scholarly journals Clustering of Diamond Nanoparticles, Fluorination and Efficiency of Slow Neutron Reflectors

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1945
Author(s):  
Aleksander Aleksenskii ◽  
Markus Bleuel ◽  
Alexei Bosak ◽  
Alexandra Chumakova ◽  
Artur Dideikin ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Red Light ◽  
Coherent Scattering ◽  
Slow Neutron ◽  
Diameter Distribution ◽  
Absolute Cross Section ◽  
X Ray Diffraction ◽  
Nanoparticle Diameter ◽  
Transmission Electron ◽  
Neutron Wavelength

Neutrons can be an instrument or an object in many fields of research. Major efforts all over the world are devoted to improving the intensity of neutron sources and the efficiency of neutron delivery for experimental installations. In this context, neutron reflectors play a key role because they allow significant improvement of both economy and efficiency. For slow neutrons, Detonation NanoDiamond (DND) powders provide exceptionally good reflecting performance due to the combination of enhanced coherent scattering and low neutron absorption. The enhancement is at maximum when the nanoparticle diameter is close to the neutron wavelength. Therefore, the mean nanoparticle diameter and the diameter distribution are important. In addition, DNDs show clustering, which increases their effective diameters. Here, we report on how breaking agglomerates affects clustering of DNDs and the overall reflector performance. We characterize DNDs using small-angle neutron scattering, X-ray diffraction, scanning and transmission electron microscopy, neutron activation analysis, dynamical light scattering, infra-red light spectroscopy, and others. Based on the results of these tests, we discuss the calculated size distribution of DNDs, the absolute cross-section of neutron scattering, the neutron albedo, and the neutron intensity gain for neutron traps with DND walls.

Controllable Synthesis of Spheroid Hydroxyapatite Nanoparticles by Rverse Microemulsion Method

2012 ◽  
Vol 602-604 ◽  
pp. 227-230
Author(s):  
Tao Fan ◽  
Yan Rong Sun ◽  
Li Guo Ma
Keyword(s):  
Aqueous Solution ◽  
Water Content ◽  
Ph Value ◽  
Particle Diameter ◽  
Diameter Distribution ◽  
Hydroxyapatite Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Homogeneous Good

Spheroid hydroxyapatite nanoparticles were successfully prepared by titrating Ca(NO3)2•4H2O and (NH4)2HPO4 aqueous solution in the reverse microemulsion, which consists of mixed OP-10(surfactant), cyclohexane(oil phase), and isobutanol (cosurfactant).The structure and morphology of the prepared powders were characterized by means of X-ray diffraction (XRD) and transmission electron microscope (TEM). The optimum composition was investigated via the analysis of the aqueous solution conductivity, and the mechanism of aqueous reaction. The effect of the pH value and the amount of surfactant on the particle size were studied. The results indicate that the best conditions are which the concentration of OP-10 and isobutanol both are 0.2 M, when the water content is between 130 ml-250 ml，it results in pure nano-hydroxyapatite spheroid-like powders, and the water content is about 200 ml, whose diameters are 50 nm-80 nm, and good particle diameter distribution, the particle microstructure is homogeneous, good crystal structure and higher crystallinity.

Luminescent properties of Y2O3:Eu3+ nanophosphor prepared from urea added precursor using flame spray pyrolysis

2009 ◽  
Vol 24 (8) ◽  
pp. 2584-2588 ◽  
Author(s):  
Jae Seok Lee ◽  
Se Jin Kim ◽  
Tae Kon Kim ◽  
Rajiv K. Singh ◽  
Madhav B. Ranade
Keyword(s):  
Electron Microscopy ◽  
Spray Pyrolysis ◽  
Red Light ◽  
Luminescent Properties ◽  
Flame Spray Pyrolysis ◽  
Cubic Phase ◽  
Flame Spray ◽  
X Ray Diffraction ◽  
Synthesis Conditions ◽  
Transmission Electron

Y2O3:Eu3+ nanophosphor was synthesized by flame spray pyrolysis (FSP) from urea added nitrate based liquid precursor. In this study, urea serves as fuel and subsequently provides additional heat in the flame zone during the synthesis of phosphor particles. The end product shows cubic phase Y2O3:Eu3+ nanophosphor successfully prepared by FSP without heat treatment. The influence of synthesis conditions such as different mol of urea and nitrate source materials in aqueous solution, and doping concentration on luminescent properties, were investigated. The characteristics of nanophosphor such as crystallinity and morphology under various experiments of conditions were carried out by x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). The particle size of product was found to be in the range of 20–30 nm from transmission electron microscopy (TEM). In photoluminescence (PL) properties, Y2O3:Eu3+ nanophosphor emitted red light with a peak wavelength of 609 nm when excited with 398 nm wavelength photons.

