Pulsed Electron Beam Evaporation Research Articles

Properties of an amorphous crystalline nanopowder Si–SiO2 produced by pulsed electron beam evaporation

A mesoporous amorphous crystalline nanopowder (NP) Si–SiO2 with a specific surface area (SSA) of 35 m2/g was produced by pulsed electron beam evaporation (PEBE) of a compact of micron commercial SiO2 powder (0.9 m2/g). Si semimetal nanoparticles (NPles) reduced in for vacuum (≈4 Pa) had a marked effect on the thermal and luminescent properties of the Si–SiO2 nanoparticles compared to the properties of amorphous SiO2 NPles produced earlier by PEBE evaporation of a target compound made from NP Aerosil 90 (Degussa). Photocatalytic capabilities of Si–SiO2 nanoparticles were evaluated. NPles Si–SiO2 showed high antioxidant activity on HELA cancer cells.

Photocatalytic activity of ZnO-Zn nanoparticles after nanosilver covering and annealing

The research evaluated the photocatalytic activity (PCA) of zinc oxide nanoparticles (NPs) produced by pulsed electron beam evaporation (PEBE). The ability of NPs to accelerate the photodegradation of methyl violet dye under UV exposure was considered. The paper presents an analysis of changes in catalytic activity after annealing and coating with nanosilver of the studied samples. It has been shown that as the annealing temperature increases, the PCA increases, especially for doped particles. The highest catalytic ability was shown by doped NPs ZnO-Zn+Ag annealed at a temperature of 400 °C. This sample allowed to increase the photodegradation of the organic dye by more than 6.5 times compared to the control.

Phase transformation in air of Bi2O3 nanopowder produced by pulsed electron beam evaporation

The present paper studies the pathways of phase transformation of heterophasic nanopowder (NP) Bi2O3 produced by pulsed electron beam evaporation (PEBE) in vacuum (4 Pa) when annealing in air. The phase transformation after annealing in air of heterophase bismuth oxide NPs leads to the formation of bismuth carbonate at an annealing temperature of 200–300 °C. The effect of NP aging in storage under normal conditions was investigated.

The Anodization of Thin Titania Layers as a Facile Process towards Semitransparent and Ordered Electrode Material.

Photoanodes consisting of titania nanotubes (TNTs) grown on transparent conductive oxides (TCO) by anodic oxidation are being widely investigated as a low-cost alternative to silicon-based materials, e.g., in solar light-harvesting applications. Intending to enhance the optical properties of those photoanodes, the modification of the surface chemistry or control of the geometrical characteristics of developed TNTs has been explored. In this review, the recent advancement in light-harvesting properties of transparent anodic TNTs formed onto TCO is summarized. The physical deposition methods such as magnetron sputtering, pulsed laser deposition and electron beam evaporation are the most reported for the deposition of Ti film onto TCO, which are subsequently anodized. A concise description of methods utilized to improve the adhesion of the deposited film and achieve TNT layers without cracks and delamination after the anodization is outlined. Then, the different models describing the formation mechanism of anodic TNTs are discussed with particular focus on the impact of the deposited Ti film thickness on the adhesion of TNTs. Finally, the effects of the modifications of both the surface chemistry and morphological features of materials on their photocatalyst and photovoltaic performances are discussed. For each section, experimental results obtained by different research groups are evoked.

Properties of ZrO2 and Ag–ZrO2 nanopowders prepared by pulsed electron beam evaporation

ZrO2 and Ag doped ZrO2 powders were prepared from mixtures of ZrO2 and AgNO3 commercial powders (99:1 and 95:5 wt %) by pulsed electron beam evaporation (PEBE) in vacuum. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), textural and magnetic analysis, photocatalytic test, photoluminescence spectroscopy (PL) and cell cytology (Vero and Hela). XRD analysis confirmed the presence of monoclinic ZrO2 phase and cubic Ag phase in the final product. НRTEM pictures showed a large range of particle sizes approximately from 10 to 500 nm; the spherical silver nanoparticles (NPles) (10 nm) were observed on the ZrO2 particle surfaces. Ferromagnetic contribution in pure ZrO2 powder was 0,002 emu/g, and in Ag doped ZrO2 powders it reached 0,016 emu/g. It was found that Ag doped ZrO2 powders showed increased photocatalytic activity in methyl orange (MO) compared with pure ZrO2 NPles. The produced powders can be used to kill Hela cancer cells, as low (<0.1 wt) Ag photocatalysts and in other applications.

