Byung Kee Moon

Pukyong National University, Tsau-liang-hai, Busan, South Korea

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Publications (182)302.6 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The SrZnO2:Sm3+ nano-phosphors were synthesized by a high energy ball milling method. It was found that under ultraviolet excitation with a wavelength of 278 nm, the phosphor presented red luminescence that was attributed to the transitions from 5D4 excited states to 6HJ ground states of Sm3+ ions. The crystallinity, morphology and particle size of SrZnO2:Sm3+ were different with different sintering temperatures. The luminescent intensity of SrZnO2:Sm3+ with different sintering temperatures was also investigated and reported.
    Ceramics International. 01/2015; 41(1).
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    ABSTRACT: A series of orange–red emitting Y6WO12:xSm3+ (0.005≤x≤0.15) phosphors were synthesized by the convenient solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of the as-synthesized phosphors. The results show an efficient energy transfer from WO66− group to Sm3+ occurs. The emission spectra of the Y6WO12:Sm3+ phosphors consisted of some sharp emission peaks of Sm3+ ions centred at 571 nm, 610 nm, 675 nm, 720 nm. The strongest one is located at 610 nm due to 4G5/2–6H7/2 transition of Sm3+, generating bright orange–red light. The optimum dopant concentration of Sm3+ ions in Y6WO12:Sm3+ is around 5 mol% and the energy transfer between Sm3+ is found to be through exchange interaction. The CIE chromaticity coordinates of the Y6WO12:0.05Sm3+ phosphor were located in the orange reddish region. The Y6WO12:Sm3+ phosphors may be potentially used as orange–red phosphors for white light-emitting diodes.
    Journal of Luminescence 11/2014; 155:317–321. · 2.14 Impact Factor
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    ABSTRACT: An intense red-emitting NaY(MoO4)2:Eu3+ nanophosphor was developed using a hydrothermal technique. A highly pure and single-phase NaY(MoO4)2:Eu3+ nanopowder was obtained after sintering the as-prepared sample at 800 °C. The crystal structure and photoluminescence properties of this double molybdate were investigated. X-ray diffraction analysis showed that the NaY(MoO4)2 nanoparticles have a scheelite-type tetragonal structure, without mixed phases. Rietveld analysis provided the atomic coordinates and Mo–O–rare-earth angles. The morphology of the molybdate precursor was controlled by adjusting the synthesis conditions. The pH was found to play a crucial role in the particle size and morphology distribution. The crystalline powder phosphor exhibited intense and efficient red emissions attributed to efficient energy-transfer from MoO2−4 to Eu3+. The chromaticity coordinates (x, y) of the NaY(MoO4)2:Eu3+ phosphor sample correspond to (0.662, 0.337). The NaY(MoO4)2:Eu3+ powder exhibited a deep-red emission under near-ultraviolet (UV) excitation, indicating a promising red phosphor for white-light-emitting diodes based on near-UV light-emitting diodes.
    Journal of Nanoscience and Nanotechnology 11/2014; 14(11). · 1.15 Impact Factor
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    ABSTRACT: A novel single-component warm white light-emitting Sr2Ca0.995MoO6: Sm3+0.005 phosphor was synthesized by solid-state reaction. The photoluminescence excitation spectra ranging from 300 to 450 nm and 460 to 500 nm broadly are observed. Direct full-color warm white light [(x, y) = 0.3221, 0.3525] was realized in this single-phase phosphor with exposure to 380 nm UV light. When this phosphor is pumped by 466 nm radiation we obtained yellow emission with an intense red component, suggesting that this material is also competitive as a blue-pumped yellow phosphor. Thus two approaches to white light are realized simultaneously in Sm3+ doped single-component phosphor for the first time. The quantum yield and the reliability of the as-synthesized phosphors for White LED applications were also investigated.
    Optics Express 10/2014; 22(21). · 3.55 Impact Factor
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    ABSTRACT: A series of Ce3+ ions doped GdSr2AlO5 (GSA) phosphors were synthesized by a citric acid based sol–gel method. The X-ray diffraction patterns confirmed their tetragonal structure after the samples were annealed at 1300 °C, and the scanning electron microscope image showed the closely packed particles. The excitation spectra revealed that the GSA phosphor effectively excited with blue light of 442 nm due to the 4f1→5d1 transition and exhibited yellow emission corresponding to the 5d1→4f1 transition of Ce3+ ions. The optimum doping concentration of Ce3+ ions was 5 mol% and the critical distance was calculated to be ~17 Å. White LEDs were fabricated by combining blue LED (465 nm) chip with Ce3+:GSA phosphor. The CIE chromaticity coordinates (0.34, 0.31) provide their emission potentiality in the white light region.