Structural characterization of manganese-substituted nanocrystalline zinc oxide using small-angle neutron scattering and high-resolution transmission electron microscopy

2009 ◽  
Vol 42 (6) ◽  
pp. 1085-1091 ◽  
Author(s):  
B. Roy ◽  
B. Karmakar ◽  
J. Bahadur ◽  
S. Mazumder ◽  
D. Sen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Zinc Oxide ◽  
High Resolution ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

A series of zinc oxide (ZnO) nanoparticles, substituted with manganese di-oxide, have been synthesized through a modified ceramic route using urea as a fuel. X-ray diffraction and high-resolution transmission electron microscopy studies indicate that the sizes of the ZnO particles are of nanometer dimension. Particles remain as single phase when the doping concentration is below 15 mol%. Small-angle neutron scattering indicates fractal-like agglomerates of these nanoparticles in powder form. The size distributions of the particles have been estimated from scattering experiments as well as microscopy studies. The average particle size estimated from small-angle scattering experiments was found to be somewhat more than that obtained from X-ray diffraction or electron microscopy measurement.

scholarly journals First Experiment of Spin Contrast Variation Small-Angle Neutron Scattering on the iMATERIA Instrument at J-PARC

2020 ◽  
Vol 4 (4) ◽  
pp. 33 ◽  
Author(s):  
Yohei Noda ◽  
Tomoki Maeda ◽  
Takayuki Oku ◽  
Satoshi Koizumi ◽  
Tomomi Masui ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Coherent Scattering ◽  
Proton Spin ◽  
Neutron Polarization ◽  
Stray Magnetic Field ◽  
Beam Experiment ◽  
Neutron Wavelength

Recently, we have developed a novel dynamic nuclear polarization (DNP) apparatus with a magnetic field of 7 T and a sample temperature of 1 K. High proton spin polarizations from −84% to 76%, for TEMPO doped polystyrene samples, have been demonstrated. This DNP apparatus satisfies the simultaneous requirement for quick and easy sample exchange and high DNP performance. On the iMATERIA (BL20) instrument at J-PARC, the first beam experiment using this DNP apparatus has been performed. For this experiment, the beamline was equipped with a supermirror polarizer. The stray magnetic field due to the superconducting magnet for DNP was also evaluated. The stray magnetic field plays an important role for in maintaining the neutron polarization during the transportation from the polarizer to the sample. The small-angle neutron scattering (SANS) profiles of silica-filled rubber under dynamically polarized conditions are presented. By applying our new analytical approach for SANS coherent scattering intensity, neutron polarization (PN) as a function of neutron wavelength was determined. Consequently, for the neutron wavelength, range from 4 Å to 10 Å, |PN| was sufficient for DNP-SANS studies.

scholarly journals Luminescence Nanothermometry Based on Pr3+ : LaF3 Single Core and Pr3+ : LaF3/LaF3 Core/Shell Nanoparticles

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
M. S. Pudovkin ◽  
D. A. Koryakovtseva ◽  
E. V. Lukinova ◽  
S. L. Korableva ◽  
R. Sh. Khusnutdinova ◽  
...  
Keyword(s):  
Coherent Scattering ◽  
Core Shell ◽  
Fluorescence Intensity Ratio ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Core Shell Nanoparticles

Core Pr3+ : LaF3 (CPr = 1%) plate-like nanoparticles (nanoplates), core/shell Pr3+ : LaF3 (CPr = 1%)/LaF3 nanoplates, core Pr3+ : LaF3 (CPr = 1%) sphere-like nanoparticles (nanospheres), and core/shell Pr3+ : LaF3 (CPr = 1%)/LaF3 nanospheres were synthesized via the coprecipitation method of synthesis. The nanoparticles (NPs) were characterized by means of transmission electron microscopy, X-ray diffraction, and optical spectroscopy. The formation of the shell was proved by detecting the increase in physical sizes, sizes of coherent scattering regions, and luminescence lifetimes of core/shell NPs comparing with single core NPs. The average physical sizes of core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres were 62.2 ± 0.9, 74.7 ± 1.2, 13.8 ± 0.9 and 22.0 ± 1.2 nm, respectively. The formation of the NP shell led to increasing of effective luminescence lifetime τeff of the 3P0 state of Pr3+ ions for the core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres the values of τeff were 2.3, 3.6, 3.2, and 4.7 μsec, respectively (at 300 K). The values of absolute sensitivity Sa for fluorescence intensity ratio (FIR) thermometry was 0.01 K−1 at 300 K for all the samples. The FIR sensitivity can be attributed to the fact that 3P1 and 3P0 states share their electronic populations according to the Boltzmann process. The values of Sa for lifetime thermometry for core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres were (36.4 ± 3.1) · 10−4, (70.7 ± 5.9) · 10−4, (40.7 ± 2.6) · 10−4, and (68.8 ± 2.4) · 10−4 K−1, respectively.

