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

我们研究的陶瓷谐振器，支持先进的信息化社会的微波通信，在原子水平上的晶体结构的基础上的性能的出现机制。1.成功地将烧结温度降低到1350℃，合成了与1450℃烧结的Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd）固溶体微波介电性能相当的改性Ba_ R_（8+2x）Ti_ O_（R=Sm，Nd）固溶体。2.研究了Bi阳离子在Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd）固溶体中的溶解条件与其微波介电性能的关系。选择Bi进行研究的原因是Bi被认为是一种阳离子，这使得它即使在高温下也能促进烧结。 关于我们 相对低温。在Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd）固溶体中加入Bi，使材料在1350℃的工业适用温度下烧结成为可能，比纯Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd）固溶体的烧结温度低100℃。虽然形成了低共熔混合物，但没有观察到固溶体，其烧结温度高达1460℃。而BaWO_4的加入则使品质系数（Qf值：2500以上）有所提高。另一方面，BaWO_4的加入使介电常数降低，频率的温度依赖性增加。4：从晶体结构的内部应变研究了钨青铜型Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd，La）固溶体的品质因子。高能加速器研究组织（KEK）利用光子工厂获得的精确的半高宽数据表明，固溶体中观察到的品质因子明显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，其晶体结构的内应力最小。5.进一步研究了Eu添加剂对Ba_<6-3x>R_（8+2x）Ti_<18>O_<54>（R=Sm，Nd）固溶体微波介电性能的影响。结果表明，Sm-Nd和Eu体系形成固溶体。Eu的加入使Qf提高到11000 GHz，并降低了谐振频率处的温度系数τ f。在Sm-Eu系中，得到了τ f = 0，Qf = 9500 GHz的固溶体。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