Papers by Keyword: BaTiO3

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Authors: Liang Luo, Yan Jun Zhu, Ling Ling Song, Xiao Bo Zhang
Abstract: A facile one-pot hydrothermal method has been developed for synthesis of porous and non-porous BaTiO3 ceramics using Ba(OH)2.8H2O, BaCO3 as barium source. In this paper, we research the effect of different barium source on the nanostructure of BaTiO3 ceramics in a solid state reaction, and the results indicated that the two different morphologies of BaTiO3 ceramics can be easily prepared by using these two different barium source. The phase composition and morphology of the as-obtained products were investigated by X-ray diffraction and field emission scanning electron microscopy (SEM).
Authors: Tetsuya Yamamoto, Toshio Sakuma
Authors: Atsushi Honda, Shin'ichi Higai, Takafumi Okamoto, Noriyuki Inoue, Yasuhiro Motoyoshi, Nobuyuki Wada, Hiroshi Takagi
Abstract: We performed first-principles calculations to examine the interaction among rare-earth (RE), alkaline-earth (AE) elements and oxygen vacancy (VO) in BaTiO3, in order to clarify the combined effects of VO trapping by two different elements. It was found that there is a synergistic effect of VO trapping by RE at Ba site and AE at Ti site, so that the co-doping is effective to improve insulating reliability of BaTiO3. We also verified that the local atomic structures around dopants obtained by calculations well agree with that obtained experimentally by extended X-ray absorption fine structure (EXAFS) analyses. The present work is the first one to clarify the structural environment around dopants including VO by both theoretical and experimental approaches.
Authors: Tomonori Nakamura, Harunobu Sano, Takehiro Konoike, Kunisaburo Tomono
Authors: Maria V. Nikolić, Vera P. Pavlović, Vladimir B. Pavlović, Nebojsa Labus, B.D. Stojanović
Abstract: In this paper a practical approach to the analysis of sintering of BaTiO3 using the Master Sintering Curve concept has been presented. Non-isothermal sintering of high-purity non-doped BaTiO3 ceramics was monitored using a sensitive dilatometer at three different heating rates (10, 20 and 30 oC/min) up to 1380oC. Densification of BaTiO3 during sintering was analyzed using the Master Curve Sintering Theory. A MSC was defined characterizing the sintering behavior of barium-titanate regardless of the heating rate. Construction of the MSC enabled estimation of the process activation energy. Using defined MSC, densification behavior of BaTiO3 ceramics during sintering can be predicted for arbitrary temperature-time excursions and these predictions can be used in controlling and planning the sintering process of this material.
Authors: Pusit Pookmanee, P. Ketwong, Sukon Phanichphant
Abstract: Barium titanate (BaTiO3) was synthesized by the oxalate method with the starting precursors as barium chloride and potassium titanium oxalate with mole ratio of 1:1. Precipitate was obtained after adding oxalic acid until the pH of the final solution was 4. The precipitate was milled and calcined at 700 oC for 2h. Mn-doped barium titanate (BaMnTiO3) was prepared by the impregnation method. Barium titanate calcined at 700 oC was mixed with 2 and 4 mole % of Mn from manganese chloride. The mixed powder was calcined at temperatures of 800 oC and 900 oC for 2h. The phase of BaMnTiO3 was studied by X-ray diffraction (XRD). Hexagonal structure of Ba(Mn0.33Ti0.67)O2.84 was obtained after calcination at 900 oC for 2h with 2 and 4 mole % of Mn. The morphology and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The particle size of Ba(Mn0.33Ti0.67)O2.84 powder was in the range of 50-60 nm with irregular in shape. The elemental composition of barium, manganese, titanium and oxygen showed the characteristic X-ray energy values.
Authors: Jung Min Lee, Myoung Pyo Chun, Hyo Soon Shin, Byung Ik Kim, Jong Heun Lee
Abstract: Two different BaTiO3 (160nm) nanopowders coated with Y and with Dy were fabricated by an aqueous chemical coating method, and their dielectric properties and microstructures were investigated with X-ray diffraction, Impedance analyzer, SEM and TEM. Y and Dy were coated on the BaTiO3 powder using nitrates. Coated BaTiO3 powders were pressed in a disk shape and sintered at 1150~1200°C for 2 hours in reduced atmosphere of 10%H2 - 90%N2. Coating layer of the BaTiO3 particle was thin with a thickness of 3 ~ 5nm. Coated BaTiO3 sintered sample exhibited a larger lattice parameter (a, c) and smaller tetragonality (c/a) than pure BaTiO3 one. Y coated BaTiO3 sample sintered at 1200°C showed good dielectric properties with a high dielectric constant of around 2000 and a stable temperature coefficient of capacitance (TCC).
Authors: Hiroaki Takeda, Han Joong Sang, Takashi Tateishi, Spela Kunej, Colin Leach, Robert Freer, Takuya Hoshina, Takaaki Tsurumi
Abstract: BaTiO3–(Bi1/2K1/2)TiO3 (abbreviated as BT-BKT) solid solution ceramics, as a lead-free PTC (positive temperature coefficient of resistivity) thermistor material usable over 130°C, has been synthesized by sintering in N2 atmosphere and after annealing in air over 1200°C. In the BT-BKT ceramics with PTC property, the impedance/modulus spectroscopic plots have revealed that a third resistance-capacitance (RC) response besides grains and grain boundaries. Using the remote electron beam induced current (REBIC) configuration, imaging has revealed EBIC contrast consistent with the presence of negatively charged electrostatic grain boundary barriers in the BT-BKT semiconducting ceramics.
Authors: Yi Ping Guo, Kazuyuki Suzuki, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: BaTiO3 films with thickness of ~1 2m were prepared by chemical solution deposition on LaNiO3/Pt/TiOx/SiO2/Si substrate with a thin highly (100)-oriented and high crystallinity BaTiO3 thin film (~140 nm) as a buffer layer. The BaTiO3 films prepared by using a 0.5 mol/L solution have high crystallinity and still show (100) preferred orientation. The electrical properties of the (100)-oriented BaTiO3 films prepared by this process have been studied. A dielectric constant of ~910 and a loss tangent of ~3.5% (1 kHz) were obtained. The remanent polarization (2 Pr) and coercive field (2 Ec) are 4.0 μC/cm2 and 35 kV/cm, respectively.
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