    Ceramics International 05/2014; 40(4):5693-5698. · 2.09 Impact Factor
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    ABSTRACT: Charge transfer (CT) energy from the ligand to the central ions is an important factor in luminescence properties for rare earth doped inorganic phosphors. The dielectric theory of complex crystals was used to calculate chemical bond properties. Combining the photoluminescence and the dielectric theory of complex crystals, the CT bands of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) for Eu(3+)-doped inorganic phosphors have been investigated experimentally and theoretically. Taking Eu(3+)-doped Ln3M5O12 (Ln = Y, Lu and M = Al, Ga), Gd3Ga5O12, MMoO4 (M = Ca, Sr, Ba) and MWO4 (M = Ca, Sr, Ba) as typical phosphors, we investigated the effects of the cation size on the CT bands and chemical bond properties including the bond length (d), the covalency (fc), the bond polarizability (αb) and the environmental factor (he) of O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+), respectively. For systematic isostructural Ln3M5O12 (Ln = Y, Lu and M = Al, Ga) phosphors, with the increasing M ion radius, the bond length of Ln-O decreases, but fc and αb increase, which is the main reason that the environmental factor increased. For the isostructural MMoO4:Eu, with the increasing M ion radius, the Mo-O bond length increases, but fc and αb decrease, and thus he decreases. However, in the compound system MWO4:Eu (M = Ca, Ba) with the increasing M ion radius, the O-W bond length increases, but fc and αb increase, and thus he increases and the O-W CT energy decreases. Their O(2-)-Eu(3+), O(2-)-Mo(6+) and O(2-)-W(6+) CT bands as well as their full width at half maximum (FWHM) were directly influenced by he. And with the increasing he, CT bands of O-Eu or O-Mo or O-W decrease and their FWHM increases. These results indicate a promising approach for changing the material properties, searching for new Eu(3+) doped molybdate, tungstate or other oxide phosphors and analyzing the experimental result.
    Dalton Transactions 04/2014; · 4.10 Impact Factor
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    ABSTRACT: Novel host-sensitized Y6WO12:xDy3+ (0.01 ≤ x ≤ 0.20) phosphors were synthesized via solid-state reaction process. X-ray diffraction analysis confirmed the phase formation of Y6WO12:Dy3+ materials. The photoluminescence excitation and emission spectra, concentration effect, thermal-quenching, and decay properties were investigated. The phosphor could be excited by the UV light region from 300 to 400 nm, and it exhibited blue (478 nm) and yellow (568 nm) emission corresponding to 4F9/2–6H15/2 transitions and 4F9/2–6H13/2 transitions, respectively. The WO6 groups in the host lattices can absorb UV light efficiently, and then transferred the energy to the activator Dy3+ ions, resulting in near white light emission. The optimum dopant concentration of Dy3+ ions in Y6WO12:xDy3+ was around 5 mol% and the critical transfer distance of Dy3+ was calculated as 12 Å. The fluorescence lifetime was also determined in Y6WO12:0.05Dy3+. The temperature dependence of photoluminescence properties was investigated from 300 to 480 K and the prepared Y6WO12:Dy3+ phosphors showed poor thermal-quenching properties.
    Journal of the American Ceramic Society 04/2014; · 2.43 Impact Factor
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    ABSTRACT: A series of new double perovskite tungstate Ba2CaWO6:xDy(3+) (0.01⩽x⩽0.15) phosphors were synthesized via solid state reaction process. XRD analysis confirmed the phase formation of Ba2CaWO6:Dy(3+) materials. The photoluminescence excitation and emission spectra, concentration effect, thermal-quenching, and decay property were investigated. The phosphor could be excited by the UV light region from 250 to 400nm, and it exhibits blue (493nm) and yellow (584nm) emission corresponding to (4)F9/2-(6)H15/2 transitions and (4)F9/2-(6)H13/2 transitions, respectively. The optimum dopant concentration of Dy(3+) ions in Ba2CaWO6:xDy(3+) is around 5mol% and the critical transfer distance of Dy(3+) is calculated as 14Å. The thermal-quenching temperature is 436K for Ba2CaWO6:0.05Dy(3+). The fluorescence lifetime is also determined in Ba2CaWO6:0.05Dy(3+).
