SiO_(2)/聚四氟乙烯(polytetrafluoroethylene,PTFE)复合介质材料的热膨胀系数和介电常数主要受到SiO_(2)填充量的影响,如何准确预测其影响至今仍是一个很大的挑战.本文通过数值模拟系统地研究SiO_(2)/PTFE复合介质材料的热膨胀系数和...SiO_(2)/聚四氟乙烯(polytetrafluoroethylene,PTFE)复合介质材料的热膨胀系数和介电常数主要受到SiO_(2)填充量的影响,如何准确预测其影响至今仍是一个很大的挑战.本文通过数值模拟系统地研究SiO_(2)/PTFE复合介质材料的热膨胀系数和介电常数.结果表明,随着SiO_(2)填充量的增加,SiO_(2)/PTFE复合介质材料的热膨胀系数降低,介电常数增加,且与文献报道数据取得良好的一致性(Han K K,Zhou J,Li Q Z,Shen J,Qi Y Y,Yao X P,Chen W 2020 J.Mater.Sci.Mater.Electron.319196).研究发现,实心SiO_(2)球(体积分数为30%)/PTFE复合介质材料的热膨胀系数最小,为7.5×10^(-5)K^(-1);而空心SiO_(2)球(体积分数为10%)/PTFE的介电常数最小,为2.06.由于底部的实心SiO_(2)球充当支撑作用,底部实心SiO_(2)球较密集的实心SiO_(2)/PTFE复合介质材料具有更低的热膨胀系数.SiO_(2)填料的大长径比会降低SiO_(2)/PTFE复合介质材料的热膨胀系数.成型工艺对实心SiO_(2)/PTFE复合介质材料的热膨胀系数几乎没有影响.该工作为通过调控SiO_(2)/PTFE复合介质材料的微观结构来控制其热膨胀系数和介电常数提供清晰的思路.展开更多
We study the Raman spectra of Bi4GeO12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by the...We study the Raman spectra of Bi4GeO12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by their high-temperature Raman spectra for the first time. The rule of structure change of BGO crystal with increasing temperature is analysed. The results show that there exists [GeO4] polyhedral structure and Bi ion independently in BGO melt. The bridge bonds Bi-O-Bi and Bi-O-Ge appear in the crystal and at the boundary layer, but disappear in the melt. The structure of the growth solid-liquid boundary layer is similar to that of BGO crystal. In the melt, the long-range order structure of the crystal disappears. The thickness of the growth solid-liquid boundary layer of BGO crystal is about 50 μm.展开更多
文摘SiO_(2)/聚四氟乙烯(polytetrafluoroethylene,PTFE)复合介质材料的热膨胀系数和介电常数主要受到SiO_(2)填充量的影响,如何准确预测其影响至今仍是一个很大的挑战.本文通过数值模拟系统地研究SiO_(2)/PTFE复合介质材料的热膨胀系数和介电常数.结果表明,随着SiO_(2)填充量的增加,SiO_(2)/PTFE复合介质材料的热膨胀系数降低,介电常数增加,且与文献报道数据取得良好的一致性(Han K K,Zhou J,Li Q Z,Shen J,Qi Y Y,Yao X P,Chen W 2020 J.Mater.Sci.Mater.Electron.319196).研究发现,实心SiO_(2)球(体积分数为30%)/PTFE复合介质材料的热膨胀系数最小,为7.5×10^(-5)K^(-1);而空心SiO_(2)球(体积分数为10%)/PTFE的介电常数最小,为2.06.由于底部的实心SiO_(2)球充当支撑作用,底部实心SiO_(2)球较密集的实心SiO_(2)/PTFE复合介质材料具有更低的热膨胀系数.SiO_(2)填料的大长径比会降低SiO_(2)/PTFE复合介质材料的热膨胀系数.成型工艺对实心SiO_(2)/PTFE复合介质材料的热膨胀系数几乎没有影响.该工作为通过调控SiO_(2)/PTFE复合介质材料的微观结构来控制其热膨胀系数和介电常数提供清晰的思路.
基金Supported by the National Natural Science Foundation of China under Grant No 50472104.
文摘We study the Raman spectra of Bi4GeO12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by their high-temperature Raman spectra for the first time. The rule of structure change of BGO crystal with increasing temperature is analysed. The results show that there exists [GeO4] polyhedral structure and Bi ion independently in BGO melt. The bridge bonds Bi-O-Bi and Bi-O-Ge appear in the crystal and at the boundary layer, but disappear in the melt. The structure of the growth solid-liquid boundary layer is similar to that of BGO crystal. In the melt, the long-range order structure of the crystal disappears. The thickness of the growth solid-liquid boundary layer of BGO crystal is about 50 μm.
