Research On Microwave Properties Of Al₂O₃ Ceramics Synthesized By Liquid-phase Method

With the booming of information on the Internet,microwave for transmission urgently needs to be upgraded to the millimeter-wave frequency band,which sets higher requirements on the performance of the microwave materials.Alumina,as a typical lowdielectric system,is considered suitable for the millimeter-wave band application.It will be of great significance to improve the comprehensive microwave performance of alumina ceramics.In this experiment,alumina powder was prepared by AACH precipitation method and alkoxide hydrolysis method.Cu O-Ti O2 and Fe2O3-Ti O2 were used as additives to improve the properties of ceramics.Finally,excellent performance of integrated microwave alumina dielectric ceramics were obtained at a lower temperature(1400?).The phase composition and microstructure were characterized by X-ray Diffraction(XRD),Scanning Electron Microscopy(SEM)and Transmission Electron Microscopy(TEM).The HP8720 ES network analyzer was used to test the microwave dielectric peroperties.The influence of raw material granularity,purity and additive content on the structure and properties of ceramics was systematically studied.Nano-powders with good dispersibility can be obtained by different liquid method calcined at 1150 ? and 1200 ?.The best dielectric properties of the ceramics were as follows: ?r = 8.3 and tan? = 1.02×10-4 at 1500? and ?r = 10.2 and tan? = 1.49 × 10-5 at 1450? by different liquid methed,respectively.The micro-nano-alumina powder as raw material,x Fe2O3-0.4 wt%Ti O2 as additive,when x is 0.4wt% and the sintering temperature is 1450?,the alumina ceramic has the best performance: the bulk density is 3.9 g/cm3,?r is 10.12,and tan? is 7.07 × 10-4.With the addition amount of Cu O-Ti O2 is 0.8 wt% and sintered at 1400 ?,the performance of ceramics samples is the best: ?r = 9.98,Q×f = 75668 GHz and ?f =-7.6 ± 0.6 ppm/?.