• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.241-245
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• 2011

A red strontium aluminate phosphor ($Sr_3Al_2O_6:Eu^{3+},Eu^{2+}$) is synthesized using a solid state reaction method in air and reducing atmosphere. The investigation of firing temperature indicates that a single phase of $Sr_3Al_2O_6$ is formed when the firing temperature is higher than $1300^{\circ}C$. The effect of firing temperature and doping concentration on luminescent properties are investigated. $Sr_3Al_2O_6$ phosphor exhibits the typical red luminescent properties of $Eu^{3+}$ and $Eu^{2+}$.

• Korean Journal of Materials Research
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• v.20 no.7
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• pp.364-369
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• 2010

A $SrAl_2O_4:Eu^{2+},Dy^{3+}$ phosphor powder with stuffed tridymite structure was synthesized by glycine-nitrate combustion method. The luminescence, formation process and microstructure of the phosphor powder were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). The XRD patterns show that the as-synthesized $SrAl_2O_4:Eu^{2+},Dy^{3+}$ phosphor was an amorphous phase. However, a crystalline $SrAl_2O_4 $ phase was formed by calcining at $1200^{\circ}C$ for 4h. From the SEM analysis, also, it was found that the as-synthesized $SrAl_2O_4:Eu^{2+},Dy^{3+}$ phosphor was in irregular porous particles of about 50 ${\mu}m$, while the calcined phosphor was aggregated in spherical particles with radius of about 0.5 ${\mu}m$. The emission spectrum of as-synthesized $SrAl_2O_4:Eu^{2+},Dy^{3+}$ phosphor did not appear, due to the amorphous phase. However, the emission spectrum of the calcined phosphor was observed at 520 nm (2.384eV); it showed green emission peaking, in the range of 450~650 nm. The excitation spectrum of the $SrAl_2O_4:Eu^{2+},Dy^{3+}$ phosphor exhibits a maximum peak intensity at 360 nm (3.44eV) in the range of 250~480 nm. After the removal of the pulse Xe-lamp excitation (360 nm), also, the decay time for the emission spectrum was very slow, which shows the excellent longphosphorescent property of the phosphor, although the decay time decreased exponentially.

• Journal of Powder Materials
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• v.16 no.3
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• pp.203-208
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• 2009

$Y_2O_3$:Eu red phosphor was prepared by microwave synthesis. The crystal phase, particle morphology, and luminescent properties were characterized by XRD, SEM, and spectrofluorometer, respectively. The prepared $Y_2O_3$:Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at $1200^{\circ}C$. The primary particle size initially formed was varied from 30 to 450 nm with microwave-irradiation (MI) time. It was found that the emission intensity of $Y_2O_3$:Eu phosphor strongly depends on the MI time. In terms of the emission intensity, it was recommended that the MI time should be less than 15 min. The emission intensity of $Y_2O_3$:Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.575-580
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• 2014

We uniformly coated Eu(III)- and Tb(III)-doped yttrium oxide onto the surface of $SiO_2$ spheres and then characterized them by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction crystallography and UV-Visible absorption. 2D and 3D photoluminescence image map profiles were reported for the core-shell type structure. Red emission peaks of Eu(III) were observed between 580 to 730 nm and assigned to $^5D_0{\rightarrow}^7F_J$ (J = 0 - 4) transitions. The green emission peaks of Tb(III) between 450 and 650 nm were attributed to the $^5D_4{\rightarrow}^7F_J$ (J = 6, 5, 4, 3) transitions. For annealed samples, Eu(III) ions were embedded at a $C_2$ symmetry site in $Y_2O_3$, which was accompanied by an increase in luminescence intensity and redness, while Tb(III) was changed to Tb(IV), which resulted in no green emission.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.131-135
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• 2020

Single crystal phased CaZrO₃ : Eu³⁺ phosphor have been synthesized by skull melting method. The crystal structure, morphology and optical properties of synthesized phosphor were investigated XRD (X-ray diffraction), SEM (scanning electron microscopy), UV (ultraviolet) fluorescence reaction and PL (photo luminescence). The starting materials having chemical composition of CaO: ZrO₂ : Eu₂O₃= 0.962 : 1.013 : 0.025 mol% were charged into a cold crucible. The cold crucible was 120 mm in inner diameter and 150 mm in inner height, and 3 kg of mixed powder (CaO, ZrO₂ and Eu₂O₃) was completely melted within 1 hour at an oscillation frequency of 3.4 MHz, maintained in the molten state for 2 hours, and finally air-cooled. The XRD results show that synthesized phosphor is stabilized in orthorhombic perovskite structure without any impurity phases. The synthesized phosphor could be excited by UV light (254 or 365 nm) and the emission spectra results indicated that bright red luminescence of CaZrO₃ : Eu³⁺ due to magnetic dipole transition ⁵D₀→⁷F₂ at 615 nm was dominant.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.618-622
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• 2014

Oxide phosphorescent phosphor has an wide application in ceramic art and decoration due to its chemical and mechanical properties. Here, phosphorescent properties of strontium aluminate phosphor ($SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$) emitting yellowish-green light was investigated with thermal treatment at $1250^{\circ}C$ under air and reducing atmosphere. The characterizations of thermally treated samples were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), fluorescence spectrometer. $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ still showed a good phosphorescent properties after annealing process in reducing atmosphere, while phosphorescence of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ annealed in air seriously degraded, due to oxidation of $Eu^{2+}$ to $Eu^{3+}$ ions. It was also observed that $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ annealed in reducing atmosphere emitted yellowish-green light during 3 h after being exposed to sunlight.

