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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Amber light-emitting diode comprising a group III-nitride nanowire active region

A temperature stable (color and efficiency) III-nitride based amber (585 nm) light-emitting diode is based on a novel hybrid nanowire-planar structure. The arrays of GaN nanowires enable radial InGaN/GaN quantum well LED structures with high indium content and high material quality. The high efficiency and temperature stable direct yellow and red phosphor-free emitters enable high efficiency white LEDs based on the RGYB color-mixing approach.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Sr{sub 2}CaW{sub x}Mo{sub 1−x}O{sub 6}:Eu{sup 3+}, Li{sup +}: An emission tunable phosphor through site symmetry and excitation wavelength

The emission of Eu{sup 3+} doped Sr{sub 2}CaW{sub x}Mo{sub 1−x}O{sub 6} phosphors could be tunable by the site symmetry of the activators and the excitation wavelengths. - Highlights: • The emission of Eu{sup 3+} depends on site symmetry and excitation wavelengths. • The color of the samples was tunable by structure and excitation wavelength. • The effect of W and Eu content on the properties of the samples was investigated. - Abstract: A series of Eu{sup 3+} substituted double-perovskite Sr{sub 2}CaW{sub x}Mo{sub 1−x}O{sub 6} phosphors were prepared by solid state reactions. The phase, photoluminescence and energy transfer of the phosphors were investigated by X-ray diffraction (XRD), photoluminescence (PL) and luminescence decay respectively. It is found that the emission of the Eu{sup 3+} substituted double perovskites depends on both the site symmetry of the activators and the excitation wavelengths. Based on the decay analysis of Sr{sub 2}CaW{sub x}Mo{sub 1−x}O{sub 6} matrix and Eu{sup 3+} doped samples, the energy transfer efficiencies between the host and activators Eu{sup 3+} were investigated. The results of the emission tunable phosphors indicate their potential applications in LEDs.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A simple way to prepare a hydrophobic Sr[LiAl3N4]:Eu2+ phosphor with improved moisture resistance

Highlights: • A simple modification method to transform SrLiAl{sub 3}N{sub 4}:Eu{sup 2+} into hydrophobic phosphor. • A thin organosilica layer (about 5–10 nm) was coated on the surface of SLA phosphor. • The modified phosphor features superior stability under extremely environment. - Abstract: The red-emitting Sr[LiAl{sub 3}N{sub 4}]:Eu{sup 2+} (SLA) phosphor was synthesized under flowing N{sub 2} gas. A thin organosilica layer (about 5–10 nm) was coated on the surface of SLA phosphors by a very simple method, which transformed the phosphor surface from hydrophilicity to hydrophobicity. The contact angle of water droplets on the surface of the packed SLA phosphors was more than 140°. Compared with the unmodified sample, the modified SLA phosphors could keep at a high emission intensity for more than twice the time under an extremely high moisture level (at relative humidity of 100%, 85 °C). The hydrophobic modification could also improve the uniform dispersion of phosphors during assembly process of white LED.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Single-phased CaAl₂Si₂O₈:Tm³⁺, Dy³⁺ white-light phosphors under ultraviolet excitation

A novel white-light-emitting phosphor CaAl₂Si₂O₈:Tm, Dy was synthesized in ambient atmosphere by solid-state reaction. The energy transfer from Tm³⁺ to Dy³⁺ ions via a dipole–quadrupole reaction was observed and investigated. Upon UV excitation, white light emission was achieved by integrating a blue emission band located at 455 nm and an orange one located at 574 nm attributed to Tm³⁺ and Dy³⁺ ions, respectively. In addition, the energy-transfer efficiency and critical distance were calculated. Results suggested that the phosphor might be promising as a single-phased white-light-emitting phosphor for UV white-light LED. - Graphical abstract: The results indicate the existence of energy transfer from Tm³⁺ to Dy³⁺. By tuning the concentration of Dy³⁺, single-phased white light can be realized. Highlights: • Energy transfer from Tm³⁺ to Dy³⁺ was investigated. • Color tunable from blue to white can be achieved. • White light can be realized in CaAl₂Si₂O₈:Tm³⁺, Dy³⁺ phosphor.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Luminescence properties of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} (R{sup +}=Li{sup +}, Na{sup +}, and K{sup +}) red emission phosphor