Влияние отжига в разных средах на свойства нанопорошка фторида кальция

Using a pulsed electron beam evaporation in vacuum a mesoporous nanopowder CaF2 with a specific surface area up to 60.5 m2/g were produced. The effect of annealing in different media on the evolution of magnetic and texture properties of CaF2 nanoparticles has been studied. For the first time, the effect of annealing medium on the specific surface area and magnetization of CaF2 nanopowders was discovered.

Effect of annealing in different medium on the properties of calcium fluoride nanopowder

Using a pulsed electron beam evaporation in vacuum a mesoporous nanopowder CaF2 with a specific surface area up to 60.5 m2/g were produced. The effect of annealing in different media on the evolution of magnetic and texture properties of CaF2 nanoparticles has been studied. For the first time, the effect of annealing medium on the specific surface area and magnetization of CaF2 nanopowders was discovered. Keywords: nanopowders, calcium fluoride, ferromagnetism, electron beam evaporation.

Properties of cerium (III) fluoride nanopowder obtained by pulsed electron beam evaporation

The method of pulsed electron beam evaporation (PEBE) in vacuum was first used to obtain CeF3 nanopowder (NP). During NP production, a high evaporation rate of the target (∼7 g/h) and a higher percentage of NP collection (> 72%) were observed, both for fluoride and the previously obtained CeO2 oxide. The main physicochemical characteristics of NP were studied: structure, porosity, thermal stability and magnetic properties. It was found that the produced NP contains two crystalline phases: hexagonal CeF3 (95 wt%, coherent scattering regions (CSR) ≈ 8 nm) and [Ce-O-F] or [Ce-F]. The last phase is obtained only at a high temperature, which is characteristic for the used NP synthesis method. The magnetic susceptibility of CeF3 nanoparticles (NPles) coincides with the susceptibility of micron particles, indicating the potential for using such NPles as a contrast agent for tomography. High specific surface area (SSA) (CeO2–270 m2/g, CeF3 - 62 m2/g) and large pore volume (0.35–0.11 cm3/g) allow the use of NP as nanocontainers for drug delivery.

Photon avalanche in nanoluminophore obtained by REE silicate evaporation

A bulk phosphor composition Sr2Y6.8YbEr0.2Si6O26 was synthesized. A nanophosphorus in an amorphous state was obtained from this sample by the method of pulsed electron beam evaporation. The spectra of upconversion photoluminescence of bulk and nanosamples were studied. In the field of pumping power of nanosample with 78 mW laser radiation with a wavelength of 980 nm, there is a threshold population of energy levels Er3+. Laser radiation carries out resonant pumping of 4I13/2 → 4F9/2 transition. Then there is an intensive red radiation upon transition 4F9/2 → 4I15/2. A photon avalanche was found in the nanophosphore, at which the intensity of red radiation increases ∼80 times compared to the bulk phosphorus.

Investigation of biological and photocatalytic activity of multimodal nanopowders produced by pulsed electron beam evaporation in vacuum

Nanopowders doped with silver were produced by the method of pulsed electron beam evaporation. The pore sizes of the nanoparticles were 25-32 nm. Evaluation of photocatalytic and cytotoxic properties on cells was carried out. The prospects of using multimodal nanopowders as a photocatalytic agent, as well as for use in medicine, have been shown.

