Research On Low Temperature Sintering And Dielectric Properties Of MgTiO₃-Based Ceramics

MgTiO₃ceramic is an important microwave dielectric material with high Q value, which haswidely used as GPS antennas, MLCC and resonators, et al. But because of its high sinteringtemperature（about1400℃） and narrow sintering range, MgTiO₃ceramic has been restricted using inthe field of microwave communication. So that, many researchers made efforts to lower its sinteringtemperature.Sintering temperature can be lowered by the way of camouflage. At the same time, ceramics cankeep excellent dielectric properties. In this paper, Zn2+ions were partly used as substitution of Mg2+ions to lower the sintering temperature of MgTiO₃ceramic. Effects of different doping quantities ofZnO on sintering and dielectric properties of MgTiO₃ceramic were investigated. The results show thatwhen doped5mol%ZnO, Mg_0.95Zn_0.05TiO₃（95MZT） ceramic has the best excellent dielectric properties.Then, effects of calcined temperature and sintering schedule on95MZT ceramic were investigated toget the optimal preparation parameters. But the sintering temperature was also high. In order to lowerthe sintering temperature more of MgTiO₃ceramic, Bi₂O₃, B₂O₃and Bi₂O₃-B₂O₃were used as sinteringaids. The main contents and results were presented as follows:First of all, Effects of doping of ZnO on properties of MgTiO₃ceramic were investigated. Thedoping of ZnO can effectively promote the sintering of MgTiO₃ceramic and lower its densificationtemperature. When the doping quantity is5mol%,95MZT ceramic owns excellent sintering anddielectric properties.The next, The preparation parameters of95MZT ceramic were investigated. According to theDSC-TG curves, calcined temperature was initially determined. Then effects of calcined temperatureand sintering schedule on sintering and dielectric properties of95MZT ceramic were investigated inorder to get the optimal preparation parameters. When calcined at1100℃and sintering at1300℃for3h,95MZT ceramic has excellent dielectric properties: ε_r=19.29, Q f=127300GHz, τ_f=-52.8ppm/℃.Once again, Effects of Bi₂O₃and B₂O₃aids on sintering and dielectric properties of95MZTceramic were investigated. The results showed that the doping of1wt%Bi₂O₃and4wt%B₂O₃canrespectively lower the sintering temperature to1075℃and1050℃.The dielectric properties of95MZT+1wt%Bi₂O₃are: ε_r=18.94, Q f=16530GHz, τ_f=-40.7ppm/℃, and95MZT+4wt%B₂O₃: ε_r=20.0,Q f=13960GHz, τ_f=-25.6ppm/℃.Finally, Effects of Bi₂O₃-B₂O₃aid on sintering and dielectric properties of95MZT ceramic wereinvestigated. The results showed that the doping of2wt%80.9Bi₂O₃-19.1B₂O₃can lower the sintering temperature to960℃.The dielectric properties are: ε_r=20.21, Q·f=13957GHz, τ_f=-20.5ppm/℃.