Microwave dielectric properties and crystal structures of spinel-structured MgAl2O4 ceramics synthesized by a molten-salt method
Microwave dielectric properties and crystal structures of spinel-structured MgAl2O4 ceramics synthesized by a molten-salt method
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DOI：
10.1016/j.jeurceramsoc.2016.10.018
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发表时间：
2017-03-01
影响因子：
5.7
通讯作者：
Ogawa, Hirotaka
中科院分区：
文献类型：
--
作者：
Takahashi, Susumu;Kan, Akinori;Ogawa, Hirotaka
本研究对采用熔盐 (MA-M) 或固态反应 (MA-S) 方法合成的 MgAl2O4 陶瓷的微波介电性能和晶体结构进行了表征。拉曼和Al-27固态核磁共振谱表明Al3+阳离子主要占据MA-M陶瓷的四面体位点。 MA-M的反转chi程度，即四面体和八面体位点的阳离子无序程度，MA-M高于MA-S； Al3+阳离子的优先占据位点增强了MO4四面体（M=Mg和Al）中M-O键的共价性，导致晶格参数降低。在 1600°C 下烧制的 MA-M 的 Q.f 为 201,690 GHz，而在 1600°C 下合成的 MA-S 的 Q.f 仅为 85,100 GHz。基于这些结果，具有较大x的中间尖晶石结构显然具有较高的Q.f，因此阳离子分布与陶瓷的Q.f密切相关。 (C) 2016 Elsevier Ltd. 保留所有权利。
The microwave dielectric properties and crystal structures of MgAl2O4 ceramics synthesized using either molten-salt (MA-M) or solid-state reaction (MA-S) methods were characterized in this study. Raman and Al-27 solid-state nuclear magnetic resonance spectra indicated that Al3+ cations primarily occupied in tetrahedral sites of the MA-M ceramic. The degree of inversion chi, i.e., degree of cation disorder in tetrahedral and octahedral sites, of the MA-M was higher than that of MA-S; such the preferential site occupation of Al3+ cations enhanced the covalency of the M-O bonds in the MO4 tetrahedra (M= Mg and Al), leading to a decrease in the lattice parameters. The Q.f of the MA-M fired at 1600 C was 201,690 GHz, while the MA-S synthesized at 1600(circle)C exhibited a Q.f of just 85,100 GHz. Based on these results, an intermediate spinel structure with a greater x evidently has a higher Q.f, and therefore the cation distribution is closely related to the Q.f of the ceramic. (C) 2016 Elsevier Ltd. All rights reserved.