• Journal of the Korean Chemical Society
• /
• v.18 no.4
• /
• pp.272-277
• /
• 1974

A relationship between the activity coefficients of tri-n-butylphosphate(TBP) and europium complex was studied in the extraction of europium by TBP in nitric acid solution. Diluents chosen are cyclohexane, toluene, benzene and chlorobenzene. Concentrations of TBP were varied from 5 to 50 by volume percent and the composition of inorganic layer was kept constant. A method of estimating the solubility parameter of TBP is suggested.

• Journal of the Korean Chemical Society
• /
• v.38 no.9
• /
• pp.653-659
• /
• 1994

The fluorescence intensities of europium and samarium can be greatly enhanced in the presence 2-thenoyltrifluoroacetone(TTA), n-octanol and Triton X-100 in aqueous solution of pH 7. It was also found that the fluorescence intensity can be greatly increased by the addition of excess of $La^{3+}$. The excitation and emission wavelengths of europium and samarium were 345 nm, 380 nm and 617 nm, 567 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium and samarium in the range TEX>$1{\times}10^{-7}∼1{\tiems}10^{-9}\;M,\;1{\tiems}10^{-5}∼1{\times}10^{-7}\;M$, respectively, and the detection limits were 1$1{\times}10^{-11}\;M$ for europium and $1{\times}10^{-8}\;M$ for samarium and the luminescence mechanism of the system is discussed.

• Korean Chemical Engineering Research
• /
• v.46 no.3
• /
• pp.506-511
• /
• 2008

In this study sol-gel and combustion process was surveyed for the preparation of the red $Y_2O_3$: Eu phosphor, and the properties of phosphor was considered. Chelation and hydrolysis in amorphous citrate sol-gel process were completed in initial reaction stage, and water-forming condensation was superior to organic acid-forming condensation. The mole ratio of citric acid to metal ion had to be above to for the progress of sol-gel process. The dried gel powders are mostly amorphous, and crystallize completely at $700^{\circ}C$, and the crystallinity increases with increasing calcining temperature. The luminescence property of the phosphor was analyzed by measuring the emission spectra. The luminescence intensity increases when the calcination temperature and concentration of metal ions in solution increase.

• Journal of Powder Materials
• /
• v.20 no.5
• /
• pp.382-387
• /
• 2013

• Journal of Soil and Groundwater Environment
• /
• v.14 no.4
• /
• pp.23-32
• /
• 2009

The sorption of europium (Eu (III)) onto kaolinite and the influence of humic acids over a range of pH 3 ~ 11 has been studied by batch adsorption experiment (V/m = 250 : 1 mL/g, $C_{Eu(III)}\;=\;1\;{\times}\;10^{-5}\;mol/L$, $C_{HA}\;=\;5{\sim}50\;mg/L$, $P_{CO2}=10^{-3.5}\;atm$). The concentrations of HA and Eu(III) in aqueous phase were measured by UV absorbance at 254nm (e.g., $UV_{254}$) and ICP-MS after microwave digestion for HA removals, respectively. Results showed that the HA sorption onto kaolinite was decreased with increasing pH and their sorption isotherms fit well with the Langmuir adsorption model (except pH 3). Maximum amount ($q_{max}$) for the HA sorption at pH 4 to 11 was ranged from 4.73 to 0.47 mg/g. Europium adsorption onto the kaolinite in the absence of HA was typical, showing an increases with pH and a distinct adsorption edge at pH 3 to 5. However in the presence of HA, Eu adsorption to kaolinite was significantly affected. HA was shown to enhance Eu adsorption in the acidic pH range (pH 3 ~ 4) due to the formation of additional binding sites for Eu coming from HA adsorbed onto kaolinite surface, but reduce Eu adsorption in the intermediate and high pH above 6 due to the formation of aqueous Eu-HA complexes. The results on the ternary interaction of kaolinte-Eu-HA are compared with those on the binary system of kaolinite-HA and kaolinite-Eu and adsorption mechanism with pH was discussed.

• Analytical Science and Technology
• /
• v.28 no.3
• /
• pp.204-211
• /
• 2015

Lanthanide complexes have attracted much attention because of their unique light emitting property. The light-emitting efficiencies of europium β-diketonate complexes were compared with those of complexes coordinated by the ligands of amines or phosphine oxides. The results demonstrated that the complexes that were coordinated by phosphine oxides had higher light-conversion performance than those coordinated by amines. The highest light-emitting efficiency was observed when the ligand of trioctylphosphine oxide was coordinated. In order to determine the coordination equivalency of trioctylphosphine oxide in the above complexes, 31P-NMR and their photoluminescence spectra were measured. The findings showed that the europium β-diketonate complex had one or two coordination equivalencies of trioctylphosphine oxide according to the steric hindrance of its original ligand.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.3
• /
• pp.263-267
• /
• 2007

