Research of microwave/millimeterwave dielectrics on the silicate system

在当今无处不在的时代，无线通信得到了极大的发展。由于常规频率区域的不足，将可用的频率区域扩展到毫米波。对于毫米波的超高频率，需要具有超高质量因数Q和低介电常数a的介质。为了缩短信号的延迟时间和使器件小型化，低Er是必要的。作为毫米波候选材料的硅酸盐具有较低的介电常数，这是因为硅氧四面体由半共价键组成。根据SiO_4四面体的连接体系对硅酸盐进行了分类。在分离的SiO_4四面体组成的新硅酸盐中，2005年澄清了橄榄石和橄榄石具有超过200000GHz的高Qf。加入高zr金红石后，谐振频率tr的温度系数由-60ppm/℃提高到0。2006年，在堇青石中加入Ni、Zn和Mn对Qf进行了改进。特别是，由于Ni的掺杂，Qf从30000GHz提高到60000GHz。利用Rietveld法对晶体结构进行分析，明确了改进的原因。SiO_4和A10_4四面体的有序降解带来了高q值，降解伴随着堇青石向堇青石转变的高对称性。在此研究期间，我们澄清了超过11种硅酸盐化合物的微波性质。这些化合物的介电常数在6 ~ 8之间，揭示了我们所提出的共价的来源。伴生的橄榄石的Qf最高。谐振频率zr的温度系数在-20 ~ -70 ppm/0C之间，温度系数相对较低

The wireless communications have been tremendously developed in the recent ubiquitous age. The utilizable frequency region has been expanded to millimeterwaves because of shortage of conventional frequency regions. For the ultra high frequencies of millimeterwaves, dielectrics with ultra high quality factor Q and low dielectric constant a are desired. Low Er is necessary to short the delay time of signals and to make devices small in size. Silicates for candidate of millimeterwave materials have low dielectric constant, because of silica-oxygen tetrahedra composed of half covalent bonds.Silicates were classified according to connecting system of SiO_4 tetrahedra. In the neso-silicates composed by isolated SiO_4 tetrahedron, it was clarified at 2005 that forsterite and willemite have high Qf more than 200000GHz. The temperature coefficients of resonant frequency tr were improved to O from -60ppm/℃ by adding rutile with high zr. At 2006, cordierite was improved the Qf adding Ni, Zn and Mn. Especially, according to doping Ni, the Qf was improved from 30000GHz to 60000GHz. The origin of the improvement was clarified by crystal structural analysis using Rietveld method. Degradation of ordering of SiO_4 and A10_4 tetrahedra brings, high Q. The degradation was accompanied with high symmetry by the transformation from cordierite to indierite. In this research period, we clarified the microwave properties of silicate compounds more than 11. The dielectric constants of these compounds have low of 6 to 8 revealing the origin of covalency presented by us. The highest Qf was obtained in the forsterite accompanied by willemite. The temperature coefficients of resonant frequency zr are located around -20 to -70 ppm/0C with relative low values