• Journal of the Korean Applied Science and Technology
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• v.23 no.3
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• pp.207-214
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• 2006

$Y_{2-x}Gd_xO_3:Eu$, phosphors for plasma display panel(PDP), were prepared by Pechini method which use yttriun chloride, gadolinium chloride, and europium oxide as starting materials. This method is a different way to the synthesis of europium(Eu)-doped phosphors, and it consists of the formation of a polymeric resin obtained by polyesterification between metal chelate compounds and a polyfunctional alcohol. This needs lower temperature than solid-state synthetic method. The prepared $Y_{2-x}Gd_xO_3:Eu$ phosphor particles had spherical shape and coherence. The luminescence intensity of $Y_{2-x}Gd_xO_3:Eu$ phosphor particles increased according to the increase of gadolinium(Gd) content(to 0.8mol%), and $Y_{1.2}Gd_{0.8}O_3:Eu$ phosphors had the highest luminescence intensity under vacuum ultra violet(VUV) excitation. The optimum concentration of Eu in the phosphor and optimum calcination temperature was 3wt% and $1100^{\circ}C$. The prepared phosphors were consist of particle, and its size was between 100nm and 150nm. Among the different polyfunctional alcohols, diethylene glycol(DEG) improved the luminescence intensities of phosphors more than other additives. The Pechini method proved that it is demonstrated to be suitable for the synthesis of phosphors used in PDP.

• Korean Journal of Materials Research
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• v.13 no.8
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• pp.537-542
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• 2003

($Y_{l-x}$ $Gd_{x}$ )$O_2$$_3$: $Eu^{ 3＋}$ red phosphors were prepared with the solvothermal synthesis using the 2-methoxy-ethanol solvents and the emission intensity was investigated that applied with the 254 nm wavelength and the maximum excitation wavelength for energy source. The used solvents for the solvothermal synthesis were made of nitrate salt solutions of Y, Gd and Eu. These solutions dropped in autoclave have be reacted with the solvothermal synthesis at $200^{\circ}C$ for 5hrs and the red phosphors prepared here in were showed the pure cubic phase after annealing at $1000∼1200^{\circ}C$. The brightness of ($Y_{l-x}$ $Gd_{x}$)$_2$$O_3$: $Eu^{3＋}$ phosphors particles was increased as an increase of Gd ratio. The maximum excitation wavelengths of ($Y_{l-x}$ $Gd_{x}$ )$_2$$O_3$: $Eu^{3＋}$ / phosphors particles were increased according to increasing Gd ratio from 253 nm to 259 nm wavelength. The maximum emission intensity of $Gd_2$$O_3$: $Eu^{3＋}$ (Y/Gd = 1/0) phosphors particles under UV 259 nm was found to be higher than the commercial product of $Y_2$$O_3$: $Eu^{3＋}$ phosphors.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.252-257
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• 2004

$Y_{2}O_{3}:Eu^{3+}$ thin films have been grown on $Al_{2}O_{3}$(0001) substrates by a pulsed laser deposition (PLD) method. The phosphor thin films were deposited at a substrate temperature of 500, 600, and $700^{\circ}C$ under the oxygen pressure of 100, 200, and 300 mTorr. The crystallinity, surface roughness and photoluminescence of the films are highly dependent on the substrate temperature and oxygen pressure. The films grown on $Al_{2}O_{3}$(0001) substrate even under the different substrate temperatures and oxygen pressures exhibited (222) preferred orientation. The luminescent spectra exhibited strong luminescence of ${^{5}D_{0}}-{^{7}F_{2}}$ transition within $Eu^{+3}$ peaking at 612 nm. The crystallinity and luminescence intensity of the films have been improved as the substrate temperature increasing. With increase of oxygen pressure from 50 to 300 mTorr, the crystallinity of the films has been uniformly decreased. The photoluminescence intensity and surface roughness have similar behaviors as a function of oxygen pressure. At 200 mTorr, both photoluminescence intensity and surface roughness show a maximum.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.727-731
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• 2013

In this study, green barium strontium silicate phosphor ($BaSrSiO_4:Eu^{3+}$, $Eu^{2+}$) was synthesized using a solid-state reaction method in air and reducing atmosphere. Investigation of the firing temperature indicates that a single phase of $BaSrSiO_4$ is formed when the firing temperature is higher than $1400^{\circ}C$. The effect of firing temperature and doping concentration on luminescent properties are investigated. The light-emitting property was the best when the molar content of $Eu_2O_3$ was 0.025 mol. Also, the luminescent brightness of the $BaSrSiO_4$ fluorescent substance was the best when the particle size of the barium was $0.5{\mu}m$. $BaSrSiO_4$ phosphors exhibit the typical green luminescent properties of $Eu^{3+}$ and $Eu^{2+}$. The characteristics of the synthesized $BaSrSiO_4:Eu^{3+}$, $Eu^{2+}$ phosphor were investigated using X-ray diffraction (XRD) and scanning electron microscopy. The maximum emission band of the $BaSrSiO_4:Eu^{3+}$, $Eu^{2+}$ was 520 nm.