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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Semiorganic nonlinear optical material: Crystal growth, structure and optical properties of NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2}

Graphical abstract: - Highlights: • Semiorganic NLO material NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has been grown with sizes up to 8 × 5 × 2 mm{sup 3}. • It crystallizes in the noncentrosymmetric Monoclinic space group P2. • Thermal analysis demonstrated NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} are thermally stable up to 280. • NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has an absorption edge about 220 nm in the UV region. • It exhibits a NLO efficiency of about two times that of KDP (KH{sub 2}PO{sub 4}) standard. - Abstract: Single crystal of the semiorganic NLO material NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has been grown with sizes up to 8 × 5 × 2 mm{sup 3} by the slow evaporation method. The crystal structure of this compound was determined by single crystal X-ray diffraction. It crystallizes in the Monoclinic space group P2 with lattice parameters a = 5.4045(11) Å, b = 11.692(2) Å, c = 9.4773(19) Å and Z = 2. Thermal analysis demonstrated NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} are thermally stable up to 280 °C. NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} exhibits an absorption edge about 220 nm in the UV region. The powder second-harmonic generation (SHG) measurement performed on the ground crystal indicates that it has a NLO efficiency of about 2 times that of KDP (KH{sub 2}PO{sub 4}) standard. In addition, the origin of stronger SHG effect was discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Hydrothermal synthesis and metal ions doping effects of single-crystal Mn{sub 3}O{sub 4}

Graphical abstract: - Highlights: • Dopant species and dopant/Mn molar ratio affect the shape of Mn{sub 3}O{sub 4} microcrystal. • For Cu and Ni doped Mn{sub 3}O{sub 4}, the spontaneous valence changes of dopant taken place. • An apparent change in the energy bandgap of Mn{sub 3}O{sub 4} with the metal doping. - Abstract: Synthesis of undoped and transition metal ion doped Mn{sub 3}O{sub 4} microcrystals were achieved through a simple hydrothermal route. The morphologies and structures of the obtained products were characterized using X-ray diffraction, X-ray photoemission spectroscopy and scanning electron microscopy. Results revealed that the low volume percentage of ethanol in the precursor solution limited formation of Mn{sup 2+}, while the introduction of doping ions into the precursor solution caused a direct synthesis of single phase Mn{sub 3}O{sub 4} crystals. For Cu and Ni doping ions, the spontaneous valence changes during the doping process were taken place. The possible doping mechanisms for the formation of single-phase Mn{sub 3}O{sub 4} were discussed briefly. UV–vis spectroscopic studies showed an apparent change in the energy bandgap of Mn{sub 3}O{sub 4} with the metal doping.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Structure and magnetic interactions in the solid solution Ba{sub 3−x}Sr{sub x}Cr{sub 2}O{sub 8}

Highlights: • We describe for the first time the preparation of single- and polycrystalline members of the solid solution Ba{sub 3−x}Sr{sub x}Cr{sub 2}O{sub 8}. • We report on the structural changes in the solid solution at room temperature depending on the stoichiometry. • We describe the peculiar change of the magnetic behavior in the solid solution with the stoichiometry. - Abstract: Solid solutions of the magnetic insulators Ba{sub 3}Cr{sub 2}O{sub 8} and Sr{sub 3}Cr{sub 2}O{sub 8} (Ba{sub 3−x}Sr{sub x}Cr{sub 2}O{sub 8}) have been prepared in polycrystalline form for the first time. Single crystalline material was obtained using a mirror image floating zone technique. X-ray diffraction data taken at room temperature indicate that the space group of Ba{sub 3−x}Sr{sub x}Cr{sub 2}O{sub 8} remains unchanged for all values of x, while the cell parameters depend on the chemical composition, as expected. Magnetization data, measured from 300 K down to 2 K, suggest that the interaction constant J{sub d} within the Cr{sup 5+} dimers varies in a peculiar way as a function of x, starting at J{sub d} = 25 K for x = 0, then first slightly dropping to J{sub d} = 18 K for x ≈ 0.75, before reaching J{sub d} = 62 K for x = 3.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Anisotropic thermal expansion and anharmonic phonon behavior of mullite-type Bi{sub 2}Ga{sub 4}O{sub 9}

