Relationship between the structure and microwave dielectric properties of non-stoichiometric Li_2+xSiO₃ ceramics

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• 作者：Yuanming Lai ; Xiaoli Tang ; Huaiwu Zhang ; Xin Huang ; Jie Li ; Hua Su ; ^{uestcsh77@163.com}
• 关键词：Structure ; Microwave dielectric properties ; Non-stoichiometric ; Li2+xSiO3 ceramics
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：1 February 2017
• 年：2017
• 卷：43
• 期：2
• 页码：2664-2669
• 全文大小：1259 K
• 卷排序：43

文摘

Li2SiO3 ceramic is one of the most important candidate materials for high-frequency microwave ceramics; however, minimal information about the relationship between the structure and microwave dielectric properties of non-stoichiometric Li2+xSiO3 ceramics is available. In the present work, nominal Li2+xSiO3 (x=0, 0.04, 0.08, 0.12 and 0.16) ceramics were prepared by a conventional solid-state sintering technique. The structure of Li2+xSiO3 ceramics was investigated via X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) as well as Raman spectra experiment and calculation. Refinements showed that part of the non-stoichiometric Li ions entered the Li2SiO3 lattice. Along with the results of the XRD analysis, Raman spectra experiment and calculation confirmed the presence of Li2Si2O5 phase in all the samples. Compared with stoichiometric Li2SiO3, non-stoichiometric Li provided higher densification and less ordering. Moreover, the SiO4 tetrahedrons formed more ionic bonds, which reduced distortion polarization. Further, the dielectric constants, which were observed to be mainly dependent on distortion polarization and densification, firstly increased then decreased slightly with increasing non-stoichiometric Li content. However, the quality factor (Q×f), which was primarily driven by ordering degree of Li-O bonds, firstly decreased then increased with increasing non-stoichiometric Li content. The results obtained on the Li2+xSiO3 ceramics, might offer some useful information for study and application about high-frequency microwave.