Bi₄Ti₃O₁₂ Nanosheets And Bi₁₂TiO₂₀ Micro-nano Structures:Synthesis And Photoluminescence

The ferroelectric oxides nanoplates and the multivariate composite metal oxides, have increasingly shown a great potential application in the field of high-density nonvolatile memory and visible light photocatalytic, respectively.Reviewed the research progress of nanomaterials and the structure of bismuth-layered perovskite Bi4Ti3O12 and sillenite Bi12TiO20, Bi4Ti3O12 nanosheets have been successfully synthesized by a PVA assisted hydrothermal route. Their photoluminescence properties were also studied. Furthermore, we explore hydrothermal synthesis of Bi12TiO20 nanosphere and microsheets.The main results are summarized as following:(1) When the ammonium bismuth citrate is introduced into the hydrothermal system, the Bi4Ti3O12 nanosheets could synthesized with lateral size of several micrometers and thickness of 60-100nm nanometers. Whereas the obtained Bi4Ti3O12 nanosheets are dominated by (010) facets, it is rational to suggest that the [(NH3)2C6H7O7]3- preferentially adsorbs on the (010) planes of Bi4Ti3O12. Furthermore, the as-synthesized Bi4Ti3O12 nanosheets exhibit strong PL emission in 407-457nm wavelength range excited at 374nm, because of relative high density of surface state in the Bi4Ti3O12 nanosheets.(2) The titanium hydroxide precipitates were used as titanium source precursors, leading to the formation of layered K2Ti6O13 nanofibers at the initial stage. When enough K+ ions are substituted by Bi3+ions in the lattice of K2Ti6O13, some TiO6 octahedron lamella exfoliate,which would as template further react with the dehydrated Bi3+ions to form Bi4Ti3O12 lamellar species. When the PVA is introduced into the hydrothermal system, the Bi4Ti3O12 nanosheets could synthesized with lateral size of 2-6 micrometers and thickness of about 20 nanometers. An obvious red shift of the absorption edge occurs for the Bi4Ti3O12 nanosheets. The estimated band gap of the single-crystalline Bi4Ti3O12 nanosheets is slightly smaller.It also exhibits strong PL emission in 325-335nm wavelength range excited at 281nm, because of relative high density of surface state in the Bi4Ti3O12 nanosheets.(3) When the ammonium bismuth citrate is introduced into the hydrothermal system, the esillenite Bi12TiO20 nanospheres could synthesized because of the [(NH3)2C6H7O7]3- organic acid ions adsorbs on the Bi3+ions of Bi12TiO20. The esillenite Bi12TiO20 microsheets have been successfully synthesized by a PVA assisted hydrothermal route.