Ionic conduction mechanism in Ca-doped lanthanum oxychloride

The mechanism of ionic conduction in Ca-doped lanthanum oxychloride (LaOCl) was investigated using first-principles calculations based on density functional theory. The calculations of the point defect formation energies suggest that Cl^- ion vacancies and substituted Ca²⁺ ions at La sites were dominant point defects. Although the migration energy of an O^2- ion is 0.95 eV, the migration energy of a Cl^- ion was calculated to be 0.44 eV, which is consistent with the reported experimental value. These results imply that the main carrier in Ca-doped LaOCl is Cl^- ions and ionic conduction occurs by a Cl^- ion vacancy mechanism.