• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.738-746
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• 1997

MgO clinker and two kinds of dolomite clinkers with different microstructures and CaO contents were used as starting materials, and the effects of Fe2O3 addition on the properties of MgO and dolomite were investigated in the range of 2 to 8 wt% of Fe2O3 content. Secondary phases contributed to densification of MgO-Fe2O3 and dolomite-Fe2O3 were magnesioferrite and dicalciumferrite, respectively. Sinterabilities of MgO-Fe2O3 and dolomite-Fe2O3 were directly proportional to the amount of secondary phases. Also, sinterability of dolomite itself was dependent on the microstructure of starting material including distribution of CaO and MgO as well as the addition amount of Fe2O3. The flexural strength of MgO-Fe2O3 content was almost constant. The hydration resistance of dolomite with large size of MgO and discontinuous distribution of CaO was higher than that of dolomite with small size of MgO and continuous distribution of CaO. Also, the minimum content of Fe2O3 to prevent they hydration of dolomite was about 4wt%. As increasing Fe2O3 content, the penetration resistance of MgO-Fe2O3 was improved by the increment of magnesioferrite. On the other hand, the penetration resistance of dolomite-Fe2O3 was decreased because of the increment of dicalciumferrite having low melting point.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.1
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• pp.40-42
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• 2002

TiO$_2$/Fe$_2$O$_3$composite thin films were prepared on common glass substrates by sol-gel processing and dip-drawing method. The effect of Fe$_2$O$_3$content on the photocatalytic and hydrophilic properties of composite films was studied. The results indicate that the photocatalytic activities of composite TiO$_2$films are superior to that of pure TiO$_2$film, and the film containing 0.5% Fe$_2$O$_3$has the best photocatalytic activity. The hydrophilicity is difference with variant Fe$_2$O$_3$content, the films containing 0.05% ~0.1% Fe$_2$O$_3$have the best hydrophilicity and their contact angles are 0。.

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.526-531
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• 2007

The sintering behavior and electrical property of $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics were investigated with the iron oxide concentration ranging from 0 to 5 mol%. Both the sintered density and grain size were found to increase up to 2 mol% $Fe_2O_3$, and then to decrease with further additions. At a higher $Fe_2O_3$ content above 3 mol%, grain size decreased by a pinning effect induced by different shape grains. The electrical conductivity was also increased with increasing $Fe_2O_3$ content up to 2 mol%. Total conductivity of 2 mol% $Fe_2O_3-added$ specimen showed the maximum conductivity of $2{\times}10^{-2}{\Omega}{\cdot}cm^{-1}$ at $500^{\circ}C$. The addition of $Fe_2O_3$ was found to promote the sintering properties and electrical conductivities of $Gd_2O_3-dope\;CeO_2$.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.311-315
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• 2017

The perovskite system $(Ba^{2+}{_{1-x}}La^{3+}{_x})Fe^{3+}{_{1-t}}Fe^{4+}{_t}O_{3-y}$ (y = (1 - x --t)/2) having a composition of x = 0.0, 0.1, 0.2, and 0.3 showedean increase in $Fe^{4+}$ mole ratios with an increase in oxygen partial pressure ($N_2{\rightarrow}air{\rightarrow}O_2$), and with an increasefin s, the $Fe^{3+}$ quantity decreased and oxygen content (3-y value) increased. For each N sampls heat-treated in $N_2$ gas, a considerable weight gain, i.e.g a steadynincrease if oxygen content, was observed in the TGA data on the cooling process. The conductivity values at a constant temperature were in the order of $N_2$$O_2$; the respective log ${\sigma}$ values (${\Omega}^{-1}{\cdot}cm^{-1}$) at 323 K of the BL0 sample were -5.75 (BL0-N), -3.39 (BL0-A), and -0.53 (BL0-O). The mixed valencies of $Fe^{3+}$ and $Fe^{4+}$ ions in each sample were also confirmed by both the oxidation curve above 350 mV and the cathodic reduction curve below 200 mV from cyclic voltammetry.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.191-196
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• 1995

NiCuZn ferrites were prepared by a solid-state reaction and sintered at $900^{\circ}C$ for 5 hours. Its properties were investigated by controlling the ferrite composition and processing. NiCuZn ferrite with a composition of ${(Ni_{0.2}Cu_{0.2}Zn_{0.6}O)}_{1.02}{(Fe_{2}O_{3})}_{0.98}$ was found to have the maximum initial permeability as a result of the variation of Cu content and the (Ni+Cu)/Zn ratio. Curie temperature($T_{c}$) of NiCuZn ferrite was decreased with the larger Cu content and increased with the larger Ni content. NiCuZn ferrites of ${(Ni_{0.2}Cu_{0.2}Zn_{0.6}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$ composition milled for 20~80 hours had the maximum initial permeability at w=-0.015 and Curie temperature ($T_{c}$) was decreased with the increasing of $Fe_{2}O_{3}$ deficiency(w).

