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1、 I 摘 要 微波介质陶瓷是指应用于微波频段电路中作为介质材料， 并完成一种或多种功能的陶瓷，是近几十年发展起来的一种新型电子材料，它具有较低的微波介质损耗，高的介电常数和接近于零的谐振频率温度系数等特点。这几年来，微波介质陶瓷的研究十分的活跃，已经成为目前功能陶瓷领域的研究热点之一。 本论文从微波介质陶瓷的研究背景、发展状况、基本特征、制备技术以及介电性能测试表征等方面对微波介质陶瓷材料进行了系统地综述。在此基础上，提出了以 BaO-Y2O3-TiO2系列为主要研究对象，系统深入地研究了包括材料的配方、制备工艺以及掺杂等对微波介电性能的影响，制备出了性能良好的微波介质陶瓷材料。 首先研究了不
2、同配方 BaO-Y2O3-kTiO2系微波介质陶瓷的性能变化，发现不同的 k（k=3，4，4.5，5）值下 BaO-Y2O3-kTiO2系列陶瓷的介电常数随 k 值的增大逐渐的降低，同时损耗也相应降低，在 k=3 时有较高材料的介电常数 r331，但是相应的介电损耗也较大tan=0.024， k=4时介电常数r=78.3, 介电损耗tan=310-3，当 k5 时候介电常数进一步减小到 r=53，tan=910-4。同时频率温度系数随着 k 值增大由 f=-280ppm/增大到 f=95ppm/。 在配方研究的基础上选择了介电常数较高、损耗较低的 BaO-Y2O3-4TiO2、BaO-Y2O3
3、-5TiO2两组配方作为进一步研究的对象，研究了不同预烧温度和烧结保温时间对微波介质陶瓷材料性能的影响， 发现不同的预烧温度对陶瓷的相组成基本没有什么影响，陶瓷主晶相都为烧绿石结构的 Y2T2O7；并且在一定的温度范围内改变预烧温度对材料介电常数的影响不大。 但是烧结保温时间对陶瓷材料的显微结构及微波介电性能有重要的影响，随着保温时间的延长，陶瓷中残余的气孔逐渐被排除，晶粒逐渐长大，致密性进一步的提高，陶瓷的介电常数也有所增大。 BaO-Y2O3-4TiO2系列陶瓷在 1240下保温 216h， r由 76.6 增加到了 79.5，BaO-Y2O3-5TiO2系列在 1240下保温 216h，
4、r由 52 增加到 53.5。同时介电损耗随着保温时间的延长也有较大的改善。BaO-Y2O3-4TiO2系列在保温时间为 8h时介电损耗最佳 tan=1.210-3， BaO-Y2O3-5TiO2系列在保温时间为 8h 时介电损II 耗最小 tan=210-4。 最后对 BaO-Y2O3-4TiO2 、BaO-Y2O3-5TiO2系陶瓷物相分析结果表明，这两个系列陶瓷的主晶相有别于 BaO-R2O3-TiO2（R=Nd，Sm，La） ，BaO-Y2O3-TiO2系陶瓷的主晶相为烧绿石结构的 Y2T2O7，而不是类乌青铜结构的相，因此本论文合成了 Y2Ti2O7,并对其微波介电性能进行了研究，发
5、现 Y2Ti2O7具有较好得微波介电性能，但其烧结温度较高、谐振频率温度系数较大。因此本文还通过掺杂Bi2O3来进一步改善其微波介电性能，并获得了介电常数为 82，介电损耗 tan=510-4的 （Bi0.2Y0.8） Ti2O7微波介质陶瓷。 同时通过复合ZnNb2O6后得到的ZnNb2O6 -Y2T2O7陶瓷也具有良好的微波介电性能。 关键词关键词：微波介质陶瓷 介电常数 介电损耗 Y2Ti2O7 III ABSTRACT Microwave dielectric ceramics are a new kind of electronic ceramics, which are widel
6、y used in the circuits of microwave frequency segment as the dielectric materials achieving one or more functions. For processing these characters such as low dielectric loss, high dielectric constant and temperature coefficient of resonant frequency close to 0, nowadays microwave dielectric ceramic
7、s have been widely researched and become one of research hotspots in the area of functional ceramics. In this paper, their research backgrounds, developments, basic characters, preparation progress, test of dielectric properties and et al are summarized. And then BaO-Y2O3-TiO2 series ceramics were c
8、hosen as the major research object. The effects of the ratios, preparation progress, and the additive to the microwave dielectric properties were studied. The microwave dielectric ceramics with excellent dielectric properties were obtained at last. Firstly, the properties of BaO-Y2O3-k TiO2 series c
9、eramics with various k values were studied. The dielectric constant of BaO-Y2O3-k TiO2 series ceramics reduced gradually with the increasing k values (k=3, 4, 4.5, 5), and the dielectric loss reduced as the same. As for k=3, the dielectric constant r was 331, but the dielectric loss tan was 0.024 wh
10、ich was too high. As for k=4, the dielectric constant r was 78.3, the dielectric loss was tan0.003. As for k=5, the dielectric constant reduced to 53, the dielectric loss tan only was 0.0009. The temperature coefficient was f-280ppm/ as for k=3 to f95ppm/ as for k=5. Based on the research above, the
11、 BaO-Y2O3-4TiO2 series with high dielectric constant and low dielectric loss were chosen, as well as BaO-Y2O3-5TiO2 series with high dielectric constant and low dielectric loss, as the two next research objects. The effects of different calcining temperature and sintering holding time on the microwa
12、ve dielectric properties were studied. Different calcining temperature had no obvious effects on the composition of crystal phases and the major crystal phase was Y2Ti2O7. The dielectric constant did not change much with the different calcining temperature. IV But the sintering holding time had a gr
13、eat effect on the microstructure and microwave dielectric properties. As the holding time prolonged, survivals air holes were eliminated gradually, and crystal grain grow up. At the same time the compact property was improved further and the dielectric constant also augmented. The dielectric constan
14、t of BaO-Y2O3-4TiO2 series ceramics increased from 76.6 to 79.5 as the holding time was prolonged from 2h to 16h. The dielectric constant of BaO-Y2O3-5TiO2 series ceramics increased from 52 to 53.5 as the holding time was prolonged from 2h to 16h. The dielectric loss was improved when the holding ti
15、me was prolonged. The least dielectric loss of BaO-Y2O3-4TiO2 series ceramics was tan=1.210-3 with 8h. The least dielectric loss of BaO-Y2O3-5TiO2 series ceramics was tan=210-4 with 8h. Finally the phase analysis of BaO-Y2O3-4TiO2 and BaO-Y2O3-5TiO2 series ceramics show that the major crystal phase
16、are pyrochlore type Y2Ti2O7 which was different to the crystal phase of new tungsten bronze type BaO-R2O3-TiO2（RNd，Sm，La）. Because of this, Y2Ti2O7 was synthesized. The microwave dielectric properties of this were also studied. And the results show it had good microwave dielectric properties, but high sintering temperature and large resonant frequency coefficient. In order to improve the properties of Y2Ti2O7, the Bi2O3 were added as an a
