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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G.
Заглавие : Ab initio calculation of the ferroelectric phase transition in disordered and ordered PbSc0.5Ta0.5O3 and PbSc0.5Nd0.5O3 solid solutions with the use of a model Hamiltonian
Разночтения заглавия :авие SCOPUS: Ab initio calculation of the ferroelectric phase transition in disordered and ordered PbSc0.5Ta0.5O3 and PbSc 0.5Nd0.5O3 solid solutions with the use of a model Hamiltonian
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 106, Is. 3. - P542-549. - ISSN 1063-7761, DOI 10.1134/S1063776108030138
Примечания : Cited References: 17
Предметные рубрики: RELAXOR FERROELECTRICS
PEROVSKITES
BATIO3
PBTIO3
Ключевые слова (''Своб.индексиров.''): approximation theory--ferroelectric materials--hamiltonians--mathematical models--monte carlo methods--phase transitions--ferroelectric phase transition--gordon-kim model--local-mode approximation--solid solutions
Аннотация: To describe the ferroelectric phase transition in ordered and disordered PbSc0.5Ta0.5O3 (PST) and PbSc0.5Nd0.5O3 (PSN) solid solutions, a model Hamiltonian is written in the local-mode approximation, in which long-range dipole-dipole and short-range interactions of local modes are taken into account. The Hamiltonian parameters are determined from the set of energies of a series of distorted structures, calculated within the nonempirical generalized Gordon-Kim model. The statistical mechanics of the systems with a model Hamiltonian is investigated by the Monte Carlo method. It is revealed that PSN solid solutions undergo a transition to the ferroelectric rhombohedral phase through an intermediate phase, existing in a narrow temperature range. PST solid solutions undergo a ferroelectric phase transition directly from the paraelectric cubic to the ferroelectric rhombohedral phase.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimov E. G., Zinenko V. I., Zamkova N. G.
Заглавие : Ab initio calculations of the physical properties of ionic crystals
Место публикации : Phys. Usp.: TURPION LTD, 2004. - Vol. 47, Is. 11. - P1075-1099. - ISSN 1063-7869, DOI 10.1070/PU2004v047n11ABEH001796
Примечания : Cited References: 90
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
LOCAL-FIELD CORRECTIONS
INDUCED BREATHING MODEL
ZINC-BLENDE STRUCTURE
ELECTRON-GAS THEORY
LATTICE-DYNAMICS
MICROSCOPIC CALCULATIONS
MACROSCOPIC POLARIZATION
STATISTICAL-MECHANICS
1ST-PRINCIPLES THEORY
Аннотация: First-principles calculations of the physical properties of ionic crystals are reviewed. Two markedly different approaches within the framework of the density functional theory are described. In one of them, the electron spectrum and wave functions are treated within the standard band picture based on the solution of Kohn-Sham equations. In the second approach, the total electron density of a crystal is represented as a super-position of the densities of individual ions. The problem of determining the electric polarization of a crystal is discussed for each approach. It is shown that it is the use of Bloch functions rather than the physics of the phenomenon that complicates the solution of this problem within the Kohn-Sham framework. The deformable and polarizable ion model is described in detail, and its application to calculating many properties of ionic crystals, including the lattice dynamics and structural stability of crystal phases, is discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : ZAMKOVA N. G., ZINENKO V. I.
Заглавие : CALCULATION OF BX4 INTERACTION CONSTANTS IN K2SO4-TYPE CRYSTALS
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 34, Is. 9. - P2735-2747. - ISSN 0367-3294
Примечания : Cited References: 29
Предметные рубрики: SUCCESSIVE PHASE-TRANSITIONS
K2COBR4
K2SEO4
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zhandun V. S., Draganyuk O. N., Zamkova N. G.
Заглавие : Doping-induced changes in the electronic and magnetic properties of Mn- and Cr-based MAX phases
Коллективы : International Baltic Conference on Magnetism, Балтийский федеральный университет им. И. Канта
Место публикации : V International Baltic Conference on Magnetism. IBCM: Book of abstracts. - 2023. - P.17
Примечания : Cited References: 2. - РНФ № 23-22-10020
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zamkova N. G., Zinenko V. I.