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.962-966
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• 1993

Effect of Fe content on the electrical properties of Zn2Y (Ba2Zn2Fe12O22) was studied by investigating X-ray diffraction patterns, microstructure and resistivity of samples. When x(Ba2Zn2Fe12＋xO$\delta$) is between ＋1 and -1, Zn2Y single phase was obtained and electrical resistivity was inversely proportional to Fe content. The possible defect model of Zn2Y was proposed based on the observation. When x<-1 or x>1, second phase(ZnFe2O4 for x<-1, ZnFe2O4 and Ba3Zn3Fe24O41 for x>1) were observed and the electrical resistivity was inversely proportional to the sample density. The activation energy of electrical conductivity of the stoichiometric Zn2Y was 0.49eV below 20$0^{\circ}C$ and 0.07eV above 50$0^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.2
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• pp.267-271
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• 1983

The southern parts varieties have shown higher content of Oleic acid, Linoleic acid, Vitamin A, Alcaloid, Ca, P and Fe than northern parts Varieties. The $N.\;P_2O_5\;and\;K_2O content of narrow leaf were higher than wide leaf, on the other hand the Ca, Mg, Fe and $SiO_2$ content of wide leaf were higher than narrow leaf. The content of $N, \;P_2O_5, \;K_2O$ have shown higher in first yellow leaf date, the content of Ca has shown higher in first falling leaf date and the content of Mn and Cu content have shown higher in second new leaf date.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.222-231
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• 2001

The material properties of $SnO_2$ were investigated as a function of the amount of $Fe_2O_3$, the partial pressure of oxygen, the concentration of CO gas, and temperature. $Fe_2O_3$-doped $SnO_2$ thick films were prepared by the screen printing technique on alumina substrate. The specimens sintered at $700^{\circ}C$ for 6 hours showed little difference of the grain size and narrow distribution with the content of $Fe_2O_3$. The electrical conductance of undoped $SnO_2$ is high at low firing temperature and at low partial pressure of oxygen. The electrical conductance of $Fe_2O_3-$-doped $SnO_2$ is increased with measurement temperature, but decreased with the content of $Fe_2O_3$. The dependence of oxygen partial pressure is decreased with dopant addition. The highest sensitivity and the good properties of response speed and repeatability for CO gas were observed on the specimen with 0.1 mol% $Fe_2O_3$ at $350^{\circ}C$.

• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.467-469
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• 2005

The purpose of this study was to investigate main ingredients of Hwangtoh (Korean yellow ochre), especially ferric oxide $(Fe_{2}O_{3})$ content. In this study, X-ray fluorescence spectrophotometry was employed to analyze the ingredients of Hwangtoh. The ferric oxide $(Fe_{2}O_{3})$ contents of Hwangtoh from Hwa Sun, Ham An, Chil Gok, Sun Chun, Ha Dong, San Chung, Go Chang, Kim Che and Jeong Eup were 1.5, 5.66, 11.76, 6.63, 2.74, 11.4, 4.84, 7.21 and 6.23%, respectively. Based on the above results, any Hwangtoh sample didn't meet the ferric oxide $(Fe_{2}O_{3})$ content criterion.

• Journal of the Korean Ceramic Society
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• v.31 no.6
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• pp.629-636
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• 1994

The ferrimagnetic glass-ceramics in the system Fe2O3-CaO-SiO2 for hyperthermia were investigated. Glasses could be prepared up to the content of 40 wt% of Fe2O3 and below the weight ratio of 1.0 of CaO/SiO2. The maximum saturation magnetization and the maximum coercive force were 29.85 emu/g and 340.1 Oe respectively, for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. And for a glass 40Fe2O3.30CaO.30SiO2 composition the maximum saturation magnetization and the maximum coercive force were 18.47 emu/g and 374.4 Oe heat-treated at 1,00$0^{\circ}C$ and 90$0^{\circ}C$ for 8 hours respectively. The maximum hysteresis loss was 1,726.3 cal/g for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. It was found that the ferrimagnetic Fe2O3.CaO.SiO2 glass-ceramics was little injurious to human body as results of biocompatibility test and biotoxicity test.