The influence of annealing in the temperature range of 150–300 °C during plasma-enhanced atomic layer deposition of HfO
2
and the conditions of the following thermal processing on microstructure and ...electrical properties have been studied. The microstructure was examined by transmission electron microscopy and electron diffraction. The as-deposited HfO
2
film consists of monoclinic crystallites embedded in an amorphous matrix. It was found that the crystallite density grows with the increase in the deposition temperature; however, the size of the crystallites does not change. Subsequent annealing at 425 °C for 30 min or at 950 °C for 4 s led to complete crystallization through the lateral growth of the crystallites of samples formed at 250 and 300 °C. However, for the sample formed at 150 °C, subsequent annealing at 425 °C resulted in the formation of dendritic-like crystalline clusters embedded in an amorphous matrix. The leakage currents in polycrystalline and even amorphous HfO
2
films after the annealing were drastically increased. That could be explained by crystallization after the annealing. However, the C impurity redistribution and the growth of an interfacial layer could also affect the leakage.
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The results of obtaining by plasma processing of spherical, including hollow, particles of cermet powder with high content of carbide inclusions have been presented. The phase composition of ...particles has been determined, their morphology and internal structure has been studied. An explanation of formation of a hollow particle has been proposed.
Synthesis of MOF-5 at room temperature was optimized. The phase-pure crystalline structure with high hydrogen capacity was prepared at room temperature and atmospheric pressure. The MOF-5 pressing ...and subsequent fractionation singificantly improves its operation properties. An adsorption apparatus was designed and assembled to study the adsorption properties of the synthesized materials under the conditions close to the real one. Experiments on studying the adsorption properties of MOF-5 under the conditions of cryogenic hydrogen adsorption showed that the samples adsorbed up 3.3 wt % H
2
at a 30 atm pressure and –196°С.
Results of an experimental study of physical properties, microstructure, and phase composition of a TiC–NiCr cermet compact obtained by hot pressing are presented. It is shown that an increase in the ...volume fraction of carbide inclusions is accompanied by an increase in hardness HRA (from 25 to 55) and microhardness HV
300
(from 350 to 1000) of the material.
Structural studies of multilayer magnetic nanostructures formed by alternating layers of transition (Fe) and rare-earth (Gd) metals, which are placed into a hydrogen atmosphere at 100°C, are ...performed. The hydrogen absorption of rare-earth metals results in the formation of GdH
x
crystalline phases, the microstructural peculiarities of which are studied by X-ray diagnostics techniques and electron microscopy.
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•The polymeric nanocomposites based on anatase type poly(titanium oxide) doped by Au or Ag nanoparticles were synthesized in one pot reaction.•The materials are optical transparent up ...to 90 % and characterized by one-electron transition Ti4+ + e- → Ti3+ under UV-irradiation. Au and Ag nanoparticles with size less than 20 nm are uniformly destributed inside polymer matrix.•The nanocomposites demonstrate the photocatalytic activity in the p-nitrophenol oxidation in aqueous solution under UV- and visible light irradiation.•The materials exhibit high photocatalytic activity in several successive experiments.
Optically transparent materials of poly(titanium oxide) in organic polymer matrix, doped by silver or gold nanoparticles of medium size (9 and 12 nm respectively), were synthesized in the reaction of titanium iso-propoxide with hydroxyethylmethacrylate in the presence of AgNO3 and HAuCl4 as dopants. The materials exhibite activity as heterogeneous photocatalysts. The decomposition of p-nitrophenol was observed in aqueous solutions under light irradiation in the presence of the obtained materials. This reaction can be initiated by both UV- and visible light. The useing of copolymers doped by Au or Ag nanoparticles lead to increased p-nitrophenol decomposition up to 70 and 85% (UV-irradiation) and up to 90% (λ > 410 nm). It was determined that the rate constants of the reactions in this case were: kAg = (23.11 ± 0.16)∙10−2 s-1 and kAu = (8.05 ± 0.13)∙10−2 s-1.
The article is dedicated to reveling the reason of unusual magnetic properties, found in one of Co/Dy periodic multilayer systems with different Co/Dy layer thickness by X-Ray reflectivity, ...scanning/transmission electron microscopy together with energy dispersive X-Ray microanalysis. Magnetic measurements did not demonstrate any peculiarities in the system with thinner Co/Dy layer thickness. However, the system with thicker layers demonstrated an anomalous behavior of the perpendicular magnetic anisotropy. Based on X-Ray reflectivity measurements, it was found that the polarizability value in the system with thicker Co/Dy layer was very high and related to glassy intermetallic DyCo2 compound formation. Electron microscopy and microanalysis data also indicated the presence of glassy intermetallic DyCo2 layers, which could be responsible for the peculiar magnetic behavior. The relation between magnetic properties and microstructure was revealed.
•Thick Co/Dy periodic multilayer system demonstrates an anomalous perpendicular magnetic anisotropy.•Thin Co/Dy system does not show any peculiarities.•Polarizability of thick Co/Dy system is high and indicates glassy DyCo2.•Intermixing and formation of partially glassy layers occur.
The anthracene coking process has been investigated in the temperature range of 400–600°C. It has been shown that intermolecular interaction of two anthracene molecules resulting in the elimination ...of hydrogen and the formation of a C–C bond between the middle rings begins at a temperature of 450°C. Increasing the coking temperature to 500–600°C leads to the formation of poorly crystallized graphite. In the case of pure anthracene, the formation of micron-sized spherical carbon particles occurs. The addition of carbon nanotubes to anthracene leads to the formation of the carbon “coat” covering their surface. The thickness of the carbon “coat” depends on the temperature of coking. An amorphous carbon layer observed on the surface of carbon nanotubes has a thickness of 1–2 nm in the case of coking temperature of 450°C or 10–15 nm in the case of coking at 600°C.
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