Prepartion of BaTiO3/Polyimide Composite Capacitors
| Autor: | Fong-ren Xie, 謝豐任 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In this work, dielectric properties of BaTiO3/polyimide hybrid capacitors prepared with two kinds of BaTiO3 powders undergoing different modifications were investigated. The results can be summarited as the following four parts. 1. The hybrid capacitors with the BaTiO3 powders from Alfa (AlFa-BT) and from our self-synthesized ones (SS-BT) were studied at different BaTiO3 volume ratios. The 50%SS-BT/polyimide capacitors had the highest dielectric constant of 51 and a loss-tangent value of 0.02. 2. The dielectric properties of BaTiO3/polyimide capacitors were investigated for ceramic powders undergoing different sintering treatments. For the Alfa-BT capacitors, the crystallinity of BaTiO3 powder was improved. The dielectric constant of hybrid capacitors with 1200oC-treated powders was 35 but it was 16 for those with the as-received powders. For the SS-BT capacitors, the BaTiO3 powders had good crystallinity after it was sintered at 1200oC. The dielectric constant of hybrid capacitors with 1200oC-treated powders was 55 and it reached 51 for those with the as-fabricated powders. 3. To investigate the effect of ceramic particle size on the dielectric properties, the SS-BT and the 1200oC-treated BaTiO3 powders were underwent the high-speed planetary ball milling. The results displayed a refinement in particle size. The SS-BT powders with a particle size of 300 nm reduced to 260 nm and 130 nm after they were ball milled for 3h and 6h, respectively. The 1200oC-treated SS-BT powders with a particle size of 356 nm reduced to 243 nm and 134 nm after they were ball milled for 3h and 6h, respectively. The generated hydroxyl group on the milled powders provided the good dispersion for the fine powders. The dielectric constant of 51 for the 50% SS-BT/polyimide capacitors decreased to 27 after the planetary ball milling. It changed from 55 to 26 for the 1200oC-treated BaTiO3/polyimide capacitors. 4. To investigate the effect of surface modification of ceramic powder on the capacitor dielectric properties, the surfaces of Alfa-BT and SS-BT powders were firstly functionalized with hydroxyl group followed by chemically bonding with 3-glycidoxypropyltrimethoxysilane (GPTMS). The dispersion of BaTiO3 in polyimide was greatly improved, but the dielectric constants of capacitors apparently reduced. The 30% Alfa-BT/polyimide capacitors reduced its dielectric constant from 16 to 14 after the surface modification by silane. It changed from 27 to 14 for the SS-BT/polyimide capacitors. Key word：Barium titanate、Polyimide |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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