• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.532-537
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• 2003

Crystallographic, electric, magnetic and heat transition properties of $\alpha$-Fe$_2$O$_3$ have been studied with a small addition of Eu impurities. Hematite($\alpha$-Fe$_2$O$_3$) is a basic ferromagnetic material having rhombohedral structure, which is similar to perovskites structure. Eu is a rare earth element that has an electric configuration of 4f$^{7}$ 6s$^2$. X-ray diffraction pattern of Fe$_{1-x}$ Eu$_{x}$O$_3$ (x = 0.00, 0.04, 0.06) shows an increament of a value when the amount of Eu impurities increased. The VSM data show an increment of magnetization by increasing the amount of Eu impurity. The one with x=0.06 shows the largest increment of magnetic remanence. The magnetic remanence varied from 0.49$\times$10$^{-3}$ emu/g to 0.62$\times$10$^{-3}$ emu/g when Eu impurity is increased by 2 %. Coercivity is decreased as Eu impurity is increased. Resistances is reduced significantly by Eu impurity. There is a clear difference in temperature-dependent resistance depending on the amount of Eu impurities. Especially, there are cusps between 150 K to 175 K. It indicates the change of electronic quantum states inside the atoms by rare earth impurities in rhombohedral structure. Temperature-dependent heat capacity shows that the most effective amount of Eu impurities is 6 %. %.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1115-1122
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• 2001

The tendency of the miximum brightness of $Y_2$O$_3$:Eu phosphor with various activator concentration, by different surface treatment methods as well as different exciting energies were investigated. The surface treatment methods were the adsorption method used $\alpha$-Fe$_2$O$_3$powder prepared emulsion-drying process and the precipitation method used FeSO$_4$/ethanol. Eu concentration of maximum brightness of $Y_2$O$_3$:Eu phosphor prepared by solid-solid state was changed with various exciting energies. The concentrations were 0.02 mol at VUV(147 nm) as well as 400 V and 0.03 mol at 5 kV. The phosphor treated both by adsorption method and precipitation method showed decreasing luminescent intensity with increasing amount of $\alpha$-Fe$_2$O$_3$, and the methods are chosen by exciting energy. Adsorption method was effective in a low voltage and VUV(147nm) region, and precipitation method was effective in the high voltage region.

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.5-5
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• 2009

• Journal of the Korean Magnetics Society
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• v.1 no.1
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• pp.1-5
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• 1991

The magnetic properties of the polycrystalline ${(Fe_{2}O_{3})}_{1-x-y}{(In_{2}O_{3})}_{x}{(Eu_{2}O_{3})}_{y}$(x=0.01, y=0.02과 x=0.02, y=0.03) have been studied by the methods of X-ray diffraction, $M\"{o}ssbauer$ effect, and magnetic hysteresis measurement. The X-ray diffraction patterns show that the samples have a same crystal structure as $\alpha-Fe_{2}O_{3}$. From the analysis of the temperature dependence of the quadrupole splitting and average half-width, it is found that the Morin transition occurs in the sample of x=0.01 and y=0.02 and the spin angle defined as the angle between the [111] crystal axis and antiferromagnetic vector, changes from about $35^{\circ}$ to the (111) plane as increasing the temperature in the sample of x=0.02 and y=O.03. The temperature dependence of magnetic hyperfine field is analyzed by using the spin-wave theory. The isomer shift values at room temperature are found to be given by about 0.35mm/s for the samples which means that the Fe ions belong to $3^{+}ion$. The temperature dependence of isomer shift was analyzed by using the Debye model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.229-233
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• 2019

Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.2
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• pp.83-92
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• 1976

