ZnNb_2O_6 -TiO_2微波介质陶瓷及其在电容器中的应用

采用固相法在880～975℃下烧结制备了添加w(CuO)为2.00%,w(B2O3)为3.00%及w(SnO2)为0.15%的ZnNb2O6-1.75TiO2基复合微波介质陶瓷。研究了该陶瓷的低温烧结机理、微波介电性能及其在多层片式陶瓷电容器中的应用。结果显示:随着烧结温度的提高,物相由Zn2TiO4,Zn0.17Nb0.33Ti0.5O2,ZnNb2O6向ZnTiNb2O8转变,εr和τf减小,Q·f升高。但当t≥975℃时,出现过烧现象,晶体缺陷增多恶化了材料的Q·f。在950℃烧结4h时,得到最好的介电性能:εr=36.7,τf=–22.6×10–6/℃,Q·f=18172.2GHz。且在此温度下制备的多层片式陶瓷电容与内电极Ag90Pd10的兼容性良好,Res为0.3426Ω,tanδ为9×10–5,可靠性良好。

ZnNb_2O_6 -TiO_2 microwave dielectric ceramics and their application in capacitors

ZnNb_2O_6-1.75TiO_2 microwave dielectric ceramics with w(CuO)=2.00%, w(B_2O_3)=3.00% and w(SnO_2)=0.15% additives were prepared at 880～975 ℃ through solid state reaction method. The mechanism of low-temperature sintering, the microwave dielectric properties and their application prepared ceramics in multi-layer chip capacitor were investigated. The results indicate that with increasing sintering temperature, the phase transforms from Zn_2TiO_4, Zn_(0.17)Nb_(0.33)Ti_(0.5)O_2, ZnNb_2O_6 to ZnTiNb_2O_8, the τ_f and ε_r values decline while the Q·f value increases. But when t≥975 ℃, Q·f value decreases because of the abnormal crystal growth and crystal defects. The materials sintered at 950 ℃ for 4 h exhibit excellent dielectric properties: εr =36.7, Q·f =18 172.2 GHz and τ_f = -22.6×10~(-6) ℃. The multi-layer chip capacitor made by this materials sintered at 950 ℃ shows good compatibility with Ag90Pd10 inner electrode and exhibit excellent properties and reliability(R_(es)=0.342 6 Ω,tanδ=9×10~(-5)).