A series of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, R{sup +}, and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} (R{sup +}=Li{sup +}, Na{sup +}, and K{sup +}) phosphors are synthesized by solid-state reaction method in air. All phosphors show bright red emissions centered at ∼617 nm upon excitation with UV light of 397 nm. Bi{sup 3+} is a sensitizer for the luminescence of Eu{sup 3+}, and can improve significantly the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} phosphor due to energy transfer between Bi{sup 3+} and Eu{sup 3+} ions. The sensitization mechanism is investigated and discussed by energy level diagrams of Bi{sup 3+} and Eu{sup 3+} ions. R{sup +} ion is used as the charge compensator to improve the luminescence intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphors, and their PL intensities are enhanced in the sequence K{sup +}→Na{sup +}→Li{sup +}. These phosphors can be promising red emitting candidate for white LED with a ∼397 nm near UV chip excitation owing to the high brightness. - Graphical abstract: Energy transfer and charge compensation can enhance PL intensity of phosphors obviously. - Highlights: • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor is synthesized. • Energy transfer between Eu{sup 3+} and Bi{sup 3+} ions benefit PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Alkaline metal ions can further improve the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} phosphor may be promising red emitting candidate for white LED.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Towards the development of new phosphors with reduced content of rare earth elements: Structural and optical characterization of Ce:Tb: Al{sub 2}SiO{sub 5}

Highlights: • A new promising inert matrix as host of luminescent ions is proposed. • Al2SiO5 matrix is free from Rare earths (critical raw materials). • Doping the matrix with Ce and Tb we obtain an efficient green emitter. • Cerium acts as sensitizer for Terbium emission. - Abstract: A new promising inert matrix as host of luminescent ions is proposed. Al2SiO5 samples, doped with rare earths (Ce, Tb single doped and co-doped) are proposed as good prospect for the development of new UV–vis converter with reduced content of rare earths elements. Structural characterization by Raman, XRD spectroscopy and TEM imaging reveals the sillimanite phase and nano sized dimension of the investigated powders. Optical characterization by steady time and time resolved emission spectroscopy for the single doped and co-doped samples allows to identify an efficient energy transfer from Ce to Tb ions under near UV excitation wavelength. The intense green emission observed in the Ce:Tb co-doped Al2SiO5 system suggests its potential application as efficient blue pumped green emitter phosphor to be exploited for white LED: to this purpose we tested the compound in combination with a red emitting doping ion recording for Ce:Tb:Cr:ASO system a correlated color temperature of 6720 K.

36 MATERIALS SCIENCE↗
DOE OSTI2014

White light emission and energy transfer in Dy{sup 3+}/Eu{sup 3+} co-doped BaLa{sub 2}WO{sub 7} phosphors

Highlights: • BaLa{sub 2}WO{sub 7}:Dy{sup 3+}, Eu{sup 3+} phosphors were synthesized by solid-state reaction. • Eu{sup 3+} compensated the red emission component of the BaLa{sub 2}WO{sub 7}:Dy{sup 3+} phosphor. • The observed emission lifetimes indicates the energy transfer from Dy{sup 3+} to Eu{sup 3+}. • BaLa{sub 2}WO{sub 7}:Dy{sup 3+}, Eu{sup 3+} are potential phosphors used in n-UV pumped white LEDs. - Abstract: Tunable full color emissive BaLa{sub 1.75−x}WO{sub 7}:0.25Dy{sup 3+}, xEu{sup 3+} phosphors which peaked at 484 nm (blue), 572 nm (yellow), 593 nm (orange), and 617 nm (red) were synthesized by the traditional solid-state reaction method. The as-synthesized phosphors were characterized by X-ray power diffraction, diffused reflectance spectra, photoluminescence decay curves, photoluminescence excitation and emission spectra. The photoluminescence excitation spectra range from 200 to 500 nm, including an O{sup 2−}⟶W{sup 6+} charge transfer band and several 4f–4f transition peaks of Dy{sup 3+} and Eu{sup 3+}. Co-doping with Eu{sup 3+} compensated the red emission component of the BaLa{sub 2}WO{sub 7}:Dy{sup 3+} phosphor. Furthermore, the energy transfer from Dy{sup 3+} to Eu{sup 3+} was confirmed based on the luminescence spectra and decay curves. The intense white light emissions are suggestive exploration for the potential phosphor for optical materials applications used in the ultraviolet excited white light emitting diodes.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Enhanced luminescence properties in (Sr{sub 1−x}Ba{sub x}){sub 2.97}SiO{sub 3}N{sub 4/3}:0.03Eu{sup 2+} oxynitride phosphor

