Low-Loss Microwave Dielectrics Using Mg2(Ti1−xSnx)O4 (x=0.01–0.09) Solid Solution
Low-loss ceramics having the chemical formula Mg2(Ti1−xSnx)O4 for x ranging from 0.01 to 0.09 have been prepared by the conventional mixed oxide route and their microwave dielectric properties have been investigated. X-ray powder diffraction patterns indicate the corundum-structured solid solutions for the prepared compounds. In addition, lattice parameters, which linearly increase from 8.4414 to 8.4441 Å with the rise of x from 0.01 to 0.09, also confirm the forming of solid solutions. By increasing x from 0.01 to 0.05, the Q×f of the specimen can be tremendously boosted from 173 000 GHz to a maximum 318 000 GHz. A fine combination of microwave dielectric properties (r∼15.57, Q×f∼318 000 GHz at 10.8 GHz, f∼−45.1 ppm/°C) was achieved for Mg2(Ti0.95Sn0.05)O4 ceramics sintered at 1390°C for 4 h. Ilmenite-structured Mg(Ti0.95Sn0.05)O3 (r∼16.67, Q×f∼275 000 GHz at 10.3 GHz, f∼−53.2 ppm/°C) was detected as a second phase. The presence of the second phase, however, would cause no significant variation in the dielectric properties of the specimen, because the second phase properties are very similar to the primary phase. These unique properties, in particular, low r and high Q×f, can be utilized as a very promising dielectric material for ultra-high-frequency applications.
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Document Type: Research Article
Affiliations: Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Publication date: October 1, 2009