• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.493-497
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• 1998

The synthesis of $Sr_{1-x}Eu_xAl_2O_4$ (x=0.005~0.2;mol%) phosphors and its properties of both photoluminescence and long-phosphorescent were investigated as a function of $Eu_2O_3$ composition. The peak wavelengths (520 nm) of phosphorescence spectra were found not to vary with the $Eu_2O_3$ composition (x) of $Sr_{1-x}Eu_xAl_2O_4$ crystals. Single phase of $SrAl_2O_4$ which determined by XRD and PL was obtained with the compositions of x<0.05 mol%. After the removal of light excitation (360 nm), the excellent after-glow characteristics of the phosphorescence were obtained with the $Eu_2O_3$ compositions of x<0.05 mol%, although the after-glow intensities for all phosphors vary exponentially with the times.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.350-355
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• 2000

The compounds, CaAl$_2$(BO$_3$)$_2$O, SrAl$_2$(BO$_3$)$_2$O and BaAl$_2$(BO$_3$)$_2$O, are good host lattices for highly efficient $Eu^{2+}$ luminescence. The europium emission peaks at 450 nm in $Eu^{2+}$:CaAl$_2$(B0$_3$)$_2$O, 411 nm in $Eu^{2+}$: SrAl$_2$(BO$_3$)$_2$O and 375 nm in $Eu^{2+}$: BaAl$_2$(BO$_3$)$_2$O. The $Eu^{2+}$: CaAl$_2$(BO$_3$)$_2$O Phosphor shows a high output and should be a good maintenance in VUV Xe lamps. It is ideally suited for use in PDP phosphors. The $Eu^{2+}$ ion is interesting because the Stokes shift emission is a strong host dependent. The difference in the Stokes shift is oneimportant factor leadingto a difference in wavelength. If the 5d level of $Eu^{2+}$ ion is lower in energy,according to a decrease in the doping lattice size, then the emission wavelength will be longer and the Stokes shift will be smaller. Therefore, a knowledge of the relationship between the crystal lattice size and the Stokes shift. (orthe energy of the 5d level),is essential for beingable to predict $Eu^{2+}$ emission properties.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.644-649
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• 2011

[ $A_{3-2x/3}Al_{1-z}In_{z}O_4F:Eu_x^{3+}$ ](A = Ca, Sr, Ba, x = -0.15, z = 0, 0.1) oxyfluoride phosphors were simply prepared by the solid-state method at $1050^{\circ}C$ in air. The phosphors had the bright red photoluminescence (PL) spectra of an $A_{3-2x/3}Al_{1-z}In_{z}O_4F$ for $Eu^{3+}$ activator. X-ray diffraction (XRD) patterns of the obtained red phosphors were exhibited for indexing peak positions and calculating unit-cell parameters. Dynamic excitation and emission spectra of $Eu^{3+}$ activated red oxyfluoride phosphors were clearly monitored. Red and blue shifts gradually occurred in the emission spectra of $Eu^{3+}$ activated $A_3AlO_4F$ oxyfluoride phosphors when $Sr^{2+}$ by $Ca^{2+}$ and $Ba^{2+}$ ions were substituted, respectively. The concentration quenching as a function of $Eu^{3+}$ contents in $A_{3-2x/3}AlO_4F:Eu^{3+}$ (A = Ca, Sr, Ba) was measured. The interesting behaviors of defect-induced $A_{3-2x/3}Al_{1-z}In_{z}O_{4-{\alpha}}F_{1-{\delta}}$ phosphors with $Eu^{3+}$ activator are discussed based on PL spectra and CIE coordinates. Substituting $In^{3+}$ into the $Al^{3+}$ position in the $A_{3-2x/3}AlO_4F:Eu^{3+}$ oxyfluorides resulted in the relative intensity of the red emitted phosphors noticeably increasing by seven times.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2769-2773
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• 2013