Заглавие : Effect of an Eu3+ impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO3 bulk crystal and thin films
Коллективы : Russian Foundation for Basic Research [12-02-00025-a], Russian Federation [NSh-924.2014.2]
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 120, Is. 1. - P.103-109. - ISSN 1063, DOI 10.1134/S1063776115010070. - ISSN 10906509(eISSN)
Примечания : Cited References:21. - This work was supported by the Russian Foundation for Basic Research (project no. 12-02-00025-a) and the program Leading Scientific Schools of the President of the Russian Federation (project no. NSh-924.2014.2).
Предметные рубрики: PEROVSKITES
Аннотация: The existence of an antiferrodistortion transition in EuTiO3 is disputable, and this question needs to be answered. One of the possible causes is the presence of an Eu3+ impurity in a sample. A nonempirical polarizable ion model is used to study the effect of a trivalent Eu3+ ion impurity on the antiferrodistortion and ferroelectric instabilities of an EuTiO3 crystal in the bulk and the thin-film states. Lattice dynamics calculation shows that a bulk impurity-free EuTiO3 crystal has no unstable modes throughout the entire phase space volume. The addition of an Eu3+ impurity leads to a significant softening of the rotational mode, the distortion in which makes tetragonal phase I4/mcm (which is experimentally observed) energetically favorable. In going from the bulk crystal to the thin film, the vibration spectrum of the impurity-free film has unstable antiferrodistortion and rotational modes. The addition of an Eu3+ impurity enhances the antiferrodistortion instability, which fully or partly suppresses ferroelectricity.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zinenko V. I., Shinkorenko A. S.
Заглавие : Effect of Ca 2+ ion substitution by the trivalent ions (Sc 3+, In 3+, La 3+, Bi 3+) on the ferroelectric instability in orthorhombic CaTiO3
Место публикации : Ferroelectrics: Special Issue: Professor Wolfgang Kleemann in honor of his 70th birthday: Taylor & Francis, 2012. - Vol. 426. - P.132-138. - ISSN 0015-0193, DOI 10.1080/00150193.2012.671657. - ISSN 1563-5112
Примечания : Cited References: 9. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00067)
Ключевые слова (''Своб.индексиров.''): ferroelectric--polarization--lattice dynamics
Аннотация: Vibration frequencies of instable ferroelectric modes, as well as dependencies of crystal energy on ion's displacement amplitudes of these modes in doped compounds Ca1–x A x Ti1–x/4□ x /4O3 (space group Pbmn) with А–Sc3+, In3+, La3+, Bi3+ (□–vacancy) have been calculated in the framework of generalized nonparametric Gordon–Kim model. To compensate excessive positive charge the vacancies were considered to be at Ti4+ sites. Calculations were carried out in the «average» crystal approximation for the impurity concentration x = 0.25. For this purpose 40 atoms’ supercell sets with the different ordering of the heterovalent ions Ca2+ and impurity А3+ have been considered. Every type of impurity has been found to induce ferroelectric instability in doped compounds.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zinenko V. I.
Заглавие : Effect of cation substitution on the lattice dynamics and ferroelectric instability of cubic BaTiO3 and BaZrO3 doped with Bi and La ions
Коллективы : Russian Foundation for Basic Research [07-02-00069]
Разночтения заглавия :авие SCOPUS: Effect of cation substitution on the lattice dynamics and ferroelectric instability of cubic BaTiO3 and BaZrO3 doped with Bi and la ions
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2009. - Vol. 51, Is. 5. - P973-981. - ISSN 1063-7834, DOI 10.1134/S1063783409050151
Примечания : Cited References: 11. - This work was supported by the Russian Foundation for Basic Research, project no. 07-02-00069.
