• Journal of Magnetics
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• v.17 no.4
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• pp.251-254
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• 2012

The electron paramagnetic resonance (EPR) of the $Eu^{2+}$ ion in $SrCl_2$:Eu single crystal has been investigated using an X-band spectrometer. The angular dependence of magnetic resonance positions for the $Eu^{2+}$ impurity ion in the crystallographic aa-plane is analyzed with effective spin-Hamiltonian. The EPR spectra of the isolated $Eu^{2+}$ center merged to each other. The hyperfine splitting of the isolated $Eu^{2+}$ center due to the $^{151}Eu$ nucleus is approximately 35 G. Three kinds of $Eu^{2+}$ centers except the isolated $Eu^{2+}$ center, $Eu^{2+}$ pairs, $Eu^{2+}$ triples, and other $Eu^{2+}$ clusters, are split from the fitting of the integrated experimental spectrum with the Gaussian curve. The calculated spectroscopic splitting parameters of the $Eu^{2+}$ pairs, $Eu^{2+}$ triples, and other $Eu^{2+}$ clusters in $SrCl_2$:Eu crystal are $g_1$ = 2.06, $g_2$ = 1.94, and $g_3$ = 1.93, respectively.

• Journal of the Korean Chemical Society
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• v.67 no.4
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• pp.236-240
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• 2023

Non-concentration quenching EuGa₂S₄ and Eu₂Ga₂S₅ phosphors, in which the concentration of Eu²⁺ activator ion is 100%, were synthesized by a solid state reaction at temperature range from 800 to 1050 ℃. The wavelength of maximum intensity (λ_max) of EuGa₂S₄ and Eu₂Ga₂S₅ phosphors are 546 and 581 nm, respectively. An examination of the X-ray diffraction patterns and photoluminescent properties of EuGa₂S₄ and Eu₂Ga₂S₅ phosphors revealed that EuGa₂S₄ and Eu₂Ga₂S₅ phosphors were formed at lower temperature range (800~900 ℃) and higher temperature range (1000~1050 ℃), respectively.

• Resources Recycling
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• v.22 no.3
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• pp.57-64
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• 2013

Sulfurization reaction characteristics of $Eu_2O_3$, uranium oxides($UO_2$, $U_3O_8$), mixture of $Eu_2O_3$ and uranium oxides, Eu-doped uranium oxides($(U,Eu)O_2$, $(U,Eu)_3O_8$), and phase-separated products prepared by HOX (High temperature OXidation) of $(U,Eu)O_2$ were investigated in the temperature range from 400 to $800^{\circ}C$. Only $Eu_2O_3$ in the mixture of $Eu_2O_3$ and uranium oxides was converted into $Eu_3S_4$ by sulfurization reaction at $450^{\circ}C$ without reaction between them. Sulfurization reaction behavior of $(U,Eu)_3O_8$ and $(U,Eu)O_2$ up to $600^{\circ}C$ was similar to $U_3O_8$ and $UO_2$, respectively, while they were sulfurized into Eu-rich $(U,Eu)S_x$ and ${\alpha}-US_2$ at $800^{\circ}C$. In the sulfurization of RE-rich $(U,Eu)_4O_9$ and $U_3O_8$ prepared by high temperature oxidation, it was confirmed that RE-rich $(U,Eu)S_x$ and UOS phases were formed at $600^{\circ}C$. For Eu-rich $(U,Eu)O_2$ and $UO_2$ prepared by reduction of HOX products, it was identified that Eu-rich (U,Eu)OS was formed at $450^{\circ}C$ by sulfurization of Eu-rich $(U,Eu)O_2$, while $UO_2$ remained unreacted.

• Journal of the Korean Chemical Society
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• v.41 no.4
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• pp.175-179
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• 1997

Luminescence of $Eu^{3+}$ has been studied in $Sr_{2-2x}Eu_xK_xSnO_4$ with two-dimensional $K_2NiF_4$ structure. The $^5D_o$ → $^7F_o$$Eu^{3+}$ ion represents the J=0 → J=0 transition which is forbidden by a Judd-Ofelt selection rule for electric dipole transition in 4f shell of $Eu^{3+}$ ions. However, the emission line of $^5D_o$ → $^7F_o$$Eu^{3+}$ emission spectra of Sr2-2xEuxKxSnO4$Sr_{2-2x}Eu_xK_xSnO_4$structure around $Eu^{3+}$ ions.