Graphical abstract: - Highlights: • Anisotropic lattice thermal expansion of Bi{sub 2}Ga{sub 4}O{sub 9} was modeled using extended Grüneisen first-order approximation. • The model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy. • Temperature dependent Raman frequency shift and line-width was analyzed using symmetric phonon decay channel. - Abstract: We report the lattice thermal expansion and the temperature-dependent phonon behavior of the mullite-type Bi{sub 2}Ga{sub 4}O{sub 9} complex oxide. The thermal expansion was studied using composite data collected from powder and single crystal X-ray diffraction between 100 K and 1273 K. The lattice expansion occurred in the order of a < c < b. The anisotropic expansion behavior was monitored with respect to thermal expansion coefficients and the anisotropy factor. The volume thermal expansion was expressed using an extended Grüneisen first-order approximation to the zero-pressure equation of state; the model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy as a function of temperature. The temperature dependent Raman spectra were collected from a single crystal between 78 K and 1273 K. The shift of the frequencies and the broadening of the line-widths with increasing temperature helped to analyze the anharmonicity and the thermal behavior of some phonons.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Improved photocatalytic activity of single crystal ZnO nanorod derived from highly effective P/N heterojunction

Graphical abstract: Schematic showing on photocatalytic degradation 2,4-DCP of ZnO NRs/BDD heterojunction. - Highlights: • Single-crystal ZnO nanorods based P/N heterojunction has been synthesized. • Vertical growth ZnO NRs on BDD can effectively photocatalytic decompose 2,4-DCP. • The rate constant of photocatalysis can be enhanced due to P/N heterojunction. - Abstract: Highly effective single-crystal ZnO nanorods based P/N heterojunction has been synthesized by a controllable crystal seed-induced hydrothermal vertical growth method, which facilitates the separation of the photogenerated electrons and holes due to its endogenous space charge region and suitable band structure. Therefore, photocatalytic activity for degradation of the toxic pollutants is markedly enhanced.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Preparation and supercapacitor application of the single crystal nickel hydroxide and oxide nanosheets

Graphical abstract: The nickel hydroxide and nickel oxide nanosheets prepared using CTAB at room temperature exhibit a high specific capacitance, prompt charge/discharge rate. - Highlights: • The nickel hydroxide nanosheets were prepared using CTAB at room temperature. • Ni(OH){sub 2} nanosheet can be successfully converted to NiO nanosheet via calcination. • The NiO nanosheet has a specific capacitance of 388 F g{sup −1} at 5 A g{sup −1} in KOH solution. • Anneal temperature impacts capacitive properties as electrode. - Abstract: The single crystalline Ni(OH){sub 2} nanosheets were synthesized by a simple chemical precipitation method using nickel chloride as precursors and ammonia as precipitating agent. The Ni(OH){sub 2} nanosheets were successfully converted to NiO nanosheets via calcination under appropriate conditions. Analytical methods such as X-ray diffraction (XRD) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Fourier transformed infrared (FTIR) spectra were employed to characterize the morphology and microstructure of the final products. The experimental results revealed that Ni(OH){sub 2} nanosheets were shape-preserved transformed to NiO nanosheets at 250 °C for 24 h. Ni(OH){sub 2} and NiO nanosheets were directly functionalized as supercapacitor electrodes for potential energy storage applications, whose charge–discharge properties, electrochemical impedance spectra, cyclic voltammetry, and cycle performance were examined. The experimental results show that the single-crystalline NiO nanosheets are a promising candidate for the supercapacitor electrode. They exhibit a high specific capacitance, prompt charge/discharge rate.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Epitaxial growth of mixed conducting layered Ruddlesden–Popper La{sub n+1}Ni{sub n}O{sub 3n+1} (n = 1, 2 and 3) phases by pulsed laser deposition

