• Journal of the Korean Ceramic Society
• /
• v.28 no.4
• /
• pp.305-314
• /
• 1991

This study was conducted to research the formation and the color development of NiO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing ZnO-Fe2O3 as a basic composition, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.Fe2O3 system, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.TiO2 system, and {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.SnO2 system were prepared with {{{{ chi }}=0, 0.2, 0.5, 0.7, 1 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 30 minutes. The reflectance measurement and the X-ray analysis of these specimens were carried out and the results were summarized as follows. 1. In the specimens which included NiO, it was difficult for the spinel structure to be formed. 2. As increasing the contents of NiO and Fe2O3, all the groups which were yellow or green colored changed to brown. 3. NiO-ZnO-Fe2O3 system and NiO-ZnO-TiO2 system formed the spinel structure and the illmenite structure appeared in NiO-TiO2 system.

• Journal of the Korean Ceramic Society
• /
• v.15 no.1
• /
• pp.9-15
• /
• 1978

The possiblity of mullitization from the domestic alunite by adding of $Fe_2O_3-MnO_2$, $Fe_2O_3-MnO_2-TiO_2$, $Fe_2O_3-MnO_2-CaF_2$, and $Fe_2O_3-MnO_2-CaF_2-TiO_2$ mixtures as mineralizers was studied at the temperature range between $1, 250^{\circ}C$~$1, 430^{\circ}C$. The modifying method of domestic alunite was performed by calcination, wet ballmilling, and washing with water. The following results were obtained; 1) When added of 3.0% $Fe_2O_3$ plus 1.0-1.5% $MnO_2$ to modified alunite, the appropriate temperature range of mullite-forming was $1, 350^{\circ}C$-$1, 400^{\circ}C$. 2) When added of $TiO_2$ as mineralizer, the mullite-forming temperature was higher than not added. 3) When added of $CaF_2$ as mineralizer, the synthesized mullite was resolve at the temperature above $1, 350^{\circ}C$.

• Journal of the Korean Ceramic Society
• /
• v.41 no.1
• /
• pp.57-61
• /
• 2004

Zinc Oxide (ZnO) have the crystal structure of wurtzite which is semiconducting oxide with band gap energy of 3.3eV. $In_2O_3$-doped ZnO films were fabricated by electron beam evaporation at $400^{\circ}C$ and their characteristics were investigated. The content of $In_2O_3$ in ZnO films had a marked effect on the electrical properties of the films. As $In_2O_3$ content decreased. $In_2O_3$-doped ZnO films was converted amorphous into crystallized films and showed a better characteristics generally as a transparent conducting oxide. As $In_2O_3$-doped ZnO films were prepared by $In_2O_3$-doped ZnO pellet with 0.2at% of $In_2O_3$ content, the value of resistivity was about $6.0 {\times} 10^{-3} {\Omega}cm$. The transmittance was higher than 85% throughout the visible range.

• Journal of the Korean Ceramic Society
• /
• v.22 no.4
• /
• pp.54-60
• /
• 1985

Gas sensing materials for detecting flammable gases such as $CH_4$, $C_3H_8$ and n-$C_4H_{10}$ were developed by util-izing $In_2O_3$ as the principal sensing material. The sensing materials were formulated by mixing $In_2O_3$ powder with one or two other chemicals such as $SnO_2$, $Y_2O_3$ and $Al_2O_3$ with a small addition of $PdCl_2$ as a catalyst. Sample of sensor were fabricated by coating each of the mixtures on a ceramic tube impregnating ethylsili-cate and firing at 75$0^{\circ}C$ Each material mixture was evaluated by measuring and comparing gas sensitivity(resistance in air/resistance with gas) to flammable gases such as $CH_4$, $C_3H-8$ and n-$C_4H_{10}$. It was found that among fifteen compositions tested three compositions as follows show the highest gas sensitivity and thus are very feasible for commercialization as the gas sensors ; o49.5 $In_2O_3$+50 Al2O3_0.5 PdCl2(wt%) o $20In_2O_3+29$ $SnO_2+50$ $Al_2O_3+1$ $PdCl_2$(wt%) o40 $In_2O_3$+9 $Y_2O_3+50$ $Al_2O_3+1$ $PdCl_2$(wt%)

