Influence of Ti4+ substitution for Ta5+ on the crystal structure,Raman spectra,and microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 ceramics |
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| Affiliation: | 1. College of electronic information, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China;2. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi''an Jiaotong University, Xi''an, 710049, Shanxi, China;3. College of Materials Sciences and Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China;4. Department of materials sciences and engineering, Shandong university of sciences and technology, Qingdao, 266590, Shandong, China;5. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China;6. Department of Materials Science and Engineering, The University of Sheffield, Sheffield, S13JD, UK;1. Guangxi Key Laboratory of Optical and Electronic Materials and Devices, College of Material Science and Engineering, Guilin University of Technology, Guilin, 541004, China;2. College of Information Science and Engineering, Guilin University of Technology, Guilin, 541004, China;1. Guangxi Key Laboratory of Optical and Electronic Materials and Devices, College of Material Science and Engineering, Guilin University of Technology, Guilin, 541004, China;2. School of Materials Science and Engineering, Nanchang University, Nanchang, 330031, People''s Republic of China;3. Department of Mechanical and Construction Engineering, Faculty of Engineering and Environment, Northumbria University at Newcastle, NE1 8ST, UK |
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| Abstract: | This paper systematically investigated the influence of Ti4+ substitution for Ta5+ on the phase composition and microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1, 0.2, and 0.3) ceramics with hexagonal tungsten bronze-like structures. X-ray diffraction and Rietveld refinement results indicated that single-phase Ba3Ta4Ti4O21 could be obtained only with the x values of 0.1 and 0.2, and a secondary phase was detected at an x value of 0.3. The valence state of Ba3Ta4-4xTi4+5xO21 (x = 0.2) ceramics was analyzed through X-ray photoelectron spectroscopy. Increasing Ti4+/Ta5+ ratios could reduce sintering temperature and improve the microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 solid solutions. However, the dielectric properties, particularly the quality factor, of Ba3Ta4-4xTi4+5xO21 ceramics deteriorated severely as a result of oxygen vacancy defects caused by the transition of the valence state from Ti4+ to Ti3+ when x = 0.2 and the coexistence of the secondary phase when x = 0.3. Infrared reflectivity spectroscopy was performed to explore the intrinsic dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1) ceramics. The measured and extrapolated microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1) ceramics sintered at 1240 °C for 6 h were εr ~ 46.5, Q × f = 13,900 GHz, τf ~ +49.4 ppm/°C, and εr ~ 44, Q × f = 34,850 GHz. |
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| Keywords: | Tungsten bronze-like structure Microwave dielectric properties Solid solution Infrared reflectivity |
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