WorldCat Identities

Ponomareva, A. V.

Works: 22 works in 23 publications in 1 language and 27 library holdings
Roles: Author, Other
Publication Timeline
Most widely held works by A. V Ponomareva
Fe-N system at high pressure reveals a compound featuring polymeric nitrogen chains by M Bykov( )

2 editions published in 2018 in English and held by 3 WorldCat member libraries worldwide

Poly-nitrogen compounds have been considered as potential high energy density materials for a long time due to the large number of energetic N-N or N=N bonds. In most cases high nitrogen content and stability at ambient conditions are mutually exclusive, thereby making the synthesis of such materials challenging. One way to stabilize such compounds is the application of high pressure. Here, through a direct reaction between Fe and N-2 in a laser-heated diamond anvil cell, we synthesize three ironnitrogen compounds Fe3N2, FeN2 and FeN4. Their crystal structures are revealed by single-crystal synchrotron X-ray diffraction. Fe3N2, synthesized at 50 GPa, is isostructural to chromium carbide Cr3C2. FeN2 has a marcasite structure type and features covalently bonded dinitrogen units in its crystal structure. FeN4, synthesized at 106 GPa, features polymeric nitrogen chains of [N-4(2-)](n) units. Based on results of structural studies and theoretical analysis, [N-4(2-)](n) units in this compound reveal catena-poly[tetraz-1-ene-1,4-diyl] anions
Use of azotobacterin in forest nurseries and in sylviculture by A. V Ponomareva( Book )

1 edition published in 1966 in English and held by 2 WorldCat member libraries worldwide

<> by A. V Ponomareva( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Erratum to: "Numerical Study of Mechanical Properties of Nanoparticles of ß-Type Ti-Nb Alloy under Conditions Identical to Laser Sintering. Multilevel Approach" by A. Yu Nikonov( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

<> by A. Yu Nikonov( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

Effect of pressure on phase stability in Fe-Cr alloys by A. V Ponomareva( )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

The effect of hydrostatic pressure on the phase stability of Fe-Cr alloys has been studied using ab initio methods. We show that while pressure decreases the tendency toward the phase separation in the paramagnetic state of bcc alloys, in the ferromagnetic state it reduces the alloy stability at low Cr concentration and vice versa, makes the solid solution more stable at higher concentrations. This behavior of the phase stability can be predicted from the deviation of the lattice parameter from Vegards law in bcc Fe-Cr alloys. On the atomic level, the pressure effect can be explained by the suppression of the local magnetic moments on Cr atoms, which gives rise to a decrease of the Fe-Cr magnetic exchange interaction at the first coordination shell and, as a result, to the observed variation of the ordering tendency between the Fe and Cr atoms
Influence of stresses on structure and properties of Ti and Zr- based alloys from first-principles simulations( )

1 edition published in 2015 in English and held by 1 WorldCat member library worldwide

Abstract: Computer simulations in the framework of the Density Functional Theory have become an established tool for computer simulations of materials properties. In most cases, however, information is obtained at ambient conditions, preventing design of materials for applications at extreme conditions. In this work we employ ab initio calculations to investigate the influence of stresses on structure and stability of Ti-Mo and Zr-Nb alloys, an important class of construction materials. Calculations reproduce known phase stability trends in these systems, and we resolve the controversy regarding the stability of body-centered cubic solid solution in Mo-rich Ti-Mo alloys against the isostructural decomposition. Calculated results are explained in terms of the electronic structure effects, as well as in terms of physically transparent thermodynamic arguments that relate phase stability to deviations of concentration dependence of atomic volume from the linear behavior
Theoretical modeling of interstitial carbon impurities in paramagnetic Fe-Mn alloys by A. V Ponomareva( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

We present a generalization of a model that takes into account the magnetic disorder of paramagnetic host with interstitial point defects towards the case of alloy hosts. In the framework of disordered local moment approach combined with magnetic sampling method, we calculate solution enthalpy of carbon impurity in the paramagnetic fcc Fe-Mn steels. First, we use the magnetic special quasirandom structure (M-SQS) method for simulation of the paramagnetic state in Fe-Mn alloys without impurity. Here, Fe and Mn atoms are randomly distributed at the sites of a supercell following the chemical SQS method. Next, to calculate the energies for various magnetic realizations around the interstitial carbon impurity, we vary the position of the impurity within the SQS. Our calculations show that in alloys containing similar to 20 at. % Mn, the solution enthalpy of carbon reduces compared to the pure fcc-Fe. By analyzing the local and global effects of impurity on the properties of the matrix, we discuss various factors that could increase the carbon solubility in high-manganese austenitic steels
Mixing enthalpies of alloys with dynamical instability bcc Ti-V system by Natalia Skripnyak( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Site preference and effect of alloying on elastic properties of ternary B2 NiAl-based alloys by A. V Ponomareva( )

1 edition published in 2012 in English and held by 1 WorldCat member library worldwide