An oxynitride phosphor (Sr{sub 1−x}Ba{sub x}){sub 2.97}SiO{sub 3}N{sub 4/3}:0.03Eu{sup 2+} (SBSON) was synthesized by the solid-state reaction at 1550 °C for 4 h. XRD results show that the major phase of the synthesized phosphors is isostructural with Sr{sub 3}SiO{sub 5} when the content of Ba{sup 2+} is not greater than 0.5. Through the doping of Ba{sup 2+} ions, the particle morphology, luminescence intensities and thermal stability are all improved obviously. When the x equals 0.5 the luminescence intensity reaches maximum which is about 1.48 times as that of the phosphor free of Ba{sup 2+}. The emission peaks can be tuned from 583 nm to 601 nm by adjusting Ba{sup 2+} content. The doping of Ba{sup 2+} can also prolong the average lifetime from 1482 to 2122 ns. With high emission intensity and thermal stability, this novel oxynitride phosphor SBSON shows potential application in white LEDs. - Graphical abstract: Through the change of micro-structure by doping Ba{sup 2+} ions proved by the XRD patterns, (Sr{sub 1−x}Ba{sub x}){sub 2.97}SiO{sub 3}N{sub 4/3}:0.03Eu{sup 2+}phosphor eventually achieves the extension of lifetime and the improvement of luminescence properties and thermal stability. - Highlights: • (Sr{sub 1−x}Ba{sub x}){sub 2.97}SiO{sub 3}N{sub 4/3}:0.03Eu phosphors were prepared by the solid-state reaction. • The synthesized phosphor (x≤0.5) is isostructural with Sr{sub 3}SiO{sub 5}. • The emission peaks red shift to 601 nm then slightly blue shift by adding Ba{sup 2+}. • The emission intensity and thermal stability are both enhanced. • Fluorescent lifetime can be prolonged by doping Ba{sup 2+}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Luminescence properties of ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors for white light emitting diodes

Highlights: • Eu{sup 3+} ions occupy C{sub 1} point group of the Zr{sup 4+} site in ZrW{sub 2}O{sub 8} crystals. • The optimum doping concentration of Eu{sup 3+} was determined for the red emission. • ZrW{sub 2}O{sub 8}:Eu possess high quantum efficiency and suitable chromaticity coordinates. - Abstract: ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors (ca. 60 nm) with different Eu{sup 3+} doping concentrations were obtained using hydrothermal syntheses. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence excitation and emission spectra as well as decay curve measurements were used for the characterization. Under 466 nm excitation, strong red emission at 616 nm corresponding to {sup 5}D{sub 0}–{sup 7}F{sub 2} transition of Eu{sup 3+} was observed for ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) phosphors. The values of intensity parameter Ω{sub 2} and Ω{sub 4} are 17.82 × 10{sup −20} cm{sup 2} and 1.092 × 10{sup −20} cm{sup 2}, respectively. The high quantum efficiency of 83.5% of the ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) suggests this material could be promising red phosphor for generating white light in phosphor-converted white light-emitting diodes (LED)

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Luminescent properties and energy transfer studies of color-tunable LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors

