• Proceedings of the Korean Vacuum Society Conference
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• 1994.02a
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• pp.43-43
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• 1994

We studied chemical reactio of Eu metal on the in situ cleaved CdTe(110) surface by pphotoemission sppectroscoppy using synchrotron radiation. The chamber was maintained with base ppressure $\leq$2${\times}$10-10 mb during the expperiment. The expperiment was carried out in pphoton Factory in Jappan. Core level pphotoemission sppectroscoppy was carried out with Al K${\alpha}$ Line. The CdTe simiconductor was determined to be pp-typpe with low dopping concentration from Hall measurement. We found that there are two reacted pphases of Te with Eu (related to divalent Eu and trivalent Eu, resppectively) from least square fitting of Te 4d sppectra, but three is no indication of Cd reaction. Trivalent Eu exists after roughly one monolayer depposition (600 sec. depposition time is considered as one monolayer), which is also observed at Eu 3d core level sppectra. Overlayer Eu is metallized after roughly 2 monolayers depposition, as can be deduced from the fact that metallic edge near Fermi level begins to appear. The intensity of core-level of Te decreases expponentially at the initial stage (near one monolayer) and after one monolayer depposition it decreases more slowly due to Te out-diffusion. We categorized the growth mode of Eu on CdTe as S-K growth mode (cluster formation after one monolayer deppisition) from the relative intensity pplot of Te 4d normalized to the cleaved surface. At cleaved surface band bending is already established due to surface defects. At first 100 sec. depposition time the shift toward lower binding side by 0.6 eV is found at all core level sppectra of all elements in semiconductor. This shift is considered as the re-adjustment of surface Fermi level to the pposition induced by Eu metal (0.2 eV above the valence band maximum).

• Journal of Powder Materials
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• v.27 no.2
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• pp.146-153
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• 2020

The co-doping effect of aliovalent metal ions such as Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Zn²⁺ on the photoluminescence of the Y₂O₃:Eu³⁺ red phosphor, prepared by spray pyrolysis, is analyzed. Mg²⁺ metal doping is found to be helpful for enhancing the luminescence of Y₂O₃:Eu³⁺. When comparing the luminescence intensity at the optimum doping level of each Mg²⁺ ion, the emission enhancement shows the order of Zn²⁺ ≈ Ba²⁺ > Ca²⁺ > Sr³⁺ > Mg²⁺. The highest emission occurs when doping approximately 1.3% Zn²⁺, which is approximately 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺. The highest emission was about 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺ when doping about 1.3% Zn²⁺. It is determined that the reason (Y, M)₂O₃:Eu³⁺ has improved luminescence compared to that of Y₂O₃:Eu³⁺ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li₂CO₃ as a flux with organic additives.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.61-64
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• 2002

A novel ceramic synthesis technique, combustion synthesis, is explored to produce a orange-emitting $SnO_{2}:Eu^{3+}$ phosphors. This technique involves a reaction of metal salts with a citric acid as an organic fuel. The variation of the ratio of citric acid to metal introduces change in reaction temperature and atmosphere of the combustion reaction, which in turn influences crystallinity and luminescence properties of the final products seriously. And, the heat treatment of the as-synthesized product increases its luminescence intensity. Especially, the samples treated at above $1100^{\circ}C$ show a orange-emission peak, which is attributed to the formation of single phase and well-crystallized $SnO_{2}:Eu$ oxides in the rutile structure

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.166-166
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• 2000

We studied electronic structure of magnetic semiconductors EuO, EuS, and EuTe. The photoemission spectra show localized Eu 4f states and broad anion p bands. As the size of anion increases from oxygen to tellurium, anion p band width increases and eventually overlaps Eu 4f states. Hence in EuO and EuS, Eu 4f states are the highest occupied stated lying above anion p band, while Te 5p band spreads widely over Eu 4f states to become valence band maximum in EuTe. It was also observed that Eu 4f states have width of 0.7eV and dispersion of 0.2eV in EuS by angle resolved photoemission spectroscopy. The width of the 4f spectra mainly originates from atomic multiplets, but the much larger dispersion than that of Eu metal is due to p-f mixing.

• Bulletin of the Korean Chemical Society
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• v.17 no.9
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• pp.790-793
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• 1996

