Flash sintering arouses the interest since high-density ceramics can be obtained at shorter dwell times and lower temperatures than conventional sintering. In this study, the cubic garnet Li6.25Al0.25La3Zr2O12 (Al-LLZO) was successfully synthesised by the solid-state method. The powders were uniaxially pressed and were subjected to flash sintering at 850°C in a tube furnace under a DC bias using various current densities. It is evidenced that control of the flash electric current is a crucial factor for densification of Al-LLZO. The sample sintered in 50 V cm−1 and 200 mA mm−2 showed a cubic LLZO, 94 ± 0.4% relative density, 0.37 mS cm−1 total ionic conductivity and 0.32 eV activation energy. In addition, it was demonstrated that increasing the current density had a considerable impact on the relative density. This outstanding ionic conductivity might be due to the lower lithium loss and higher density as a result of flash sintering method applied.
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