Synthesis of Metal Oxide Nanostructures and Applications to Low Dielectric Loss Microwave Ceramics
| Autor: | WEI-MINLI, 李偉民 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 In recent years, applications and synthesis route of nanoscaled materials have attracted a lot of attention. Because of their unique properties, nanoparticles were widely applied to many fields. The nanoparticles have also been proven to benefit the fabrication of ceramics. In addition, the low dielectric loss materials play important roles in microwave frequency. Therefore, the nanoscaled materials were synthesized by chemical routes and applied in microwave low dielectric loss ceramics in this thesis. The behavior of nanoparticles sintering was investigated. The applications of nanoparticles and dielectric are also realized. As mentioned above, the main research of this dissertation is divided into four parts which synthesis of nanoparticles, ultra low dielectric loss magnesium titanate ceramics, low sintering temperature zinc titanate ceramics, applications to hexavalent chromium removal and CPW resonator. ZnO nanorods, TiO2 nanowires (~220 m2/g), and Mg(OH)2 nanospheres (~90 m2/g) were synthesized by chemical routes. Then, the nanoscaled powders were made for mass production and used as starting materials for ceramic sintering. The sintering behaviors and dielectric behaviors of zinc titanate and magnesium titanate were elucidate and compared. Magnesium titanate with low loss tangent (ε_r = 15.2, Q×f = 186,000 GHz, τ_f = ~ -55) was synthesized by reactive sintering method at 1400 oC. An extremely high Q×f of 368,000 GHz (ε_r = 15, τ_f = ~ -56 ) can be achieved by classical sintering at 1300 oC. The lattice constant and grain size distribution were measured to explain the Q×f difference caused by the different ceramics and initial powders. Zn2TiO4 with sufficient density, a moderate dielectric constant, a negative τ_f, and a high Q×f value have potential applications to LTCCs or microwave devices. In Zn2TiO4:xTiO2 syntheses: additive of 8 wt.% of TiO2: ε_r = ~24, Q×f = 36,300 GHz, additive of 12 wt.% of TiO2: ε_r = ~22, Q×f = 30,000 GHz, τ_f = ~0 2.4 GHz coplanar waveguide bandpass filters were simulated and designed on FR-4, Al2O3, and MgTiO3 substrates. Using the MgTiO3 substrate, the circuit area was further reduced to 50%. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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