Large single-crystal growth of tetragonal garnet-type Li7La3Zr2O12 by melting method

A tetragonal Li7La3Zr2O12 single-crystalline rod was grown by the floating zone method for the first time. The single-crystalline rod was 8 mm in diameter and 50 mm in length. Tetragonal Li7La3Zr2O12 crystallized in the tetragonal crystal system, space group I41acd, with lattice parameters of a = 13.1200(7) Å and c = 12.6753(7) Å. The crystal structure of tetragonal Li7La3Zr2O12 was refined to conventional values of R = 3.74% and wR = 3.85% for single-crystal X-ray diffraction data. The crystal structure was the same as that previously reported. The total lithium-ion conductivity in tetragonal Li7La3Zr2O12 was estimated to be 2.58 × 10−5 S cm−1 at 298 K from the results of alternating current (AC) impedance measurements. The lithium-ion conductivity was higher than the value reported for a normally sintered body, and it agreed well with the value of the high-density sintered body produced by the hot-press method. •The single-crystal of tetragonal garnet-type Li7La3Zr2O12 synthesis by FZ method•The crystal structure refinement by single-crystal X-ray diffraction technique•The lithium-ion conductivity properties measurements