Microwave dielectric properties and crystal structures of spinel-structured MgAl2O4 ceramics synthesized by a molten-salt method |
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| Affiliation: | 1. School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073, China;2. School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China;3. Nano Science and Technology Research Center, Wuhan University, Wuhan 430072, China;1. State Key Laboratory Breeding Base of Nonferrous Metals and Specific Materials Processing, Guangxi Universities Key Laboratory of Non-Ferrous Metal Oxide Electronic Functional Materials and Devices, College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, China;2. Guangxi Key Laboratory of New Energy and Building Energy Saving, Guilin University of Technology, Guilin 541004, China;3. College of Information Science and Engineering, Guilin University of Technology, Guilin 541004, China;1. School of Science, Xi’an University of Posts and Telecommunications, Xi’an 710121, China;2. College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, China;1. College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, PR China;2. Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 210009, PR China;3. State Key Laboratory of Advanced Materials and Electronic Components, Guangdong Fenghua Advanced Technology Holding Co., Ltd, Zhaoqing 526020, PR China |
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| Abstract: | 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 27Al solid-state nuclear magnetic resonance spectra indicated that Al3+ cations primarily occupied in tetrahedral sites of the MA-M ceramic. The degree of inversion x, 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 °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. |
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| Keywords: | Spinel Microwave dielectric Molten-salt method Cation distribution MgAl2O4 |
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