Electron Beam Evaporation In Vacuum Research Articles

ALUMINUM OXIDE IN VACUUM CONDENSATES BASED ON COPPER

Strengthening of copper and copper alloys with aluminum oxide particles is an important technological technique. Composite materials based on copper strengthened with aluminum oxide particles have a significant operating temperature range and better mechanical properties at elevated temperatures than age-hardening alloys. However, at moderate operating temperatures, the use of age-hardening alloys remains more economically justified. The main direction in the development of composites strengthened with oxide particles is the dispersion of the strengthening phase to sizes of several or one nanometer, which will bring their mechanical properties to the level of age-hardening alloys. However, dispersion leads to a significant increase not only in strength, but also in electrical resistance. The adverse effect on the electrical conductivity of dispersed particles will decrease with a decrease in the volume fraction of oxide, bringing the electrical conductivity closer to the level of copper. Based on an analysis of the materials of scientific research devoted to the production of dispersion-strengthened Cu–Al2O3 composites, it was concluded that the most significant progress in the dispersion of oxide particles with uniform distribution in the copper matrix of the composite was achieved using the method of electron beam evaporation and simultaneous deposition (condensation) of vapors of components in vacuum (EB–PVD). Structural studies of the morphology of aluminum oxide particles in dispersion-strengthened copper composites were carried out using methods such as: X-ray fluorescence analysis, transmission electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). The average size of aluminum oxide particles in the studied dispersion-strengthened composites was in the range from 1.8 to 3 nm. In the work, the dependence of the specific electrical resistance of composites (ρ) on the oxide content was investigated. It was found that a decrease in the size of oxide particles leads to an increase in the electrical resistance of the dispersion-strengthened composite. The studies of the method of electron beam evaporation and subsequent condensation in vacuum, presented in the work, confirm the possibility of further dispersion of aluminum oxide particles with simultaneous narrowing of the distribution histogram. This opens up prospects for further improvement of vacuum dispersion-strengthened copper-based composites.

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.

Особливості структури і фізико-хімічних властивостей міді, отриманої способом електронно-променевого випаровування-конденсації у вакуумі

Особливості структури і фізико-хімічних властивостей міді, отриманої способом електронно-променевого випаровування-конденсації у вакуумі

Features of the structure and physico-chemical properties of copper produced by the method of electron beam evaporation and condensation in vacuum

Features of the structure and physico-chemical properties of copper produced by the method of electron beam evaporation and condensation in vacuum

Enhanced Field Emission Properties of ZnO:Al/SrTiO3 Perovskite Composite Films by ZnO:Al Film

ZnO:Al(Al‐doped zinc oxide)/SrTiO3 composite thin film field emission (FE) devices are fabricated on heavily doped n‐type silicon substrates using a vacuum electron beam evaporation vapor deposition technique and hydrogen plasma treated technique. The morphology and thickness of SrTiO3 film and ZnO:Al film are controlled by adjusting and optimizing the growth conditions, deposition time, and post‐treatment conditions. FE experimental results show that the addition of ZnO:Al films can significantly improve the FE properties of ZnO:Al/SrTiO3 composite film. The maximum current density of the FE sample increases from 230 μA cm−2 of the monolayer SrTiO3 film sample, which is treated by hydrogen plasma (H–SrTiO3) to 951 μA cm−2 of the ZnO:Al/H–SrTiO3 composite film sample, which increases by more than 4 times. Meanwhile, at the applied electric field intensity of 3.6 V μm−1, the FE current density of ZnO:Al/H–SrTiO3 composite film is 48 times that of monolayer H–SrTiO3 film. Each field emission sample device has good working stability and experimental repeatability.

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.

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.

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.

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

UV/Ozone Treatment and Open-Air Copper Plasmonics

Thin copper films with thickness ∼28 nm deposited on SiO2 substrate with the vacuum electron beam evaporation method and treated by UV-ozone are studied. It was found that a UV-ozone treatment of the copper film causes rapid formation of the thin ∼3-4 nm oxide film. XPS analysis showed that CuO oxide predominates in this film. The formed oxide film effectively protects the copper against the following oxidation. The presented method of UV-ozone treatment is a simpler and cheaper approach compared to many other ways to form protective coatings of copper to preserve its functional properties. This method can be useful in nanoelectronic, nanooptical, and biosensors applications.

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.

Effect of Metallic Nanocoatings Deposited on Silicon Oxide on Wetting by Filler Melts II. Effect from the Annealing of Nanocoatings Deposited on SiO2 on their Structure and Interaction with the Oxide

The sessile drop method using capillary melt cleaning was employed in the experiment to study the effect of metallic nanocoatings (single Ti, Nb, and Mo coatings and binary Ti–Cu, Nb–Cu, and Mo–Cu coatings with a copper layer of constant thickness) on the wetting of silicon oxide by Pb–15 wt.% In melt in 1 ∙ 10–3 Pa vacuum at 500°C after their annealing at 900°C. The metallic coatings were applied by electron beam evaporation in vacuum. The binary coatings were produced by sequential deposition of layers. The dependences of contact angle on coating thickness show that the ‘threshold’ thickness is determined by the annealing temperature of the coating or, in other words, its structure. The threshold coating thickness for different metals depends on their chemical affinity to oxygen. When freshly applied and annealed single Mo, Nb, and Ti coatings are wetted, their threshold thickness increases from 70 to 80 nm for the titanium coating, from 63 to 70 nm for the niobium coating, and from 50 to 60 nm for the molybdenum coating. The structure of Cu, Ni, Mo, Cr, Nb, and Ti coatings annealed at 600, 900, and 1200°C was studied. The initial (freshly deposited) metallic coatings showed high integrity. The coatings became dispersed after annealing and their integrity decreased with increasing temperature. The dispersed metallic coatings formed ‘islands’ of various shapes, round shape being predominant, depending on the chemical affinity of the coating metal to oxygen. The so-called ‘solid’ wetting was observed. The shape of the islands is determined by equilibrium between the metal–substrate attraction forces (interaction, adhesion) and the very strong surface tension of the metal (at such a small coating thickness). To use metallic coatings for brazing quartz with aluminum alloys, coatings of adhesive metals (Mo, Cr, Nb, Ti) should be annealed at temperatures of 900–1000°C with a holding time of 10 min. The coating thickness should be within the threshold range.