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Sintering and Dielectric Properties of Excess Bi 2 O 3 doped
| Content Provider | Semantic Scholar |
|---|---|
| Author | Chung, Ho-Hua Yang, Cheng-Fu Chung, Yi-Chang Kung, Cheng-Yuan |
| Copyright Year | 2005 |
| Abstract | In this study, ferroelectric materials with Bi-layered structure BaBi2Nb2O9 with excess x wt% Bi2O3 (x=0, 1.5, and 3) are investigated as the main compositions, and the sintering is proceeded from 1000C~1100C. The effect of Bi2O3 on the morphologies, crystal structure, and dielectric characteristics of BaBi2Nb2O9 ceramics is developed with the aid of SEM, X-ray diffraction, and dielectric-temperature curves. Dielectric properties are investigated in the temperature of 25C~ 465C at frequency 10KHz~1MHz. It is found that sintering temperature and Bi2O3 content has no apparent influence on the Curie temperatures, but they have large influence on the maximum dielectric constants. Introduction The layer structured ferroelectrics compound is one of the most technologically interesting materials for the memory application of ferroelectrics thin films. The layer structured bismuth oxides consist of one to three slabs of perovskite-like layers, separated by fluorite-like (Bi2O2) layers [1] and have the general formula: An-1Bi2BnO3n+3, where A is usually a divalent ion, such as Sr, Ba, or Pb, and B is Ti, Nb, or Ta [2-4]. Systematic analysis has shown that the large spontaneous polarization observed along the pseudo-cubic a axis can be largely attributed to the displacement of the A-site cation in the perovskite block and not the movement of the B-site cation. The spontaneous polarization of layer structured bismuth oxides increase in Bi3TiNbO9 and Bi4Ti3O12 due to the gross underbonding of Bi on the perovskite A site [5,6]. BaBi2Nb2O9 is one of the Aurivillus phases, which are a class of layer structured bismuth oxides [7]. Though excess amount of Bi2O3 in layer structure bismuth oxides is known to affect the ferroelectric properties as well as the crystal structure [8,9], a comprehensive study of excess Bi2O3 on BaBi2Nb2O9 is still lacking. In this study, we are interesting to investigate ceramic materials based on BaBi2Nb2O9 composition, excess Bi2O3 is added to develop the sintering and dielectric properties of BaBi2Nb2O9 ceramics. Excess Bi2O3-doped BaBi2Nb2O9 compositions are sintered at different temperature and their crystal structures are examined. The dielectric characteristics are investigated as a function of sintering temperature, Bi2O3 content, and measured frequency. Experimental Procedures The ceramic materials BaBi2Nb2O9 were prepared by the mixed oxide method. Reagent-grade raw materials of BaCO3, Bi2O3, and Nb2O5 with higher than 99.5% purity were used as starting materials, mixed according to the composition BaBi2Nb2O9 + x wt% Bi2O3 (x=0, 1.5, and 3) and ball-milled for 5h with deionized water. After drying and grinding, then the powder was calcined at 850C for 3h. After calcination the powders were ground again, then polyvinylalcohol (PVA) was added as a binder. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.kyu.edu.tw/93/95paper/v8/95-071.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
