Effect of substitution (Ta, Al, Ga) on the conductivity of Li7La3Zr2O12

Cubic garnets of composition Li6.75La3Zr1.75Ta0.25O12, Li6.15La3Zr1.75Ta0.25Al0.2O12, and Li6.15La3Zr1.75Ta0.25Ga0.2O12 were prepared from a co-precipitated precursor and consolidated by hot-pressing to a relative density of ∼96–98%. The total Li-ion conductivities at 298 K and activation energies (in parentheses) of Li6.75La3Zr1.75Ta0.25O12, Li6.15La3Zr1.75Ta0.25Al0.2O12 and Li6.15La3Zr1.75Ta0.25Ga0.2O12 were 0.87 mS cm−1 (0.22 eV), 0.37 mS cm−1 (0.30 eV) and 0.41 mS cm−1 (0.27 eV), respectively. The above results suggest that cubic stabilizing substitutions outside of the Li-ion sub-lattice are preferable to obtain faster Li-ion conductivity.

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► We studied the effect of Ta, Al and Ga-substitution on Li7La3Zr2O12.
► The 25 °C total Li-ion conductivity of Li6.75La3Zr1.75Ta0.25O12 was 0.87 mS cm−1.
► Li6.15La3Zr1.75Ta0.25(Al or Ga)0.2O12 had lower Li-ion conductivity.
► Substitutions outside the Li-ion sub-lattice lead to faster Li-ion conductivity.