• Journal of the Korean Ceramic Society
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• v.48 no.4
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• pp.303-306
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• 2011

[ $V_2O_5$ ]doped Karrooite pigments were synthesized by the solid state method to get stabilized brown pigment in oxidation and reduction atmosphere. Optimum substitution condition and limited dopant with $V_2O_5$ for Karrooite pigment was investigated. With calcination at $1250^{\circ}C{\sim}1400^{\circ}C$, compositions were designed varying $V_2O_5$ molar ratio by increasing 0.02mole to the formula $Mg_1-xTi_2-xM_{2x}O_5$(x = 0.01~0.09 mole). Synthesized pigments were analyzed by XRD, Raman spectroscopy and UV-vis. When $V_2O_5$ was doped from 0.01 to 0.05 mole, single phase of Karrooite was observed at temperature $1300^{\circ}C$ and soaking time 4h by Raman spectroscopy. However, it was found that excess $VO_2$ peak appeared with 0.07 and 0.09 mole of $V_2O_5$ doped to $MgTi_2O_5$. This result indicated that the maximum limit of solid solution is 0.05 mole $V_2O_5$. Karrooite pigments were applied as a ceramic pigment to achieve brown colors in lime magnesia glaze and lime barium graze at both of oxidation and reduction atmosphere. CIE color coordinates are $L^*$ = 40.34, $a^*$ = 9.94, $b^*$ = 21.40 in lime magnesia glaze.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.515-519
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• 2011

The purpose of this study was to determine the optimal firing condition and composition for $Al_2TiO_5$ crystal, which is suitable for stable coloration in glazes at high temperatures, using $Cr_2O_3$ as chromophore for the synthesis of $Al_2TiO_5$ system pigments. $Al_2TiO_5$ has a high refractive index and good solubility of chromophore in the $Al_2TiO_5$ lattice, making this structure a good candidate for the development of new ceramic pigments. Pigments were synthesized by using $Al_2O_3$ and $TiO_2$ mainly. Various amounts of $Cr_2O_3$ such as 0.01, 0.02, 0.03, 0.04 and 0.05 mole were also added. Each compound was synthesized at $1300^{\circ}C$, $1400^{\circ}C$, and $1500^{\circ}C$ for 2 hours and cooled naturally. The crystal structure, solubility limit, and color of the synthesized pigments were analyzed by XRD, SEM, Raman spectroscopy, UV and UV-vis. The changes in color as the result of applying 6 wt% of the synthesized pigments to lime barium glaze were expressed as CIE-L*a*b* values. A $Cr_2O_3$ 0.03 mole doped $Al_2TiO_5$ brown pigment was successfully synthesize at $1400^{\circ}C$, and the values of CIE-L*a*b* parameters were L* = 44.62, a* = 3.10, and b* = 17.25. In the case of the pigment synthesized at $1500^{\circ}C$, the brown color was obtained at 0.01 mole and 0.02 mole $Cr_2O_3$, and the CIE-L*a*b* values were 55.34, 1.73, 28.64, and 49.39, 0.51, 21.33, respectively. At $1500^{\circ}C$, the maximum limit of solid solution was 0.03 mole $Cr_2O_3$. The glazed sample showed green color, and the values of the CIEL* a*b* parameters were L* = 45.69, a* = -0.98, and b* = 20.38.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.608-612
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• 2010

Uvarovite Garnet is green pigment prepared by using $Cr_2O_3$, CaO and $SiO_2$ which are widely used in ceramic industry. The synthesis of above pigment was carried out by mixing $K_2Cr_2O_7$, $SiO_2$ and $CaCO_3$ as formulated and then firing at $1000{\sim}1200^{\circ}C$. To investigate the optimum synthesis condition of the Uvarovite Garnet. it was prepared by using CaO to replace $CaCO_3$, $CaF_2$ and $CaCl_2$. To get green brighter color, $Al^{3+}$ was substituted for $Cr^{3+}$. They were characterized by X-ray diffraction, UV-Vis spectroscopy, Raman spectroscopy and SEM analysis. When the pigments were applied to lime glazes (6 wt%), color parameters of Uvarovite Garnet showed the $L^*$=40.99, $a^*$=-16.23 and $b^*$=17.04.