• Journal of the Korean Ceramic Society
• /
• v.32 no.9
• /
• pp.1040-1046
• /
• 1995

The formation free energy of Y2Cu2O5 was measured by the partial ion exchanged (Cu2+, Na+)-$\beta$/$\beta$"-Al2O3 as solid state electrolyte. The formation cell was built as follows: Pt(O2)/Y2Cu2O5＋Y2O3//(Cu2+, Na+)-$\beta$/$\beta$"-Al2O3//CuO/(O2)Pt The virtual formation formation formula, and the calculated formation free energy of Y2Cu2O5 as a function of temperature are as follows: 2CuO＋Y2O3=Y2Cu2O5 ΔfG0/kJ.mol-1=13.19-16.25*10-3T/K.5*10-3T/K.

• Journal of the Korean Ceramic Society
• /
• v.26 no.4
• /
• pp.479-486
• /
• 1989

According to the phase diagram, 6Bi2O3.GeO2 composition melts congruently at 93$0^{\circ}C$ and forms a stable ${\gamma}$-6Bi2O3.GeO2 crystal phase below the melting point. But when the melt of this composition was cooled at a rate 1-15$0^{\circ}C$/min without tapping by a glass rod or impurity addition, a metastable $\delta$-6Bi2O3.GeO2 crystal phase was formed. It is due to that as the nucleation energy barrier of $\delta$-6Bi2O3.GeO2 crystals, which have more open and defective structure, is lower than that of ${\gamma}$-6Bi2O3.GeO2 crystals. When impurities or ${\gamma}$-6Bi2O3.GeO2 crystals existed in the melt, stable ${\gamma}$-6Bi2O3.GeO2 crystal phase was formed at various cooling rate. It is because of that the impurities or the ${\gamma}$-6Bi2O3.GeO2 crystals role as a seed crystal and as a result the nucleation energy barrier of ${\gamma}$-6Bi2O3.GeO2 crystals is lowered.

• Journal of the Korean Ceramic Society
• /
• v.27 no.3
• /
• pp.361-368
• /
• 1990

The properties of the powder of ZrO2＋3m/o Y2O3 system prepared by co-precipitation method at the pH values of 7, 9, 10 and 11 were investigated. ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Zirconium hydroxide near by Zr(OH)4 structure showed more excellent crystallinity and lower formation temperature of tetragonal ZrO2. In the range of this study, cubic ZrO2 was not formed and stability of tetragonal ZrO2 prepared in the conditiion of pH 7 was most excellent. Average particle sizes and specific surface areas of tetragonal ZrO2 powders, prepared as calcining amorphous zirconium hydroxides at $600^{\circ}C$ for 1h, were 0.6-0.8${\mu}{\textrm}{m}$ and 45-70$m^2$/g, respectively.

• Proceedings of the KIEE Conference
• /
• 2000.11c
• /
• pp.506-508
• /
• 2000

Oxide of the form $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ present properties that make them useful as multilayer chip NTC thermistor for mobile phone NTC thermistor electric properties of $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ system has been measured as a function of temperature and composition. In $Mn_{3}O_{4}-NiO-Fe_{2}O_{3}$ composition, it can be seen that resistivity and B-constant were increased as the ratio of $Mn_{3}O_{4}/F_{2}O_{3}$ and $Mn_{3}O_{4}$/NiO was increased. In particular, resistance change ratio (${\Delta}R$), the important factor for reliability varied within ${\pm}1%$, indicating the compositions of these products could be available for mobile phone.

• Journal of the Korean Ceramic Society
• /
• v.21 no.4
• /
• pp.373-381
• /
• 1984

The coloration of the $Nd_2O_3$ contained $R_2O-BaO-SrO-ZrO_2-SiO_2$ glass added the various amount of $CeO_2$ $MnO_2$, $Fe_2O_3$ and $As_2O_3$ alone or together by the irradiation of X-ray irradiation,. The glasses added $CeO_2$ in proportion to amount were more effective on preventing coloration by X-ray irradiation but the addition of $MnO_2$ produced different color according to the amount of addition. The addition of the $Fe_2O_3$, $TiO_2$ and $As_2O_3$ did not give much effects to the transmission changes of $Nd_2O_3$ contained glass by X-ray irradiation but the glass added $CeO_2$ , $Fe_2O_3$, $TiO_2$ together was most effective to prevent coloration and transmisson changes.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.3
• /
• pp.195-214
• /
• 2020

