Low-Temperature Sintering and Microwave Dielectric Properties of Zinc Metatitanate-Rutile Mixtures Using Boron |
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Authors: | Hyo Tae Kim Seong Ho Kim Sahn Nahm Jae Dong Byun Yoonho Kim |
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Affiliation: | Division of Material Science and Engineering, Korea University, 136–701, Seoul, Korea;Division of Ceramics, Korea Institute of Science and Technology (KIST), 136–791, Seoul, Korea |
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Abstract: | Mixtures of zinc metatitanate and rutile (ZnTiO3+ x TiO2, where x = 0-0.5) have been prepared via the conventional mixed-oxide method. Centrifugal planetary milling with zirconia beads 1 mm in diameter produced very fine powders (mean particle size of 0.2 µm), which allowed the synthesis of ZnTiO3 and sintering at temperatures <945°C, which is the decomposition temperature of ZnTiO3. Sintering of the mixtures was enhanced further by the addition of B2O3. Densities of >94% of the theoretical density have been attained for the specimens that were sintered at 875°C for 4 h with B2O3 additions of <1 wt%. Microwave dielectric properties of the aforementioned compositions were as follows: dielectric constant of 29-31, normalized quality factor of 56000-69000 GHz, and a temperature coefficient of resonance frequency between -10 and +10 ppm/°C. Sintering was enhanced by the formation of a ZnO-B2O3 liquid phase, which affected the microwave properties, because of variation in the phase composition. |
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