Graphical abstract: - Highlights: • High quality epitaxial thin films of layered Ruddlesden–Popper nickelates were prepared. • For the first time this has been achieved by the PLD process. • n = 1, 2 and 3 films were successfully deposited on SrTiO{sub 3} and NdGaO{sub 3} substrates. • c-Axis oriented films were confirmed by XRD analysis. • In-plane and out-of-plane strain effects on lattice are discussed. - Abstract: Layered Ruddlesden–Popper phases of composition La{sub n+1}Ni{sub n}O{sub 3n+1} (n = 1, 2 and 3) have been epitaxially grown on SrTiO{sub 3} (0 0 1) or NdGaO{sub 3} (1 1 0) single crystal substrates using the pulsed laser deposition technique. X-ray diffraction analyses (θ/2θ, rocking curves, and φ-scans) and atomic force microscopy confirms the high-quality growth of the series of films with low surface roughness values (less than 1 nm). In particular, epitaxial growth of the higher order phases (n = 2 and 3) of lanthanum nickelate have been demonstrated for the first time.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Observation of crystallization and characterizations on thiourea cadmium iodide: A semi-organic optical material

Graphical abstract: - Highlights: • Thiourea cadmium iodide (TCI) was grown by slow evaporation solution technique. • Morphology and growth rate of the grown compound are determined with the help of inverted microscope. • Optical band gap has been determined. • Microstructure analysis has been reported. • Electrical study has been reported and discussed. - Abstract: In this work, the single crystals of thiourea cadmium iodide were grown by slow evaporation solution technique in two different ratios 2:1 and 1:1. During the formation of their single crystals the morphological features and its live growth process were recorded with the help of inverted microscope. Structural studies of the grown crystals have been carried out by powder X-ray diffraction to confirm the crystal system and vibrational modes by Raman spectroscopy. The optical energy band gaps were investigated through UV–vis spectroscopy study. The surface morphology of the grown single crystals was analyzed by using Scanning Electron Microscope and thermal analysis was carried out by using thermogravimetric analysis. The electrical properties were also studied as a function of frequency and the obtained results are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Hydrostatic pressure (8 GPa) dependence of electrical resistivity of BaCo{sub 2}As{sub 2} single crystal

Graphical abstract: - Highlights: • Single crystals of BaCo{sub 2}As{sub 2} were grown by CoAs self-flux method. • We have studied pressure effects (8 GPa) on dc electrical resistivity of BaCo{sub 2}As{sub 2}. • On applied external pressure BaCo{sub 2}As{sub 2} remains a metallic state up to 8 GPa. • Superconductivity is absent in BaCo{sub 2}As{sub 2} because of its proximity to ferromagnetism. - Abstract: The pressure dependence of the electrical resistivity of BaCo{sub 2}As{sub 2} single crystal as a function of temperature was measured at ambient and high pressures up to 8 GPa for the first time using cubic anvil high pressure cell. It is observed that at room temperature the resistivity monotonically decreases with increasing pressure and it remains in the metallic state even at an applied pressure of 8 GPa. From the temperature dependence of the resistivity measurements under pressure, we found that superconductivity is absent up to 8 GPa. The value of the electron's scattering factor (A) is found to be large at ambient pressure and it decreases with the application of pressure, indicating that the substantial electron correlation effect of BaCo{sub 2}As{sub 2} is reduced under pressure, revealing a dramatic change of density of states at the Fermi energy.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Piezoelectric and ferroelectric properties of lead-free niobium-rich potassium lithium tantalate niobate single crystals

