Materials design and development of microwave dielectrics based on the crystal structure

我们从晶体结构出发，在原子水平上研究了支持先进信息社会微波通信的陶瓷谐振器特性的产生机理。本研究是为了设计和开发新型陶瓷谐振器而进行的。1.成功地将烧结温度降低到1350℃，合成了与1450℃下烧结的固溶体微波介电性能几乎相当的改性固溶体Ba1450；6-3x&gt；这是由于初始混合成分被稍稍向TiO2侧倾斜，使其成为共晶成分。2.明确了铋离子在Ba2x；6-3x&gt；R&lt；82x&gt；18&gt；O&lt；54&gt；(R=Sm，Nd)固溶体中的溶解条件与其微波介电性能的关系。之所以选择铋进行研究，是因为铋是一种阳离子，即使在…也能促进烧结相对较低的温度较多。在Ba&lt；6-3x&gt；6-3x&gt；8 2x&gt；Ti_&lt；18&gt；O_&lt；54&gt；(R=Sm，ND)固溶体中加入铋使该材料在1350℃的工业适用温度下烧结成为可能，该温度比纯Ba&lt；6-3x&gt；R_&lt；82x&gt；Ti_&lt；18&gt；O_&lt；54&gt；(r=Sm，Nd)固溶体。3.研究了BaWO_4对钨青铜类ND系固溶体的添加效应。虽然形成了共晶混合物，但没有观察到固溶体，其烧结温度高达1460℃。但BaWO_4的加入提高了材料的品质因数(Q_f值：2500 UP)。另一方面，介电常数随BaWO_4的加入而降低，频率的温度依赖性增大。从晶体结构的内应变分析了BaWO_4的介电常数和介电常数随温度的变化：发现了钨青铜结构的品质因数，如：Ba_&lt；6-3x&gt；利用高能加速器研究组织(KEK)的光子工厂获得的准确的半高宽数据表明，在固溶体中观察到的品质因数显著依赖于晶体结构的内部应变。结果表明，Sm系固溶体具有最好的微波介电性能，其晶体结构内应变最小。5：进一步研究了Eu添加剂对Ba2x&gt；6-3x&gt；R_&lt；8 2x&gt；Ti_&lt；18&gt；O_&lt；54&gt；(R=Sm，Nd)固溶体微波介电性能的影响。结果表明，Sm-ND和Eu系形成固溶体。Eu的加入使材料的品质因数Qf提高到11000 GHz，谐振频率的温度系数(τ_f)降低。在Sm-Eu系中，得到了τ_f为0，Q_f为9500 GHz的固溶体。较少

We investigated emergence mechanisms in the properties of ceramic resonators, which support microwave communication for advanced information-oriented society, in the atom level based on the crystal structure. This research was performed for the purpose of the design and development of new ceramic resonators.1 : It was succeeded in making sintering temperature decrease to 1350℃ for synthesis of modified Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd) solid solutions with almost equivalent microwave dielectric properties to the solid solutions sintered at 1450℃. This was attained by that the starting mixing composition was sifted slightly to the TiO_2 side for making it the eutectic composition.2 : The correlation with the soluble condition of Bi cation into Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd) solid solutions and their micowave dielectric properties was made clear. The reason why Bi was chosen for the investigation was that Bi is known as a cation which made it promote sintering even at … More relative low temperature. Addition of Bi into Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd) solid solutions was made it possible that the material was sintered at industrial applicable temperature of 1350℃ which was 100℃ lower than that needed for pure Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd) solid solutions.3 : Additive effects of BaWO_4 to the tungstenbronze type like Nd-system solid solutions were studied. Although an eutectic mixture was formed, no solid solutions were observed and its sintering temperature was as high as 1460℃. However, the improvement of the quality coefficient (Q fvalue : 2500 up) was seen by the addition of BaWO_4. On the other hand, the dielectric constant decrease and the temperature dependence of the frequency increased with addition of BaWO_4.4 : The quality factor of the tungstenbronze type like Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd, La) solid solutions was examined from the internal strain in the crystal structure. Accurate FWHM data obtained by using photon factory in the High Energy Accelerator Research Organization (KEK) made it clear that the quality factor observed in the solid solutions significantly depended on the internal strain of the crystal structure. It was cleared that Sm-system solid solutions, which exhibited the best microwave dielectric properties of all the systems, demonstrated the smallest internal strain of the crystal structure of the specimens examined.5 : Further, effects of Eu additive on the microwave dielectric properties of Ba_<6-3x>R_<8+2x>Ti_<18>O_<54> (R=Sm, Nd) solid solutions were studied. It was cleared that Sm-Nd and Eu systems forms solid solutions. The quality factor Q f was improved to 11000GHz and the temperature coefficient (τ_f) at the resonant frequency was decreased by the addition of Eu. In the Sm-Eu system, a solid solution with τ_f of 0 and Q f of 9500GHz was obtained. Less