Crystallographic phase evolution of ternary Zn-Ti-O nanomaterials during high-temperature annealing of ZnO-TiO2 nanocomposites

This study investigates the phase evolution of ternary Zn-Ti-O nanomaterials by high-temperature annealing of ZnO-TiO2 core shell nanowires at 800 degrees C-1000 degrees C. Scanning electron microscopy images show the surface morphology of the nanowires becomes rough with an increase in annealing temperature. Moreover, X-ray diffraction (XRD) patterns and transmittance electron microscopy (TEM) analysis show that multiple Zn-Ti-O ternary compounds exist in the high-temperature annealed ZnO-TiO2 nanocomposites. These are Zn2TiO4 and ZnTiO3. The nanowires annealed at 800 degrees C form hexagonal ZnTiO3 and cubic Zn2TiO4 mixed phases. When the annealing temperature reaches 1000 degrees C, a pure and efficient crystalline Zn2TiO4 phase is obtained in the nanowires. The experimental results herein demonstrate that the annealing temperature is a substantial factor dominating the phase evolution of Zn-Ti-O ternary compounds in the solid-state reaction between the ZnO core and TiO2 shell nanolayers.