Helium defectoscopy of cerium gadolinium ceramics Ce0.8Gd0.2O1.9with a submicrocrystalline structure in the impurity disorder region

Abstract

The concentration of impurity anion vacancies formed upon the dissociation of gadolinium-vacancy complexes has been determined using helium defectoscopy of the cerium gadolinium ceramics Ce0.8Gd0.2O1.9with a submicrocrystalline structure in the temperature range T = 740-1123 K and at saturation pressures ranging from 0.05 to 15 MPa. It has been found that the energy of dissociation of gadoliniumvacancy complexes is Eeff D= 0.26 ± 0.06 eV, and the energy of dissolution of helium in anion vacancies in the impurity disorder region is EP= -0.31 ± 0.09 eV. The proposed mechanism of dissolution has been confirmed by the investigation of the electrical conductivity of the cerium gadolinium ceramics, as well as by the high-speed molecular dynamics simulation of the dissociation of gadolinium-vacancy complexes. It has been assumed that a decrease in the effective dissolution energy in comparison with the results of the previously performed low-temperature investigations is caused by the mutual repulsion of vacancies formed upon the dissociation of gadolinium-vacancy complexes in highly concentrated solutions of gadolinium in CeO2with increasing temperature. © 2013 Pleiades Publishing, Ltd.