Study on the transformation from NaCl-type Na 2TiO _3 to layered titanate

摘要

NaCl-type crystal structure sodium titanate (Na _2TiO _3), which exhibits a unit cell parameter of a=4.49 ?, was obtained by high temperature molten salt reaction. An intermediate phase product with layered structure was prepared by leaching the obtained Na _2TiO _3. We propose that the layered titanate structure is composed of Na _2TiO _3 and H _2O, corresponding to the host-layer and guest-substance, respectively. Furthermore, the crystal structures of layered titanate were optimized by the density functional theory (DFT). This indicates that water molecules are distributed in an orderly manner in the interlayer through the formation of hydrogen-bonded chain. Moreover, the position of the adjacent lamella translates to c/2 along the c-axis after the intercalation of water.