Transformation of Dion–Jacobson phase to Aurivillius phase: synthesis of (PbBiO2)MNb2O7 (M = La, Bi)

We describe transformations of the Dion–Jacobson (D–J) phases, $KLaNb_2O_7$ and $RbBiNb_2O_7$, to the Aurivillius (A) phases, $(PbBiO_2)LaNb_2O_7$ (1) and $(PbBiO_2)BiNb_2O_7$ (2), in a metathesis reaction with $PbBiO_2Cl$. Oxide 1 adopts centrosymmetric tetragonal structure $(a = 3.905(1) \AA , c = 25.66(1) \AA )$, whereas oxide 2 crystallizes in a noncentrosymmetric orthorhombic $(A2_1am)$ $(a = 5.489(1) \AA , b = 5.496(2) \AA , c = 25.53(1) \AA )$ structure. Oxide 2 shows a distinct SHG response towards 1064 nm laser radiation. The role of $La^{3+}$ versus $Bi^{3+}$ in the perovskite slabs for the occurrence of noncentrosymmetric structure/ferroic property in these materials is pointed out.