Phase transitions of low-temperature sintering tungsten-doped ZnO-TiO ₂ ceramics

WO ₃-doped zinc titanate ceramics were prepared by conventional mixed-oxide method combined with a chemical processing. The effects of WO ₃ addition on the low-temperature sintering behavior, phase transition and dielectric properties of zinc titanate ceramics were investigated. The results show that the densification temperature of ZnTiO ₃ ceramics can be reduced from 1150 to 900°C with WO ₃ addition and chemical processing. Small amount of WO ₃ (<1.00wt %) accelerated the decomposition of hexagonal ZnTiO ₃ phase to cubic Zn ₃TiO ₃ phase, while excessive addition (for example, 3.00wt %) restrained the decomposition. At the same time, the phase transition temperature from hexagonal ZnTiO ₃ phase to cubic Zn ₂TiO ₄ is lowered by adding WO ₃. WO ₃ addition affects the dielectric properties of ceramics. The dielectric properties of WO ₃-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 the best dielectric properties for 1.0% WO ₃-doped ceramics.