The Samgwang Au-Ag deposit has been one of the largest deposits in Korea. The deposit consists of eight lens-shaped quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock, which feature suggest that it is an orogenic-type deposit. The Ti-bearing minerals occur in wallrock (titanite, ilmenite and rutile) and laminated quartz vein (rutile). They occur minerals including biotite, muscovite, chlorite, white mica, monazite, zircon, apatite in wallrock and white mica, chlorite, arsenopyrite in laminated quartz vein. Chemical composition of titanite has maximum vaules of 3.94 wt.% (Al₂O₃), 0.49 wt.% (FeO), 0.52 wt.% (Nb₂O₅), 0.46 wt.% (Y₂O₃) and 0.43 wt.% (V₂O₅). Titanite with 0.06~0.14 (Fe/Al ratio) and 0.06~0.15 (X_Al (=Al/Al+Fe³⁺+Ti)) corresponds with metamorphic origin and low-Al variety. Chemical composition of ilmenite has maximum values of 0.07 wt.% (ZrO₂), 0.12 wt.% (HfO₂), 0.26 wt.% (Nb₂O₅), 0.04 wt.% (Sb₂O₅), 0.13 wt.% (Ta₂O₅), 2.62 wt.% (As₂O₅), 0.29 wt.% (V₂O₅), 0.12 wt.% (Al₂O₃) and 1.59 wt.% (ZnO). Chemical composition of rutile in wallrock and laminated quartz vein has maximum values of 0.35 wt.%, 0.65 wt.% (HfO₂), 2.52 wt.%, 0.19 wt.% (WO₃), 1.28 wt.%, 1.71 wt.% (Nb₂O₃), 0.03 wt.%, 0.07 wt.% (Sb₂O₃), 0.28 wt.%, 0.21 wt.% (As₂O₅), 0.68 wt.%, 0.70 wt.% (V₂O₃), 0.48 wt.%, 0.59 wt.% (Cr₂O₃), 0.70 wt.%, 1.90 wt.% (Al₂O₃) and 4.76 wt.%, 3.17 wt.% (FeO), respectively. Rutile in laminated quartz vein is higher contents (HfO₂, Nb₂O₃, As₂O₅, Cr₂O₃, Al₂O₃ and FeO) and lower content (WO₃) than rutile in wallrock. The substitutions of rutile in wallrock and laminated quatz vein are as followed : rutile in wallrock [(Fe³⁺, Al³⁺, Cr³⁺) + Hf⁴⁺ + (W⁵⁺, As⁵⁺, Nb⁵⁺) ⟵⟶ 2Ti⁴⁺ + V⁴⁺, 2Fe²⁺ + (Al³⁺, Cr³⁺) + Hf⁴⁺ + (W⁵⁺, As⁵⁺, Nb⁵⁺) ⟵⟶ 2Ti⁴⁺ + 2V⁴⁺], rutile in laminated quartz vein [(Fe³⁺, Al³⁺) + As⁵⁺ ⟵⟶ Ti⁴⁺ + V⁴⁺, (Fe³⁺, Al³⁺) + As⁵⁺ ⟵⟶ Ti⁴⁺ + Hf⁴⁺, 4(Fe³⁺, Al³⁺) ⟵⟶ Ti⁴⁺ + (W⁵⁺, Nb⁵⁺) + Cr³⁺], respectively. Based on these data, titanite, ilmenite and rutile in wallrock were formed by resolution and reconcentration of cations (W⁵⁺, Nb⁵⁺, As⁵⁺, Hf⁴⁺, V⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Fe²⁺) in minerals of wallrock during regional metamorphism. And then rutile in laminated quartz vein was formed by reconcentration of cations (Nb⁵⁺, As⁵⁺, Hf⁴⁺, Cr³⁺, Al³⁺, Fe³⁺, Fe²⁺) in alteration minerals (white mica, chlorite) and Ti-bearing minerals reaction between hydrothermal fluid originated during ductile shear and Ti-bearing minerals (titanite, ilmenite and rutile) in wallrock.