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2014; · 1.98 Impact Factor
  • Journal of Luminescence 01/2014; · 2.14 Impact Factor
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    ABSTRACT: A series of Tm3+ and/or Eu3+ doped Ca9Gd(VO4)7 single composition phosphors were synthesized by a solid state reaction method, and their luminescence properties were investigated. Tm3+ and Eu3+ co-doped Ca9Gd(VO4)7 phosphors showed a blue with the peak at 477 nm and red with the stronger peak at 620 nm dual emission bands under the UV excitation, which originates from the f-f transitions of Tm3+ and Eu3+ ions, respectively. The energy transfer from O2--V5+ CT (charge transfer) energy to Tm3+ and Eu3+ ions as well as the energy transfer from Tm3+ to Eu3+ ions were investigated. The photoluminescence intensity ratio of blue and red emission could be tuned by adjusting the concentration of Tm3+ and Eu3+ ions and as a result the emission color varies from blue to white to red. The white-light emission is realized in single phased phosphor of Ca9Gd(VO4)7:Tm3+, Eu3+ by combining the Tm3+-emission and the Eu3+-emission.
    Optical Materials Express 01/2014; 4(1). · 2.92 Impact Factor
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    ABSTRACT: Y6(WMo)0.5O12 activated with Eu(3+) ions was investigated as a red-emitting conversion phosphor for white light emitting diodes (WLEDs). The phosphors were synthesized by calcining a citrate-complexation precursor at different temperatures. The photoluminescence properties of the phosphors and the energy transfer mechanisms involved were studied as a function of structure evolution. It was found that the host lattices were crystallized in a cubic or a hexagonal phase depending on the synthesis conditions. Although all the phosphors showed intensive red emission under an excitation of near-UV or blue light due to energy transfer from the host lattices to Eu(3+) ions, the photoluminescence spectra and temporal decay features were found to vary significantly with the structure and crystallinity of the host lattice. The mechanisms of the energy transfer from the host lattices to Eu(3+) ions and energy quenching among Eu(3+) ions were discussed on the basis of structure evolution of the host lattice. Phosphors calcined at 800 and 1300 °C were suggested to be promising candidates for blue and near-UV light excited WLEDs, respectively.
    Inorganic Chemistry 09/2013; · 4.59 Impact Factor
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    ABSTRACT: The phosphor of CeO2 activated with the trivalent rare-earth Sm3+ ions were synthesized by using a solvothermal method. The CeO2:Sm3+ powders were finally obtained through calcination process sintered in the air at 800-1200 degrees C. The synthesized phosphors were characterized systematically by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and photoluminescence excitation spectra (PLE). The XRD and FE-SEM results reveal that the phosphor exhibit agglomerated spherical shape and with the increase of sintering temperature peaks become sharper and narrower and the crystal sizes also increase, respectively. The room temperature photoluminescence spectra of Sm3+ doped CeO2 powders were recorded on a PTI (Photon Technology International) flurimeter using a Xe-arc lamp with a power of 60 W. The emitted radiation was dominated by the orange light with the characteristic emission of Sm3+ from the transitions of 4G5/2 --> 6H5/2,7/2. The sharp emission properties show that the CeO2 has the potential to serve as a host material for rare-earth doped laser crystal and phosphor material.
    Journal of Nanoscience and Nanotechnology 09/2013; 13(9):6060-3. · 1.15 Impact Factor
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    ABSTRACT: By controlling the volume of HF and the alkaline earth ion introducing, a series of GdF3 samples have been synthesized by a hydrothermal method without any surfactant. The samples are characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, energy-dispersive spectroscopy (EDS) spectra, photoluminescence (PL) excitation and emission spectra as well as the luminescence dynamic decay curves. The optical properties of Tb3+ and the energy transfer from host Gd3+ to Tb3+ have been investigated and discussed in detail based on the volume of HF used in the synthesis procedure and the alkaline earth ion introducing. The experimental results suggest that the optical properties of Tb3+ can be controlled by the deliberately ion introducing as well as the volume of HF used in the synthesis procedure. Though the optical properties of Tb3+ can be adjusted by different ways, a green, easy, and cost saving way, such as deliberately ion introducing, is a good choice in modifying the optical properties of Tb3+.
