Lithium dimer formation in the Li-conducting garnets Li5+xBaxLa3-xTa2O12 (0 < x <= 1.6)

The garnet system Li5+xBaxLa3-xTa2O12 shows an unprecedented Li+ content (x <= 1.6) and short Li-Li distances of ca 2.44 angstrom between majority occupied sites suggesting that the high Li+ mobility requires a complex cooperative mechanism.