Electric Relaxation Studies of Defects and Defect Associates in Dilute Ceria‐Lanthanum Oxide Solid Solutions

Electric modulus formalism was used to study relaxation processes in the 0.75‐mol%‐La 2 O 3 ‐doped CeO 2 system between 387 and 470 K in the frequency range 5 to 10 7 Hz. Two relaxation processes were observed in the isothermal studies: one at low frequencies due to long‐range migration of free oxygen vacancies (process A) and one at high frequencies due to charge reorientation relaxation of (La Ce V o ’defect associates (process B). The relaxation processes were analyzed using a nonexponential decay function (φ(t) = exp[—(t/τ o β] for 0<β1) of the electric field. The activation enthalpy estimated for process A is 0.72 eV and for process B is 0.55 eV.