Sintering and Phase Transition of 0.25CuO-0.75MoO_3 Doped ZnO-TiO_2 Microwave Dielectric Ceramics

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 er=28.6,quality factor Qf=12150GHz and temperature coefficient of resonant frequency τf=+17.8×10-6/℃.