• Journal of the Korean Ceramic Society
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• v.45 no.5
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• pp.268-275
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• 2008

In high temperature ceramic glazes, a stable range of pink-red colors producing $Cr_2O_3-SnO_2-CaO-SiO_2$ pigments are factored by Cassiterite and Malayaite relationship with $Cr_2O_3$. The experiment described the effect of $CrCl_3$ by adding $H_3BO_3$ as a mineralizer to increase the formation of Malayaite crystal, substituting $CrCl_3$ instead of $Cr_2O_3$ in pigment as a chromophore. Synthesized pigments were analyzed by XRD, FT-IR, Raman Spectroscop, UV and UV-vis. The result shows the differences in amount of crystal phases and oxidation state of Cr ion, which causes the color change. The melting point of $CrCl_3$ is lower than $Cr_2O_3$ which act as a mineralizer and makes the pigment synthesized in lower temperature at $1200^{\circ}C$. Holding 3 h firing at $900^{\circ}C$ where the synthesize forms shows better effect of Malayaite crystal phases and increasing engaged effect of $CrCl_3$ where the color pigmentation is more defined then in $Cr_2O_3$.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.672-679
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• 2013

$Fe_4[Fe(CN)_6]_3$ coated on a mica or $TiO_2$/mica surface as infrared reflective blue pigment was prepared by a hydrothermal method. $Fe_4[Fe(CN)_6]_3$, used as coloring agent, was uniformly coated on mica or $TiO_2$/mica under the optimized condition of a 1.2 : 1 weight ratio between iron(III) chloride hexahydrate and potassium ferrocyanidetrihydrate at the initial pH level of 4.5 at $70^{\circ}C$. The infrared (IR)-reflective pigments were characterized by SEM, Zeta-potenial, FT-IR, and UV-VIS NIR spectrophotometry. Especially the CIE color coordinate and total solar reflectance(TSR) properties of the pigments were investigated in relation to variation of the coating and coated substrate thicknesses. Isolation-heat paint was prepared with 20 wt% blue pigments fully dispersed in acryl-urethane resin and several additives to coat the film uniformly. The films were also measured with CIE color coordinate, TSR, and the surface temperature was recorded by an isolation-heat measuring system. The pigments and films of $Fe_4[Fe(CN)_6]_3$ coated on mica and $TiO_2$/mica showed high TSR values compared with the TSR value of $Fe_4[Fe(CN)_6]_3$ itself. According to the increase of TSR value, the property of isolation-heat is effective. To realize the optimal blue color, we applied the the pigment to $TiO_2$ coated mica(TM(b)) which has blueish interference color. The pigment of $Fe_4[Fe(CN)_6]_3$ coated on TM(b) shows a strong blue color compared with that of $Fe_4[Fe(CN)_6]_3$ coated on $TiO_2$/Mmca(TM(w)), which has a whitish interference color.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.405-412
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• 2009

In high temperature ceramic glazes, a stable range of pink-red colors that produced $Cr_2O_3-SnO_2-CaO-SiO_2$ pigments were factored by Cassiterite($SnO_2$) and Malayaite($CaSnSiO_5$) by $Cr_2O_3$. The experiment examined the influence of $CrCl_3$, a Sn-Cr substitution added with a mineralizer ($H_3BO_3$), as a chromophore in pigments. The experiment also studied the effect of $H_3BO_3$ (2 wt%) when added to malayaite($CaSnSiO_5$) to see if the crystalline reaction will increase. $Cr_2O_3$ was also substituted with $CrCl_3$ in order to prove how much influence $CrCl_3$ had on the $H_3BO_3$. Malayaite and cassiterite were the basic compound materials and the experiment was conducted both with and without mineralizers (2 wt% of $H_3BO_3$). Each compound was synthesized at 800, 1000, 1200, 1300, 1400, $1500^{\circ}C$ for 2 h. Synthesized pigments were analyzed by XRD, FT-IR and UV-Vis. The temperature variation produced two crystal phases that showed the different engaging effects of Cr oxidation. $CrCl_3$ produced a better effect on the malayaite crystal phase, resulting in a more defined pigmentation of the pink-red coloration compared to $Cr_2O_3$.

