Cerium atomization enthalpy

Question 2.3 Assuming lattice energies for CeFs and Cep4 of —4915 and —8391 kJ/mol respectively, and using the same enthalpy of atomization and electron affinity for fluorine as in the lanthanum examples (Section 2.9.1.), calculate A7/f for Cep3 and Cep4. Take an enthalpy of atomization of 398 kJ/mol for cerium (Table 2.6). Use ionization energies from Table 2.2. 

From Eq. (8) it can be seen that the intrinsic defect concentrations will increase with increasing temperature and they will be low for high enthalpies of defect formation. The application of these equations to some specific systems would be illustrative. From thermodynamic measurements on cerium hydride CeH2, it was deduced that the intrinsic defects were anti-Frenkel defects -f Vj) and a value of 3.0 X 10 was computed for K p at 600°C. This compound has the fluorite structure which contains one octahedral interstice per Ce atom. Therefore a = 1. Since the compound is a dihydride, s = 2. Equation (25) then can be written... 

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