Transparent polycrystalline MgAl2O4 ceramic fabricated by spark plasma sintering: Microwave dielectric and optical properties |
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Authors: | Ping Fu Wenzhong Lu Wen Lei Yong Xu Xuehua Wang Jiamin Wu |
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Affiliation: | 1. Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China;2. Key Laboratory of Functional Materials for Electronic Information(B) MOE, Huazhong University of Science and Technology, Wuhan 430074, China;3. Department of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073, China |
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Abstract: | The optical properties and microwave dielectric properties of transparent polycrystalline MgAl2O4 ceramics sintered by spark plasma sintering (SPS) through homemade nanosized MgAl2O4 powders at temperatures between 1250 °C and 1375 °C are discussed. The results indicate that, with increasing sintering temperatures, grain growth and densification occurred up to 1275 °C, and above 1350 °C, rapid grain and pore growth occurred. The in-line light transmission increases with the densification and decreases with the grain/pore growth, which can be as high as 70% at the wavelength of 550 nm and 82% at the wavelength of 2000 nm, respectively. As the sintering temperature increases, Q×f and dielectric constant εr values increase to maximum and then decrease respectively, while τf value is almost independent of the sintering temperatures and remains between −77 and −71 ppm/°C. The optimal microwave dielectric properties (εr=8.38, Q×f=54,000 GHz and τf=−74 ppm/°C) are achieved for transparent MgAl2O4 ceramics produced by spark plasma sintering at 1325 °C for 20 min. |
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Keywords: | Transparent MgAl2O4 ceramics Spark plasma sintering In-line transmittance Microwave dielectric properties |
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