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860 results on '"Lopatin S"'

8. Atomic scale spectral control of thermal transport in phononic crystal superlattices

Author

Meyer, D., Roddatis, V., Bange, J. P., Lopatin, S., Keunecke, M., Metternich, D., Roß, U., Maznichenko, I. V., Ostanin, S., Mertig, I., Radisch, V., Egoavil, R., Lazić, I., Moshnyaga, V., and Ulrichs, H.

Subjects
Condensed Matter - Materials Science
Abstract

We present experimental and theoretical investigations of phonon thermal transport in (LaMnO$_3$)$_m$/(SrMnO$_3$)$_n$ superlattices (LMO/SMO SLs) with the thickness of individual layers $m,n = 3 - 10\;$ u.c. and the thickness ratio $m/n = 1, 2$. Optical transient thermal reflectivity measurements reveal a pronounced difference in the thermal conductivity between SLs with $m/n = 1$, and SLs with $m/n = 2$. State-of-the art electron microscopy techniques and ab-initio density functional calculations enables us to assign the origin of this difference to the absence ($m/n = 1$) or presence ($m/n = 2$) of spatially periodic, static oxygen octahedral rotation (OOR) inside the LMO layers. The experimental data analysis shows that the effective thermal conductance of the LMO/SMO interfaces strongly changes from $0.3$ GW/m$^2$K for $m/n = 2$ SLs with OOR to a surprisingly large value of $1.8$ GW/m$^2$K for $m/n = 1$ SLs without OOR. An instructive lattice dynamical model rationalizes our experimental findings as a result of coherent phonon transmission for $m/n = 1$ versus coherent phonon blocking in SLs with $m/n = 2$. We briefly discuss the possibilities to exploit these results for atomic-scale engineering of a crystalline phonon insulator. The thermal resistivity of this proposal for a thermal metamaterial surpasses the amorphous limit, although phonons still propagate coherently., Comment: Revision changes article focus from structural properties to thermal transport properties of SL

Published
2020

22. Mass Spectrometric Study of the Interaction of Y2O3 with Carbon at High Temperatures.

Author

Folomeikin, Yu. I., Stolyarova, V. L., and Lopatin, S. I.

Abstract

The evaporation of Y2O3 in the presence of carbon was studied by high-temperature differential mass spectrometry. In the temperature range 1950–2200 K, the vapor above the Y2O3–C system contains YO and atomic yttrium. At elevated temperatures, the partial pressure of YO vapor over the Y2O3–C system decreases compared to the partial pressure of YO vapor over individual Y2O3, leading to a decrease in the activity of yttrium oxide in the system. [ABSTRACT FROM AUTHOR]

Published
2024
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27. Superconducting-coil--resistor circuit with electric field quadratic in the current

Author

Poklonski, N. A. and Lopatin, S. Yu.

Subjects
Condensed Matter - Superconductivity, Physics - Instrumentation and Detectors
Abstract

It is shown for the first time that the observed [Phys. Lett. A 162 (1992) 105] potential difference Phi_t between the resistor and the screen surrounding the circuit is caused by polarization of the resistor because of the kinetic energy of the electrons of the superconducting coil. The proportionality of Phi_t to the square of the current and to the length of the superconducting wire is explained. It is pointed out that measuring Phi_t makes it possible to determine the Fermi quasimomentum of the electrons of a metal resistor., Comment: 2 pages, 1 figure

Published
2010
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38. Vaporization Processes and Thermodynamic Properties of the SrO–ZrO2 System at High Temperatures.

Author

Lopatin, S. I., Stolyarova, V. L., Fedorova, A. V., and Selyutin, A. A.

Abstract

Evaporation processes in the SrO–ZrO2 system and its thermodynamic properties in the concentration range from 10 to 90 mol % of SrO were studied by high-temperature differential mass spectrometry. The samples under study were evaporated from tungsten Knudsen effusion cells. Partial pressures of vapor species in the temperature range of 1975–2800 K were determined. The SrO and ZrO2 activities, and also Gibbs energies, and excess Gibbs energies in the range of compositions from 90 to 45 mol % of SrO at 1940 K and from 45 to 10 mol % of SrO at 2123 K were determined. Minor negative deviations from ideal behavior are observed in the SrO–ZrO2 system. [ABSTRACT FROM AUTHOR]

Published
2023
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39. Mass Spectrometric Thermodynamic Study of the Fe2O3–TiO2 System.

Author

Stolyarova, V. L., Lopatin, S. I., Vorozhtcov, V. A., Fedorova, A. V., Selyutin, A. A., and Shilov, A. L.

Subjects
*THERMODYNAMICS, *GIBBS' free energy, *LATTICE theory, *FERRIC oxide, *VAPOR pressure, *PARTIAL pressure
Abstract

High-temperature differential mass spectrometry was used to study the vaporization processes and thermodynamic properties of samples of the Fe2O3–TiO2 system containing 25, 35, and 45 mol. % iron oxide. As shown earlier, at temperatures above 1400 K, Fe2O3, losing oxygen, turns into FeO. Therefore, in this article, a mass spectrometric thermodynamic study of the FeO–TiO2 system was carried out at a temperature of 1760 K. The composition and partial pressures of vapor, as well as the values of FeO activities and excess Gibbs energy in the FeO–TiO2 system were determined. Using the Wilson polynomial made it possible for the first time to estimate the mixing enthalpy and excess entropy in the FeO–TiO2 system at 1760 K. The thermodynamic properties of melts of the FeO–TiO2 system at 1760 K were modeled using the generalized lattice theory of associated solutions, and the relative numbers of bonds of various types in the model melt lattice were calculated, indicating the preferential formation of Fe–O–Ti bonds at a FeO content of 55 mol %. It is shown that at a temperature of 1760 K, the found values of the excess Gibbs energy in the FeO–TiO2 system are evidence of negative deviations from the ideality. [ABSTRACT FROM AUTHOR]

Published
2023
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