Bulk reduction and oxygen migration in the ceria-based oxides

Cubic solid solutions of general formula Ce1-xMxO2 (M = Zr, Th, Hf) have be en modeled in the range (0 < x < 1) using atomistic simulation methods. The Ce4+/Ce3+ reduction energy in the bulk materials and the activation energy for oxygen migration have been calculated. The Ce4+/Ce3+ reduction energy decreases with increasing M content for M = Zr,Th, the most remarkable effe ct being displayed for IM = Th. An opposite trend is obtained when M = Hf. The activation energy for oxygen migration decreases with increasing M cont ent. The effect of Th is similar to that of Zr and consists of a substantia l decrease of the activation energy at high concentrations. On the other ha nd, the activation energy decreases only slightly when M = Hf.