The azacrown compound, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N"-tri(methyl-acetic acid)(N3O2-tri(methylacetic acid)) was synthesized by modified procedure of Krespan. Potentiometric method has been used to determine the protonation constants of N3O2-tri(methylacetic acid) and stability constants of complexes on the divalent transition metal ions (Co2+, Ni2+, Cu2+, and Zn2+) and trivalent metal ions (Ce3+, Eu3+, Gd3+, and Yb3+) with N3O2-tri(methylacetic acid). The stability constants for the complexes of the divalent transition metal ions studied in the present work with N3O2-tri(methylacetic acid) were 11.4 for Co2+, 11.63 for Ni2+, 13.51 for Cu2+, and 11.65 for Zn2+, respectively. Thus, the order of the stability constants for complexes on the transition metal ions with N3O2-tri(methylacetic acid) was shown Co2+ < Ni2+ < Cu2+ > Zn2+ as same as the order of Irving-Williams series. The stability constants of Ce3+, Eu3+, Gd3+, and Yb3+ trivalent lanthanide metal ion complexes of N3O2-tri(methylacetic acid) were, respectively, 11.26 for Ce3+, 11.56 for Eu3+, 11.49 for Gd3+, and 11.80 for Yb3+. The values of the stability constants on trivalent metal ions with the ligand are increasing according to increase atomic number, due to increase acidity. But the value of stability constant of Gd3+ ion is less than the value of Eu3+ ion. This disordered behavior is also reported by Moeller.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1279-1282
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• 2009

The luminescence properties of a potential blue-emitting $RbBaPO_4:Eu^{2+}$ phosphor substituted with various metal ions have been investigated. The main emission wavelength of the phosphor samples was red-shifted by the substitution with K and Sr ions. The maximum peak intensity was obtained from the sample $Rb_{0.25}K_{0.75}Ba_{0.99}Eu_{0.01}PO_4$ which showed 144% relative intensity versus that of BAM:$Eu^{2+}$ phosphor under 254 nm excitation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.5-16
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• 1991

It was grown Cubic $ZrO_2(10 mol% Y_2O_3)$ single crystals doped with 1 wt% rare earth metal oxides (RE=Ce, Pr, Nd, Eu, Er) by Skull method. It was investigated electrical properties on (111) plane of grown single crystals by Impedance Spectroscopy. It was potted relation between temperature and electrical conductivities and observed the transition at $약300-400^{\circ}$ It was obtained activation energy on the migration of oxygen vacancy between low temperature (before the transition) and high temperature (after the transition till ${\11}500^{\circ}$) and its difference can be seen the activation energy of the formation of oxygen vacancies by break up defect complexes. It was obtained the activation energy according as add yttria and rare earth metal oxides and discussed ionic conduction mechanism. Grown single crystals showed Ce: orange - red, Pr: golden - yellow, Nd: lilac, Eu: light pink, Er: pink due to dopant effect from the light absorption data in the visible range.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.478-482
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• 2021

The catalytic yields of partial oxidation of methane (POM) to hydrogen over Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Eu, Pr, and Tb) were investigated in a fixed bed flow reactor under atmosphere. As 1 wt% of Eu was added to Ni(5)/SBA-15 catalyst, the O1s and Si2p core electron levels of Eu(1)-Ni(5)/SBA-15 showed the chemical shift by XPS. XPS analysis also demonstrated that the atomic ratio of O1s, Ni2p_3/2, and Si2p increased to 1.284, 1.298, and 1.058, respectively, and exhibited O^-, and O^2- oxygen and metal ions such as Eu³⁺, Ni⁰, Ni²⁺, and Si⁴⁺ on the catalyst surface. The yield of hydrogen on the Eu(1)-Ni(5)/SBA-15 was 57.2%, which was better than that of Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Pr, and Tb), the catalytic activity was kept steady even 25 h. As 1 wt% of Eu was added to Ni(5)/SBA-15, the oxygen vacancies caused by strong metal-support interaction (SMSI) effect due to the strong interaction between metals and carrier are made. They are resulted in increasing the dispersion of Ni⁰, and Ni²⁺ nano particles on the surface of catalyst, and are kept catalytic activity.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.831-834
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• 2002

A novel ceramic synthesis technique, combustion synthesis, is explored to produce an orange-emitting $SnO_2:Eu^{3+}$ phosphors. This technique involves a reaction of metal salts with a citric acid as an organic fuel. The variation of the ratio of citric acid to metal introduces change in reaction temperature and atmosphere of the combustion reaction, which in turn influences crystallinity and luminescence properties of the final products significantly. And the heat treatment of the as-synthesized product improved the CL intensity of the products. Especially, the sample treated at above 1100 $^{\circ}C$ shows an orange-emission, which is attributed to the formation of single phase and well-crystallized $SnO_2$:Eu in rutile structure.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2489-2497
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• 2023

Co and Eu impurities in the SSCs are nuclides that dominantly influence the neutron-induced radioactive inventory in metal and concrete radwastes (radioactive wastes) during NPP decommission. The impurity concentrations provided by NUREG/CR-3474 were used for the practical range of Co and Eu impurity concentrations to be applied to the code calculations. Metal structures near the core were evaluated to be ILW (intermediate-level waste) for the whole range of Co impurity concentration, so the boundary line between ILW and LLW (low-level waste) has no change for the whole concentration range provided by NUREG/CR-3474. Also, the boundary line between VLLW (very low-level waste) and CW (clearance waste) in the concrete shield could alter a little depending on the Eu impurity concentration within the range provided by NUREG/CR-3474. From this work, it is found that the concentration of material impurities of SSCs gives no critical impact on determining radwaste levels.