Effect of coating layers on nano-TiO2 particles on the preparation of nanocrystalline λ-Ti3O5 by carbonthermal reduction

Three different kinds of rutile TiO2 nanoparticles with different surface coating conditions were prepared by precipitation method for synthesizing λ-Ti3O5. The effect of surface layers on nano rutile TiO2 particles on the preparation of λ-Ti3O5 was firstly investigated. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and transmission electron microscope were used to characterize these powders. The nano rutile TiO2 powders were mixed with carbon black separately and then annealed at an isothermal heat condition. The phase structures of the products demonstrate that high purity nanocrystalline λ-Ti3O5 powders can be synthesized by carbothermal reduction of the Al2O3–SiO2 dual-coated TiO2 powders, but not by the uncoated and SiO2-coated TiO2 powders. Thus, the coating layers of the TiO2 nanoparticles played a decisive role in the formation of nanocrystalline λ-Ti3O5. It proposed that both of the coating layers and metal ion (i.e. Al3+) make a contribution to stabilize the metastable phase λ-Ti3O5 to ambient temperature in the carbothermal reduction of the TiO2/C system. This study provided considerable insights into the preparation of nanocrystalline λ-Ti3O5.