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429 results on '"A, Sidorov"'

23. Synthesis of Superconducting Boron-Doped Diamond in Carbon and Boron Solutions in Molten Gold and Copper.

Author

Ekimov, E. A., Sidorov, V. A., Khmel'nitskii, R. A., and Lyapin, S. G.

Subjects
*SUPERCONDUCTING transition temperature, *DOPING agents (Chemistry), *DIAMONDS, *BORON, *COPPER, *GOLD
Abstract

The Au–B–C and Cu–B–C growth systems, which do not form borides, have been used for the first time for the synthesis of boron-doped superconducting diamond. In these systems, the graphite-to-diamond transformation occurs at pressures from 8 to 9 GPa and temperatures from 1620 to 1770 K, suitable for commercial-scale production. The presence of boron in melts is assumed to be responsible for the decrease in synthesis temperature in molten copper and the diamond-forming ability of gold-based melts. The synthesized diamond exhibits metallic behavior of conductivity at ordinary temperatures and undergoes a superconducting transition between 4.5 and 2.5 K. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Structural Defects and Photoluminescence in Zinc-Doped Lithium Niobate Crystals

Author

N. V. Sidorov, Natalya A. Teplyakova, M. V. Smirnov, and M. N. Palatnikov

Subjects
Photoluminescence, Materials science, business.industry, General Chemical Engineering, Doping, Lithium niobate, Metals and Alloys, chemistry.chemical_element, Zinc, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Materials Chemistry, Optoelectronics, business
Published
2021

40. Electrical Conductivity and Dielectric Permittivity of Directly Doped LiNbO3:Zn,Mg Crystals in the Temperature Range 450–900 K

Author

M. N. Palatnikov, N. V. Sidorov, I. V. Biryukova, Olga V. Makarova, and V. A. Sandler

Subjects
010302 applied physics, Materials science, General Chemical Engineering, Doping, Enthalpy, Metals and Alloys, Analytical chemistry, 02 engineering and technology, Conductivity, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Thermal conduction, 01 natural sciences, Ion, Inorganic Chemistry, Electrical resistivity and conductivity, 0103 physical sciences, Materials Chemistry, Ionic conductivity, 0210 nano-technology
Abstract

The electrical conductivity σ of a series of multidomain LiNbO3:Zn,Mg crystals prepared via direct doping in the composition ranges ~1 ± 0.02 mol % MgO and ~2.8–4.6 mol % ZnO has been shown to undergo a sharp increase at T* ≈ 800 K, accompanied by anomalies in temperature dependences of their dielectric permittivity, e(T). The largest increase in their static bulk conductivity near T* has been observed in a narrow composition range (≈1 ± 0.02 mol % MgО and ≈3.9–4.3 mol % ZnO). Above T*, the LiNbO3:Zn,Mg crystals have an activation enthalpy for ionic conduction (Ha ≈ 1.76–2.15 eV) and enthalpy of transport (Hm ≈ 1.66–2.06 eV) unusually high for cation conductors, whereas below T* both quantities are characteristic of Li+ ion conduction in LiNbO3 crystals (На ≈ 1.15–1.35 eV and Нm ≈ 1.0–1.1 eV). The anomalous increase in Ha and Hm is caused by the formation of associated vacancies (divacancies) and correlated pair hopping of Li+ ions above T*.

Published
2020

41. Luminescence of LiNbO3:Zn (0.03–5.50 mol % ZnO) Crystals of Different Origins

Author

M. V. Smirnov, M. N. Palatnikov, and N. V. Sidorov

Subjects
010302 applied physics, Materials science, General Chemical Engineering, Doping, Metals and Alloys, Analytical chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Inorganic Chemistry, Crystal, 0103 physical sciences, Mole, Materials Chemistry, 0210 nano-technology, Luminescence, Intensity (heat transfer)
Abstract

A LiNbO3:Zn (4.69 mol % ZnO) crystal grown from a charge synthesized using homogeneously doped Nb2O5 as a precursor has been shown to contain less luminescence centers in comparison with a LiNbO3:Zn (4.60 mol % ZnO) crystal prepared via direct doping. In the case of LiNbO3:Zn crystals prepared via direct doping, the intensity of all luminescence bands varies monotonically as the ZnO concentration is raised to 4.60 mol %. At a ZnO concentration of ~4.60 mol %, the intensity of all the bands changes sharply, suggesting that the system of luminescence centers in the material undergoes structural changes.

