Alkali Lanthanide Pyrosilicates (general formula = A3LnSi2O7) are promising candidates for use as solid electrolytes in all solid state Li-ion and Na-ion batteries. To date the structure of Li3LnSi2O7 has not been reported. We have synthesized powder samples of A3LnSi2O7 (A = Li, Na; Ln = Gd-Er) and characterized them by powder X-ray diffraction and impedance spectroscopy. For a full analysis of the crystal structure of A3LnSi2O7, we require neutron powder diffraction to determine the position of the Li, Na, Si, and O atoms in the presence of the heavy Ln atoms; and neutron total scattering to study the effect of alkali ion site disorder on the alkali ion conduction mechanisms in the lanthanide silicate framework.