Electrical Properties of Nanocrystalline Tungsten Trioxide

1999 ◽  
Vol 581 ◽  
Author(s):  
A. Hoel ◽  
L.B. Kish ◽  
R. Vajtai ◽  
G.A. Niklasson ◽  
C.G. Granqvist ◽  
...  
Keyword(s):  
Tungsten Trioxide ◽  
Impedance Spectrum ◽  
Ambient Air ◽  
Vapor Condensation ◽  
Smart Windows ◽  
Primary Particles ◽  
Significant Interest ◽  
Average Size ◽  
Capacitance Effects ◽  
Evaporation Unit

ABSTRACTTungsten oxide is a material of significant interest for applications in several areas. It can, for example, be used as the electrochromic film in smart windows. Tungsten trioxide nanoparticles were produced using an advanced gas evaporation unit in which the tungsten was oxidized in low pressure ambient air. The tungsten trioxide particles were formed via vapor condensation and were deposited by gas deposition technique to avoid coagulation effects. The average size of the primary particles was around 5 nm, depending on the heating power and the pressure. The particles exhibited a body centred cubic structure. The impedance spectrum of particle deposits showed resonance and negative capacitance effects. The correlation between fabrication conditions, structure and impedance spectrum is discussed.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

scholarly journals Influence of reducing agents and surfactants on size and shape of silver fine powder particles

2014 ◽  
Vol 20 (2) ◽  
pp. 73-88 ◽  
Author(s):  
Stevan P. Dimitrijević ◽  
Željko Kamberović ◽  
Marija Korać ◽  
Zoran Anđić ◽  
Silvana Dimitrijević ◽  
...  
Keyword(s):  
Chemical Reduction ◽  
Nitrate Solution ◽  
Fine Powder ◽  
Production Scale ◽  
Scale Reduction ◽  
Primary Particles ◽  
Powder Particles ◽  
Different Shapes ◽  
Average Size ◽  
Scanning Electron

Silver fine powder with different shapes and sizes were prepared by chemical reduction and characterized by scanning electron microscope. In this paper was presented the method for the preparation of the fine Ag powder with particles size smaller than 2.5 µm with suitability for the mass-production scale. Reduction was performed from nitrate solution directly by vigorous stirring at room temperature by three different reduction agents, with and without presence of two dispersants. Scanning electron microscopy revealed the preferred size of the particles obtained in all experiments with aim of the protecting agent. Larger particles and wider size distribution were obtained without surfactants although with average size of about 1 µm and small quantity of larger clusters of primary particles that is out of the fine powder classification. High purity, 99.999%, of silver was obtained in every experiment. 

scholarly journals The Morphology of Freeze-Dried Rubidium Chloride Powder

1989 ◽  
Vol 155 ◽  
Author(s):  
J. K. G. Panitz ◽  
J. A. Voigt ◽  
F. A. Greulich ◽  
M. J. Carr ◽  
M. O. Eatough
Keyword(s):  
Droplet Size ◽  
Freeze Drying ◽  
Low Concentrations ◽  
Aerosol Spray ◽  
Freeze Dried ◽  
Primary Particles ◽  
Ionic Compounds ◽  
Freezing Cycle ◽  
Average Size ◽  
Stock Solutions

ABSTRACTWe have formed powders of a strongly ionic compound, RbCl by freezedrying. Stock solutions, varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water to saturated solutions with 80 gm reagent in 100 cc water, were sprayed into isopentane at -160°C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to extremely small droplets in an aerosol spray. It was determined that both the concentration of the stock solution and the droplet size affect the average size and the size distribution of the primary particles formed and the way in which these primary particles are bonded together. Unlike the powders of many less ionic compounds that are produced by freeze-drying, the primary particles in these RbCl powders are crystalline rather than amorphous. Analysis with an x-ray diffractometer with a cold stage indicates that crystallization occurs during the freezing cycle rather than during the sublimation period of the freeze-drying process.