Highlights: • A series of color-tunable LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors were synthesized. • Phosphors exhibit strong blue/green/red emission under UV excitation. • The reason of high Tb{sup 3+} content required for Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer is unveiled. • Green and red LED prototypes were fabricated and characterized. - Abstract: A series of LuBO{sub 3}: Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} phosphors were synthesized via solid state reaction. The Ce{sup 3+}/Tb{sup 3+} co-doped and Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} tri-doped phosphors absorb near UV light through 4f-5d transitions of Ce{sup 3+}, followed by sensitized Tb{sup 3+} green and Eu{sup 3+} red emission. Decay curves investigations for samples with various Tb{sup 3+} and Eu{sup 3+} contents reveal the occurrence of Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer. It is found that due to relative low Tb{sup 3+} → Eu{sup 3+} energy transfer rate, a high Tb{sup 3+} content (>40%) is required for efficient Ce{sup 3+} → Tb{sup 3+} → Eu{sup 3+} energy transfer. Emission color of LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+}, Eu{sup 3+} varies from blue through green to red with Ce{sup 3+}/Tb{sup 3+}/Eu{sup 3+} ratio. The quantum efficiency of LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+} green phosphor and LuBO{sub 3}: Ce{sup 3+}, Tb{sup 3+}, Eu{sup 3+} red phosphor is 50% and 30%, respectively. Green and red LED prototypes were fabricated. The results show that the obtained phosphors are potential candidates as down-converted phosphors for NUV LEDs.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Effect of variable cerium concentration on photoluminescence behaviour in ZrO{sub 2} phosphor synthesized by combustion synthesis method

Present paper reports synthesis and characterization of trivalent cerium (Ce{sup 3+}) doped zirconium dioxide (ZrO{sub 2}) phosphors. Effect of variable concentration of cerium on photoluminescence (PL) is studied. Samples were prepared by combustion synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. Starting material used for sample preparation are Zr(NO{sub 3}){sub 3} and Ce(NO{sub 3}){sub 3} and urea used as a fuel. All prepared phosphor with variable concentration of Ce{sup 3+} (0.1 to 2mol%) was studied by photoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broad excitation centred at 390nm. The excitation spectra with variable concentration of Ce{sup 3+} show strong peaks at 447nm. Spectrophotometric determinations of peaks are evaluated by Commission Internationale de I’Eclairage technique. Using this phosphor, the desired CIE values including emissions throughout the violet (390 nm) and blue (427 nm) of the spectra were achieved. Efficient blue light emitting diodes were fabricated using Ce{sup 3+} doped phosphor based on near ultraviolet (NUV) excited LED lights.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Highly Enhanced Luminescence Performance of LEDs via Controllable Layer‐Structured 3D Photonic Crystals and Photonic Crystal Beads

Abstract Controllable layer‐structured 3D photonic crystals (PCs) are prepared using the combination of the Langmuir–Blodgett (LB) technique and layer‐by‐layer stacking method. They are used for research into the influence of the number of the layers on the enhancement of the efficiency of light emission from light‐emitting diodes (LEDs) and quantum dots (QDs). The luminescence properties of blue, green, and white LEDs are improved dramatically while applying such controllable layer‐structured 3D PCs as reflectors and the enhancement efficiencies are shown to increase with PC thickness. In addition, the fluorescence intensity increases 7.8‐fold and 5.4‐fold for red and green QDs, respectively, and the fluorescence intensity can be accurately controlled by using PCs with different layers. In addition, PC beads with yellow and red photonic bandgaps are used to improve the luminescence of a white LED with angle‐independent enhancement. These beads are simply doped into the phosphor without any other treatment. Interestingly, the light intensity of the PC bead based LED is remarkably enhanced. These quantized enhanced effect of light intensity on the thickness of PC layers, along with new generation of PC bead based LED, might offer a strategy for designing high brightness LEDs with energy‐saving performance.