• Korean Journal of Materials Research
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• v.21 no.8
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• pp.450-455
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• 2011

[ $Al_2TiO_5$ ]has a high refractive index and good solubility of the chromophore in the $Al_2TiO_5$ lattice, which allows this structure to be a good candidate for the development of new ceramic pigments. However, pure $Al_2TiO_5$ is well known to decompose on firing at $900{\sim}1100^{\circ}C$. However, this process can be inhibited by the incorporation of certain metal cations into its crystalline lattice. In this study, the synthesis of gray ceramic pigment was performed by doping cobalt on the $Al_2TiO_5$ crystal structure. The $Al_2TiO_5$ was synthesized using $Al_2O_3$ and $TiO_2$, and doped with $Co_3O_4$ as a chromophore material. In order to prevent the thermal decomposition during the cooling procedure, MgO was added to samples by 0.05 mole, 0.1 mole, and 0.15 mole as a stabilizer. The samples were fired at $1500^{\circ}C$ for 2 hours and cooled naturally. The crystal structure, solubility limit, and color of the synthesized pigment were analyzed using XRD, Raman spectroscopy, UV, and UV-vis. $Al_2O_3$ was available for the formation of $CoAl_2O_4$, which should also be considered in order to explain the small amount of this phase detected in the sample with the higher $Co^{2+}$ content (${\geq}$ 0.03 mole). It was found that the solubility limit of $Co^{2+}$ in the $Al_2TiO_5$ crystal was 0.02 mole% through an analysis of Raman spectroscopy. Through the addition of a pigment with 0.02 mole% of $Co^{2+}$ to lime-barium glaze, stabilized gray color pigments with 66.54, -2.35, and 4.68 as CIE-$L^*a^*b^*$ were synthesized.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.510-517
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• 2013

In this study, the properties of blue inorganic nano-pigments with a spinel structure were systematically investigated. We report the preparation of a blue ceramic nano-pigment and the Co and Ni substitutional effects on the blue color. $MgAl_2O_4$ was selected as the crystalline host network for the synthesis of cobalt and nickel-based blue ceramic nano-pigments. Various compositions of $Co_xMg_{1-x}Al_2O_4$ and $Ni_xMg_{1-x}Al_2O_4$ ($0{\leq}x{\leq}1$) powders were prepared using apolymerized complex method. The obtained powder was preheated at $400^{\circ}C$ for 5 h and then calcined at $1000^{\circ}C$ for 5 h. XRD patterns of the (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ samples showed a single phase of the spinel structure in all compositions. TEM results indicated nano-sized pigments for (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ with a particle size ranging from 20 to 50 nm. The characteristics of the color tones of (Co,Mg)$Al_2O_4$ and (Ni,Mg)$Al_2O_4$ were analyzed by CIE $L^*a^*b^*$ measurements. In addition, the thermal stability and the binding characteristics of (Co,Mg)$Al_2O_4$, (Ni,Mg)$Al_2O_4$ are discussed in terms of the TG-DSC and FT-IR results, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.2
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• pp.101-109
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• 2002

Samples of enamel wear for kitchen works were made at the Kordco Enamel Co. We analyzed the colors of enamel wears with Color Meter (JS555). The colors of enamel wears could be controled by mixing ratio of frits and pigments. Many kinds of frits and pigments were tested, and colors of enamel wears could be changed by variable frits. Colors were weakly changed by several mixing ratio of pigments.

• Journal of Powder Materials
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• v.16 no.6
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• pp.396-402
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• 2009

Tantalum nitrides ($Ta_3N_5$) have been developed to substitute the Cd based pigments for non-toxic red pigment. Various doping elements were doped to reduce the amount of high price Tantalum element used and preserve the red color tonality. Doping elements were added in the synthesizing process of precursor of amorphous tantalum oxides and then Tantalum nitrides doped with various elements were obtained by ammonolysis process. The average particle size of final nitrides with secondary phases was larger than the nitride without the secondary phases. Also secondary phases reduced the red color tonality of final products. On the other hand, final nitrides without secondary phase had orthorhombic crystal system and presented good red color. In other words, in the case of nitrides without secondary phases, doping elements made a solid solution of tantalum nitride. In this context, doping process controlled the ionic state of nitrides and the amount of oxygen/nitrogen in final nitrides affected the color tonality.