• Korean Journal of Materials Research
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• v.28 no.8
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• pp.474-477
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• 2018

$Ca_3MgSi_2O_8:Eu^{2+}$(x = 0.003, 0.005, 0.007, 0.01, 0.03 mol) white phosphors for Light Emitting Diodes(LED) are synthesized with different concentrations of $Eu^{2+}$ ions using a solid state reaction method. The crystal structures, surface and optical properties of the phosphors are investigated using X-Ray Diffraction(XRD), Scanning Electron Microscope(SEM) and photoluminescence(PL). The X-Ray Diffraction results reveals that the crystal structure of the $Ca_3MgSi_2O_8:Eu^{2+}$ is a monoclinic system. The particle size of $Ca_3MgSi_2O_8:Eu^{2+}$ white phosphors is about $1{\sim}5{\mu}m$, as confirmed by SEM images. The maximum emission spectra of the phosphors are observed at 0.01 mol $Eu^{2+}$ concentration. The decrease in PL intensity in the $Ca_3MgSi_2O_8:Eu^{2+}$ white phosphors with $Eu^{2+}$ concentration is interpreted by concentration quenching. The International Commission on Illumination(CIE) coordinate of 0.01 mol Eu doped $Ca_3MgSi_2O_8$ is X = 0.2136, Y = 0.3771.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.59-64
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• 1996

The 7F0→5D0excitation spectra of Eu(Ⅲ) complexed with polyfunctional monocarboxylic acid(glycolic acid, glycine and thioglycolic acid) containing a terminal O, N and S neutral donors and propionic acid were investigated using Eu(Ⅲ) luminescence spectroscopy. In the excitation spectra of Eu(Ⅲ)-propionate system, the stepwise appearance of the peaks was observed at 579.0, 579.2 and 579.5 nm with increasing in the ligand-to-metal ratio, which correspond to the formation of Eu(propionate)2+, Eu(propionate)2+ and Eu(propionate)3 species. Three maximum peaks were also obtained for Eu(Ⅲ)-glycolate, Eu(Ⅲ)-glycinate and Eu(Ⅲ)-thioglycolate systems and were found to be quite similar to those of Eu(Ⅲ)-propionate system. The q values (number of coordinated water molecules of Eu(Ⅲ) ion) obtained from the luminescence decay constants of Eu(Ⅲ)-glycolate and Eu(Ⅲ)-thioglycolate were 7.0 and 7.1, and compare well with 7.3 for Eu(Ⅲ)-propionate: Each ligand units replace around two coordinated water molecules. These results show that the polyfunctional monocarboxylates behaves like the propionate for Eu(Ⅲ) ion coordination.

• Korean Journal of Materials Research
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• v.31 no.10
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• pp.582-585
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• 2021

Y₂O₃:Eu_x (x = 0.005, 0.01, 0.02, 0.03, 0.05, 0.1 mol) phosphors are synthesized with different concentrations of Eu³⁺ ions by solvothermal method. The crystal structure, surface and optical properties of the Eu doped Y₂O₃ phosphors are investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) and photoluminescence excitation (PLE) analyses. From X-ray diffraction (XRD) results, the crystal structure of the Eu doped Y₂O₃ phosphor is found to be cubic. The maximum emission spectra of the Eu doped Y₂O₃ phosphors are observed at 0.05 mol Eu³⁺ concentration. The photoluminescence of 615 nm in the Eu doped Y₂O₃ phosphors is associated with ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions. The decrease in emission intensity of 0.1 mol Eu doped Y₂O₃ is interpreted by concentration quenching. The International Commission on Illumination (CIE) coordinates of 0.05 mol Eu doped Y₂O₃ phosphor are X = 0.6547, Y = 0.3374.

• Progress in Superconductivity
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• v.13 no.1
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• pp.12-17
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• 2011

