Low temperature sintering and microwave dielectric properties of the LBSCA-doped (Zn^sub 0.95^Co^sub 0.05^)^sub 2^SiO^sub 4^ ceramics

The (Zn^sub 0.095^Co^sub 0.05^)^sub 2^SiO^sub 4^ powers were fabricated through a traditional solid-state preparation process. Li^sub 2^O-B^sub 2^O3-SiO2-CaO-Al^sub 2^O3 (LBSCA) glass was successfully developed as a low-doped sintering aid and it was found that LBSCA glass could significantly lower the sintering temperature of the synthesized powers from 1,300 °C to around 900 °C. Only 1 wt% of LBSCA-doping contributed to a 24.9 % increase of the relative density. X-ray diffraction spectra indicated that pure willemite phase was obtained. Scanning electron microscope images demonstrated that low LBSCA-doping (≤2 wt%) promoted the grain densification and uniformity of the specimens. A dense microstructure with uniform grain size could be obtained with 2 wt% LBSCA and sintered at 900 °C. The specimen also presented high microwave dielectric properties: [straight epsilon] ^sub r^ = 6.5, Q × f = 57,000 GHz and τ^sub f^ = -55 ppm/°C.