Defect chemistry and oxygen ion migration in the apatite-type materials La9.33Si6O26 and La8Sr2Si6O26

• DOI: 10.1039/b302748c
• Publication Date: 2003-07-21T11:58:31Z
• Authors: Julian R. Tolchard; M. Saiful Islam; Peter R. Slater
• Keywords: 01 natural sciences; 0104 chemical sciences

Computer modelling techniques have been used to examine the mechanistic features of oxygen ion transport in La8Sr2Si6O26 and La9.33Si6O26 apatite-oxides at atomic level. The potential model reproduces observed complex structures both phases, which are comprised [SiO4] tetrahedral units La/O channels. Defect simulations examined lowest energy interstitial vacancy sites. results suggest that migration is via a mechanism with direct linear path between O5 Interstitial predicted for La9.33Si6O26via non-linear (sinusoidal-like) pathway through La3/O5 channel. demonstrate importance local relaxation tetrahedra assist facile conduction ions. In general, study confirms high ionic conductivity silicate-based apatites (with excess or cation vacancies) mediated by migration.