The Investigation Of Preparation And Doping Modification Of ZnTiNb₂O₈Microwave Dielectric Ceramics

In this paper, ceramics were prepared by a conventional mixed oxide method andconventional sintering. ZnTiNb₂O₈system microwave dielectric ceramic wasinvestigated. The experimental results show that phase composition and doping have agreat impact on ceramic microwave dielectric properties.In this paper, TiO₂was added to improve microwave performance and sinteringadditives BCB was added to lower the sintering temperature. XRD results showedthat after the addition of TiO₂, the second phase Zn0.17Nb0.33Ti0.5O2appeared,resulting in the increase of the dielectric constant （ε_r）, decrease of the Q×f value andthe temperature coefficient of resonant frequency （τ_f） moving to the positive direction.Due to the effect of liquid phase sintering of BCB, ZnTiNb₂O₈-0.8TiO₂-3wt.%BCBceramics can be sintered at975°C. The microwave dielectric properties of ε_r=39.01,Q×f=22,678GHz, Ï„_f=+2.1ppm/°C were obtained.The article explores the effect of calcination temperature, secondary milling timeand sintering holding time on ZnTiNb₂O₈system microwave dielectric ceramics. Theexperimental results showed that: calcination temperature of1050°C, secondarymilling time of12h and sintering holding time of4h represent the best microwavedielectric properties.In this paper, Co doping modification of ZnTiNb₂O₈system was studied. Thebest recipe was obtained by varying Co doping amount. Due to the addition of Co, thesecond phase （Zn,Co）0.17Nb0.33Ti0.5O2appeared, resulting in the increase of thedielectric constant （ε_r）, decrease of the Q×f value and the temperature coefficient ofresonant frequency （τ_f） moving to the positive direction. When the amount of Codoping is30%mol,（Zn0.7Co0.3）TiNb₂O₈ceramics can be sintered at1075°C. Theexcellent microwave dielectric properties of ε_r=35.93, Q×f=35,125GHz, Ï„_f=0ppm/°C were obtained. On this basis, as1wt.%BCB was added,（Zn0.64Co0.36）TiNb₂O₈-1wt.%BCB ceramics can be sintered at975°C. The excellentmicrowave dielectric properties of ε_r=33.04, Q×f=22,000GHz, Ï„_f=-2.7ppm/°Cwere obtained.In this paper, Mg doping modification of ZnTiNb₂O₈system was studied. Theresults showed that a trace amount of Mg doping improved the Q value, however, had a bad impact on temperature stability. Therefore, When the Mg doping amount was5mol%, TiO₂was added to improve the resonance frequency temperature coefficient ofthe system.（Zn0.95Mg0.05）TiNb₂O₈-0.8TiO₂ceramics could be sintered at1100°Cand the microwave dielectric properties of ε_r=49.1, Q×f=21,110GHz, Ï„_f=-8.7ppm/°C were obtained. Then BCB was added to lower sintering temperature, themicrowave dielectric properties sintered at975°C was ε_r=43.7, Q×f=17,906GHz,Ï„_f=-2.3ppm/°C...