Novel Preparation Method and Luminescent Properties of Eu3+ Doped CdWO4 Nanorod

2013 ◽  
Vol 652-654 ◽  
pp. 664-668 ◽  
Author(s):  
Fang Lei ◽  
Hao Hong Chen ◽  
Ying Shi ◽  
Jian Jun Xie ◽  
He Feng
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Red Light ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Pxrd Pattern ◽  
Red Phosphor ◽  
Transmission Electron ◽  
Length Width ◽  
20 Nm ◽  
The Eu

Eu3+ doped CdWO4 nanorods, with nearly uniform nanoscale was synthesized via a novel simple hydrothermal method easy for commercial run at 160 °C, of which the average dimensions are about 250, 50 and 20 nm in length, width and height respectively from the result of transmission electron microscopy (TEM). Powder X-ray diffraction (PXRD) pattern shows the product is pure wolframite structure. Different from undoped products showed brilliant blue-green irradiation and block crystals with multi-emission bands in red light range, the Eu doped nanorods give preferred strong 5D0→7F2 transition and are excellent red phosphor with high color purity supported by the photoluminescent (PL) measurements and ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). This suggests that a combination of the Eu3+ doped and undoped products are potential to realize the white lighting LED with blue, green and red components.

Preparation and Properties of Polyvinylpyrrolidone / Zinc Oxide Composite Nanofibers

2011 ◽  
Vol 399-401 ◽  
pp. 407-414
Author(s):  
Guo Qiang Xu ◽  
Li Guo Sun ◽  
Shu Hong Wang ◽  
Yang Xie ◽  
Cheng Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Composite Nanofibers ◽  
Diameter Distribution ◽  
Gravimetric Analysis ◽  
Mixed Solution ◽  
X Ray Diffraction ◽  
Phosphorescence Lifetime ◽  
Transmission Electron

Zinc Oxide (ZnO) nanoparticles were firstly synthesized by the hydration of alkoxide. The as-synthesized ZnO were dispersed in the polyvinylpyrrolidone (PVP) solution. PVP/ZnO composite nanofibers were prepared via electrospinning the PVP/ZnO mixed solution. The morphology of ZnO nanoparticles and as-spun nanofibers was measured by scanning electron microscopy (SEM). The as-synthesized ZnO nanoparticles were homogeneous and stable, and their size ranged from 30 to 40 nm. The composite nanofibers showed a uniform and continuous morphology. With the increase of the ZnO content in the composite nanofibers, the diameter distribution of the composite nanofibers became wider. Transmission electron microscopy (TEM) images clearly showed that ZnO nanoparticles were distributed uniformly in the PVP/ZnO composite nanofibers without any aggregation, although the ZnO content reached as highly as 6 wt. %. The structures and properties of the composite nanofibers were investigated using X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and Combined Stead State Fluorescence and Phosphorescence Lifetime Spectrometer (FLSP).

Morphology of TiO2 Aerogels

1994 ◽  
Vol 346 ◽  
Author(s):  
Zhu Zhu ◽  
Micha Tomkiewicz
Keyword(s):  
Titanium Dioxide ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Complementary Techniques

ABSTRACTThe morphology of titanium dioxide aerogel was studied using a variety of complementary techniques that include: nitrogen adsorption, Small-Angle Neutron Scattering (SANS), scanning and transmission electron microscopies (SEM/TEM) and X-ray diffraction. Since these techniques sense different components of the microstructure, global parametrization should coalesce the results into a uniform framework.

Preparation and Characterization of PVP/Fe3O4 Composite Nanofibers

2011 ◽  
Vol 332-334 ◽  
pp. 783-786
Author(s):  
Xin Wang ◽  
Xue Jia Li ◽  
Qing Qing Wang ◽  
Qu Fu Wei
Keyword(s):  
Electron Microscopy ◽  
Composite Nanofibers ◽  
Average Diameter ◽  
Diameter Distribution ◽  
Fe3o4 Nanoparticle ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Nanofiber Diameter ◽  
And Performance

The PVP/Fe3O4 composite nanofibers with different Fe3O4 nanoparticle loading were obtained by electrospinning. The characterization and performance analysis of the composite nanofibers were studied by scanning electron microscopy (SEM), X-Ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and antistatic fabric instrument. The results showed that the average diameter of PVP/Fe3O4 composite nanofibers is smaller than that of pure PVP. At 5wt% Fe3O4 nanoparticle loading, the coefficient of variation CV value was low, while the composite nanofiber diameter distribution was good. Fe3O4 nanoparticles were spherical and had no obvious agglomeration. With increasing Fe3O4 nanoparticle loading, the thermal and antistatic properties of PVP/Fe3O4 composite nanofibers were significantly improved.

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