We investigated the effects of Ba and Cu co-substitution on the structural and superconducting properties of ($Ru_{1-y}Cu_y$)($Sr_{1.67-x}Ba_xEu_{0.33}$)($Eu_{1.34}Ce_{0.66}$)$Cu_2O_z$ samples. X-ray diffraction(XRD) reveals that single-phase samples can be obtained in the range from x = 0.1 to 0.2 for ($Ru_{0.5}Cu_{0.5}$)($Sr_{1.67-x}Ba_xEu_{0.33}$)($Eu_{1.34}Ce_{0.66}$)$Cu_2O_z$ and from y = 0.25 to 0.5 for ($Ru_{1-y}Cu_y$)($Sr_{1.47}Ba_{0.2}Eu_{0.33}$)($Eu_{1.34}Ce_{0.66}$)$Cu_2O_z$, respectively. All samples with compositions of ($Ru_{0.5}Cu_{0.5}$)($Sr_{1.67-x}Ba_xEu_{0.33}$) ($Eu_{1.34}Ce_{0.66}$)$Cu_2O_z$ (x = 0 - 0.33) show superconducting transition behavior and the onset transition temperature decreases slightly with increasing x in consistent with the change of hole concentration estimated from room temperature thermoelectric power measurements. The XRD and resistivity measurements for the ($Ru_{1-y}Cu_y$)($Sr_{1.47}Ba_{0.2}Eu_{0.33}$)($Eu_{1.34}Ce_{0.66}$) $Cu_2O_z$ system indicate that the partial substitution of Cu for Ru is necessary to form phase pure samples, but result in a small change in transition temperature in the single-phase region from x = 0.25 to 0.5.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.184-189
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• 2013

$Ba_2SiO_4:Eu^{2+}$ ($B_2S:Eu^{2+}$) powders were prepared by firing the dry gel obtained by the sol-gel and the hybrid process (sol-gel and combustion), respectively, and their structure and luminescence were investigated. Tetraethyl orthosilicate (TEOS) was used as a Si source. The phase transition was observed with the TEOS content. With 1.2M TEOS, the powders prepared by the sol-gel process without prior calcination were composed of the $B_2S:Eu^{2+}$ single phase, whereas those by the sol-gel and the hybrid process with prior calcination consisted of the dominant $B_2S:Eu^{2+}$ and minor $BaSiO_3:Eu^{2+}$ ($BS:Eu^{2+}$) phases and their emission intensities were approximately two times higher than those without prior calcination. The hybrid process could reduce the process time innovatively compared to the sol-gel process, even though the former was a little inferior to the latter in the emission intensity of $B_2S:Eu^{2+}$. With 1.1M TEOS, the $B_2S:Eu^{2+}$ single phase was obtained by the hybrid process, and its green emission was observed at 505 nm originated from the $4f^65d^1{\rightarrow}4f^7$ transition of $Eu^{2+}$ ions.

• Journal of radiological science and technology
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• v.29 no.3
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• pp.141-145
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• 2006

In this study, $Eu^{2+}$ ion was used as an activator in order to enhance the PL(photoluminescene) and PSL(photostimulated luminescence) intensity of $MCl_2:Eu^{2+}$(M = Ca, Sr, Ba)phosphors and the chracteristics of PL and PSL of the phosphors were investigated. The emission of $MCl_2:Eu^{2+}$(M = Ca, Sr, Ba) phosphors shows a shift wavelength when the host caution changes. The optimal preparing conditions of $CaCl_2:Eu^{2+}$ phosphor were 0.5 mol％ of $EuCl_2$ and the sintering temperature were $745^{\circ}C$, 45 min. in $H_2$ atmosphere. The PL and PSL spectra of $CaCl_2:Eu^{2+}$ locate in the range of $365{\sim}388\;nm$, peaking at 370 and 380 nm. The optimal preparing conditions of $BaCl_2:Eu^{2+}$ phosphor were 0.5 mol％ of $EuCl_2$ and the sintering temperature were $905^{\circ}C$, 45 min. in $H_2$ atmosphere. The PL and PSL spectra of $BaCl_2:Eu^{2+}$ locate in the range of $370{\sim}460\;nm$, peaking at 398 nm. The optimal preparing conditions of $SrCl_2:Eu^{2+}$ phosphor were 0.5mol％ of $EuCl_2$ and the sintering temperature were $840^{\circ}C$, 45min. in $H_2$ atmosphere. The PL and PSL spectra of $SrCl_2:Eu^{2+}$ locate in the range of $380{\sim}440\;nm$, peaking at 407 nm. The dose response of the $MCl_2:Eu^{2+}$(0.5 mol%)(M = Ba, Sr) phosphors were linear within $0.25{\sim}200\;mGy$ of 100 kV X-ray and the PSL intensity of the $SrCl_2:Eu^{2+}$ and $BaCl_2:Eu^{2+}$ phosphors faded to approximately 60 and 40% respectively after 120 min at room temperature.