scholarly journals Properties of Silicon Dioxide Amorphous Nanopowder Produced by Pulsed Electron Beam Evaporation

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Vladislav G. Il’ves ◽  
Michael G. Zuev ◽  
Sergey Yu. Sokovnin
Keyword(s):  
Optical Properties ◽  
Electron Beam ◽  
Silicon Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Room Temperature ◽  
Luminescent Properties ◽  
Electron Beam Evaporation ◽  
Pulsed Electron Beam

SiO2amorphous nanopowder (NP) is produced with the specific surface area of 154 m2/g by means of evaporation by a pulsed electron beam aimed at Aerosil 90 pyrogenic amorphous NP (90 m2/g) as a target. SiO2NP nanoparticles showed improved magnetic, thermal, and optical properties in comparison to Aerosil 90 NP. Possible reasons of emergence of d0ferromagnetism at the room temperature in SiO2amorphous NP are discussed. Photoluminescent and cathode luminescent properties of the SiO2NP were investigated.

scholarly journals Образование при отжиге дроплетов в нанопорошке Bi-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-, полученном импульсным электронным испарением в вакууме

2021 ◽  
Vol 47 (16) ◽  
pp. 16
Author(s):  
С.Ю. Соковнин ◽  
В.Г. Ильвес
Keyword(s):  
Electron Beam ◽  
Specific Surface ◽  
Surface Area ◽  
Thermal Annealing ◽  
Specific Surface Area ◽  
Electron Beam Evaporation ◽  
Pulsed Electron Beam ◽  
Liquid Bismuth

Using a method of pulsed electron beam evaporation in vacuum was produced the mesoporous multiphase amorphous and crystal nanopowder of Bi2O3 with a specific surface area up to 23 sq.m/g. Influence of thermal annealing of powder (200-300 0C) in air is investigated. The formation of droplets with a size of 2-5 nm was found on the surface of all large nanoparticles that make up the framework 3D nanopowder agglomerates due to extrusion of liquid bismuth from the volume during cooling.

scholarly journals Влияние отжига на структурные, текстурные, термические, магнитные и люминесцентные свойства наночастиц фторида кальция

2019 ◽  
Vol 61 (11) ◽  
pp. 2216 ◽  
Author(s):  
В.Г. Ильвес ◽  
С.Ю. Соковнин ◽  
М.Г. Зуев ◽  
М.А. Уймин ◽  
M. Rahn ◽  
...  
Keyword(s):  
Particle Size ◽  
Electron Beam ◽  
Specific Surface ◽  
Surface Area ◽  
Luminescent Properties ◽  
Electron Beam Evaporation ◽  
Radiation Defects ◽  
Pulsed Electron Beam ◽  
Strong Deviation ◽  
Pulsed Cathodoluminescence

Mesoporous nanocrystalline CaF2 powder was obtained by pulsed electron beam evaporation (PEBE) in vacuum. The specific surface area (SSA) of the nanopowder (NP) of CaF2 reached 88.7 m2g. The effect of thermal annealing in air in the temperature range 200–900 oC on particle size, morphology, textural, thermal, magnetic, and luminescent properties of NP was studied. A strong deviation of the obtained nanoparticles from stoichiometry and a significant increase in SSA after annealing at 200 ° C was observed. The obtained CaF2 NP showed ferromagnetic (FM) behavior. The appearance of the FM response can be explained by the formation of structures and radiation defects. An analysis of the pulsed cathodoluminescence (PCL) curves and the magnetization of NP CaF2 allows us to draw conclusions about their relationship.

Concept of Full Surface at Syntesis and Application of Silica Nanopowder

2014 ◽  
Vol 9 (4) ◽  
pp. 80-88
Author(s):  
Alexey Zavialov ◽  
Konstantin Zobov ◽  
Vyacheslav Syzrantsev ◽  
Sergey Bardakhanov
Keyword(s):  
Electron Beam ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Theoretical Models ◽  
Electron Beam Evaporation ◽  
Synthesis Process ◽  
Nano Silica ◽  
Silica Nanopowder ◽  
Main Factor

The paper describes a model of synthesis and analysis of the application of nano-silica obtained by electron beam evaporation. The authors developed the approach that shows of the specific and fully surfaces of nanopowders to have more significance then the size of the nanoparticles. The experimental results and theoretical models supporting this concept are presented. In particular, the connection between the strength of the epoxy and the total surface value dispersed into epoxy is shown. In the synthesis of large quantities of nanopowder we can use the model concepts to predict specific surface directly from the averaged parameters of synthesis. The main factor for a used synthesis scheme is presented: the multiplication a product of mass performance on specific surface area. The combination of this factor with the model representations of specific surface evaluation allows to estimate the quality and efficiency of the synthesis process. The nanopowder total surface versatility as a criterion of comparability of different modes, and possibly synthesis processes is shown

scholarly journals Исследование свойств нанопорошка фторида кальция после облучения наносекундным электронным пучком

2020 ◽  
Vol 46 (8) ◽  
pp. 47
Author(s):  
С.Ю. Соковнин ◽  
В.Г. Ильвес ◽  
М.Е. Балезин ◽  
М.А. Уймин
Keyword(s):  
Electron Beam ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Electron Beam Evaporation ◽  
Beam Irradiation ◽  
Evaporation Method ◽  
Texture Properties ◽  
First Time

Mesoporous CaF2 nanopowders with specific surface area up to 91.5 m2/g have been produced using by electron beam evaporation method in vacuum. The effect of nanosecond e-beam irradiation in air on magnetic and texture properties this nanopowders has been studied. The irradiation influence on the specific surface area and magnetization of CaF2 nanopowder has been discovered for the first time.

scholarly journals Preparation and Application of 2D MXene-Based Gas Sensors: A Review

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 225
Author(s):  
Qingting Li ◽  
Yanqiong Li ◽  
Wen Zeng
Keyword(s):  
Composite Materials ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Specific Surface Area ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Interlayer Spacing ◽  
Preparation Methods

Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed.

Preparation of mesoporous silicon dioxide with high specific surface area

2009 ◽  
Vol 82 (1) ◽  
pp. 1-5 ◽  
Author(s):  
N. B. Kondrashova ◽  
O. G. Vasil’eva ◽  
V. A. Val’tsifer ◽  
S. A. Astaf’eva ◽  
V. N. Strel’nikov
Keyword(s):  
Silicon Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Mesoporous Silicon ◽  
Mesoporous Silicon Dioxide

scholarly journals Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 323 ◽  
Author(s):  
Ludovico Macera ◽  
Giuliana Taglieri ◽  
Valeria Daniele ◽  
Maurizio Passacantando ◽  
Franco D’Orazio
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Ambient Pressure ◽  
Synthesis Method ◽  
Hematite Nanoparticles ◽  
X Ray

This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2/g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2/g, which is among the highest values reported in the literature for hematite NPs.

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