Red phosphors $Ca_{(1-1.5x)}Eu_xWO_4$ and $Ca_{(1-2x)}Eu^_xNa_xWO_4$ were synthesized with various concentrations x of $Eu^{3+}$ ions by using a solid-state reaction method. The crystal structure of the red phosphors were found to be a tetragonal scheelite structure with space group $I4_1/a$. X-ray diffraction (XRD) results show the (112) main diffraction peak centered at $2{\theta}=28.71^{\circ}$, and indicate that there is no basic structural deformation caused by the vacancies ${V_{Ca}}^{{\prime}{\prime}}$ or the $Eu^{3+}$ (and $Na^+$) ions in the host crystals. Densities of $Ca_{(1-1.5x)}Eu_xWO_4$ were measured on a (helium) gas pycnometer. Comparative results between the experimental and theoretical densities reveal that $Eu^{3+}$ (and $Na^+$) ions replace the $Ca^{2+}$ ions in the host $CaWO_4$. Also, the photoluminescence (PL) emission and photoluminescence excitation (PLE) spectra show the optical properties of trivalent $Eu^{3+}$ ions, not of divalent $Eu^{2+}$. Raman spectra exhibit that, without showing any difference before and after the doping of activators to the host material $CaWO_4$, all the gerade normal modes occur at the identical frequencies with the same shapes and weaker intensities after the substitution. However, the FT-IR spectra show that some of the ungerade normal modes have shifted positions and different shapes, caused by different masses of $Eu^{3+}$ ions (or $Na^+$ ions, or ${V_{Ca}}^{{\prime}{\prime}}$ vacancies) from $Ca^{2+}$.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.6-9
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• 2012

Eu3+-doped RE2O3 (RE = Gd, Y and La) phosphors were prepared by solvothermal reaction method and their crystalline structure, phase transformation and surface morphologies were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). The obtained RE2O3:Eu3+ phosphors are nanocrystalline-sized. The luminescence properties of Eu3+ ions in different host materials, namely, Gd2O3, Y2O3 and La2O3 have been investigated. PACS number: 32.50.+d, 78.55.-m, 81.40.Tv.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.253-257
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• 2016

We added 0 ~ 5 wt% $YBO_3:Eu^{3+}$ nano powders in a scattering layer of a working electrode to improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). FESEM and XRD were used to characterize the microstructure and phase. PL and micro Raman were used to determine the fluorescence and the composition of $YBO_3:Eu^{3+}$ phosphor. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with $YBO_3:Eu^{3+}$. From the results of the microstructure and phase of the fabricated $YBO_3:Eu^{3+}$ nano powders, we identified $YBO_3:Eu^{3+}$ having particle size less than 100 nm. Based on the microstructure and micro Raman results, we confirmed the existence of $YBO_3:Eu^{3+}$ in the scattering layer and found that it was dispersed uniformly. Through photovoltaic properties results, the maximum ECE was shown to be 5.20%, which can be compared to the value of 5.00% without $YBO_3:Eu^{3+}$. As these results are derived from conversion of light in the UV range into visible light by employing $YBO_3:Eu^{3+}$ in the scattering layer, these indicate that the ECE of a DSSC can be enhanced by employing an appropriate amount of $YBO_3:Eu^{3+}$.

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.611-616
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• 2011

Red-orange phosphors $Gd_{1-x}PO_4:{Eu_x}^{3+}$ (x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized with changing the concentration of $Eu^{3+}$ ions using a solid-state reaction method. The crystal structures, surface morphology, and optical properties of the ceramic phosphors were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectrophotometry. The XRD results were in accordance with JCPDS (32-0386), and the crystal structures of all the red-orange phosphors were found to be a monoclinic system. The SEM results showed that the size of grains increases and then decreases as the concentration of $Eu^{3+}$ ionincreases. As for the PL properties, all of the ceramic phosphors, irrespective of $Eu^{3+}$ ion concentration, had orange and red emissions peaks at 594 nm and 613 nm, respectively. The maximum excitation and emission spectra were observed at 0.10 mol of $Eu^{3+}$ ion concentration, just like the grain size. An orange color stronger than the red means that $^5D_0{\rightarrow}^7F_1$ (magnetic dipole transition) is dominant over the $^5D_0{\rightarrow}^7F_2$ (electric dipole transition), and $Eu^{3+}$ is located at the center of the inversion symmetry. These properties contrasted with those of a red phosphor $Y_{1-x}PO_4:{Eu_x}^{3+}$, which has a tetragonal system. Therefore, we confirm that the crystal structure of the host material has a major effect on the resulting color.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.425-428
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• 2022

