What is Structure types?

Example 6.7 (Sodium chloride and caesium chloride)

Sodium chloride has $a = 564.1\,\mathrm{pm}$: $r_+ + r_- = a/2 = 282.0\,\mathrm{pm}$, against $102 + 181 = 283\,\mathrm{pm}$ from the Shannon radii; $x = 102/181 = 0.56$, in the octahedral range. Its density is $\rho = 4 \times 58.44/(6.022 \times 10^{23} \times (5.641 \times 10^{-8})^3) = 2.16\,\mathrm{g}/\mathrm{cm}^{3}$, measured $2.17\,\mathrm{g}/\mathrm{cm}^{3}$. Caesium chloride has $a = 412.3\,\mathrm{pm}$: $r_+ + r_- = a\sqrt3/2 = 357.1\,\mathrm{pm}$, and $x = 174/181 = 0.96$, in the cubic range.

Example 6.9 (Zinc blende and fluorite)

Zinc blende has $a = 540.9\,\mathrm{pm}$: $r_+ + r_- = a\sqrt3/4 = 234.2\,\mathrm{pm}$ (Shannon: $60 + 184 = 244\,\mathrm{pm}$, the sulfide radius being tabulated only for six neighbours), and $x = 60/184 = 0.33$, in the tetrahedral range. Fluorite has $a = 546.3\,\mathrm{pm}$: $r_+ + r_- = 236.6\,\mathrm{pm}$ (Shannon $112 + 131 = 243\,\mathrm{pm}$), and $x = 0.85$: the cation sits in a cube of 8 anions, as the rule demands.