Production of nanopowders of bismuth oxide doped with silver by pulsed electron beam evaporation in vacuum

Various bismuth containing compounds are promising in many applications, including for creating photocatalysts based on them using a visible range of light. However, strong polymorphism (9 polymophic phases of Bi2O3), thermal instability and changes in the properties of bismuth oxide during long-term storage significantly complicate work with it. One way to increase stability and improve photocatalytic properties is by doping Bi2O3 with various metals. Ag doped Bi2O3 nanoparticles (NPs) are typically produced using chemical techniques often associated with the presence of toxic chemicals. The present paper used an environmentally friendly method of producing NPs using the method of pulsed electron beam evaporation in vacuum. The evaporation target was obtained by solid phase synthesis in an electric furnace on air using silver nitrate additives (1 and 5 wt.%). Textural, thermal and magnetic properties of the obtained NPs have been studied. Was found that the Ag-Bi2O3 NPs have a specific surface area (SSA) of 23.7 m2/g, which was almost 2 times bigger than the SSA of the pure Bi2O3 (13.2 m2/g) obtained previously. The thermal stability of the Ag-doped Bi2O3 samples was maintained to the temperature 350°C. While further heating on air took place the phase transition β → α

Production of nanopowder of cerium (III) fluoride obtained by pulsed electron beam evaporation in vacuum

The method of pulsed electron beam evaporation in vacuum was first used to obtain CeF3 nanopowder (NP). During NP production, a high evaporation rate of the target (~ 7 g/h) and a higher percentage of NP collection (> 72%) were observed, both for fluoride and the previously obtained CeO2 oxide. It was found that the produced NP contains two crystalline phases: hexagonal CeF3 (95 wt.%, coherent scattering region ≈ 8 nm and [Ce-O-F] or [Ce-F]. The magnetic susceptibility of CeF3 nanoparticles (NPles) coincides with the susceptibility of micron particles, indicating the potential for using such NPles as a contrast agent for tomography. High specific surface area (CeO2-270 m2/g, CeF3 – 62 m2/g), large pore volume (0.35-0.11 cm3/g) allow the use of NPles as nanocontainers for drug delivery.

Formation of Droplets during Annealing of Bi2O3 Nanopowder Obtained by Pulsed Electron Beam Evaporation in Vacuum

Formation of Droplets during Annealing of Bi2O3 Nanopowder Obtained by Pulsed Electron Beam Evaporation in Vacuum

Production and investigation of biological and photocatalytic activit multimodal nanopowders produced by pulsed electron beam evaporation in vacuum

Nanopowders doped with silver were produced by the methode pulsed electron beam evaporation.

Formation of droplets in a heterophasic amorphocrystalline nanopowder Bi2O3 produced by pulsed electron beam evaporation in vacuum

In the present work, a mesoporous multiphase amorphous crystal nanopowder Bi2O3 with a specific surface area of up to 23 m2/g was produced by pulsed electron beam evaporation in vacuum. Influence of thermal annealing (200-500 °C) of powders in air is investigated. The formation of droplets with a size of 3-5 nm on the surface of all large nanoparticles constituting the framework 3D nanopowder agglomerates was found due to extrusion of liquid bismuth from the volume during cooling.

Phase transformation in vacuum and basic physicochemical properties of heterophasic amorphocrystalline Bi2O3-based nanopowder produced by pulsed electron beam evaporation

In this work the method of pulsed electron beam evaporation (PEBE) in vacuum (4 Pa) was used to produce the mesoporous multiphase (α, β and amorphous) amorphocrystalline nanopowder (ACN) of Bi2O3 with specific surface area (SSA) up to 23 m2/g. The effect of thermal annealing on the properties of Bi2O3 ACN was investigated in vacuum and in air. Using the HTXRD method in a vacuum (10−4 mbar) in the RT-510 °С temperature range, the phase transformation of the NP was established according to the scheme (α + β + amorph) ⟶200°C(α+β+R)⟶280°C(α+R)⟶510°C(α). The formation of uniform Bi amorphocrystalline nanoparticles (droplets) with a size of 3–5 nm was observed on the surface of all bismuth oxide samples (S200, S300 and S500) that were annealed in air in the temperature range of 200–500 °С, respectively, due to extrusion of liquid Bi from the volume to the surface of large nanoparticles (NPles) forming the framework of 3D nanoparticle agglomerates during the cooling of the annealed NPs. The presence of NPles of metallic Bi in the original sample was confirmed directly by HRTEM and indirectly by RS, DSC and PCL. The magnetic behavior of annealed samples confirmed their diamagnetic nature. The weak ferromagnetic response (3–4 memu/g) in the as prepared sample was associated with its very defective structure. The photocatalytic activity of NPs was confirmed in decomposition of MO colorant during UV irradiation.