Insight role of TiO2 to improve the photocatalytic performance of WO3 nanostructures for the efficient degradation of ciprofloxacin

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Muhammad Bilal Tahir ◽  
Sohail Farman ◽  
Adil Rasheed ◽  
Hussein Alrobei ◽  
Khurram Shahzad ◽  
...  
Keyword(s):  
Tungsten Trioxide ◽  
Research Work ◽  
Morphological Structure ◽  
Composite Catalyst ◽  
Excitation Wavelength ◽  
Spherical Structure ◽  
Vis Spectroscopy ◽  
Average Size ◽  
Wo3 Nanostructures

Abstract The current research work is to investigate the photocatalytic efficiency and degradation of ciprofloxacin using WO3/TiO2 nanoparticles under visible light irradiation. The nanoparticles of tungsten trioxide (WO3) and its composite with titanium dioxide (TiO2) i.e. WO3/TiO2 was prepared by hydrothermal method. Four basic characterizations were performed to study the prepared sample materials. To study the morphology of the prepared samples, scanning electron microscopy (SEM) was used. The results of SEM clearly showed that tungsten trioxide (WO3) has Rectangular shaped structure. The average size of the pure Tungsten trioxide nanoparticles was about 40–540 nm. The composite of WO3/TiO2 has spherical structure. The reason behind that was the addition of TiO2 in WO3 changes the morphology of pure WO3, and transformed the rectangular structure to a spherical structure. The presence of TiO2 changes the position and orientation of the nanorods in all possible directions. For the detailed analysis of the functional groups present in these samples, band gap, and optical properties of these samples, Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV–VIS) spectroscopy and Photoluminescence (PL) emission spectroscopy was used. UV–Vis spectroscopy results showed that the bandgaps of prepared catalysts vary within the range of 2.76 – 2.5 eV. This decrease in bandgap is directly related with the concentration ratio of TiO2 in WO3. The maximum excitation wavelength observed at 440 nm. The maximum degradation efficiency was at 2% of WO3/TiO2 composite catalyst due to unique morphological structure and increase rate of photo absorption.

scholarly journals Synthesis and Characterization of La0.8Sr0.2Ga0.8Mg0.2O3-δ Nano-Particle by Aerosol Plasma Pyrolysis

2010 ◽  
Vol 445 ◽  
pp. 82-85
Author(s):  
Kenichi Myoujin ◽  
Araki Toriyama ◽  
Takayuki Kodera ◽  
Takashi Ogihara
Keyword(s):  
Metal Nitrate ◽  
Nano Particle ◽  
X Ray Diffraction ◽  
Bimodal Size Distribution ◽  
Primary Particles ◽  
Plasma Pyrolysis ◽  
Xrd Patterns ◽  
Average Size ◽  
Precursor Powders

Spherical La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) precursor powders were synthesized by aerosol plasma pyrolysis using an aqueous solution of metal nitrate. As-prepared powders obtained by this method were found to have a spherical morphology with a bimodal size distribution of nanosized (primary) and submicron-sized (secondary) particles. The average size of the primary particles was less than 100 nm. X-ray diffraction (XRD) patterns showed that as-prepared powders crystallized to LSGM and other phases. XRD revealed that LSGM pellets were crystallized to a perovskite structure after sintering at 1300 °C for 10 h.

scholarly journals Electrically tuning soft membranes to both a higher and a lower transparency

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Leihao Chen ◽  
Michele Ghilardi ◽  
James J. C. Busfield ◽  
Federico Carpi
Keyword(s):  
Surface Topography ◽  
Applied Voltage ◽  
Tuning Range ◽  
State Of The Art ◽  
Optical Transmittance ◽  
Optical Transparency ◽  
Smart Windows ◽  
Significant Interest ◽  
Thin Membranes ◽  
Stretchable Conductor

AbstractThe possibility to electrically tune the optical transparency of thin membranes is of significant interest for a number of possible applications, such as controllable light diffusers and smart windows, both for residential and mobile use. As a difference from state-of-the-art approaches, where with an applied voltage the transparency can only increase or decrease, this paper presents the first concept to make it electrically tuneable to both higher and lower values, within the same device. The concept is applicable to any soft insulating membrane, by coating both of its surfaces with a circular transparent stretchable conductor, surrounded by a stretchable annular conductor. The two conductors are used as independently addressable electrodes to generate a dielectric elastomer-based actuation of the membrane, so as to electrically control its surface topography. We show that the optical transmittance can electrically be modulated within a broad range, between 25% and 83%. This approach could be especially advantageous for systems that require such a broad tuning range within structures that have to be thin, lightweight and acoustically silent in operation.

