Papers by Keyword: Green Phosphor

Abstract: The Tb³⁺doped Bi₂WO₆ luminescent materials are synthesized by a co-precipitation method. The structure and composition of the samples were characterized by DTA-TG and XRD. The results showed that the formula of the sample is Bi₂WO₆ at the temperature of 600°C~900°C, which belongs to the needed and stable orthorhombic ctystal. The luminescence properties were characterized by UV-vis and fluorescence spectrophotometer. The results showed that, the phosphor can be effectively stimulated by blue light of 488 nm, we can get the intense green-emission, which corresponds to the ⁵D₄→⁷F₅ transitions of Tb³⁺. It indicates that the samples match the light-emitting wavelength of the common blue-emitting InGaN chips and are expected to be applicable to a new type of green-emission light conversion materials which are applicable to the blue LED chips.

Abstract: Being added by H₃BO₃ as flux, the nanosize strong green phosphor Zn₂SiO₄: Mn²⁺ was prepared by an improved sol-gel method. The structure and the morphology of the samples were examined by XRD, UV-VL spectrophotometer and SEM. The photoluminescence properties were measured by fluorescence spectrometer. Results show that, when the samples were annealed at 850°C for 2 hours, the intensity of emission spectrum of the sample is not strictly followed the monotonically increasing with the increase of Mn²⁺ doping concentration. It appears in a fluctuated tendency with the increase of doping concentration. In the 4% Mn²⁺ doping concentration and annealing temperature 950°C, the most strong green emission spectrum can be obtained. The mechanism of luminescence properties of this kind of material is analyzed.

Abstract: Novel Ce³⁺ and Tb³⁺ co-doped LiLa2BO5 phosphor, synthesized by a solid state reaction in reductive atmosphere, exhibits enriched emission spectrum in the green region .The XRD patterns, photoluminescence spectra and SEM were recorded and the effects of Tb³⁺ and Ce³⁺ concentration, sintering condition on the luminescent properties of as-synthesized phosphors were investigated. The emission spectra under ultraviolet (200--350 nm) radiation showed a dominant peak at 544 nm attributed to the ⁵D₄⁷F_J(J=0,1,2...6) transition of Tb³⁺, which was greatly enhanced by the co-doping of Ce³⁺, indicating that there occurred an efficient nonradioactive energy transfer from Ce³⁺ to Tb³⁺. The experimental result shows that the optimum Ce³⁺ and Tb³⁺ doping concentrations are 15 at% and 10 at% respectively.Keywords: Green phosphor; High luminescence efficiency; LiLa2BO5:Ce³⁺,Tb³⁺ ; Rare earths

Abstract: A novel green-emitting phosphors Tb³⁺-doped LiLa2BO5 phosphor was synthesized by different methods: the solid-state reaction method and solgel method. The green phosphor was characterized by XRD. The green phosphor has a dominant excitation peak located at 280nm. The emission intensity was enhanced by Tb³⁺ doped ion, and decreased due to concentration quenching. Under the excitation wavelength of 280 nm, the relative intensity of the solgel derived phosphor is about 81% of solid-state reaction derived phosphor. The intense green emission of LiLa2BO5 under 280nm excitation suggests that Tb³⁺ -doped LiLa2BO5 phosphor is a potential green phosphor for near-UV LEDs.

Abstract: In this article, La0.6Ce0.27Tb0.13PO4 green phosphor has been successfully synthesized through the method of co-percipition. The surface composition, morphology, and fluorescence properties of luminescent materials were characterized by XRD, SEM, and PL. The results showed that: the added sensitizer of Ce3+ ion rapidly increased the fluorescence intensity, further proved that Ce3+ ions have sensitization on Tb3+ ions. In system of La1-x-yPO4: yCe, the fluorescence intensity of xTb, La0.8PO4:0.1Ce,0.1Tb is strongest, and it’s the best ratio of the system.

Abstract: SiO2，CaO and MgO was chosen as main raw material and Solid State method was used to prepare the sample. The precursor was directly sintered at 1000°C with reducing atmosphere for 3 h to obtain new green CaMgSi2O6:Tb3+,Li+Phosphors.The effects of the content of the doping ions Tb3+ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by XRD,SEM,UV and PL-PLE spectra respectively.The results showed that the CaMgSi2O6:Tb3+,Li+ was base-centered monoclinic crystals, the phosphor particle distributed uniformly.The phosphor has a strong absorptive capacity excited by 230 nm ultraviolet ray, and could emit the strong green light with the wavelength of 543 nm(5D4→7F5). The CaMgSi2O6:Tb3+,Li+ is a new type of green fluorescent material.

Abstract: CaCO3 was chosen as main raw material and wet chemical method was used to prepare the precursor. The precursor was directly sintered at 1060oC with reducing atmosphere for 3 h to obtain new green CaO:Tb3+ ,Li+ Phosphors. The effects of the content of the doping ions Tb3+ and Li+ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by XRD, laser particle size analyzer, SEM, UV and PL-PLE spectra respectively. The results showed that the CaO:Tb3+,Li+ was a single face-centered cubic crystals, the phosphor particle distributed uniformly, the average size of particle was 2μm. The phosphor has a strong absorptive capacity excited by 282 nm ultraviolet ray, and could emit the strong green light with the wavelength of 543 nm(5D4→7F5). The CaO:Tb3+,Li+ is a new type of green fluorescent material.

Abstract: Green phosphor of La(BO3, PO4): Ce, Tb was synthesized by means of sol-gel method and conventional solid state method. The thermal formation process was characterized by thermogravimetric analysis (TG) and (DTA). The effects of synthesis method and conditions on the crystal and morphological structure were investigated by (XRD) and (SEM). The results revealed that La (BO3, PO4): Ce, Tb phosphors with monocline structure and high purity were successfully prepared by sol-gel method. Compared with solid state method, the products synthesized by sol-gel method presented well developed crystal structure, small particle size, narrow size distribution and high luminescent performances. The product synthesized at 1050°C for 2h had better emission intensity.

Abstract: The effect of a binary surfactant on the luminance efficiency of a green phosphor was investigated with an emphasis on the chemical control of interactions between the suspension components. The dispersion system of the green phosphor paste was designed by an evaluation of the acid and base properties of the green phosphor and the surface active organic molecules by a non-aqueous titration method. Oleyl amine and 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethylene phosphoric acid (hereafter SAIT7) were added into the green phosphor paste taking into account the ratio between the acid and base sites of the green phosphor particle’s surface. This resulted in a higher maximum solid loading and a further decrease in the viscosity of the green phosphor paste compared to a single addition of SAIT7 and oleyl amine. The green phosphor paste with the binary surfactant exhibited a much improved photoluminescence intensity and homogeneity of the emission properties than a single addition of the dispersant.