Using the exact muffin-tin orbitals method in conjunction with the coherent potential approximation, we study the site preference of transition metal impurities X (X = Sc, Ti, V, Cr, W, Re, Co) in B2 NiAl and their effect on its elastic properties. Analyzing interatomic bonding of NiAl-X alloys and elastic characteristics evaluated from the elastic constants C-11, C-12, and C-44, we predict that the addition of W, V, Ti, and Re atoms could yield improved ductility for B2 NiAl-X alloys without significant changes in the macroscopic elastic moduli
The magnetization profile induced by the double magnetic proximity effect in an Fe/Fe0.30V0.70 superlattice by Hetti Palonen( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

The double magnetic proximity effect (MPE) in an Fe/Fe0.30V0.70 superlattice is studied by a direct measurement of the magnetization profile using polarized neutron reflectivity. The experimental magnetization profile is shown to qualitatively agree with a profile calculated using density functional theory. The profile is divided into a short range interfacial part and a long range tail. The interfacial part is explained by charge transfer and induced magnetization, while the tail is attributed to the inhomogeneous nature of the FeV alloy. The long range tail in the magnetization persists up to 170% above the intrinsic ordering temperature of the FeV alloy. The observed effects can be used to design systems with a direct exchange coupling between layers over long distances through a network of connected atoms. When combined with the recent advances in tuning and switching, the MPE with electric fields and currents, the results can be applied in spintronic devices. Published under license by AIP Publishing
Magnetic and structural properties of FeCO3 at high pressures by N. O Golosova( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

The structural and magnetic properties of siderite FeCO3 have been studied by means of neutron powder diffraction at pressures up to 7.5 GPa and first-principles theoretical calculations. The lattice compression in the rhombohedral calcite-type structure is dominated by the reduction of the Fe-O bonds, while the changes of the C-O bonds are much less pronounced. The Neel temperature of the antiferromagnetic (AFM) ground state increases substantially under pressure with a coefficient dT(N)/dP = 1.8K/GPa, which is about 1.5 times larger in comparison with those predicted by the empirical Bloch rule. The ab initio calculations were performed in the framework of the density functional theory including Hubbard-U correction. The calculated structural parameters and Neel temperature as functions of pressure provide a reasonable agreement with the experimental results. The analysis of the density of electronic states points toward increased covalent bonding between the Fe and O atoms upon pressure, giving rise to unexpectedly large pressure coefficient of the Neel temperature and reduced ordered magnetic moments of Fe atoms
Thermodynamic and physical properties of Zr3Fe and ZrFe2 intermetallic compounds by B. O Mukhamedov( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Experimental differential scanning calorimetry measurements and ab-initio simulations were carried out to define the heat capacities of Zr3Fe and C15-ZrFe2 compounds from 0 K up to their maximum stability temperatures. Experimental measurements of heat capacity of each compound were performed for the first time in wide range of temperatures. Density functional theory and quasi-harmonic approximation (QHA) were employed to calculate the free energy of the studied systems as a function of volume and temperature. A good agreement was observed between theoretical and experimental heat capacities within validity range of the QHA. This makes it possible to combine theoretical and experimental data to determine the standard entropies of intermetallic compounds
Theoretical Modeling of Thermodynamic and Mechanical Properties of the Pure Components of Ti and Zr Based Alloys Using the Exact Muffin-Tin Orbitals Method by Igor Abrikosov( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

The exact muffin-tin orbitals (EMTO) method belongs to the third and latest generation of first-principles methods of calculating the electronic structure of materials in the so-called approximation of muffin-tin (MT) orbitals within the framework of the density functional theory. A study has been performed of its applicability for modeling the thermodynamic and mechanical properties of the pure components of Ti and Zr based alloys. The total energies of Ti, Zr, Nb, V, Mo, and Al are calculated in three crystal structures - face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP). For all of these elements and crystal structures, we have calculated the theoretical values of the lattice constants, elastic constants, and equations of state. The stable crystal structures have been determined. In all cases, calculations by the EMTO method predict the correct structure of the ground state. For stable structures we compared the obtained results with experiment and with calculations using full potential methods. We have demonstrated the reliability of the EMTO method and conclude that its further application for effective modeling of the properties of disordered alloys based on Ti and Zr is possible
Ab initio calculation of the solution enthalpies of substitutional and interstitial impurities in paramagnetic fcc Fe by A. V Ponomareva( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

In the framework of disordered local moment approach by using magnetic sampling method, we suggested a model that takes into account the magnetic disorder in paramagnetic Fe with point defects. We calculate solution enthalpies of substitutional (Nb, V) and interstitial (C, N) impurities in paramagnetic face-centered cubic Fe and obtain results that are in agreement with available experimental data. It is found that both interstitial and substitutional atoms may favor the local magnetic polarization of the Fe host around the impurities by decreasing the potential energy of the system. The possibility of a formation of predominantly ferromagnetic Fe clusters around carbon in the temperature range of overcooled austenite is discussed
Pressure-induced spin-state transition of iron in magnesiowustite (Fe, Mg)O by I Leonov( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

