A series of Li3YBrxCl6-x (x = [0, 6] steps of 1.5) solid electrolytes were synthesized by direct co-melting of the precursors in evacuated silica ampoules at 650 ℃. The powders obtained were phase-pure for all compositions. The X-ray diffraction patterns shown in Figure clearly show that the materials crystallize in two different phases, depending on the ratio between Cl and Br. (Li3YBr6/Cl6 from ref. , Li3YBr3Cl3 from ref. ).