Two alternative products from the intercalation of alkali metals into cation-defective Ruddlesden-Popper oxysulfides

Sodium may be topotactically inserted into the perovskite layers (under thermodynamic control) or the rock-salt layers (under kinetic control) of the cation-deficient n=2 Ruddlesden-Popper oxysulfides Ln(2)Ti(2)O(5)S(2) with concomitant reduction of Ti-IV.