• 보존과학회지
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• 제38권1호
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• pp.1-13
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• 2022

Colour consistency is an important consideration when selecting pigments used on works of art. In this study, we analyse the colour difference between two sets of synthetic blue glass pigments acquired at least 8 years apart from the same manufacturer in Japan. The old pigment set (unused, dry powder with four different grain sizes) appears faded compared to the new set. These pigments are made available for artistic use, commonly in Nihonga or Japanese paintings. Raman spectroscopy and SEM-EDS results characterize these pigments as cobalt aluminate spinels dissolved in leaded glaze, a special class of complex coloured inorganic pigments that is not well-understood in the field of conservation. Colour difference between the old and new pigments with four different grain sizes were quantified by analysing photomicrographs with image analysis software. Blue pigments with coarse and extremely fine grains showed significant colour change compared to pigments with medium and fine grain sizes. The high occurrence of crystallites in the finer grains give a final colour that is bluer and lighter. Possible causes for the colour difference including manufacturing methods and storage environment are discussed.

• 한국응용과학기술학회지
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• 제30권2호
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• pp.233-243
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• 2013

무지개 빛을 내는 무기진주광택안료는, 내광성, 내용제성 및 내열성 등이 물리적 화학적 안정성이 우수하여 다양한 분야에서 응용되고 있다. 본 연구는 수열합성방법을 사용하여 마이카 티타니아에 파란색 코팅 안료인 염화코발트를 기본으로 화장품 안료로 사용되는 진주광택안료를 합성하였다. 코발트에 의한 안료의 색상을 보완하고자 코발트와 금속 염의 비를 달리하여 안료를 코팅하고, 이를 통해 금속염의 종류에 따라 다양한 색차값을 구현하는 진주광택 안료를 합성하였다. 코발트와 첨가된 금속 염 전구체의 조성비와, 금속 염의 종류에 따라 코팅 특성과 색상을 조절할 수 있었고, 안료의 다양한 색상변화 특성을 색차계를 통해 확인 하였다. 합성된 안료는 SPM, SEM, XRD, EDS 기기를 통해 특성을 분석하였다.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.47-51
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• 2010

A powder, containing 80 percent of blue cobalt aluminate $(CoAl_2O_4)$ crystallites, was synthesized at $210 ^{\circ}C$ using a (metal nitrate-malonic acid-ammonium hydroxide-ammonium nitrate) system. The optimal amount of concentrated ammonia water and initial decomposition temperature were determined for the blue $CoAl_2O_4$ crystallites preparation. Three $CoAl_2O_4$ precursor pastes, corresponding to the various amounts of concentrated ammonia water, were prepared by evaporating the initial solutions in an electric furnace fixed at $80 ^{\circ}C$ under a vacuum of 25 torr. The initial solution was used to dissolve the starting materials. The powder with the maximum content (80%) of blue $CoAl_2O_4$ crystallites was prepared when the prepared precursor was decomposed at $210 ^{\circ}C$. The blue $CoAl_2O_4$ crystallite content in the prepared sample decreased with increasing initial decomposition temperature. For 0.2 mole of the $Al^{3+}$ ion, the chemical compositions of the precursor corresponded to molar ratios of 0.4, 1.40, 2.56 and 2.00 for the $Co^{2+}$ ion, malonic acid, ammonia and ammonium nitrate per mole of the $Al^{3+}$ ion, respectively. The blue $CoAl_2O_4$ crystallite content in the sample decreased with the amount of ammonia deviated from the optimal value. The characteristics of the powders were examined using X-ray diffraction, optical microscopy, Fourier transformation infrared spectroscopy and the Brunauer-Emmett-Teller technique.

• Advances in nano research
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• 제12권4호
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• pp.415-426
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• 2022

Nickel substituted cobalt-zinc ferrite nanoparticles with composition Co_0.5Zn_0.5Ni_xFe_2-xO₄ (x = 0.25, 0.5, 0.75, 1.0) were synthesized using a wet chemical method named citrate precursor method. Various characterizations of the prepared nanoferrites were done using X-ray powder diffractometry (XRD), Scanning electron microscopy (SEM), UV visible spectroscopy and Fourier transform spectroscopy technique (FT-IR). XRD confirmed the formation of cubic spinel structure of the samples with single phase having one characteristic peak at (311). The value of optical band gap (E_g) was found to decrease with Ni substitution and have values in the range 2.30eV to 1.69eV. A Fenton-type system was created by photocatalytic activity using source of visible light for removal of methylene blue dye. Observations revealed increase in the degradation of methylene blue dye with increasing nickel content in the samples. The degradation percentage was increased from 77.32% for x = 0.25 to 90.16% for x = 1.0 in one hour under the irradiation of visible light. Also, the degradation process was found to have pseudo first order kinetics model. Hence, it can be observed that synthesized nickel doped cobalt-zinc ferrites have good capability for water purification and its degradation efficiency enhanced with increase in nickel concentration.

