• 분석과학
• /
• 제11권4호
• /
• pp.260-265
• /
• 1998

$Ba^{2+}$와 $Ti^{4+}$이온의 산성용액에서 dimethyl oxalate의 열분해에 의해서 구형이고 ${\mu}m$크기의 barium titanyl oxalate입자를 합성하였다. 침전은 몇 가지 음이온이 공존이온으로 존재하는데서 수행하였다. 입자의 평균크기가 $0.2{\sim}3{\mu}m$이고 독특한 입자분포를 가진 구형의 입자가 지지 음이온의 종류, 옥살산 음이온의 생성속도, 그리고 숙성시간에 따라서 형성되었다. 숙성시간이 120 min에서 용기 밑바닥에 가라앉은 barium titanyl oxalate 입자는 지지 음이온의 종류에 따라 약 $1.5{\sim}3{\mu}m$의 단일 임계크기까지 성장하였다. 고품위의 barium titanyl oxalate를 제조하기 위해 염산이온을 지지음이온으로 선택하고 반응온도를 높혀주어야함을 이로부터 만든 barium titanate의 XRD 스펙트라 및 화학분석 데이터의 검토로 알 수 있었다.

• 대한금속재료학회지
• /
• 제49권12호
• /
• pp.977-982
• /
• 2011

Migration and interaction of multi-protons in a zinc-doped barium zirconate (Zn-doped $BaZrO_3$) super cell were investigated using a density functional theory. O ions in the super cell form interconnected octahedrons with Zr or Zn ions positioned in their centers and Ba ions positioned among the eight octahedrons. When one proton was added to the super cell, the energy barrier of 0.80 eV for proton transfer from the first to second nearest O ion sites from the Zn ion reached its highest value. When two protons were added to the super cell, the two protons preferred the first nearest O ions from the Zn ion. The two protons were accommodated by pushing the neighboring Zn ion further away from the center of the octahedron. Energy barriers for proton transfer from the Zn-octahedron to the neighboring Zr-octahedron were spread in the range of 0.36 ~ 1.02 eV.

• 멤브레인
• /
• 제29권6호
• /
• pp.355-361
• /
• 2019

본 연구에서는 기존의 CDI (capacitive deionization)를 이용해 산업 폐수에 함유되어있을 수 있는 바륨 이온 제거에 관해서 연구하였다. Feed 용액은 30 mg/L의 BaCl₂ (barium chloride dihydrate) 수용액을 사용하였고, 유속은 10 mL/min 설정하였다. 흡착 조건을 1.2 V에서 3, 5, 7분으로, 탈착 조건은 각각 -1, -1.5, -2 V 및 1, 2, 3분으로 다양하게 조정하여 가장 효율이 높은 조건을 선정하는 실험을 진행하였고, 그 결과 흡착 1.2 V/7분 탈착 -1 V/1분의 조건에서 64.4%의 바륨 이온 제거효율을 나타내었다. 동일한 실험 조건으로 바륨과 같은 농도인 30 mg/L NaCl 수용액에 대하여 CDI의 제거효율과 비교 분석한 결과 흡착 1.2 V/7분 탈착 -1 V/1분의 조건에서 69.9%의 제거효율을 나타내었다.

• Applied Microscopy
• /
• 제48권1호
• /
• pp.27-32
• /
• 2018

Barium titanate ($BaTiO_3$) nanoparticle is one of the most promising materials for future multi-layer ceramic capacitor and ferroelectric random access memory. It is well known that electrical property of nanoparticles depends on the atomistic structure. Although surface may possibly have an impact on the atomistic structure, reconstructed structure at the surface has not been widely investigated. In the present study, Ba-ion position near surface in a $BaTiO_3$ nanoparticle has been quantitatively characterized by scanning transmission electron microscopy. It was found that some Ba ions at the surface were greatly displaced in non-uniform directions.

