scholarly journals Synthesis, Characterization, and NIR Reflectance of Highly Dispersed NiTiO3and NiTiO3/TiO2Composite Pigments

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Yuping Tong ◽  
Jing Fu ◽  
Zheng Chen
Keyword(s):  
Diffuse Reflectance ◽  
Combustion Method ◽  
Spherical Particles ◽  
Optical Data ◽  
Uniform Size ◽  
Highly Dispersed ◽  
Nanometer Particles ◽  
Chromatic Properties ◽  
Uniform Size Distribution ◽  
Composite Samples

The highly dispersed nanostructured NiTiO3pigments and NiTiO3/TiO2composite pigments can be synthesized at relative low temperature. The activation energy of crystal growth of NiTiO3during calcinations via salt-assistant combustion method is 9.35 kJ/mol. The UV-vis spectra results revealed that the absorbance decreased with the increasing of calcinations temperature due to small size effect of nanometer particles. The optical data of NiTiO3nanocrystals were analyzed at the near-absorption edge. SEM showed that the obtained NiTiO3nanocrystals and NiTiO3/TiO2nanocomposite were composed of highly dispersed spherical-like and spherical particles with uniform size distribution, respectively. The chromatic properties and diffuse reflectance of samples were investigated. The obtained NiTiO3/TiO2composite samples have higher NIR reflectance than NiTiO3pigments.

scholarly journals Highly Dispersed Re-Doped CoAl2O4Nanopigments: Synthesis and Chromatic Properties

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yuping Tong ◽  
Hailong Zhang ◽  
Shun Wang ◽  
Zheng Chen ◽  
Baixue Bian
Keyword(s):  
Solid Solution ◽  
Size Distribution ◽  
Complex Oxides ◽  
Combustion Method ◽  
Uniform Size ◽  
Highly Dispersed ◽  
Chemical Segregation ◽  
Segregation Phenomenon ◽  
Chromatic Properties ◽  
Uniform Size Distribution

Nanosized spinelCoAl2-xRexO4complex oxides were prepared by self-propagation combustion method. The products have been characterized by XRD, SEM, and EDS. The results indicated that Al3+can be partly replaced by Re3+when the doped amount is less than 10%, which forms single solid solution. The NIR reflectance and chromatic properties of samples have also been investigated. The substitution of Re3+for Al3+in CoAl2O4can increase the blueness of pigments. SEM results revealed that the obtainedCoAl2-xRexO4pigments consisted of highly dispersed spherical-like nanoparticles with uniform size distribution. EDS results indicated that the distribution of element was considerably uniform with no chemical segregation phenomenon.

Optical Data of Rough-Surfaced Ceramics: Infrared Specular and Diffuse Reflectance versus Spectra Simulation

1993 ◽  
Vol 47 (4) ◽  
pp. 423-429 ◽  
Author(s):  
V. Hopfe ◽  
E. H. Korte ◽  
P. Klobes ◽  
W. Grählert
Keyword(s):  
Phase Shift ◽  
Smooth Surface ◽  
Diffuse Reflectance ◽  
Optical Data ◽  
Evaluation Procedure ◽  
Alumina Ceramics ◽  
Specular Reflectance ◽  
Optical Functions ◽  
Infrared Reflection ◽  
Simple Evaluation

Infrared reflection of strongly absorbing as well as scattering samples was studied. The optical functions of sintered alumina ceramics were derived with the use of the Kramers-Kronig transformation to reconstruct the phase shift under the assumption of a semi-infinite sample with an ideal plane and, in any scale, a smooth surface. In order to validate this procedure and to optimize measuring parameters, the results were compared to their simulated counterparts. Starting from the dielectric functions of monocrystalline Al2O3, the optical response of the sample was calculated by taking into account the polycrystallinity of the bulk and the roughness of the surface; eventually the spectra of specular reflectance were simulated on this basis for different angles of incidence. It turned out that the comparably simple evaluation procedure is well suited in spite of the rough surface and is particularly reliable in the case of large angles of incidence whereby scattering is minimized. Some characteristics of this diffusely reflected component are discussed.

Germanium dots with highly uniform size distribution grown on Si(100) substrate by molecular beam epitaxy

1997 ◽  
Vol 71 (24) ◽  
pp. 3543-3545 ◽  
Author(s):  
Xun Wang ◽  
Zui-min Jiang ◽  
Hai-jun Zhu ◽  
Fang Lu ◽  
Daming Huang ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Size Distribution ◽  
Molecular Beam ◽  
Uniform Size ◽  
Highly Uniform ◽  
Uniform Size Distribution

Synthesis of LiCoO2 particles with tunable sizes by a urea-based-homogeneous-precipitation method

2020 ◽  
Vol 111 (4) ◽  
pp. 347-355
Author(s):  
Munekazu Motoyama ◽  
Hiroki Iwasaki ◽  
Miyuki Sakakura ◽  
Takayuki Yamamoto ◽  
Yasutoshi Iriyama
Keyword(s):  
Size Distribution ◽  
Average Diameter ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
Homogeneous Precipitation Method ◽  
Wide Range ◽  
Size Uniformity ◽  
Average Size ◽  
Uniform Size Distribution

Abstract This paper reports the synthesis of monodisperse spherical LiCoO2 particles in a wide range of average diameter using a urea-based-uniform-precipitation method. The average diameter of LiCoO2 particles can be varied from 2 to 14 lm with a uniform size distribution. The effective approach to maintain the size uniformity while changing the average size of LiCoO2 particles is to keep the ratio of [CO(NH2)2] to [CoSO4] at 8 even when the CoSO4 and urea concentrations are changed.