The relationships between various nitrogen efficiencies among 57 rice cultivars grouped into three developmental categories were investigated by simple correlation with (12kg/10a) and without nitrogen fertilizer under the field condition. The relationship showed similar in a group or among all varieties of three groups. Yield among varieties showed highly significant correlation with Fe (fertilization efficiency: yield increment/nitrogen applied), E (nitrogen efficiency for yield), Ef(efficiency of nitrogen derived from fertilizer) and Eu (fertilizer use efficiency: nitrogen derived from fertilizer divided by total nitrogen applied). The E was correlated significantly and positively with harvest index (HI), percent translocation (T) of nitrogen to ear and negatively with nitrogen uptake amount (N), nitrogen concentration in grain (GN%) and in straw (SN%). The E depends almost on Ef and only inTongil group partly on Es (efficiency of nitrogen derived from soil). The Ef contributes to Fe more than Eu does (Fe = $Ef{\cdot}Eu$). It appears that Ef and Eu increased from the old group to the recommended local varieties, but only EF and Es increased markedly when rice was developed from recommended local group to Tongil line ($indica{\times}japonica$ hybrid selction). The fact that E and Fe depend more on Ef among rice varieties is very good contrast to the result that E and Fe depend more on Es and Eu respectively among soils in the previous investigatigation. The Ef appears as the most important parameter for rice varietal selection under fertilizer application system.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.101-107
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• 1993

The crystallographic properties of the polycrystalline materials $Fe_{1+X}Eu_{1-X}O_{3}$(X = -0.06, 0.0, 0.1, 0.2, 0.3, 0.4) have been studied by the methods of X-ray diffraction and $M\"{o}ssbauer$ spectroscopy. The results showed that the samples with the composition range of $0.2{\leq}x{\leq}0.3$ had the garnet crystal phase, while those with $-0.06{\leq}x{\leq}0.0$ had the orthoferrite phase. However, with the tendency for the orthoferrite phase to convert into the trigonal phase via garnet phase as increasing the composition x, the orthoferrite-garnet and garnet-trigonal phase coexisted dominantly in the range of 0.0 < x < 0.2 and $0.4{\geq}x$, respectively. The analyzed results of $M\"{o}ssbauer$ spectrum indicated existence of some vacancies in the d-site of garnet phase, which can be related to the change of intensity in X-ray diffraction patterns.

• The Journal of the Petrological Society of Korea
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• v.12 no.3
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• pp.119-134
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• 2003

Yuksipryeong two-mica granite presents strongly peraluminous characteristics in both mineralogy and geochemistry. It has high aluminum saturation index with 1.15∼l.20 and high corundum with 2.20∼2.98 wt% CIPW norm. As the color index is <16% and FeO$\^$T/+ MgO + TiO$_2$is average 1.9 wt％, it corresponds to leucogranite. Yuksipryeong two-mica leucogranite shows negative linear trend for TiO$_2$, Al$_2$O$_3$, FeO, Fe$_2$O$_3$, MgO, CaO, K$_2$O, P$_2$O$\_$5/, Rb, Ba, and Sr as SiO$_2$increases, and the positive relation of Zr and Th, which result from feldspar, biotite, apatite and zircon fractionation. Pegmatitic dike has higher SiO$_2$and P$_2$O$\_$5/, but lower another major elements. Yuksipryeong two-mica leucogranite has lower Rb, but higher Ba and Sr than Manaslu, Hercynian two-mica leucogranites, and S-type granites in Lachlan Fold Belt. Pegmatitic dike has higher Rb and Nb but lower Ba, Sr, Zr, Th, and Pb contents than Yuksipryeong two-mica leucogranite, resulting in removing or mobilizing for some trace elements from the granitic melt. Yuksipryeong two-mica leucogranite has total REEs with 95.7∼l23.3 ppm, and chondrite-normalized REE pattern is very steep ((La/Yb)$\_$N/ = 6.9∼24.8), light REEs (LREEs)-enriched End heavy REEs (HREEs)- depleted pattern with low to moderate Eu anomalies (Eu/Eu＊= 0.7∼0.9). While pegmatitic dike has low total REEs with 7.0 ppm, and chondrite-normalized REE pattern is flat-pattern ((La/Yb)$\_$N/ = 2.1) with strong negative Eu anomalies (Eu/Eu＊= 0.2). The melt compositions having formed two-mica leucogranites depend on not only the source rock but also the amounts of the residual remaining after melting of source rocks. The CaO/Na$_2$O and Rb/Sr-Rb/Ba ratios depend mainly on the composition of source rocks in the strongly peraluminous granite, that is, plagioclase/clay ratio of the source rocks. Yuksipryeong two-mica leucogranite has higher CaO/Na$_2$O and lower Rb/Sr-Rb/Ba ratios than Manaslu and Hercynian two-mica leucogranites (Millevaches and Gueret) derived from clay-rich, plagioclase-poor (polite), which suggest that the probable source rocks for Yuksipryeong two-mica leucogranite is clay-poor, plagioclase-rich quartzofeldspathic rocks. As the concentrations of Al$_2$O$_3$remain nearly constant but those of TiO$_2$increases as increasing temperature in the strong peraluminous melt, the Al$_2$O$_3$/TiO$_2$ratio may reflect relative temperature at which the melts have formed. Comparing the polite-derived Manaslu and Hercynian two- mica leucogranites, Manaslu two-mica leucogranite has higher Al$_2$O$_3$/TiO$_2$ratio than latter, and its melt have formed at relatively lower temperature ($\leq$ 875$^{\circ}C$) than Hercynian two-mica leucogranites. Likewise, comparing the quartzofeldspathic rock-derived granites, Yuksipryeong two-mica granite has higher Al$_2$O$_3$/TiO$_2$, ratio than S-type granites in Lachlan Fold Belt (>875$^{\circ}C$). The melt formed Yuksipryeong two-mica leucogranite are considered to have been formed at temperature at below the maximum 875$^{\circ}C$C$.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.2
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• pp.69-80
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• 1975

