TY  - JOUR
AU  - Schultze, Tim
AU  - Arnold, John P.
AU  - Grieshammer, Steffen
TI  - Ab Initio Investigation of Migration Mechanisms in La Apatites
JO  - ACS applied energy materials
VL  - 2
IS  - 7
SN  - 2574-0962
CY  - Washington, DC
PB  - ACS Publications
M1  - FZJ-2019-06487
SP  - 4708 - 4717
PY  - 2019
AB  - Lanthanum-apatite structures are promising materials for solid-state electrolytes, exceeding the oxygen ion conductivity of yttria-stabilized zirconia at intermediate temperatures. In recent years, several experimental contributions on La-apatites have been published, however, with divergent results. A comprehensive description of migration in dependence on composition is required to further optimize these materials and to predict the properties of similar structures. In this work, the compositions La9.33Si6O26, La10Si6O27 and La8B2Si6O26 (B = Mg, Ca, Sr, Ba) are investigated by means of density functional theory. Different migration paths are considered, and migration energies are obtained via climbing-image nudged elastic band calculations for both the vacancy and interstitialcy mechanism. Migration inside the highly conductive La-tunnel and in the ab plane between La-tunnels is taken into consideration. Among all investigated B doped compositions, La8Sr2Si6O26 shows a minimum in migration energy along the c-axis for the vacancy and interstitialcy mechanism in agreement with the experimental data. Furthermore, the results indicate that the type of migration mechanism depends on the synthesized composition, while the thermal excitation of defects plays a minor role. From our results, we infer that the activation energy of oxygen ion conductivity is mainly governed by the migration in the ab plane.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000477074700017
DO  - DOI:10.1021/acsaem.9b00226
UR  - https://juser.fz-juelich.de/record/867885
ER  -