Crystal structures and ionic conductivity of Na5MP2O8F2 (MAl, Ga)
Single crystals of Na5MP2O8F2(MAl, Ga) were prepared by the flux technique. Both the compounds crystallize in the space group P3 with a = b = 10.468(3), c = 6.599(2) A for the Al compound and a = b = 10.560(2), c = 6.660(2) A for the Ga compound. Low ionic conductivity in these solids is attributed to a highly ordered distribution of the sodium ions in the lattice.