• 수완나부미
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• 제2권1호
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• pp.1-16
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• 2010

Vietnamese Blue and White Porcelain is famous for its unique form and colour of cobalt. It is said to be producted from the late of 14th Century to now. Vietnamese Blue and White Porcelain of 14th Century has a Mum design similar to that of Blue and White Porcelain of 14th Century in China. The Vietnamese Blue and White Porcelain of 15th, 16th Century was trade Ceramics which were shipped overseas. A base, having a dated inscription corresponding to 1450 and kept in the Topkapi Saray Museum is the best example of Vietnamese trade ceramics. The Vietnamese Blue and White Porcelain of 15th, 16th Century was a substitute for Chinese trade ceramics in these times when China had a police of the closure of China borderers to sea trade to protect China and was exported to the western Asia and the Southeast Asia. In recent, Fustat relics of Egypt was excavated the Vietnamese Blue and White Porcelain. It means that Vietnamese Ceramics of 15th, 16th Century was substitute for Chinese trade ceramics. In addition, Thai Blue celadon of 15th Century was exported to the western Asia as like Vietnamese Blue and White Porcelain. But when a police of the closure of China borderers to sea trade in China was stopped in the late of 16th Century and Chinese Ceramics were reborn in the same time, the Vietnamese Blue and White Porcelain was declined as trade items.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.101-106
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• 1997

• 대한한의학회지
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• 제18권2호
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• pp.15-32
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• 1997

This study was undertaken to define the mechanism of Siegesbeckiae Herba-induced relaxation in rabbit common carotid artery contracted by agonists. In order to investigate the effect of Siegesbeckiae Herba on contracted rabbit carotid arterial strips, transverse strips with intact or damaged endothelium were used for the experiment using organ bath. To analyze the mechanism of Siegesbeckiae Herba-induced relaxation, Siegesbeckiae Herba extract infused into contracted arterial strips induced by agonists after treatment of lanthanum chloride, indomethacin, atropine, $N\omega-nitro-{_L}-arginine$, cobalt chloride or methylene blue. The relaxation effect of Siegesbeckiae Herba was dependent on the presence of endothelium, showing that Siegesbeckiae Herba-induced relaxation was not observed in the strips without endothelium. The endothelium-dependent relaxation induced by Siegesbeckiae Herba was suppressed by the pretreatment of lanthanum chloride, $N\omega-nitro-{_L}-arginine$, cobalt chloride or methylene blue, but it was not observed in the strips pretreated with indomethacin or atropine. These results demonstrated that Siegesbeckiae Herba may inhibit agonist-induced contraction through an increase in the cyclic GMP by the production of nitric oxide in the vascular endothelial cells.

• 한국세라믹학회지
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• 제48권2호
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• pp.134-140
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• 2011

To study the effect of color development of Ni-doped willemite blue pigments, five batches of compositions were prepared and fired at $1350^{\circ}C$/hold for 1 h. When Ni was substituted for ZnO by 0.03 mole the optimum result were obtained. Then they were fired at $1300^{\circ}C$ and held for 1, 2, 4 and 6 h respectively for the purpose sake. XRD, Raman spectroscopy, FT-IR, UV-vis were used to analyze the results of experiment. The substitution of 0.03mole Ni for Zn was most optimum and which produced good willemite at the temperature of $1300^{\circ}C$, holding for 6 h. In ceramic arts, cobalt has been used for blue coloring, in most cases, despite of its high cost. If the low cost Ni-doped willemite blue pigments supplies for them with stable and multiple shades of blue pigment, using NiO at high temperature, it would provide various blues for ceramic wares.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3031-3038
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• 2009

코발트 적재된 활성탄소섬유(ACFs)는 이산화티탄($TiO_2$) 광촉매 반응을 촉진시키는 것을 발전되었다. Co-ACFs/$TiO_2$ 광촉매는 SEM, XRD, EDX 및 UV-vis 분광기를 사용하여 분석하였다. Co-ACFs/$TiO_2$ 광촉매에 대한 메틸렌불루(MB)의 분해 효과는 300분 반응해서 거의 100%를 도달하였다. 용액에 있는 MB 분자들은 ACFs의 흡착에 의해 $TiO_2$ 입자의 주위에 응축한다고 가정되었다. 그래서 이 광촉매 복합체는 MB 광분해에 대한 활성탄의 흡착성과 $TiO_2$의 광촉매 특성의 결합한 성능을 가지고 있다. 코발트가 전자 천이 효과를 가지고 있기 때문에 MB 용액의 광분해가 증가되는 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1929-1933
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• 2012

Two cobalt(II) compounds $[Co(2,2{^\prime}-bipy)(H_2O)_2(SO_4)]_n$ (1) and $[Co_2(2,2^{\prime}-bipy)_2(btec)(H_2O)_6]{\cdot}2H_2O$ (2) (2,2'-bipy = 2,2'-bipyridine, $H_4btec$ = 1,2,4,5-benzenetetracarboxylic acid), have been simultaneously synthesized by a one-pot slow solvent evaporation reaction. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction (XRPD), IR, elemental and thermogravimetric analysis (TGA). The structural analysis reveals that compound 1 exhibits an infinite 1D chain structure with the octahedral Co(II) centers bridging by the tetrahedral ${\mu}_2-SO{_4}^{2-}$ ligands, while compound 2 possesses a dinuclear $Co_2(2,2^{\prime}-bipy)_2(btec)(H_2O)_6$ unit and the two adjacent octahedral Co(II) ions are linked by the bismonodentately coordinated btec ligand. Additionally, compound 2 exhibits blue fluorescent emission in the solid state at room temperature.