We investigate the influence of the ambient gas during thermal annealing on the photoluminescence (PL) properties of europium-silicate thin films. The films were fabricated on substrates by using a radio-frequency magnetron sputtering method and subsequent rapid thermal annealing (RTA). The mechanism for the formation of the europium silicates during the annealing process was investigated by using X-ray diffraction (XRD) spectroscopy, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). A series of narrow PL spectra from $Eu^{3+}$ ions was observed from the film annealed in $O_2$ ambient. Broad PL spectra associated with $Eu^{2+}$ ions, with a maximum intensity at 600 nm and a FWHM of 110 nm, were observed from the thin film annealed at $1000^{\circ}C$ in $N_2$ ambient.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.82-89
• /
• 1989

The fluorescence of $Eu^{3+},\;Tb^{3+}$ substituted for $La^{3+}$ in Lanthanum Oxychloride (LaOCl) has been studied. The fluorescence intensity of the $Eu^{3+},\;Tb^{3+}$ in LaOCl excited by Ultra-violet light were investigated on its activator concentration and discussed as the energy transfer process. The energy transfer from $Tb^{3+}\;to\;Eu^{3+}$ take place in the $Eu^{3+}\;and\;Tb^{3+}$ codoped LaOCl crystal. This process was confirmed to the change of concentration and the measurement of fluorescence decay time.

• Journal of the Korean Chemical Society
• /
• v.41 no.5
• /
• pp.251-255
• /
• 1997

Fluorescence spectra and life time of $Eu^{3+}$ ion in borosilicate glass medium are measured. Electronic transitions of $Eu^{3+}$ ion in borosilicate glass medium are found to come from $5D0{\rightarrow}7FJ$(J=0, 1, 2, 3, 4) transitions of SL coupling system in $f^b$ electrons configuration. From the number of Stark sublevels in spetra, crystal field for $Eu^{3+}$ ion is also found to have the symmetric character of low symmetry order, $n{\leq}2$. The fraction and the number of components of life times were varied depending on the composition of $Eu^{3+}$ in borosilicate glasses, from which the binding condition between the $Eu^{3+}$ ion and anionic oxygen of borosilicate glass can be deduced.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.165-165
• /
• 2013

희토류 발광 물질은 4f 껍질에 위치하는 전자의 독특한 특성 때문에 발광 소자와 디스플레이에 그 응용성을 확장하고 있다. 본 연구에서는 고효율의 적색과 주황색 형광체를 합성하기 위하여 모체 격자 CaNb2O6에 희토류 이온인 유로퓸과 사마륨을 치환 고용하여 최적의 합성 조건을 조사하였다. Ca1-1.5xNb2O6:REx3+ (RE=Eu, Sm) 형광체 분말 시료는 고상반응법을 사용하여 활성제 이온인 Eu3+와 Sm3+의 농도비를 0, 0.01, 0.05, 0.10, 0.15, 0.20 mol 로 변화시키면서 합성하였다. 초기 물질 CaO, Nb2O5, Eu2O3와 Sm2O3을 화학 적량으로 측정하고, 400 rpm의 속도로 24시간 밀링 작업을 수행한 후에, 건조기 $60^{\circ}C$에서 28시간 건조하고, 시료를 막자 사발에서 갈아 세라믹 도가니에 담아 튜브형 전기로에서 분당 $5^{\circ}C$의 비율로 승온시켜 $500^{\circ}C$에서 5시간 동안 하소와 $1,100^{\circ}C$에서 6시간 소결하여 합성하였다. Eu3+가 도핑된 경우에, 발광 스펙트럼은 Eu3+ 이온의 농도비에 관계없이 강한 적색 발광 스펙트럼이 616 nm에서 관측되었다. 이외에도, 596 nm와 708 nm에서 상대적으로 발광 세기가 약한 주황색 발광과 적색 발광 신호가 검출되었으며, 541 nm에서는 매우 약한 녹색스펙트럼이 관측되었다. Eu3+ 이온의 농도비에 0.01 mol에서 0.15 mol로 증가함에 따라 주발광 신호의 세기는 점점 증가하였으며, 0.15 mol에서 최대 발광 세기를 나타내었다. Eu3+ 이온의 농도비가 0.20 mol 로 더욱 증가함에 따라 주 피크의 세기는 농도 소강 현상에 의하여 현저히 감소함을 보였다. 한편, 주된 흡광 스펙트럼은 279 nm에서 나타났는데, 이것은 전하전달밴드 신호이다. Sm3+가 도핑된 형광체 분말의 발광 스펙트럼은 모든 시료의 경우에 613 nm에서 강한 적주황색 발광 스펙트럼이 관측되었고, 상대적으로 세기가 약한 570 nm와 660 nm에 피크를 갖는 황색과 적색 발광 스펙트럼이 발생하였다. 흡광과 발광 스펙트럼의 최대 세기는 0.05 mol에서 나타났으며, Sm3+ 이온의 농도비가 더욱 증가함에 따라 흡광과 발광 세기는 급격하게 감소하였다.