We present a detailed theoretical study of the electronic, magnetic, and structural properties of magnesiowustite Fe-1 Mg-x(x) O with x in the range between 0 and 0.875 using a fully charge self-consistent implementation of the density functional theory plus dynamical mean-field theory method. In particular, we compute the electronic structure and phase stability of the rocksalt B1-structured (Fe, Mg) O at high pressures relevant for the Earths lower mantle. We find that upon compression paramagnetic (Fe, Mg) O exhibits a spin-state transition of Fe2+ ions from a high-spin to low-spin (HS-LS) state which is accompanied by a collapse of local magnetic moments. The HS-LS transition results in a substantial drop in the lattice volume by about 4%-8%, implying a complex interplay between electronic and lattice degrees of freedom. Our results reveal a strong sensitivity of the calculated transition pressure P-tr. upon addition of Mg. While, for Fe-rich magnesiowustite with Mg x amp;lt; 0.5, Ptr. is about 80 GPa, for Mg x = 0.75 it drops to 52 GPa, i. e., by 35%. This behavior is accompanied by a substantial change in the spin transition range from 50 to 140 GPa in FeO to 30 to 90 GPa for x = 0.75. In addition, the calculated bulk modulus (in the HS state) is found to increase by similar to 12% from 142 GPa in FeO to 159 GPa in (Fe, Mg) O with Mg x = 0.875. We find that the pressure-induced HS-LS transition has different consequences for the electronic properties of the Fe-rich and -poor (Fe, Mg) O. For the Fe-rich (Fe, Mg) O, the transition is found to be accompanied by a Mott insulator to a (semi) metal phase transition. In contrast to that, for x amp;gt; 0.25, (Fe, Mg) O remains insulating up to the highest studied pressures, implying a Mott-insulator to band-insulator phase transition at the HS-LS transformation
Dal'nevostočnyj kraj by G Prokopenko( Book )

1 edition published in 1932 in Undetermined and held by 1 WorldCat member library worldwide

Effect of Re content on elastic properties of B2 NiAl from ab initio calculations by A. V Ponomareva( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

The effect of substitutional alloying of Re on elastic properties of B2 NiAl has been studied using first-principles electronic-structure calculations by the exact muffin-tin orbitals method and the coherent potential approximation. Our calculations have shown that elastic constants C-12, C-44 and bulk modulus B of (Ni1-xRex) Al alloys increase with Re composition almost linearly, but concentration dependence of elastic constants C-11, Young modulus E, shear modulus G, G/B ratio and the Cauchy pressure P-C is strongly nonmonotonously and has peculiarities near the concentration x = 30 at.% Re. Analyzing the density of states and Fermi surface sections we have a direct connection between the behavior of the elastic constants of (Ni1-xRex) Al alloys and changes in the interatomic bonding and Fermi surface topology
Nanodomain structure of single crystalline nickel oxide by B Walls( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

In this work we present a comprehensive study of the domain structure of a nickel oxide single crystal grown by floating zone melting and suggest a correlation between point defects and the observed domain structure. The properties and structure of domains dictate the dynamics of resistive switching, water splitting and gas sensing, to name but a few. Investigating the correlation between point defects and domain structure can provide a deeper understanding of their formation and structure, which potentially allows one to tailor domain structure and the dynamics of the aforementioned applications. A range of inhomogeneities are observed by diffraction and microscopy techniques. X-ray and low-energy electron diffraction reveal domains on the submicron- and nanometer-scales, respectively. In turn, these domains are visualised by atomic force and scanning tunneling microscopy (STM), respectively. A comprehensive transmission electron microscopy (TEM) study reveals inhomogeneities ranging from domains of varying size, misorientation of domains, variation of the lattice constant and bending of lattice planes. X-ray photoelectron spectroscopy and electron energy-loss spectroscopy indicate the crystal is Ni deficient. Density functional theory calculations-considering the spatial and electronic disturbance induced by the favourable nickel vacancy-reveal a nanoscale distortion comparable to STM and TEM observations. The different inhomogeneities are understood in terms of the structural relaxation induced by ordering of nickel vacancies, which is predicted to be favourable
Achieving low elastic moduli of bcc Ti-V alloys in vicinity of mechanical instability by N. V Skripnyak( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Body centered cubic (bcc) Ti-based alloys are of interest for multiple technological applications ranging from aerospace technology to biomedicine. However, these alloys are usually unstable at low temperatures. Indeed, the calculated elastic modulus C ' of bcc Ti-V alloys with low V concentrations is negative at 0 K temperature, indicating their mechanical instability. Here, we investigate elastic moduli of the Ti-V system in the vicinity of mechanical instability theoretically and experimentally. Our calculations predict that mechanical stabilization of bcc Ti-V alloys, which is governed by the hardening of C ', is possible at as low V concentration as 18 at.%. We synthesize single-phase bcc alloys with as little as 22 at.% of V with low values of Young's modulus. Moreover, we predict strong concentration dependence of anisotropy of Young's modulus in these alloys that can also be used in tuning the alloy composition to design materials for specific applications
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Audience level: 0.95 (from 0.82 for Fe-N syste ... to 0.97 for Fe-N syste ...)

Alternative Names
Ponomareva, Anna Vasilʹevna

Пономарева, А. В

English (20)