岩盐结构微波介质陶瓷的制备及改性研究
发布时间：2018-07-26 11:19
【摘要】：本文采用传统固相合成法,系统地研究了以Li3Mg2NbO6和Li2TiO3为代表的岩盐结构体系的微波介质陶瓷,实验结果表明相组成及掺杂对其微波介电性能产生较大的影响。本文研究了Zn2+对Li3Mg2NbO6微波介质陶瓷的掺杂改性,通过改变Zn2+不同掺杂量确定了最佳配方。由于掺杂离子Zn2+的半径比Mg2+略大,导致Li3Mg2NbO6陶瓷的晶格发生畸变,从而促进了Q×f值的极大提高,同时还略微降低了该体系的烧结温度。当Zn2+的掺杂量为8mo1%,陶瓷样品在1120℃烧结获得了最好的微波介电性能：εr=17.2,Q×f=142331GHz,τf=23.2ppm/℃C。在此基础上添加0.5wt%低烧助剂0.17Li2O-0.83V2O5后,其可在925℃烧结得到较好的微波介电性能：εr =14,Q×f=83395GHz,τf=-37.2ppm/℃。于此同时,该低烧样品又与Ag电极具有良好的化学兼容性。基于上述实验结果,由于Li3(Mg0.92Zn0.08)2NbO6陶瓷的谐振频率温度系数τf仍然较负,本文进一步研究了添加Ba3(VO4)2对其微波介电性能和烧结温度的影响。XRD结果表明在全组成范围内,由于Li3(Mg0.92Zn0.08)2NbO6与Ba3(VO4)2的晶体结构不同,使二者形成了复相陶瓷。由于Ba3(VO4)2较低的介电常数和Q×f值以及正的τf值,导致该体系的介电常数εr和Q×f值均降低,而谐振频率温度系数τf的符号向正方向偏移。同时由于Ba3(VO4)2的加入,引起部分V5+扩散至基体主晶相中,从而明显降低了体系的烧结温度。当添加30vol%的Ba3(VO4)2在950℃烧结后,其微波介电性能：εr:16.3,Q×f=50084GHz,τf=1.5ppm/℃。同时,该复相体系与Ag电极也具有很好的化学兼容性。另外,本文还系统地研究了(Al0.5Nb0.5)4+掺杂取代对Li2TiO3陶瓷微结构和微波介电性能的影响。实验结果表明Al3+和Nb5+的共取代对Li2TiO3的微观形貌产生了明显的影响。微裂纹的消除和晶粒的长大是其Q×f值提高的主要原因。在固溶体组成范围内,介电常数εr和τf的降低分别归因于离子极化和晶胞体积的变化。当(Al0.5Nb0.5)4+掺杂量为15mol%时,陶瓷样品在1150℃烧结取得了最佳的微波介电性能：εr=21.2,Q×f=181800GHz,τf=12.8ppm/℃。当加入6wt%的BaCu(B2O5)后,样品的烧结温度可明显降低至950℃,同时也兼具较优异的微波介电性能：εr=20.4,Q×f=53290GHz,τf=3.6ppm/℃。且该体系与Ag电极共烧时不发生任何化学反应,表明其可用作低温共烧陶瓷技术(LTCC)。
[Abstract]:In this paper, microwave dielectric ceramics with Li3Mg2NbO6 and Li2TiO3 as the representative of rock salt structure were systematically studied by the traditional solid state synthesis method. The experimental results show that the phase composition and doping have great influence on the microwave dielectric properties of the ceramics. The doping modification of Li3Mg2NbO6 microwave dielectric ceramics by Zn2 was studied in this paper. The optimum formula was determined by changing the doping amount of Zn2. Because the radius of doped ion Zn2 is slightly larger than that of Mg2, the lattice of Li3Mg2NbO6 ceramics is distorted, thus the Q 脳 f value is greatly increased, and the sintering temperature of the system is also slightly reduced. When the doping amount of Zn2 is 8 mol / 1, the best microwave dielectric properties are obtained by sintering the ceramics at 1120 鈩，
本文编号：2145843
[Abstract]:In this paper, microwave dielectric ceramics with Li3Mg2NbO6 and Li2TiO3 as the representative of rock salt structure were systematically studied by the traditional solid state synthesis method. The experimental results show that the phase composition and doping have great influence on the microwave dielectric properties of the ceramics. The doping modification of Li3Mg2NbO6 microwave dielectric ceramics by Zn2 was studied in this paper. The optimum formula was determined by changing the doping amount of Zn2. Because the radius of doped ion Zn2 is slightly larger than that of Mg2, the lattice of Li3Mg2NbO6 ceramics is distorted, thus the Q 脳 f value is greatly increased, and the sintering temperature of the system is also slightly reduced. When the doping amount of Zn2 is 8 mol / 1, the best microwave dielectric properties are obtained by sintering the ceramics at 1120 鈩，
本文编号：2145843
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