Doping Concentration Of Ce3 Research Articles

Effect of H3BO3 on preparation and luminescence properties of submicron green-emitting Ca3Sc2Si3O12 ∶Ce phosphor

Green-emitting Ca3Sc2Si3O12:Ce3+ phosphors for white LED are successfully synthesized by a gel-combustion method. The as-synthesized phosphors are investigated by XRD, SEM, and fluorescence spectrophotometer. The results indicate that the crystal structure of the phosphor is pure. The particle morphology of the sample is basically spherical in shape. The particle size is smaller than 1μm. The emission spectrum shows a broad band emission, and the main emission peak locates at 505 nm. Bright green-emission broadening is attributed to the characteristic emissions 5d-2F5/2 and 5d-2F7/2 transitions of Ce3+. The optimal doping concentration of Ce in Ca3-xSc2Si3O12:Ce is x=0.1. The thermal stability and the luminescence intensity of the Ca3Sc2Si3O12:Ce3+ are significantly improved compare with those of YAG:Ce.

Investigation of Ce:YAG Doping Effect on Thermal Aging for High-Power Phosphor-Converted White-Light-Emitting Diodes

In this paper, high-power phosphor-converted white-light-emitting diodes (PC-LEDs) with selected concentration and thickness of cerium-doped yttrium aluminum garnet (Ce:YAG) phosphor-doped silicones are investigated to study the thermal-degradation effect of the Ce:YAG phosphor-silicone layer. The experimental results showed that the lumen loss, chromaticity (CIE shift), and spectrum intensity reduction increase as the concentration of Ce:YAG phosphor-doped silicone increases. Although silicone degradation attributed to the final thermal degradation, it is not a dominant factor until a much thicker silicone is employed in PC-LEDs. The major degradation mechanism of the PC-LEDs results from the higher doping concentration of Ce:YAG in silicone. We found that 94% lumen loss was attributed to 5.5 wt% Ce:YAG doping and only 6% of the lumen loss was due to a 1-mm thickness of silicone degradation. However, the negligible differences of measured fluorescent lifetimes among the test samples before and after thermal aging (at 150 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">deg</sup> C for 500 h) eliminated any significant nonradioactive quenching processes that existed in the aged samples. The emission spectra indicate that a higher doping concentration in silicone causes a higher degree of loss at the emission wavelength of Ce:YAG. Therefore, minimizing any unwanted interactions, such as refractive index and thermal-expansion mismatches, between the phosphor and the silicone during thermal aging is a new direction of addressing thermal reliability for high-power PC-LEDs. From practical points of view, we found that a lower doping concentration of the Ce:YAG phosphor in thin silicone is a better choice in terms of having less thermal degradation for use in packaging of the high-power PC-LEDs modules and is essential to extend the operating lifetime of the phosphor-based white LED modules.

The Effect of Electron Doping on the Physical Properties of La 1 − x Ce x MnO3 Manganites

The morphology, structural and magnetic properties of La 1 − x Ce x MnO 3 manganites oxides, prepared by sol-gel method, have been investigated to study the effect of the substitution of La by Ce. The images of the scan electron microscopy (SEM) show that our samples are constituted of homogenous particles, ranging in size from (1.75–3.75 μ m). The Rietveld refinements of the X-ray diffraction reveal the presence of both orthorhombic structure with the Pnma space group and an unreacted CeO 2 phase. We have found that when increasing the x doping concentration of Ce the volume decreases. Magnetic measurements versus temperature in an applied magnetic field of 0.1T show that all samples exhibit a paramagnetic-ferromagnetic transition and the curie temperature T C decreases.

Effect of introducing Ce3+ on the emission properties of Er3+/Yb3+-doped TeO2-WO3-ZnO glasses

Ce3+ ions were introduced into the Er3+/Yb3+-codoped TeO2-WO3-ZnO glasses, and the effect of Ce3+ on the emission properties at 1.5μm band and the upconversion luminescence of Er3+ in the glasses was investigated. With the increasing of Ce3+ concentration, the emission intensity of Er3+ at 1.5μm band increases firstly, and then decreases. The optimal doping concentration of Ce3+ is about 2.07×1020/cm3. As for the Er3+ emission at 1.5-μm band, the fluorescence lifetime decreases a little from 3.4ms to 3.0ms, while the full width at half maximum (FWHM) hardly changes with the increase of Ce3+ concentration. Due to the effective cross relaxation between Ce3+ and Er3+: Er3+(4I11/2)+Ce3+(2F5/2)→Er3+(4I13/2)+Ce3+(2F7/2), the upconversion emission intensity of Er3+ is reduced greatly. But when Ce3+-doping concentration is too high, the other cross relaxation between Ce3+ and Er3+: Er3+(4I13/2)+Ce3+(2F5/2)→Er3+(4I15/2)+Ce3+(2F7/2) happens, which depopulates the 4I13/2 level of Er3+ and results in the decrease of the emission intensity and fluorescence lifetime of Er3+ at 1.5μm band.

TFEL of Ce3+ in zine sulpho-oxide

A new TFEL material ZnSxO1−x: Ce3+ is prepared. The EL brightness of ZnSxO1−x: Ce3+ is at least one order higher than that of ZnS: Ce3+ at the same doping concentration of Ce3+. The EL emission wavelength of ZnSxO1−x: Ce3+ (X = 0.5) ranges from 400 to 600 nm. The emission of ZnSxO1−x: Ce3+ may be used as the blue part of white TFEL.