Ba Nd - Ti Series Of Microwave Dielectric Ceramics Research In Low Temperature

With the highly-speed development of modern communication technology, thetrend of comminication devices to miniaturization, highly-integrtation andhigh-frequency strongly requires for more research and development on new functionalmicrowave dielectric material.In order to decrease the sintering temperatures and production cost, this workinvestigates the influence of a series of sintering addictives on microstructurecomposition, sintering process and microwave properties based on BaO-Nd₂O₃-TiO₂.The addictives used in our work were Bi₂O₃, MnO₂, Ca-B-Si, La-B-Zn-C and Ba-B-Zn.1. This work has done deep-research about these sintering aids by traditional solidreaction mothod, and the investigation showed that oxide aids like Bi2O3can effectivelydecrease the sintering temperature to some extent. Bi2O3can decrease the sinteringtemperature from1450℃to around1350℃. When the material compostion wasBa_0.75Sr_0.25(Nd_0.75Bi_0.25)₂Ti₄O₁2, it possoses the maximum properties: εr=118.5，Q×f=4607GHz （f=2.8GH_z）. The temperature decreased by doping MnO₂is similar toBi2O3, yet it slightly deteriated the microwave dilelectric properties.2. Ca-B-Si compositive sintering addictives can effectively decreasing thedensifying temperature of BaNd₂Ti4O₁2. The samples doped with9wt%CBS sintered at980℃possessed the maximum microwave properties:Q×f=3737GHz, εr=65.7, τf=21.3ppm·℃^-1. The Ba_0.75Sr_0.25(Nd_0.75Bi_0.25)₂Ti4O₁2doped with15wt%La-B-Zn-Cacomposite sintering aids can be densified at900℃. And then it can be co-sintered withAg electrode. The specimen doped with15wt%La-B-Zn-Ca sintered at900℃for0.5hshows excellent dielectric properties: εr=57.85，Q×f=2949GHz and τf=17.17ppm·℃^-1.This can be potentially used for the required filter. When the doping content was small,the main phase is BaNd₂Ti₄O₁2. With the increasing of La-B-Zn-Ca, Ba₂Ti₉O₂₀tends tobe the main phrase from the inferior one. Ba-B-Zn can greatly decrease the sinteringtemperature of BaNd₂Ti₄O₁2samples, when the deping content is20wt%, the materialcan be densified at900℃. And with the increasing of doping content and sinteringtemperature, there isn’t second phase formed. The specimen doped with20wt%BZB and sintered at900℃for0.5h shows excellent dielectric properties:Q×f=3234GHz,ε_r=63.2and τ_f=－10.9ppm·℃^-1. Through further improvement, these materials can beused as LTCC microwave dielectric material.