Lamp phosphors

Peters, T. M.; Pappalardo, R.; Hunt, R.B.

doi:10.1007/978-94-011-1522-3_10

Cited by 8 publications

(3 citation statements)

References 37 publications

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“…Y 2 O 3 :Eu is a superior red phosphor with a quantum efficiency of nearly 100% . Commercially, it has applications in fluorescent lamps, , projection televisions, , and FEDs. , As an oxide, it is more stable than sulfur-containing phosphors which undergo changes in their surface chemistry when interacting with the electron beam, seriously degrading their cathodoluminescent brightness and releasing gases that can poison the field emitting tips. , …”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction

2003

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(Y0.95Eu0.05)2O3 nanoparticles have been synthesized by subambient homogeneous reduction using alkalide solutions and subsequent oxidation. As synthesized, the material consists of free-flowing agglomerates of ill-defined, amorphous, or subnanocrystalline nanoparticles. Samples annealed at 500 °C or greater are crystalline, consisting of agglomerated nanocrystals. As the annealing temperature is raised from 500 to 900 °C, the nanocrystals grow from an average of 10.9 to 14.2 nm, the agglomerates decrease in size, and the surface area increases from 49 to 59 m2/g. The crystallite size determined by X-ray diffraction line-broadening correlates well with TEM observations, indicating that the particles are individual nanocrystals. The increase in the surface area is consistent with the uncovering of the surfaces of the nanocrystals as a result of the reduction of the size of the agglomerates, counteracting the loss of surface area due to crystallite growth. Annealing at 1000 °C results in growth of the nanocrystals to an average size of 25.1 nm and a decrease in the surface area to 35 m2/g. Photoluminescence spectra do not show any fluorescence from samples until they have been annealed at 500 °C or higher. Visual inspection found fluorescence from a small fraction of samples annealed at temperatures as low as 200 °C. The photoluminescence intensity of the 5D0 → 7F2 transition increases with annealing temperature from 500 to 700 °C, levels-off between 700 and 900 °C, then dramatically increases after annealing at 1000 °C. This trend mirrors that seen for the cell parameter for this cubic system, which decreases from 10.639 to 10.615 Å, larger than the 10.604 Å expected for bulk material. The expanded cell volume may play an important role in the low quantum yields found for these nanocrystalline samples (<8%).

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Section: Introductionmentioning

confidence: 99%

Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction

2003

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“…In particular, red-emitting europium-activated yttrium oxide (Y 2 O 3 :Eu) has attracted much attention both as one of the most promising oxide-based red phosphor systems , due to its excellent luminescence efficiency, color purity, and stability and also as a model system for studying the effect of the interplay of radiative and nonradiative processes on phosphor efficiency. Y 2 O 3 :Eu exhibits strong UV and cathode-ray-excited luminescence with a quantum efficiency of nearly 100% 3 and is useful in lighting and cathode ray tubes, display materials, tricolor fluorescent lamps, ,, projection televisions, , field emission displays, , laser devices, and so forth. − As an oxide, it is more stable than sulfur-containing phosphors which undergo changes in their surface chemistry when interacting with the electron beam, seriously degrading their cathodoluminescent brightness and releasing gases that can poison the field-emitting tips.…”

Section: Introductionmentioning

confidence: 99%

Site-Selective Deposition and Micropatterning of Visible-Light-Emitting Europium-Doped Yttrium Oxide Thin Film on Self-Assembled Monolayers

2007

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We have developed a novel process for preparing a micropattern of europium-doped yttrium oxide thin films using a patterned self-assembled monolayer. The thin film was transformed into the crystalline phase by annealing at 800 °C for 1 h. Europium-doped yttrium oxide films showed red emission (611 nm) due to photoluminescence excited by 266 nm. The deposition and micropatterning of visible-lightemitting europium-doped yttrium oxide was successfully realized in an aqueous solution under environmentally friendly conditions.