Graphical abstract: - Highlights: • Lead-free K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} single crystals were grown using the top-seeded melt growth method. • The piezoelectric and ferroelectric properties of as-grown crystals were systematically investigated. • The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N. • The coercive fields of P–E hysteresis loops are quite small, about or less than 1 kV/mm. - Abstract: Lead-free potassium lithium tantalate niobate single crystals with the composition of K{sub 0.95}Li{sub 0.05}Ta{sub 1−x}Nb{sub x}O{sub 3} (abbreviated as KLTN, x = 0.51, 0.60, 0.69, 0.78) were grown using the top-seeded melt growth method. Their piezoelectric and ferroelectric properties in as-grown crystals have been systematically investigated. The phase transitions and Curie temperatures were determined from dielectric and pyroelectric measurements. Piezoelectric coefficients and electromechanical coupling factors in thickness mode, length-extensional mode and longitudinal mode were obtained. The piezoelectric properties are very attractive, e.g. for x = 0.60 composition, k{sub t} ≈ 70%, k{sub 31} ≈ 70%, k{sub 33} ≈ 77%, d{sub 31} ≈ 230 pC/N, d{sub 33} ≈ 600 pC/N are comparable to the lead-based PZT composition. The polarization versus electric field hysteresis loops show saturated shapes. In short, lead-free niobium-rich KLTN system possesses comparable properties to those in important lead-based piezoelectric material nowadays.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Synthesis and electrochemical properties of NiO nanospindles

Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Large scale and fast synthesis of multiferroic TbMn{sub 2}O{sub 5} single-crystalline nanorods

Graphical abstract: - Highlights: • Pure TbMn{sub 2}O{sub 5} phase was synthesized in a wide temperature range for a short time. • Smooth and uniform single-crystalline nanorods were obtained. • The element Mn in TbMn{sub 2}O{sub 5} exhibits a mix Mn{sup 3+/4+} valence state with an average value of 3.5+, and the element Tb exhibits Tb{sup 3+}. - Abstract: Crystalline multiferroic TbMn{sub 2}O{sub 5} nanorods were successfully synthesized by a facile and scalable molten salt synthesis with NaCl–Na{sub 2}SO{sub 4} eutectic salts used in the temperature range of 750–900 °C for only 2 h. The obtained TbMn{sub 2}O{sub 5} could be indexed to an orthorhombic phase by the results of XRD patterns. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), combined with high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and EDS, have been employed to investigate the morphology, size, crystallinity, structure, and composition of the as-synthesized TbMn{sub 2}O{sub 5} nanorods. The TbMn{sub 2}O{sub 5} product exhibits smooth, uniform and crystalline nanorods with diameters of 30–70 nm, and length of varying from 3 to 6 μm. The results of X-ray photoelectron spectroscopy (XPS) analysis indicate that the elements Mn and Tb in TbMn{sub 2}O{sub 5} exhibit Mn{sup 3+/4+} and Tb{sup 3+}, respectively. The magnetic properties of the as-prepared TbMn{sub 2}O{sub 5} nanorods have been also characterized by physical properties measurement system (PPMS)

36 MATERIALS SCIENCE↗
DOE OSTI2014

The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF{sub 2} > MgF{sub 2}. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF{sub 2} and MgF{sub 2}. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Growth and characterization of diammonium copper disulphate hexahydrate single crystal

Graphical abstract: Diammonium copper disulphate hexahydrate (DACS) is one of the most promising inorganic dielectric crystals with exceptional mechanical properties. Good quality crystals of DACS were grown by using solution method in a period of 30 days. The grown crystals were subjected to single crystal X-ray diffraction analysis in order to establish their crystalline nature. Thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis were performed for the crystal. Several solid state physical parameters have been determined for the grown crystals. The dielectric constant and the dielectric loss and AC conductivity of the grown crystal were studied as a function of frequency and temperature has been calculated and plotted. - Highlights: • Diammonium copper disulphate is grown for the first time and CCDC number obtained. • Thermal analysis is done to see the stability range of the crystals. • Band gap and UV cut off wavelength of the crystal are determined to be 2.4 eV and 472.86 nm, respectively. • Dielectric constant, dielectric loss and AC conductivity are plotted as a function of applied field. - Abstract: Diammonium copper disulphate hexahydrate is one of the most promising inorganic crystals with exceptional dielectric properties. A good quality crystal was harvested in a 30-day period using solution growth method. The grown crystal was subjected to various characterization techniques like single crystal X-ray diffraction analysis, thermo gravimetric, differential thermal analysis, FTIR, and UV–vis–NIR analysis. Unit cell dimensions of the grown crystal have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Thermal stability of the samples was checked by TG/DTA studies. Band gap of the crystal was calculated. The dielectric constant and dielectric loss were studied as a function of frequency of the applied field. AC conductivity was plotted as a function of temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2014

PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Investigations of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal as a scintillator

Highlights: • Eu{sup 2+}-activated Ba{sub 3}BP{sub 3}O{sub 12} single crystals have been grown by the top-seeded solution growth method (TSSG) for the first time. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm. • Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal shows high overall scintillation efficiency (1.8 times of BGO) and moderate decay time (860 ns). - Abstract: Single crystals of Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} with high optical quality have been grown by the top-seeded solution growth (TSSG) method using BPO{sub 4}–NaF mixture as the flux. Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal exhibits wide transparency in the wavelength range from 250 to 700 nm, and shows a broad emission band in the wavelength range of 350–650 nm when excited by X-ray radiation. The overall scintillation efficiency is about 1.8 times of that of BGO crystal under the same conditions. Its room temperature fluorescence decay curve exhibits a single-exponent shape with decay time of about 860 ns. It is worth noting that Ba{sub 3}BP{sub 3}O{sub 12}:Eu{sup 2+} single crystal may be of great interest for applications in the field of scintillation materials considering its scintillation properties, as well as the good chemical stability.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Low temperature and self catalytic growth of ultrafine ITO nanowires by electron beam evaporation method and their optical and electrical properties

Highlights: • ITO nanowires were grown by e-beam evaporation method. • ITO nanowires growth done at low substrate temperature of 350 °C. • Nanowires growth was carried out without use of catalyst and reactive oxygen gas. • Nanowires growth proceeds via self catalytic VLS growth. • Grown nanowires have diameter 10–20 nm and length 1–4 μm long. • ITO nanowire films have shown good antireflection property. - Abstract: We report the self catalytic growth of Sn-doped indium oxide (ITO) nanowires (NWs) over a large area glass and silicon substrates by electron beam evaporation method at low substrate temperatures of 250–400 °C. The ITO NWs growth was carried out without using an additional reactive oxygen gas and a metal catalyst particle. Ultrafine diameter (∼10–15 nm) and micron long ITO NWs growth was observed in a temperature window of 300–400 °C. Transmission electron microscope studies confirmed single crystalline nature of the NWs and energy dispersive spectroscopy studies on the NWs confirmed that the NWs growth proceeds via self catalytic vapor-liquid-solid (VLS) growth mechanism. ITO nanowire films grown on glass substrates at a substrate temperature of 300–400 °C have shown ∼2–6% reflection and ∼70–85% transmission in the visible region. Effect of deposition parameters was systematically investigated. The large area growth of ITO nanowire films would find potential applications in the optoelectronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2014

A facile route to high-purity BN nanoplates with ultraviolet cathodoluminescence emissions at room temperature

Highlights: • We present a novel and simple approach to great-scale fabrication of BN nanoplates. • The as-synthesized products are extensively characterized. • The formation mechanism of BN nanoplates are elucidated based on experimental observations. • A growth model was proposed according to our experimental observations and analysis. • BN nanoplates’ CL performance envisions its applications such as UV emitters. - Abstract: We present a novel and notably simple approach to fabricate BN nanoplates in large scale employing ammonia borane as a single-source precursor. The structure and chemical composition of the as-synthesized products are extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS). XRD analysis indicates that the products are hexagonal BN crystal. SEM images confirm that the BN nanoplates have an average diameter of about 200 nm and thickness of tens of nanometers. HRTEM results illustrate the BN nanoplates to be single-crystals. EELS result suggests the nanoplates are composed of boron and nitride elements. The formation mechanism of the BN nanoplates has been elucidated based on our experimental observations, and a growth model has been proposed accordingly. Cathodoluminescence spectroscopic analysis is performed and strong ultraviolet (UV) emissions are detected. Our method provides a simple route towards the large-scale fabrication of high-quality BN nanoplates, for which various promising applications such as compact UV emitters can be envisioned.

36 MATERIALS SCIENCE↗