Tian, Yu↗
DOE OSTI2018

Luminescence properties of Eu2+-activated NaCaBeSi2O6F for white light-emitting diode applications

Highlights: • A novel blue-emitting garnet NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} phosphor was synthesized. • The broad NUV excitation band (300–400 nm) gives blue emission. • The LED made with NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} and green and red-emitting phosphors gives white-light emission. - Abstract: A series of blue-emitting NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} phosphors were obtained via a solid state reaction. NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} exhibit a broad absorption from 250 to 450 nm when monitored at 467 nm and display a broad emission band from 400 to 600 nm when excited at 397 nm. The concentration quenching was obtained when the concentration of Eu{sup 2+} was increased to 0.8 mol%. Energy transfer interactions between Eu{sup 2+} in host is due to dipole-dipole mechanisms and the critical distance was calculated to be 31.96 Å. The results obtained in this study highly indicates that NaCaBeSi{sub 2}O{sub 6}F:Eu{sup 2+} can be a potential blue-emitting phosphor for light quality improvement in white-LED applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

NIR to visible upconversion emission in Tm{sup 3+} doped Na{sub 2}Y{sub 2}B{sub 2}O{sub 7} powder phosphor

Tm{sup 3+} ions doped Na{sub 2}Y{sub 2}B{sub 2}O{sub 7} powder phosphor has been synthesized through combustion method. Crystal structure and phase of the prepared sample have been investigated by powder X-ray diffraction (XRD) analysis. Upconversion emission bands in the 400-900 nm range under the excitation of 980nm diode laser have been acquired, and involved upconversion mechanism has been discussed with the help of a suitable energy level diagram. The colour coordinate of developed phosphor has been calculated by CIE chromaticity diagram. Present phosphor can be used in fabrication of upconverting LEDs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Tunable color and energy transfer in single-phase white-emitting Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} phosphors for UV white light-emitting diodes

Ce{sup 3+} and/or Dy{sup 3+} activated Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68} phosphors were synthesized by high temperature solid state reaction and their luminescent properties were studied. There are two emissions peaking at 407 and 577 nm in the emission spectra of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+}, Dy{sup 3+}, which are due to the transitions of Ce{sup 3+} and Dy{sup 3+} ions, respectively. More importantly, the effective energy transfer from Ce{sup 3+} to Dy{sup 3+} ions has been confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and mechanism of energy transfer were investigated and it was demonstrated to be resonant type via dipole–dipole reaction. Under the excitation of 345 nm, the emitting color can change from blue to white by adjusting the relative doping concentration of Ce{sup 3+} and Dy{sup 3+} ions, indicating that the phosphors Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+}, Dy{sup 3+} are promising single-phase white-emitting phosphors for application in pc-white LEDs. - Highlights: • The Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} are novel luminescent materials that have not been reported before. • The crystal structure of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68} and energy transfer from Ce{sup 3+} to Dy{sup 3+} were investigated. • The emission color of Ca{sub 20}Al{sub 26}Mg{sub 3}Si{sub 3}O{sub 68}:Ce{sup 3+},Dy{sup 3+} can be adjusted from blue to white. • The phosphors have great application value in WLEDs as a kind of blue-to-white emitting phosphors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Photoluminescence properties of a new orange–red emitting Sm{sup 3+}-doped Y{sub 2}Mo{sub 4}O{sub 15} phosphor