    Optics Communications 08/2013; s 301–302:106–111. · 1.44 Impact Factor
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    ABSTRACT: Eu3+ activated oxyapatite Ca2Gd8Si6O26 (CGS) nanophosphors were synthesized using a solvothermal reaction method. The structural and luminescent properties of these nanophosphors were investigated as a function of sintering temperature and Eu3+ ion concentration. The SEM images of the prepared phosphors reveal spherically shaped particles in the nanometer range and the XRD patterns confirm their hexagonal structure. The photoluminescence excitation (PLE) spectra of Eu3+:CGS showed the charge transfer band (CTB) and intense f–f transitions of Eu3+ and Gd3+. The intensity of the f–f transitions of Gd3+ increases with increasing the sintering temperature and decreases with increasing the Eu3+ concentration. It was observed that the CTB of Eu3+ shifted to a shorter wavelength region with an increase the crystallite size due to the variation of coordination environments. The photoluminescence (PL) spectra of Eu3+:CGS exhibit two emission lines corresponding to the 5D0 → 7F0 transition which results from occupation of Eu3+ ions in two different low symmetry local sites in CGS host lattice. The optimized sintering temperature and concentration of Eu3+ were observed for Eu3+:CGS nanophosphors based on the dominant red (5D0 → 7F2) emission intensity under NUV (395 nm) excitation. The decay curves of 5D0 level show that the lifetime decreases with increasing the crystallite size. These luminescent powders are expected to find potential applications such as WLEDs and optical display systems.
    Sensors and Actuators B Chemical 06/2013; · 3.84 Impact Factor
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    ABSTRACT: Bi3+ and Tb3+ ions co-doped GdAlO3 (GAP) nanophosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GAP phosphor confirms their orthorhombic phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of GAP:Tb3+, Bi3+ phosphors consist of a broad band in the shorter wavelength region due to the 4f8 → 4f75d1 transition of Tb3+ ions overlapped with the 6s2 → 6s16p1 (1S0 → 3P1) transition of Bi3+ ions and some sharp peaks in the longer wavelength region due to f → f transitions of Tb3+ ions. The present phosphors exhibit green color due to strong 5D4 → 7F5 transition of Tb3+ ions. The emission intensity was enhanced by co-doping with Bi3+ ions under 292 nm excitation, which indicate that the efficient energy transfer occurred from Bi3+ to Tb3+ ions.
    Materials Research Bulletin 06/2013; · 1.97 Impact Factor
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    ABSTRACT: Different concentrations of Tb3+ ion-doped gadolinium aluminum garnet (GAG) nanophosphors have been synthesized by solvothermal reaction method and sintered at 1300 °C. The XRD patterns confirm that the GAG phosphors sintered at 1300 °C have a garnet structure with single cubic phase. The calculated crystallite size is about 92 nm. The SEM images of the phosphors show the spherical morphology agglomerated with many small particles. The luminescence properties of these phosphors have been carried out by the emission and excitation spectra along with lifetime measurements. The excitation spectra of GAG:Tb3+ phosphors consist of three broad bands due to the 4f8→4f75d1 transition and some sharp peaks due to the 4f8→4f8 transition. The emission spectra of the phosphors reveal two colors, such as blue due to 5D3→7FJ transitions and green due to the 5D4→7FJ transitions. The dynamics of the phosphors have been investigated by decay curves and the cross-relaxation process and is observed at 0.5 mol% Tb3+ concentration.
    Journal of Luminescence 06/2013; · 2.14 Impact Factor
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    ABSTRACT: A series of Zn1−xGa2S4:xMn2+ (0.005 ≤ x ≤ 0.08) phosphors has been synthesized by solid-state reaction at 950 °C for 2 h in a flowing H2S stream. The structural and photoluminescence properties of Zn1−xGa2S4:xMn2+ phosphors have been investigated. Under an excitation wavelength of λex = 336 nm, ZnGa2S4:Mn2+ exhibits a red emission band at about 612 nm owing to the Mn2+4T1(4G) → 6A1(6S) transition. The luminescence band shifts to longer wavelength and is accompanied by a decrease in decay time with increasing Mn2+ concentration. The maximum PL intensity of the phosphor is obtained at x = 0.03. The critical transfer distance of Mn2+ is calculated as 21 Å. The decay time for ZnGa2S4:0.03Mn2+ is 1.79 ms. The calculated CIE coordinates indicate that ZnGa2S4:Mn2+ has good color purity. Mn2+-activated ZnGa2S4 phosphors have great potential for application in UV white LED and display devices.
