Investigation of the Dielectric Tunability of Doped-Barium Strontium Titanate Capacitor
| Autor: | Yih-Chien Chen, 陳逸謙 |
|---|---|
| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 88 Dielectric properties of (Ba0.6Sr0.4)TiO3, Al2O3-doped (Ba0.6Sr0.4)TiO3 and ZrO2-doped (Ba0.6Sr0.4)TiO3 have been characterized. The grain size of the specimen is maximum for (Ba0.6Sr0.4)TiO3 doped with 1 wt% Al2O3 content and that for (Ba0.6Sr0.4)TiO3 doped with 0.5 wt% ZrO2 content. The density and the real part of the relative dielectric constant decrease with increasing both doping content. Addition of both Al2O3 and ZrO2 broadened the real part of the relative dielectric constant-temperature dependence, which made the cubic (paraelectric) to tetragonal (ferroelectric) transition temperature ambiguous value. The dielectric constant of the specimens decreases with increasing applied DC field. The influence of DC field to the loss factor is much less than that to the dielectric constant. The tunability is about 24% for (Ba0.6Sr0.5)TiO3 doped with 1 wt% Al2O3 content and about 50% for (Ba0.6Sr0.5)TiO3 doped with 0.5 wt% ZrO2 content. Variation of fitted phenomenological coefficients with both Al2O3 and ZrO2 contents below 10 wt% is small and a rapid increase of the fitted phenomenological coefficient occurs above 10 wt%. Variation of field coefficient A and tunability with Al2O3 contents has the same trend as that of the grain size. The real part of the relative dielectric constant of Al2O3 doped barium strontium titanate decreases rapidly before 1.0 KV/cm and slowly after 1 KV/cm compare to the data obtained by the curve fitting. This can be explained by the grain boundary theory. There is a conduction loss mechanism other than the intrinsic dielectric loss for the dielectric loss under bias electric field. The variation of the saving energy ratio of the specimen with doping content has the same trend as that of the tunability. So the saving energy ratio is affected by the ratio of initial to final capacitance of the specimen. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|