In this study, Y₃Al₅O₁₂:Eu³⁺ red phosphors were synthesized at different temperatures using a solid state reaction method. The crystal structures, surface and optical properties of the Y₃Al₅O₁₂:Eu³⁺ red phosphors were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and photoluminescence (PL) analyses. From XRD results, the crystal structure of the Y₃Al₅O₁₂:Eu³⁺ red phosphors was determined to be cubic. The maximum emission spectra were observed for the Y₃Al₅O₁₂:Eu³⁺ red phosphor prepared by annealing for 4h at 1,700 ℃. The 565~590 nm photoluminescent spectra of the Y₃Al₅O₁₂:Eu³⁺ red phosphors is associated with the ⁵D₀ → ⁷F₂ magnetic dipole transition of the Eu³⁺ ions. The intensity of the photoluminescent spectra in the red phosphors is more dominant for the magnetic dipole transition than the electric dipole transition with increasing annealing temperature. The International Commission on Illumination (CIE) coordinates of Y₃Al₅O₁₂:Eu³⁺ red phosphors prepared by 1,700 ℃ annealing temperature are X = 0.5994, Y = 0.3647.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.193-197
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• 2012

$Gd_{1-x}VO_4:{Eu_x}^{3+}$ red phosphors were synthesized with changing the concentration of $Eu^{3+}$ ion by using a solid-state reaction method. The crystal structure, surface morphology, and photoluminescence and photoluminescence excitation properties of the red phosphors were measured by using X-ray diffractometer, field emission-scanning electron microscopy, and florescence spectrometer, respectively. The XRD results showed that the main peak of all the phosphor powders occurs at (200) plane. As for the photoluminescence properties, the maximum excitation spectrum occurred at 306 nm due to the charge transfer band from ${VO_4}^{3-}$ to $Eu^{3+}$ ions and the maximum emission spectrum was the red luminescence peaking at 619 nm when the concentration of $Eu^{3+}$ ion was 0.10 mol.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.353-366
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• 2021

The solubilities of different multicomponent lanthanide oxide (Ln₂O₃) solid solutions including binary (Ln₁ and Ln₂ = La, Nd, Eu, or Tm), ternary (Ln₁, Ln₂, and Ln₃ = La, Nd, Eu, or Tm), and higher systems (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were studied after aging for four weeks at 60℃. Our recent study revealed that the phase transformations in binary ((La, Nd) and (La, Eu)) and ternary (La, Nd, Eu) systems are responsible for the formation of (La, Nd)(OH)₃, (La, Eu)(OH)₃, and (La, Nd, Eu)(OH)₃ solid solutions, respectively. The variations in the mole fractions of La³⁺, Nd³⁺, and Eu³⁺ in the sample solutions of these hydroxide solid solutions indicated that a thermodynamic equilibrium might account for the apparent La, Nd, and Eu solubilities. Conversely, the binary and ternary systems containing Tm₂O₃ as the heavy lanthanide oxide retained the oxide-based solid solutions, and their solubility behaviors were dominated by their congruent dissolutions. In the higher multicomponent system, the X-ray diffraction patterns of the solid phases, before and after contact with the aqueous phase indicated the formation of a stable oxide solid solution and their solubility behavior was explained by its congruent dissolution.