title: DFT Study of the Role of Al3+in the Fast Ion-Conductor Li7-3xAl3+xLa3Zr2O12Garnet.
abstract: We investigate theoretically the site occupancy of Al3+in the fast-ion-conducting cubic-garnet Li7-3xAl3+xLa3Zr2O12(Ia-3d)using density functional theory. By comparing calculated and measured27Al NMR chemical shifts an analysis shows that Al3+prefers the tetrahedrally coordinated 24dsite and a distorted 4-fold coordinated 96hsite. The site energies for Al3+ions, which are slightly displaced from the exact crystallographic sites (i.e., 24dand 96h), are similar leading to a distribution of slightly different local oxygen coordination environments. Thus, broad27Al NMR resonances result reflecting the distribution of different isotropic chemical shifts and quadrupole coupling constants. From an energetic point of view, there is evidence that Al3+could also occupy the 48gsite with its almost regular octahedral coordination sphere. Although this has been reported by neutron powder diffraction, the NMR chemical shift calculated for such an Al3+site has not been observed experimentally.
authors: Department of Materials Research and Physics, University of Salzburg , 5020 Salzburg, Austria.
authors: Daniel
authors: D
authors: Rettenwander
authors: Institute of Materials Chemistry, Vienna University of Technology , 1060 Vienna, Austria.
authors: Peter
authors: P
authors: Blaha
authors: Institute of High Performance Computing, Agency for Science, Technology, and Research (ASTAR), 138632 Singapore.
authors: Robert
authors: R
authors: Laskowski
authors: Institute of Materials Chemistry, Vienna University of Technology , 1060 Vienna, Austria.
authors: Karlheinz
authors: K
authors: Schwarz
authors: Christian Doppler Laboratory for Lithium Batteries, Institute for Chemistry and Technology of Materials, Graz University of Technology , 8010 Graz, Austria.
authors: Patrick
authors: P
authors: Bottke
authors: Christian Doppler Laboratory for Lithium Batteries, Institute for Chemistry and Technology of Materials, Graz University of Technology , 8010 Graz, Austria.
authors: Martin
authors: M
authors: Wilkening
authors: Department of Materials Research and Physics, University of Salzburg , 5020 Salzburg, Austria.
authors: Charles A
authors: CA
authors: Geiger
authors: Department of Materials Research and Physics, University of Salzburg , 5020 Salzburg, Austria.
authors: Georg
authors: G
authors: Amthauer