Microstructure and Spectroscopy of Lu2O3:Eu Prepared Using Various Synthesis Techniques

2004 ◽  
Vol 99-100 ◽  
pp. 25-30 ◽  
Author(s):  
E. Zych ◽  
J. Trojan-Piegza ◽  
L. Kępiński ◽  
P. Dorenbos
Keyword(s):  
Uniform Distribution ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Nanocrystalline Powder ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
X Ray ◽  
Methods Of Synthesis ◽  
Excited Luminescence ◽  
Subsequent Decomposition

Nanocrystalline powders of Lu2O3:Eu with activator content varying between 0.2%-10% were prepared using four different methods of synthesis. The products differed in their microstructure and crystallites sizes. Combustion of Lu(NO3)3 with urea produced strongly agglomerated material, most probably with significantly non-uniform distribution of the Eu3+ dopant. Replacing urea with glycine for the combustion produced only slightly agglomerated, voluminous, fluffy powder. Applying the Pechini technique resulted in significantly agglomerated powder while the homogeneous precipitation of Lu(OH)3 with urea at 90 °C and its subsequent decomposition to Lu2O3 at 650 °C resulted in a powder of perfectly spherical particles with a uniform size of about 130 nm with very low agglomeration. The efficiency of X-ray excited luminescence of our nanocrystalline Lu2O3:5%Eu was compared to that of the commercial microcrystalline Gd2O2S:Eu. It was found that the commercial phosphor performed four times more efficiently than our nanocrystalline powder. We consider this to be rather encouraging as the fabrication of our powder is not optimized yet. It seems that Lu2O3:Eu, even in nanocrystalline form, can perform much more efficiently which would make it a promising X-ray phosphor.

Study on the Fabrication of Carbon Nanotube - Mesocarbon Microbead Composites

2013 ◽  
Vol 631-632 ◽  
pp. 486-489
Author(s):  
Zhi Wang
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Coal Tar ◽  
Coal Tar Pitch ◽  
Lower Yield ◽  
Uniform Size ◽  
Thermal Condensation ◽  
Mesocarbon Microbeads ◽  
Uniform Size Distribution ◽  
Made In

Carbon nanotube-Mesocarbon microbead composites were synthesized from coal tar pitch with carbon nanotubes (CNTs) as additive. The effect of CNTs addition and process parameters on the growth and morphologies of Mesocarbon microbeads (MCMBs) was investigated. The results show that adding CNTs enhances the nucleation and inhibits the growth and coalescence of MCMBs. Under the same thermal condensation conditions, the MCMBs made in the presence of CNTs tend to have smaller size, lower yield and more uniform size distribution, but more CNTs can lead to poor spherical degrees. Compared with the raw CNTs, the CNTs treated with blended acid can achieve better sphere and more uniform MCMBs with increasing CNTs ratio.

scholarly journals Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5328
Author(s):  
Iwona Pełech ◽  
Daniel Sibera ◽  
Piotr Staciwa ◽  
Urszula Narkiewicz ◽  
Robert Cormia
Keyword(s):  
Co2 Adsorption ◽  
Applied Pressure ◽  
Low Pressure ◽  
Spherical Particles ◽  
Co2 Uptake ◽  
Pressure Treatment ◽  
Carbon Spheres ◽  
Potassium Oxalate ◽  
Uniform Size ◽  
Pressure Synthesis

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

scholarly journals One-Step Synthesis of Highly Dispersed and Stable Ni Nanoparticles Confined by CeO2 on SiO2 for Dry Reforming of Methane

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5956
Author(s):  
Chengyang Zhang ◽  
Renkun Zhang ◽  
Hui Liu ◽  
Qinhong Wei ◽  
Dandan Gong ◽  
...  
Keyword(s):  
Carbon Deposition ◽  
Combustion Method ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Solution Combustion ◽  
Spatial Confinement ◽  
Oxide Interfaces ◽  
Highly Dispersed ◽  
One Step ◽  
The One

Sintering and carbon deposition are the two main ways to deactivate Ni-based catalysts during methane reforming. Herein, a stable Ni-CeO2/SiO2(CSC) catalyst was prepared by a one-step colloidal solution combustion method (CSC) and used for dry reforming of methane. In the catalyst, the small Ni particles were confined by CeO2 particles and highly dispersed on the surface of SiO2, forming a spatial confinement structure with a rich Ni-CeO2 interface in the catalyst. The Ni-CeO2/SiO2(CSC) catalyst prepared by the one-step CSC method exhibited superior activity at 700 °C during dry reforming of methane, and the performance of the catalyst was stable after 20 h of reaction with only a small amount of carbon deposition present (1.8%). Due to the spatial confinement effect, Ni was stable and less than 5 nm during reaction. The small Ni particle size and rich Ni-CeO2 interface reduced the rate of carbon deposition. This colloidal combustion method could be applied to prepare stable metal-based catalysts with rich metal–oxide interfaces for high-temperature reactions.

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