Question

Calculate the planar densities in ions per square nanometer on the (111) and (110) planes for (a) CoO and (b) ThO2. Ionic radii are Co2+ = 0.082 nm, O2- = 0.132 nm, and Th4+ = 0.110 nm. CoO has NaCl structure, while ThO2 has fluorite structure.

Answer 1

(a) For CoO, if we consider the 2 O − anions to be located at the FCC positions of a cubic unit cell, then the (111) plane contains the equivalent of two anions.

b) If we consider the Th 4+ cations to be located at the FCC positions of a cubic unit cell, and the O 2− anions in the tetrahedral interstitial sites, then the (111) plane contains the equivalent of two cations.