Published
2020

42. Luminescence Properties of Sol–Gel Derived Ceramic GdNbхTa1 –хO4 and YNbхTa1 –хO4 Solid Solutions

Author

M. N. Palatnikov, N. V. Sidorov, S. M. Masloboeva, M. V. Belobeletskaya, O. B. Shcherbina, N. I. Steblevskaya, and M. V. Smirnov

Subjects
Materials science, General Chemical Engineering, Energy transfer, Metals and Alloys, Analytical chemistry, Tantalum, chemistry.chemical_element, Inorganic Chemistry, chemistry, visual_art, Materials Chemistry, visual_art.visual_art_medium, Ceramic, Luminescence, Intensity (heat transfer), Excitation, Sol-gel, Solid solution
Abstract

GdNbхTa1 –хO4 and YNbхTa1 –хO4 (x = 0–1) ceramic samples have been prepared by a sol–gel process, and the luminescence properties of the solid solutions have been studied under UV excitation. The results demonstrate that even a relatively small amount of tantalum (x = 0.9) in GdNbхTa1 –хO4 leads to a sharp increase in the luminescence intensity related to Nb4+–O– centers, which exceeds the luminescence intensity in the GdNbO4 and GdTaO4 individual compounds by a factor of 3–6.5. The luminescence signal in the YNbхTa1 –хO4 solid solutions exceeds that in the YNbO4 and YTaO4 end-members at any Nb : Ta ratio, owing to energy transfer between Nb4+–O– and Ta4+–O– emission centers.

Published
2020

43. Molecular Structure of a Carbosilane Oligomer

Author

D. V. Zhigalov, D. V. Sidorov, G. I. Shcherbakova, P. A. Storozhenko, A. D. Kirilin, A. P. Mapolis, and L. O. Belova

Subjects
010302 applied physics, Thesaurus (information retrieval), Materials science, Polymer science, General Chemical Engineering, Metals and Alloys, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Oligomer, Visualization, Inorganic Chemistry, chemistry.chemical_compound, chemistry, 0103 physical sciences, Materials Chemistry, Molecule, 0210 nano-technology
Abstract

In this paper, we report a detailed study of the molecular structure of a preceramic carbosilane and the visualization and optimization of its geometric structure. Using quantum-chemical calculations, we have identified the most probable structure of the oligomeric carbosilane and obtained thermodynamic data for it.

Published
2020

44. Crystallization Behavior and Resistivity of Al–Ni–Co–Nd(Sm) Amorphous Alloys

Author

S. A. Petrova, Dušan Janičkovič, V. E. Sidorov, Boris Rusanov, and Peter Švec

Subjects
010302 applied physics, Amorphous metal, Materials science, General Chemical Engineering, Metals and Alloys, Analytical chemistry, 02 engineering and technology, Atmospheric temperature range, 021001 nanoscience & nanotechnology, 01 natural sciences, Amorphous solid, law.invention, Inorganic Chemistry, Differential scanning calorimetry, Electrical resistivity and conductivity, law, 0103 physical sciences, Materials Chemistry, Melt spinning, Crystallization, 0210 nano-technology, Ternary operation
Abstract

Aluminum-based metallic ribbons with the compositions Al86Ni4Co4Nd(Sm)6 and Al86Ni6Co2Nd(Sm)6 were produced by melt spinning. X-ray diffraction characterization showed that the ribbons had an amorphous structure. Their crystallization kinetics were studied by differential scanning calorimetry and their resistivity was measured by a standard four probe method. The Al–Ni–Co–REM ribbons were shown to have a broader temperature range of an amorphous state than do Al–Ni(Co)–REM ternary alloys. We found compositions with an enhanced glass-forming ability.

Published
2020

50. A Comparative Study of the Structure and Chemical Homogeneity of LiNbO3:Mg(~5.3 mol %) Crystals Grown from Charges of Different Origins

Author

M. N. Palatnikov, Natalya A. Teplyakova, Olga V. Makarova, L. A. Bobreva, and N. V. Sidorov

Subjects
010302 applied physics, Materials science, Hydrogen bond, General Chemical Engineering, Doping, Metals and Alloys, Physics::Optics, Infrared spectroscopy, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Inorganic Chemistry, Crystal, Partition coefficient, Condensed Matter::Materials Science, Crystallography, Covalent bond, Condensed Matter::Superconductivity, 0103 physical sciences, Homogeneity (physics), Materials Chemistry, 0210 nano-technology, Spectroscopy
Abstract

—LiNbO3:Mg(~5.3 mol %) crystals grown from directly and homogeneously doped charges have been studied using a number of characterization techniques. Both crystals offer high chemical homogeneity, with an even Mg distribution over the boule. At the same time, the estimated effective distribution coefficient is larger in the homogeneously doped LiNbO3:Mg crystal. Moreover, the homogeneously doped crystal has a more ordered system of hydrogen bonds. Our results suggest that the distinctions between the fine structural features and chemical homogeneity of the crystals can be due to the effect of organic inclusions with rigid covalent bonds on the structure and physical characteristics of the growth charge prepared using a homogeneously doped Nb2O5:Mg precursor.

Published
2019

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