Relationships between yield and various nitrogen efficiencies, between efficiencies and between efficiency and nitrogen uptake amount of rice plant were proposed and tested using data from N.P.K simple trials about 30 to 50 locations, for three years. Established relationships are well in accordance with experimental results by showing highly significant correlations between them. The overall indications are that high yielding capacity of fields with fertilizer application, depends primarily on high fertilizer nitrogen uptake by increasing fertilizer use efficiency (Eu), secondly the efficiency (Ef) of absorbed fertilizer nitrogen (Nf) and fertilization efficiency (Fe) and also depends much on nitrogen efficiency for grain yield (E) to great extend and that the efficiency (Es) of soil nitrogen (Ns) contributes to E more than Ef does. All nitrogen efficiencies are negatively correlated with the uptake amount of corresponding nitrogen and counterpart efficiency. Es and Ef could be determined firstly by difference method and secondly E versus Cs (Cs=Ns/Ns+Nf) plotting and thirdly E-Cs plotting with labelled fertilizermethod using the equation E=Es Cs+B where B=Ef Cf but a constant under the given condition and at last Y-Ns plotting with labelled fertilizer using Eq Y=$Es{\cdot}Ns+B$ where B=$Ef{\cdot}Nf$. Es which seems not much variable from field to field is mostly greater (about 80% of tested fields) than Ef which is much variable and depends much on fertilizer form. The relationships tested and well agreed are as follows: 1. Y=$Es{\cdot}Ns+Ef{\cdot}Nf$ (Y is yield) 2. E=$Es{\cdot}Cs+Ef{\cdot}Cf$ where Cf=Nf/Nf+Ns 3. E=b-aN where E=E, Es or Ef and N=N, Ns or Nf respectively, (E=Y/N, N=Nf+Ns), b is theoretical maximum under the given system and a is tangent at N=O of the curve, Y=EN. 4. Fe=Ef Eu and Se=$Es{\cdot}Eu$ where Se is efficiency of soil available nitrogen. 5. E=$(Se{\cdot}Cs+Fe{\cdot}Cf)/Eu$ 6. Y=$Es{\cdot}Eu{\cdot}Sf+Ef{\cdot}Eu{\cdot}Fn$or Y=$Es{\cdot}Eu{\cdot}Ea{\cdot}Sn+Ef{\cdot}Eu{\cdot}Fn $where Sf=$Ea{\cdot}Sn$, Ea is soil available nitrogen equivalent to fertilizer(Sf) divided by total soil nitrogen (Sn).

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.6-6
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• 2009