As a member of the BLSFs, BIT  consists of the (Bi2Ti3O10)2− (pseudo-) perovskite layers interleaved by (Bi2O2)2+ fluorite layers, in which the A site is occupied by Bi3+. The A 350619 from BIT with layered structure into NBT with perovskite structure should contain two processes: one is that Na+ dissolved into the perovskite-like layer lattice and replaced the Bi3+ partially with preserved particle morphology. Since the radii of Na+ and Bi3+ cations are very close, which are 0.97 Å and 0.96 Å, respectively, it is easy for Na+ to diffuse into the BIT lattice and partly replace Bi3+ with heat treatment. Then the remnant stoichiometric Na+, Bi3+, Ti4+, and O2− reacted and changed the (Bi2O2)2+ layers to the perovskite NBT particle. The platelet and equiaxed NBT particles are formed in the initial period of topochemical reaction in the flux. The TMC-derived NBT templates could maintain the morphology of BIT with a high degree of preferred  orientation.