5. The energy of formation of defects in PbF, are: anion Frenkel defect, 0.69 eV; cation Frenkel defect, 4.53 eV; Schottky defect, 1.96 eV. (a) What point defects do these consist of? (b) What are approximately) the relative numbers of these defects in a crystal at 300 K? (Data from H. Jiang et al., 2000)