• 전기의세계
• /
• 제26권1호
• /
• pp.82-86
• /
• 1977

Semiconducting Barium Titanate shows resistivity anomaly near the transition temperature 120.deg. C. Its transition temperature decreases about 6-7.deg. C per 1 mole % SnO$_{2}$, which is likely to compose (BaSb) (TiSn) $O_{3}$ structure by making Sn$^{+4}$ ions occupy Ti$^{+4}$ ion sites. Grain boundories, whose existance is the cause of having high resistivity in Semiconducting BaTiO$_{3}$ disappear due to the spontaneous polarization below the transition temperature, and it is believed that the phase transition makes semiconducting BaTiO$_{3}$ have resistivity anomaly at certain temperature. Temperature and frequency dependencies of resistivity are also investigated for practical application.ion.

• Journal of Magnetics
• /
• 제4권2호
• /
• pp.65-68
• /
• 1999

The M-type barium ferrite ($BaFe_{12}O_{19}$) is well known magnetic material to be used as a permanent magnet due to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ sublattices reduces the uniaxial anisotropy and those compounds open a new application field of noise suppressor at high frequencies. In this study, the magnetic and microwave absorbing properties are investigated in Ti-and Co-substituted barium ferrites ($BaFe_{12-2X} Ti_XCo_XO_{19}$). The saturated magnetization decreases linearly with the substitution of Ti and Co. The rapid drop in coercive force is observed with Ti and Co substitution upto x=1.2. The magnetic permeability spectrum shows the natural magnetic resonance in the specimens with small coercive force and large attenuation of microwave is predicted in those specimens at high frequencies (above 4 GHz).

• Bulletin of the Korean Chemical Society
• /
• 제18권6호
• /
• pp.600-603
• /
• 1997

Spherical, submicrometer particles of barium-titanyl oxalate were homogeneously precipitated by thermal decomposition of diethyl oxalate in acidic aqueous solutions. The rates of oxalate ion generations, determined by various combinations of temperature and initial concentration of diethyl oxalate had a very important effect on the particle size distribution. Monosized, bimodal, or broad unimodal powders were obtained under certain combinations of experimental variables.

• Bulletin of the Korean Chemical Society
• /
• 제7권4호
• /
• pp.267-271
• /
• 1986

The ionomeric blend and the ionic aggregation studies by using a Fourier-transform infrared spectroscopy(FT-IR) are presented. Two ionomers were prepared, one is barium polyacrylate and the other is barium polystyrenesulfonate. The blend of the two ionomers of the barium salts shows intermolecular ionic interaction between the carboxylated ionomer and the sulfonated ionomer. This interaction leads to considerable differences between the spectrum of the blend and the sum of the spectra of the pure ionomers. From our results, it is shown that ionic interactions must play an important role in the compatibility of the two ionomers. In the ionic aggregation study, the bands due to asymmetric stretching mode of carboxylate anion(COO-) in the carboxylated ionomer and the ionomer blend increase in intensity with increasing the divalent barium cations. These results indicate the formation of ion pairs. The doublet due to the asymmetric stretching modes of the carboxylate anion(COO-) is concerned with a sort of local structure found in the ion aggregation. By considering a possible structure for multiplets in the blend, the spectral splitting and the frequency shift are well explained.

• Journal of Magnetics
• /
• 제21권4호
• /
• pp.496-502
• /
• 2016

Doped and undoped barium hexaferrite powders ($BaFe_{12}O_{19}$, $Ba_{0.7}Ti_{0.3}Fe_{12}O_{19}$ and $Ba_{0.7}La_{0.3}Fe_{12}O_{19}$) were produced by the sol-gel method. The effects of substituting elements were studied in terms of the magnetic properties of barium hexaferrite powders. The magnetic properties were remarkably changed by the substitution of $La^{3+}$ and $Ti^{4+}$ ions for the $Ba^{2+}$ ion and were accompanied by oxygen deficiency in the $BaFe_{12}O_{19}$. Coercivities ($H_C$) from 4200 to 5100 Oe, remanences ($M_R$) from 22 to 49 emu/g and saturation magnetizations ($M_S$) from 41 to 73 emu/g were obtained for different samples. The obtained results were discussed in detail.

• 한국대기환경학회지
• /
• 제29권1호
• /
• pp.56-63
• /
• 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.