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

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.

The effect of permanent magnetic field on photoluminescence of nanopowder oxides produced by pulsed electron beam evaporation

The effect of a permanent magnetic field on shift of photoluminescent peaks of nanopowder oxides produced by pulsed electron beam evaporation in vacuum has been discovered for the first time. It has been established that when the magnetic field of 0.154 T is superimposed, shifts in photoluminescence spectrum maxima are observed for Al2O3 in the yellow region (14 nm) and for CeO2 in the red region (50 nm). It is possible that the shifts are a consequence of the interaction of the permanent magnetic field with the magnetic moments of nanoparticles that are defective in nature.

Upconversion luminescence of germanate nanophosphors activated by Er3+ and Yb3+ ions

The crystallophores of the composition Sr2La8(1x-y)ErxYbyGe6O26 (x = 0.01, 0.05, 0.075, 0.1, 0.15) were synthesized. Nanophosphores in the amorphous state were obtained for the first time by the method of pulsed electron beam evaporation using a phosphor of the composition Sr2La7.85Er0.075Yb0.075Ge6O26 with the structure of oxyapatites as a target. DSC-TGA analysis was performed to determine the temperature stability and the onset of crystallization of the nanosample. A change in the Raman spectra of the samples with a decrease in the particle dimension from the bulk to nanoscale state was found. The spectral characteristics of the upconversion photoluminescence of samples in polycrystalline and nano-amorphous states are studied. It has been shown that luminescence is influenced by nonradiative processes between different transitions of Er3+ ions. There is a threshold population of the Er3+ and Yb3+ levels (level 2F5/2) in the region of relatively low pumping powers of nanosamples by laser radiation with a wavelength of λex = 980 nm. Above this threshold a sharp increase in the intensity of upconversion photoluminescence occurs.

Study of d0 magnetism of BaF2 nanopowder after thermal and radiation exposure

Mesoporous nanocrystal BaF2 nanopowders (NPs) have been obtained with the pulsed electron beam evaporation (PEBE) technique. The transformation of the structure and morphology of BaF2 nanoparticles (NPles) induced by thermal annealing in air at temperatures of 200, 400, and 900 °C has been monitored with the XRD, SEM, and HRTEM methods. The HRTEM analysis has shown the presence of three polymorph phases (cubic, octahedral, and hexagonal) in the unannealed NP. Upon the transition into the nanoscale, diamagnetic (DM) BaF2 (in the volume state) has demonstrated both paramagnetic (PM) and ferromagnetic (FM) responses at room temperature. The thermal analysis (TA) has confirmed the strong adsorption of CO2 while synthesizingthe BaF2 NP via PEBE method and adsorption of different NOx oxides following irradiation of the BaF2 NP (in air by 700 keV electrons) The appearance of the FM contribution in the diamagnetic BaF2 NP after annealing at a temperature of 600–900 °C is likely associated with the achievement of the percolation threshold with an increase of the BaO oxide concentration. This is in agreement with the well-known theoretical predictions of d0 magnetism in N-doped (C-doped) BaO. The appearance and variations of the FM contribution to the BaF2 NP irradiated by 700 keV electrons are likely connected with an increase of the NOx oxide concentration (due to an increase of the time of electron irradiation), which confirms the hypothesis on the appearance of the FM response in solid-state N (C)-BaO solutions. The FM decrease with time is indicative of the surface character of d0 magnetism in the barium fluoride under study.