scholarly journals Flow Characterization of Gas-Solid Mixture in Fluidized Bed Combustion

2018 ◽  
Author(s):  
Rosyida Permatasari
Keyword(s):  
Fluidized Bed ◽  
Ambient Air ◽  
Numerical Results ◽  
Silica Sand ◽  
Airflow Rate ◽  
Multiphase Model ◽  
Fluidized Bed Combustion ◽  
Solid Mixture ◽  
Group B ◽  
Average Size

The fluidization behavior of a non reactive gas-solid in the fluidized bed is experimentally and numerically studied. The numerical results are analyzed, and compared with experimental data. Some results on particle image velocimetry (PIV) in 2-D fluidized beds are presented. The PIV applications were used in order to determine the origin of the ejected particles and the particle velocity distribution, using silica sand particles as inert bed material of Fluidized Bed Combustion. The model used commercial CFD software, Fluent, in two-dimensional simulations. Fluent predicted the fluid bed behavior by utilizing its Eulerian Granular Multiphase model where both the gas and solids phases are assumed continuous and fully interpenetrating. The model incorporated the kinetic theory to predict gas-solid interaction. The silica sand (Geldart particle group B) with average size 300μm and 10 cm height are fluidized with ambient air. Some flow rate of air are introduced i.e. 20 CFM, 30 CFM and 40 CFM. When the sand fluidized in FBC, the results show the formation of a big vortex. It happened at the height 0.25–0.33 m from the base. Both the experimental and the numerical results show that increasing the fluidization velocity and fluidization height is correlated with airflow rate

scholarly journals Свойства синтезированных методом пиролиза ультразвуковой аэрозоли наночастиц MgFe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- для биомедицинских применений

2019 ◽  
Vol 61 (6) ◽  
pp. 1175
Author(s):  
А.С. Камзин ◽  
А.А. Валиуллин ◽  
В.Г. Семенов ◽  
Harinarayan Das ◽  
Naoki Wakiya
Keyword(s):  
Spin Structure ◽  
Single Phase ◽  
Spherical Particles ◽  
Magnesium Ferrite ◽  
Hyperthermia Therapy ◽  
Canted Spin ◽  
Primary Particles ◽  
Average Size ◽  
Superparamagnetic State ◽  
Ferrite Spinel

AbstractWe present the data of studies on the structure, phase states, and magnetic properties of magnetic nanoparticles (MNPs) of magnesium ferrite spinel (MgFe_2O_4), synthesized by ultrasonic aerosols pyrolysis. Primary single-phase MNPs with an average size of 9.6, 11.5, and 14.0 nm, synthesized from precursors at concentrations of 0.06, 0.12, and 0.24 M, respectively, agglomerate into tightly aggregated spherical particles (secondary particles) with sizes of 206, 300, and 340 nm, respectively. Primary particles inside the spheres do not interact with each other and are in a superparamagnetic state. There is a layer on the surface of the particles, the magnetic structure of which differs from the structure of the inner part of the MNP; this is explained by the formation of a canted spin structure or a spin glass state in the surface layer of the MNPs. MgFe_2O_4 nanospheres obtained from a precursor at a concentration of 0.06 M are most promising as valid sources of heat in magnetic hyperthermia therapy.

Tungsten Trioxide Doped with CdSe Quantum Dots for Smart Windows

2018 ◽  
Vol 10 (50) ◽  
pp. 43785-43791 ◽  
Author(s):  
Amirhossein Hasani ◽  
Quyet Van Le ◽  
Mahider Tekalgne ◽  
Wenwu Guo ◽  
Sung Hyun Hong ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Tungsten Trioxide ◽  
Cdse Quantum Dots ◽  
Smart Windows
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