 4.05, the relation between the lattice constant and d_hkl takes the form

Figure 4.05: Schematic of different cubic systems.

In the tetragonal system, the spacing involves both a and c as they are not generally equal (see Figure 4.06).

Figure 4.06: Schematic of tetragonal system.

Hence, the value of d_hkl takes different form,