• Title/Summary/Keyword: Barium Hydroxide

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Synthesis of Monodispersed Barium Titanate Nanopowders by Alkoxide-Hydroxide Sol-Precipitation Method

  • Yoon, Song-Hak;Kim, Min-Gyu;Shin, Nam-Soo;Kim, In-Sung;Baik, Sung-Gi
    • Journal of the Korean Ceramic Society
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    • v.43 no.11 s.294
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    • pp.710-714
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    • 2006
  • Barium titanate nanoparticles were synthesized under N$_2$ atmosphere by the hydrolysis and condensation of barium hydroxide octahydrate and titanium (IV) isopropoxide. The synthesized particles were aggregates of nanosized primary particles. The primary particles of about 20-50 nm in diameter became building blocks of larger secondary particles, which are in most cases spherical in shape. The size and morphological evolution of secondary particles are strongly related to the precursor concentration. The observations suggest that formation and control of secondary particles is an essential step in the alkoxidehydroxide sol-precipitation process to obtain monodispersed barium titanate nanopowders.

Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.350-355
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    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

A new low dielectric constant barium titanate - poly (methyl methacrylate) nanocomposite films

  • Upadhyay, Ravindra H.;Deshmukh, Rajendra R.
    • Advances in materials Research
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    • v.2 no.2
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    • pp.99-109
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    • 2013
  • In the present investigation, nanocomposite films with poly(methyl methacrylate) (PMMA) as a polymer matrix and barium titanate as a filler were prepared by solution casting method. Barium titanate nano particles were prepared using Ti(IV) triethanolaminato isopropoxide and hydrated barium hydroxide as precursors and tetra methyl ammonium hydroxide (TMAH) as a base. The nanocomposite films were characterized using XRD, FTIR, SEM and dielectric spectroscopy techniques. Dielectric measurements were performed in the frequency range 100 Hz-10 MHz. Dielectric constant of nanocomposites were found to depend on the frequency, the temperature and the filler fraction. Dissipation factors were also influenced by the frequency and the temperature but not much influenced by the filler fractions. The 10 wt% of BT-PMMA nanocomposite had the lowest dielectric constant of 3.58 and dielectric loss tangent of 0.024 at 1MHz and $25^{\circ}C$. The dielectric mixing model of Modified Lichtenecker showed the close fit to the experimental data.

Development and Evaluation of a Carbon Dioxide Diffusive Sampling Method using Barium Hydroxide (수산화바륨을 이용한 이산화탄소 확산측정법의 개발 및 평가)

  • Yim, Bongbeen
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.1
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    • pp.56-63
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    • 2013
  • This study was aimed at developing and evaluating a diffusive sampling method using a barium hydroxide solution as an absorbent for measuring carbon dioxide ($CO_2$) in ambient air. The collected $CO_2$ concentration was calculated by the change of conductivity resulted in the reaction of $CO_3{^{2-}}$ and $Ba^{2+}$ in aqueous solution. The sampling rate for the diffusive sampler was determined 0.218 mL/min, as obtained from the slope of the linear correlation between the $CO_2$ mass collected by the diffusive sampler and the time-weighted $CO_2$ concentration with the active sampling method. The unexposed blank sampler sealed in aluminium foil-polyethylene laminated packets has remained stable during at least one-month storage period. A good correlation was observed between the diffusive sampler and active sampler with a coefficient of determination of 0.956. This diffusive sampler would be suitable for the indoor $CO_2$ concentration monitoring.

Preparation of Submicron Barium Titanate Powders. (초미립 $BaTiO_3$의 합성)

  • 안영필;김복희;황재석;유경섭
    • Journal of the Korean Ceramic Society
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    • v.21 no.3
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    • pp.278-282
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    • 1984
  • Barium titanate powder was made by firing the complex hydroxide which had been synthesized with chemical wet process by the medium of $H_2O_2$. This experiment was done as following A mixed solution of $BaCl_2$, $TiCl_4$ and $H_2O_2$ with 1:1:10 mol ratio was prepared. Ammonium hydroxide was added into the mixed solution. In the range of pH 8-10 $BaTiO_3$ complex hydroxide was obtained and treated at room temperature 11$0^{\circ}C$, 20$0^{\circ}C$, 40$0^{\circ}C$ and $600^{\circ}C$. The results obtaiined from this experiment were as follows. At room temperature $BaTiO_3$ complex hydroxide was amorphous. Above 10$0^{\circ}C$ crystalline $BaTiO_3$ was obtained and particle size of $BaTiO_3$ was increased with elevated temperature. So the particle size of BaTiO3 could be controlled by the firing temperature. After treating $BaTiO_3$ complex hydroxide at 10$0^{\circ}C$ the average particle size of $BaTiO_3$ was 0.22$\mu\textrm{m}$.

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Conditions for the Formation of Ba-Ferrite by Hydrothermal Synthesis (수열합성에 의한 Ba-Ferrite의 형성조건)

  • 이경희;이병하;윤갑중
    • Journal of the Korean Ceramic Society
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    • v.22 no.5
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    • pp.61-65
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    • 1985
  • This stud deals with the conditions for the Formation of Ba-Ferrite by Hydrothemal synthesis Suspensions Containing either iron(III) hydroxide or hydroxide oxide and barium ians were subjected to autoclavings at various temperatures from 150 to 30$0^{\circ}C$. A ferromagnetic precipitate BaO.$6Fe_2O_3$ consisting of hexagonal plate-like particle was obtained by suitable combination of temperature and concentration of KOH

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Fabrication of YBa_2Cu_3O_{7-x}$ceramic using the Sol-Gel process (졸-겔 법으로 YBa_2Cu_3O_{7-x}$세라믹의 제조)

  • Kim, Hyun-Taek;Kang, Hyung-Boo;Kim, Bong-Heup
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.299-301
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    • 1989
  • This study presents a method of preparing $YBa_2Cu_3O_{7-x}$ ceramic and chlorine doping in it for the purpose of Jc enhancement us ins sol-gel process.Tetramethylammonium-hydroxide and pottasium carbonate solution were added to the aqueous solution of Yttrium nitrate, Barium chloride and Copper nitrate for pH control as well as forming hydroxy-carbonate precipitation. Instead of Barium nitrate, Barium chloride was used for doping chloride impurities in the specimen. The resulted materal showed good high Tc-superconductivity after calcination. Tc and Jc value are 92 K and 120.8 $A/cm^2$ respectively.

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