A series of novel Y{sub 2}Mo{sub 4}O{sub 15}:xSm{sup 3+} ( (0.01 ≤ x ≤ 0.20) phosphors for white light-emitting (W-LEDs) were successfully prepared by the solid state reaction technology at 973 K for 12 h. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of the as-synthesized phosphors. The emission spectra of the Y{sub 2}Mo{sub 4}O{sub 15}:Sm{sup 3+} phosphors consisted of some sharp emission peaks of Sm{sup 3+} ions centered at 565 nm, 605 nm, 650 nm, and 712 nm. The strongest one is located at 605 nm due to {sup 4}G{sub 5/2}–{sup 6}H{sub 7/2} transition of Sm{sup 3+}, generating bright orange–red light. The optimum dopant concentration of Sm{sup 3+} ions in Y{sub 2}Mo{sub 4}O{sub 15}:xSm{sup 3+} is around 5 mol% and the critical transfer distance of Sm{sup 3+} is calculated as 23.32 Å. The CIE chromaticity coordinates of the Y{sub 2}Mo{sub 4}O{sub 15}:0.05Sm{sup 3+} phosphors were located in the orange reddish region. The Y{sub 2}Mo{sub 4}O{sub 15}:Sm{sup 3+} phosphors may be potentially used as red phosphors for white light-emitting diodes. - Graphical abstract: The excitation spectrum of Y{sub 2}Mo{sub 4}O{sub 15}:Sm{sup 3+} is composed of a broad band and some sharp f–f transitions. Under 407 nm excitation, the phosphor presents some sharp emission peaks of Sm{sup 3+} ions. - Highlights: • An orange–red emitting Y{sub 2}Mo{sub 4}O{sub 15}:Sm{sup 3+} phosphor has been firstly synthesized. • Their structures, luminescent properties have also been investigated. • The optical absorption edge for the molybdate lies around 325 nm. • The CIE chromaticity coordinates were located in the orange reddish region.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Nanoscale Li, Na, and K ion-conducting polyphosphazenes by atomic layer deposition

A key trailblazer in the development of thin-film solid-state electrolytes has been lithium phosphorous oxynitride (LiPON), the success of which has led to recent progress in thin-film ion conductors. Here we compare the structural, electrochemical, and processing parameters between previously published LiPON and NaPON ALD processes with a novel ALD process for the K analogue potassium phosphorous oxynitride (KPON). In each ALD process, alkali tert-butoxides and diethylphosphoramidate are used as precursors. To understand the ALD surface reactions, this work proposes a reaction mechanism determined by in-operando mass spectrometry for the LiPON process as key to understanding the characteristics of the APON (A = Li, Na, K) family. As expected, NaPON and LiPON share similar reaction mechanisms as their structures are strikingly similar. KPON, however, exhibits similar ALD process parameters but the resulting film composition is quite different, showing little nitrogen incorporation and more closely resembling a phosphate glass. Due to the profound difference in structure, KPON likely undergoes an entirely different reaction mechanism. Furthermore, this paper presents a comprehensive summary of ALD ion conducting APON films as well as a perspective that highlights the versatility of ALD chemistries as a tool for the development of novel thin film ion-conductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Hydrothermal synthesis and characteristics of anions-doped calcium molybdate red powder phosphors

Graphical abstract: - Highlights: • Four anion-doped CaMoO{sub 4}:Eu{sup 3+} red phosphors were prepared by hydrothermal approach. • Some samples exhibit nearly spherical morphology and well-distributed fine particles. • The red luminescence can be obviously enhanced after certain amount of anion doping. • The improved phosphor system is a potential candidate for white LED applications. - Abstract: Applying hydrothermal and subsequent heat-treatment process, CaMoO{sub 4}:Eu{sup 3+} was doped with four anions (SiO{sub 3}{sup 2−}, PO{sub 4}{sup 3−}, SO{sub 4}{sup 2−} and ClO{sub 3}{sup −}) to prepare fine red powder phosphors. The introduction of small amount of anions into the host had little influence on the structure, which was confirmed by X-ray diffraction patterns. The anion-doped phosphor samples (except SiO{sub 3}{sup 2−}) exhibited nearly spherical morphology, and the particle sizes were in the range of 0.3–0.4 μm for SO{sub 4}{sup 2−}-doped samples, and 0.8–1.2 μm for PO{sub 4}{sup 3−} and ClO{sub 3}{sup −}-doped samples. Excited with 395 nm near-UV light, all samples showed typical Eu{sup 3+} red emission at 615 nm, and PO{sub 4}{sup 3−}, SO{sub 4}{sup 2−} and ClO{sub 3}{sup −}-doped samples enhanced the red luminescence as compared with the individual CaMoO{sub 4}:Eu{sup 3+} sample. In particular, relative emission intensity for optimum ClO{sub 3}{sup −}-doped phosphors reached more than 6-fold that of the commercial red phosphor, which is highly desirable for the powder phosphors used in the solid-state lighting industry.

36 MATERIALS SCIENCE↗