The Li6.5La3Zr1.5Ta0.5O12 single crystal was pulled from a melt using the Czochralski technique. The thoroughly sintered initial material containing an excess of 20 Mol% Li2O was melted in an inductively heated iridium crucible in pure Ar atmosphere and the crystal was pulled at a rate of 0.4 mm/h on a rotating seed oriented along [100]. The obtained crystal ingot was 15 mm in diameter and approximately 30 mm long, mainly transparent of slightly yellow color. The upper, first-grown part was covered by a thick film of opaque white material resulting from Li2O depletion caused by evaporation. The hot pressed polycrystals with the composition Li6.4Ta0.6La3Zr1.4O12 were acquired from commercial sources (Toshima). The single and polycrystals were cut into 3x3x0.7 mm cuboids.