Papers by Keyword: Barium Titanate (BT)

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Authors: J. Azadmanjiri, Hojjatollah K. Salehani, A. Dehghan Hamedan, M. Sadeghi
Abstract: In this work, high purity BaTiO3 (BT) nano-powders by a sol-gel process was prepared with Ba(NO3)2 and Ti(C4H9O)4 materials in order to acquire uniform size grains. The effects of the crystallinity, microstructure of BT nano-powders calcined at different temperatures and dielectric properties of the ceramics were investigated by XRD, SEM and impedance analyzer, respectively. Scanning electron microscopy and X-ray diffraction investigation revealed cubic plates and crystallite size. The results revealed that crystallite size and calcination temperature of BT and influence on the dielectric constant.
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Authors: Yong Fei Cui, Joe Briscoe, Steve Dunn
Abstract: We use BaTiO3 as a model photocatalyst to investigate the effect of ferroelectricity on catalytic activity against photocatalytic decolourisation of Acid Black 1. We find that there is a strong relationship between the degree of ferroelectric nature of the BaTiO3 and the catalytic activity. When Ag is photodeposited onto BaTiO3 to produce a modified BaTiO3, the higher tetragonal material content shows the highest photocatalytic efficiency even though there is a reduced surface area due to heat treatment. This change in the performance of the catalyst is associated with improvements in charge carrier separation due to the internal space charge layer formed in a ferroelectric due to the internal dipole.
190
Authors: Sen Wang, Zhi Hui Li, Xin Liu, Huan Zhang
Abstract: Anti–reducing effect of CaO in barium titanate based ceramic materials sintered at reducing atmosphere and the structure development of the materials has been studied in this paper.The results show: Addition of CaO in barium titanate based ceramic will keep resistivity of the sample sintered at reducing atmosphere at a high level. The resistivity of the materials increase with the increasing of CaO, and the resistivity keep in constant after the amount of CaO excess 3mol%. In the sample with sintering aid of SiO2 and BaO-excess, introducing of CaO may improve the resistivity of the materials obviously. A slight new phase formation was found in the BaO-excess sample, but no new phase formation was found in the non BaO-excess sample. If there is sintering aid of SiO2 in the sample, CaO may accelerate liquid phase film formation at the surface of grains, which will suppress the diffusion of oxygen in the grains to the environment.
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Authors: Takuya Hoshina, Hirofumi Kakemoto, Takaaki Tsurumi, Satoshi Wada, Masatomo Yashima, Kenichi Kato, Masaki Takata
Abstract: The crystal structures of barium titanate (BaTiO3) fine particles with a size around 140 nm were investigated using a synchrotron radiation X-ray diffraction method. The observed diffraction pattern was analyzed by Rietveld method assuming several models. As a result, it is found that the BaTiO3 fine particles have composite structures include (a) a tetragonal region with a constant c/a ratio, (b) a tetragonal region with gradient c/a ratios and (c) a cubic region. In order to estimate these structures, the partial profile relaxation technique was applied in the Rietveld refinement. It is considered that the composite structure is important for the size effect on BaTiO3 fine particles.
239
Authors: Takashi Oyama, Nobuyuki Wada, Hiroshi Takagi
Abstract: The role of grain boundaries (GBs) in the diffusion of oxygen vacancies (VO••s) in barium titanate (BaTiO3) and its mechanism were investigated using atomistic simulation techniques. It was found that GBs trapped VO••s at specific sites in the course of the diffusion, and the excess energy reflecting structural distortion of the GB was closely related to the availability of the trapping. GBs therefore act as a resistance of the diffusion of VO••s, suggesting that electrical degradation of multilayer ceramic capacitors (MLCCs), which is derived from vacancy diffusion, enables to be additionally improved by controlling GB structures in BaTiO3-based dielectrics.
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Authors: Gianni Ciofani, Serena Danti, Leonardo Ricotti, Delfo D’Alessandro, Stefania Moscato, Arianna Menciassi, Virgilio Mattoli
Abstract: This paper reports on two examples of biomedical applications of ceramic nanoparticles. Thanks to their physical and chemical inertia, barium titanate nanoparticles and boron nitride nanotubes have been proved to have an optimal in vitro biocompatibility, even at high concentrations. Barium titanate nanoparticles-doxorubicin composites are successfully internalized by cancer cells, and allow for a considerable enhancement of drug up-take. Conversely, boron nitride nanotubes are explored as “nanotransducers”, thanks to their excellent piezoelectric properties. These two examples encourage further investigations and applications in biology and medicine of ceramic nanomaterials, that exhibit interesting advantages respect to traditional materials.
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Authors: Tunchanoke Khongnakhon, Oratai Jongprateep
Abstract: Barium titanate has been a common material for fabrication of capacitors. Synthesis of barium titanate can be achieved by various techniques. These techniques are believed to affect dielectric properties. This research was aimed at synthesizing BaTiO3 and Ba0.9 A0.1TiO3 (A = Al and Mg) powders by solid state reaction technique. Dielectric constant of barium titanate and the ones doped with 10 at% Al and Mg prepared by the solid state reaction technique had dielectric constant ranging from 109 to 280 at 1 MHz. Results from density examination revealed that barium titanate samples prepared by the solid state reaction had low density. This may leads to the decrease of dielectric constant. Results from this study suggested that the decline of the dielectric properties was attributed to chemical composition and density of samples.
603
Authors: Yong Jun Wu, Juan Li, Makoto Kuwabara
Abstract: Electron beam lithography combined with electrophoretic deposition was investigated to fabricate micropatterned barium titanate (BTO) with nanostructures. High quality resist molds with micropatterns of microgrids and microdot arrays were prepared on Pt/Ti/SiO2/Si substrate by electron beam lithography. BTO nanocrystallites in a pseudo-cubic perovskite phase with an average particle size of about 10 nm were synthesized by a high-concentration sol-gel process. Well-dispersed and stable suspensions of barium titanate nanocrystallites were synthesized. Then, BTO microlines, microgrids and microdot arrays were electrophoretically deposited on micropatterned Pt/Ti/SiO2/Si substrate from these suspensions. The microstructure and properties of the BTO micropatterns were evaluated.
247
Authors: Pusit Pookmanee, Chanitpa Khantha, Sukon Phanichphant
Abstract: Barium titanate nanopowders were prepared from the modified oxalate co-precipitation method. Barium chloride dihydrate and potassium titanyl oxalate dihydrate were used as the starting precursors with the mole ratio of Ba:Ti as 1:1. Barium titanyl oxalate complex powders were obtained after adjusting the final of pH of the solution to 1. The precipitates were filtered, washed and dried at 100 oC for 5h. The precipitate powders were calcined at 400-700 oC for 2h. The phase transition was studied by X-ray diffractometry (XRD). Cubic structure of barium titanate was obtained after calcinations at 700 oC for 2h. The morphology and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The range of particle size was 50-100 nm with irregular in shape. The elemental composition of barium, titanium and oxygen showed the characteristic X-ray energy values.
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Authors: E.C.S. Rigo, L.A. dos Santos, L.C. de Oliveira, R.G. Carrodéguas, A.O. Boschi
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