91Ó°ÊÓ

The metal rhodium (Rh) has an FCC crystal structure. If the angle of diffraction for the (311) set of planes occurs at \(36.12^{\circ}\) (first-order reflection) when monochromatic \(\mathrm{x}\)-radiation having a wavelength of \(0.0711 \mathrm{~nm}\) is used, compute the following: (a) The interplanar spacing for this set of planes (b) The atomic radius for a Rh atom

The metal niobium (Nb) has a BCC crystal structure. If the angle of diffraction for the (211) set of planes occurs at \(75.99^{\circ}\) (first-order reflection) when monochromatic x-radiation having a wavelength of \(0.1659 \mathrm{~nm}\) is used, compute the following: (a) The interplanar spacing for this set of planes (b) The atomic radius for the Nb atom

For which set of crystallographic planes will a first-order diffraction peak occur at a diffraction angle of \(44.53^{\circ}\) for BCC tantalum (Ta) when monochromatic radiation having a wavelength of \(0.1937 \mathrm{~nm}\) is used?

The following table lists diffraction angles for the first four peaks (first- order) of the x-ray diffraction pattern for platinum (Pt), which has an FCC crystal structure; monochromatic \(\mathrm{x}\)-radiation having a wavelength of \(0.0711 \mathrm{~nm}\) was used. (a) Determine the interplanar spacing for each of the peaks. (b) For each peak, determine the atomic radius for \(\mathrm{Pt}\), and compare these with the value presented in Table \(3.1\).

Would you expect a material in which the atomic bonding is predominantly ionic in nature to be more likely or less likely to form a noncrystalline solid upon solidification than a covalent material? Why? (See Section 2.6.)