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“…Considerable interest exists to develop advanced phosphor microparticles with uniform, controlled shapes and tailored inorganic chemistries for brighter, more efficient light-emission sources and for higher-resolution optical displays ͑e.g., for fluorescent lighting, high-definition televisions, flat panel displays, and portable cell phones͒. [1][2][3][4] The deposition, microstructure ͑uniformity, packing den-sity͒, and properties ͑resolution, brightness, uniformity, efficiency, stability͒ of powder-based phosphor coatings are strongly dependent on the shapes and size distributions of the phosphor particles. [5][6][7][8][9][10][11][12][13][14] Conventional processing methods are not capable of yielding chemically tailored phosphor microparticles with precisely controlled three-dimensional ͑3D͒ morphologies in the desired 1-8 m range.…”

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confidence: 99%

Phosphor Microparticles of Controlled Three-Dimensional Shape from Phytoplankton

Weatherspoon

Haluska

Cai

et al. 2006

J. Electrochem. Soc.

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We demonstrate how the precise three-dimensional ͑3D͒ assembly characteristics of biomineralizing micro-organisms may be combined with synthetic chemical processing to generate photoluminescent microparticles with specific 3D shapes and tailored chemistries. Silica-based microshells with a rich variety of controlled shapes are assembled by a type of unicellular algal phytoplankton known as diatoms ͑Bacillariophyceae͒. Each of the tens of thousands of diatom species generates a microshell with a particular 3D morphology that can be used as a shape-dictating particle template. In this demonstration, the microshells of Aulacoseira diatoms were converted into Eu 3+ -doped BaTiO 3 -bearing microparticles. The silica-based microshells were first converted into magnesia-based replicas via a gas/solid displacement reaction ͑the silica of native diatom microshells is not chemically compatible with barium titanate͒. A conformal, sol-gel-derived coating of europium-doped barium titanate was then applied to the chemically compatible magnesia replicas to yield photoluminescent particles that retained the starting microshell shape. Upon stimulation with 337 nm ͑UV͒ light, the 3D microparticle replicas exhibited a bright red emission associated with the 5 D 0 → 7 F 2 transition of Eu +3 .Considerable interest exists to develop advanced phosphor microparticles with uniform, controlled shapes and tailored inorganic chemistries for brighter, more efficient light-emission sources and for higher-resolution optical displays ͑e.g., for fluorescent lighting, high-definition televisions, flat panel displays, and portable cell phones͒. 1-4 The deposition, microstructure ͑uniformity, packing density͒, and properties ͑resolution, brightness, uniformity, efficiency, stability͒ of powder-based phosphor coatings are strongly dependent on the shapes and size distributions of the phosphor particles. 5-14 Conventional processing methods are not capable of yielding chemically tailored phosphor microparticles with precisely controlled three-dimensional ͑3D͒ morphologies in the desired 1-8 m range. 9,11,12 The processing of micrometer-sized phosphor particles usually involves a milling step, which results in particles of nonuniform shape and a reduction in the photoluminescent brightness. 10,12-14 Thus, novel powder synthesis routes that provide enhanced control over particle morphologies and that are chemically versatile ͑i.e., for a variety of luminescent compositions͒ could be quite attractive for phosphor coating applications.Numerous examples exist in nature of microorganisms that assemble rigid microscale structures ͑microshells͒ with precisely controlled morphologies. 15-17 For example, tens of thousands of uniquely shaped three-dimensional microshells are generated by aquatic micro-organisms known as diatoms. [18][19][20] Diatoms are planktonic, unicellular algae that are prevalent in a wide variety of marine and freshwater environments. 18-20 Each of the estimated 10 4 -10 5 extant diatom species assembles a silica-based microshell ͑frustu...

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Lamp phosphors

Cited by 8 publications

References 37 publications

Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction

Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction

Site-Selective Deposition and Micropatterning of Visible-Light-Emitting Europium-Doped Yttrium Oxide Thin Film on Self-Assembled Monolayers

Phosphor Microparticles of Controlled Three-Dimensional Shape from Phytoplankton

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Lamp phosphors

Cited by 8 publications

References 37 publications

Nanocrystalline Y2O3:Eu Phosphors Prepared by Alkalide Reduction

Nanocrystalline Y2O3:Eu Phosphors Prepared by Alkalide Reduction

Site-Selective Deposition and Micropatterning of Visible-Light-Emitting Europium-Doped Yttrium Oxide Thin Film on Self-Assembled Monolayers

Phosphor Microparticles of Controlled Three-Dimensional Shape from Phytoplankton

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Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction

Nanocrystalline Y₂O₃:Eu Phosphors Prepared by Alkalide Reduction