Effects of WO3 additions on the phase structure and transition of zinc titanate ceramics

WO3-doped zinc titanate ceramics were prepared by conventional mixed-oxide method combined with a chemical processing. The effects of WO3 additions on the phase structure and phase transitions of zinc titanate ceramics were investigated by high-temperature X-ray diffractometry (HTXRD) and transmission electron microscopy (TEM). The results showed that the major phase of zinc titanate ceramics transformed from zinc orthotitanate phase to zinc metatitanate phase with the amounts of WO3 additions increasing. Small WO3 (<1.00 mass%) addition accelerated the transition of ZnTiO3 to Zn2TiO4, while excessive WO3 addition restrained the transition. HTXRD showed that WO3 enhanced the stability of Zn2Ti3O8 and weakened the stability of ZnTiO3. A precipitate within the Zn2TiO4 matrix was observed. Viewed along the [0 2¯ 1] orientation of Zn2TiO4, the precipitate was found to have a rectangular shape and to be nanometer level in size; its composition was concluded to be Zn2Ti3O8. The dielectric properties of WO3-doped zinc titanate ceramics were measured at different frequencies. The results showed the decreasing tendency with the increasing measuring frequencies for both the dielectric constants and the loss tangents, and there existed maximum values when the amount of WO3 was 0.50 mass%.