Abstract:

The effects of 0.25CuO-0.75MoO₃ (in mole ratio, abbreviated to CM) addition on the sintering behavior, phase transition and microwave dielectric properties of ZnO-TiO₂ (ZT) ceramics were investigated. CM-doped ZT ceramics were prepared by conventional solid-state reaction method and sintered at temperatures ranging from 900℃ to 1050℃. The micrographs, elemental composition, phase structures and microwave dielectric properties of the samples prepared were characterized or measured by field-emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and a network analyzer, respectively. It is demonstrated that both Cu²⁺ and Mo⁶⁺ are introduced into the lattice of the main phase which lower the decomposition temperature of ZnTiO₃ and the onset temperature at which Zn₂TiO₄ and rutile could form solid solution (Zn₂Ti₃O₈). Meanwhile, it is confirmed that, the doping of CM can effectively enhance the densification of ZT ceramics at relatively low sintering temperatures. The ZT ceramic sample with 4wt% CM addition sintered at 975℃ for 4h reaches a density value of 94% theoretical density, and exhibited microwave dielectric properties as follows: dielectric constant ε_r=28.6, quality factor Qf=12150GHz and temperature coefficient of resonant frequency τ_f=+17.8×10^-6/℃.

Key words: ZnO-TiO₂, low temperature sintering, phase transitions, microwave dielectric properties