Research of microwave/millimeterwave dielectrics on the silicate system

在最近的泛在时代，无线通信得到了极大的发展。由于常规频率区的不足，可利用的频率区已扩展到毫米波。对于毫米波的超高频，需要具有超高品质因数Q和低介电常数a的介质。为了缩短信号的延迟时间并使器件尺寸更小，必须使用低ER。硅酸盐是由半共价键组成的硅氧四面体，具有较低的介电常数。根据SiO_4四面体的连接体系对硅酸盐进行分类。在由孤立的SiO_4四面体组成的次硅酸盐中，2005年明确了镁橄榄石和硅辉石具有超过20万GHz的高Qf。加入高ZR的金红石，使材料的共振频率温度系数由-60ppm/℃提高到O。2006年，通过添加镍、锌、锰等元素，对堇青石进行了QF改性。特别是掺镍后，QF从3万GHz提高到6万GHz。用Rietveld方法对晶体结构进行了分析，明确了改进的原因。SiO_4和A10_4四面体的有序化退化带来高Q，伴随着由堇青石向铟铁矿的转变而产生的高度对称性。在本研究期间，我们阐明了大于11的硅酸盐化合物的微波性质。这些化合物的介电常数在6到8之间，揭示了我们提出的共价性的起源。镁橄榄石与硅辉石共生时，QF最高。谐振频率ZR的温度系数在-20~-70ppm/0C附近，具有较低的值

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