Fast ionic conduction in cubic hafnium garnet Li7La3Hf2O12
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A new member of the family of garnets with fast lithium ion conduction has been found with the composition Li7La3Hf2O12. The anion arrangement corresponds to the oxygen framework in garnets, e.g., in Ca3Fe2Si3O12. Hafnium is coordinated octahedrally while the lanthanum environment can be described as a distorted cube. Lithium occupies a large number of positions with tetrahedral, trigonal planar, and metaprismatic coordination. Li7La3Hf2O12 shows a lithium bulk ion conductivity of 2.4 × 10−4 Ω−1 cm−1 at room temperature with an activation energy of 0.29 eV.
KeywordsLi-ion batteries Non-aqueous electrolytes Materials preparations Ionic conductivities XRD