    Materials Research Bulletin. 06/2013; 48(6):2154–2158.
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    ABSTRACT: The upconversion luminescence properties of ZrO2:Ho3+ and co-doped ZrO2:Ho3+, Yb3+ nanophosphors with various concentrations of Yb3+ ions were synthesized via a solvothermal reaction method. Our samples have a nearby spherical shape and an average crystal size was about 80 nm. For low concentrations of Yb3+ ion, the crystalline structure changed from tetragonal to monoclinic phase as the Yb3+ concentration increased to 3 mol% Yb3+ ions. As the Yb3+ concentration increased to above 5 mol%, ZrO2 nanophosphors displayed a very stable tetragonal phase. The sample shows a strong green (550 nm) and weak red (660 nm) and near infrared (757 nm) upconversion emission corresponding to the transitions of Ho3+:5F4/5S2 --> 5I8, 5F5 --> 5I8 and 5S2 --> 5I7, respectively. The energy transfer (ET) processes between the Ho3+ and Yb3+ ions and the involved mechanisms have been investigated. Experimental results suggest that two-photon upconversion processes are taking place under excitation by a 975 nm.
    Journal of Nanoscience and Nanotechnology 06/2013; 13(6):4006-9. · 1.15 Impact Factor
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    ABSTRACT: A new thiogallate-based green-emitting phosphor, MgGa2S4:Eu2+, was first synthesized via a high-temperature solid-state reaction in a CS2 atmosphere. We then investigated the structures and luminescent properties of the MgGa2S4:Eu2+ phosphors. The MgGa2S4:Eu2+ phosphors can be excited efficiently by UV–visible light in the wavelength range from 350 to 520 nm and they emit an intensely green light with emission bands peaking at 538 nm. The optimal concentration for Eu2+ in MgGa2S4 was found to be about 6 mol%, and the corresponding concentration quenching mechanism was the electric multipole–multipole interaction. The quenching temperature was calculated to be 402 K, and the Huang–Rhys factor was about 4. The energy barrier for thermal quenching was calculated to be 0.28 and 0.27 eV by the two types of the Arrhenius equations. The small variation in the color coordinates of MgGa2S4:Eu2+ under high temperatures indicates that the as-synthesized phosphor has good color stability. Due to their broadband absorption in the 350–520 nm wavelength range, these phosphors may be able to fulfill the requirements for application in the development of Ga(In)N-based white LEDs.
    Journal of the American Ceramic Society 06/2013; 96(6). · 2.43 Impact Factor
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    ABSTRACT: Rare earth molybdates R4MoO9 (R = Y, Gd, and Lu) with Eu3+ ion-doped were synthesized by solid-state reaction. The phase structure, optical absorption and photoluminescence properties of the as-prepared powder samples were studied. The powder X-ray diffraction patterns indicated that all the compounds crystallized in a hexagonal structure, and the lattice parameters reduced in the order of the ionic radii of R. The UV–visible diffuse reflectance spectra revealed that the compounds had a strong absorption of near-UV light due to the excitation of MoO6 groups in the host lattices. The energy absorbed by the host lattices could then be transferred to doped Eu3+ ions, resulting in red emission due to the f–f transitions of Eu3+ ions. The optical absorption and photoluminescence properties of the compounds indicated that they might be candidates as the color-conversion red phosphors for solid-state lighting.
    Materials Chemistry and Physics 05/2013; 139(s 2–3):998–1002. · 2.07 Impact Factor

Publication Stats

280 Citations
302.60 Total Impact Points

Institutions

  • 1999–2014
    • Pukyong National University
      • Department of Physics
      Tsau-liang-hai, Busan, South Korea
  • 2013
    • Korea Institute of Energy Research
      Sŏul, Seoul, South Korea
    • Liaocheng Teachers University
      Tungchangfu, Shandong Sheng, China
  • 2009–2013
    • Dong-Eui University
      • Department of Physics
      Pusan, Busan, South Korea
  • 2011
    • Jinggangshan University
      Jiang’an, Jiangsu Sheng, China
  • 2005
    • Ajou University
      • Department of Anesthesiology and Pain Medicine
      Seoul, Seoul, South Korea
  • 2003–2005
    • Silla University
      Tsau-liang-hai, Busan, South Korea