Y2O3:Eux (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.

The co-doping effect of aliovalent metal ions such as Mg2+, Ca2+, Sr2+, Ba2+, and Zn2+ on the photoluminescence of the Y2O3:Eu3+ red phosphor, prepared by spray pyrolysis, is analyzed. Mg2+ metal doping is found to be helpful for enhancing the luminescence of Y2O3:Eu3+. When comparing the luminescence intensity at the optimum doping level of each Mg2+ ion, the emission enhancement shows the order of Zn2+ Ba2+ > Ca2+ > Sr3+> Mg2+. The highest emission occurs when doping approximately 1.3% Zn2+, which is approximately 127% of the luminescence intensity of pure Y2O3:Eu3+. The highest emission was about 127% of the luminescence intensity of pure Y2O3:Eu3+ when doping about 1.3% Zn2+. It is determined that the reason (Y, M)2O3:Eu3+ has improved luminescence compared to that of Y2O3:Eu3+ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li2CO3 as a flux with organic additives.

Nanosized and aggregated Y2O3:Eu Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of Y2O3:Eu red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated Y2O3:Eu Red phosphor under bead mill wet process. The dispersion property of the Y2O3:Eu nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size (D50) of Y2O3:Eu nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of Y2O3:Eu nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of Y2O3:Eu nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.

Y2O3–H3BO3:Eu3+ powders are synthesized using a mechanical alloying method, and their photoluminescence (PL) properties are investigated through luminescence spectrophotometry. For samples milled for 300 min, some Y2O3 peaks ([222], [440], and [622]) and amorphous formations are observed. The 300-min-milled mixture annealed at 800°C for 1 h with Eu = 8 mol% has the strongest PL intensity at every temperature increase of 100°C (increasing from 700 to 1200°C in 100°C increments). PL peaks of the powder mixture, as excited by a xenon discharge lamp (20 kW) at 240 nm, are detected at approximately 592 nm (orange light, 5Do → 7F1), 613 nm, 628 nm (red light, 5Do → 7F2), and 650 nm. The PL intensity of powder mixtures milled for 120 min is generally lower than that of powder mixtures milled for 300 min under the same conditions. PL peaks due to YBO3 and Y2O3 are observed for 300-min-milled Y2O3–H3BO3 with Eu = 8 mol% after annealing at 800°C for 1 h.

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 :Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at . 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 :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 :Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm

Eu3+ -doped Y2O3 red phosphor was synthesized in a flux method using the chemicals Y2O3, Eu2O3,H3BO3 and BaCl2·2H2O. The effect of a flux addition on the preparation of Y2O3:Eu3+ red phosphor used asa cold cathode fluorescence lamp was investigated. H3BO3 and BaCl2·2H2O fluxes were used due to theirdifferent melting points. The crystallinity, thermal properties, morphology, and emission characteristics weremeasured using XRD, TG-DTA, SEM, and a photo-excited spectrometer. Under UV excitation of 254nm, Eu2O33.7mol% doped Y2O3 exhibited a strong narrow-band red emission, peaking at 612nm. From this result, thephosphor synthesized by firing Y2O3 with 3.7mol% of Eu2O3, 0.25mol% of H3BO3 and 0.5mol% of BaCl2·2H2Ofluxes at 1400oC for 2 hours had a larger particle size of 4µm on average compared to the phosphor of theH3BO3 flux alone. In addition, a phosphor synthesized by the two fluxes together had a rounder corner shape,which led to the maximum emission intensity.