Предметные рубрики: CERAMICS
Аннотация: The spectra of lattice vibration frequencies of solid solutions Ba1 - x Bi(2x/3)a-- Ti-x/3(Zr)O-3 and Ba1 - x La (x) Ti(Zr)(1 - x/4)a-- O-x/4(3) are calculated in terms of a generalized Gordon-Kim model with inclusion of the dipole and quadrupole polarizabilities. Over the entire concentration range, the calculated phonon spectra contain a ferroelectric soft mode. The effect of various interactions on the ferroelectric instability of these solid solutions is studied. It is shown that the character of ferroelectric instability is largely determined by the mechanism of charge compensation.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Tarasov I. A., Varnakov S. N., Yakovlev I. A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Effect of electron correlations on the Fe3Si and α- FeSi2 band structure and optical properties
Коллективы : Russian Fund of Basic Research [14002-00186, 13-02-01265]; President of Russia Grants [2886.2014.2, 924.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 20. - Ст.205129. - ISSN 1098-0121, DOI 10.1103/PhysRevB.92.205129. - ISSN 1550-235X(eISSN)
Примечания : Cited References:69. - The theoretical part of this work was supported by Russian Fund of Basic Research, Grant No. 14002-00186 and the President of Russia Grants No. 2886.2014.2 and No. 924.2014.2 for support of Leading Scientific School. The calculations were performed with the computer resources of NRC "Kurchatov Institute" (ui2.computing.kiae.ru). The experimental work was supported by Russian Fund of Basic Research, Grant No. 13-02-01265. I.S. thanks A. Ruban for useful discussion.
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
AUGMENTED-WAVE METHOD
BASIS-SET
METALS
ABSORPTION
EMISSION
SURFACES
ALLOYS
LAYERS
Аннотация: We use the Vienna ab initio simulation package (vasp) for evaluation of the quasiparticle spectra and their spectral weights within Hedin's GW approximation (GWA) for Fe3Si and α-FeSi2 within the non-self-consistent one-shot approximation G0W0 and self-consistent scGWA with the vertex corrections in the particle-hole channel, taken in the form of two-point kernel. As input for G0W0, the band structure and wave functions evaluated within the generalized gradient corrected local-density approximation to density functional theory (GGA) have been used. The spectral weights of quasiparticles in these compounds deviate from unity everywhere and show nonmonotonic behavior in those parts of bands where the delocalized states contribute to their formation. The G0W0 and scGWA spectral weights are the same within 2%–5%. The scGWA shows a general tendency to return G0W0 bands to their GGA positions for the delocalized states, while in the flat bands it flattens even more. Variable angle spectroscopic ellipsometry measurements at T=296 K on grown single-crystalline ∼50-nm-thick films of Fe3Si on n-Si(111) wafer have been performed in the interval of energies ω∼(1.3–5) eV. The comparison of G0W0 and scGW theory with experimental real and imaginary parts of permittivity, refractive index, extinction and absorption coefficients, reflectivity, and electron energy loss function shows that both G0W0 and scGW qualitatively describe experiment correctly, the position of the low-energy peaks is described better by the scGW theory, however, its detailed structure is not observed in the experimental curves. We suggest that the angle-resolved photoemission spectroscopy experiments, which can reveal the fine details of the quasiparticle band structure and spectral weights, could help to understand (i) if the scGWA with this type of vertex correction is sufficiently good for description of these iron silicides and, possibly, (ii) why some features of calculated permittivity are not seen in optical experiments.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Ovchinnikov S. G., Sandalov I. S.
Заглавие : Effect of local environment on moment formation in iron silicides
Место публикации : J. Alloys Compd.: Elsevier, 2017. - Vol. 695. - P.1213-1222. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2016.10.248
Примечания : Cited References: 40. - This work was supported by the Grants of Russian Foundation for Basic Research № 14-02-00186, № 17-02-00161 and by the Grants of Russian Foundation for Basic Research and Government of Krasnoyarsk Territory № 16-42-243035, 16-42-242036. The authors would like to thank AS Shinkorenko for the technical support.
Ключевые слова (''Своб.индексиров.''): ab initio calculations--iron silicides--magnetic properties--multiorbital model--spin-crossover
Аннотация: he effect of local environment on the formation of magnetic moments on Fe atoms in iron silicides is studied by combination of ab initio and model calculations. The suggested model includes all Fe d- and Si p-orbitals, intra-atomic Coulomb interactions, inter-atomic Fe-Fe exchange and hopping of electrons to nearest and next nearest neighboring atoms. The parameters of the model are found from the requirement that self-consistent moments on atoms and density of states found from ab initio and model calculations within the Hartree-Fock approximation are close to each other as much as possible. Contrary to the commonly accepted statement that in the ordered Fe3Si and FexSi1−x alloys an increase of the Si concentration within nearest environment of Fe atoms results in a decrease of Fe magnetic moment we find that a crucial role in the formation of magnetic moments is played by the second coordination sphere of Fe atoms. Particularly, the Fe atoms have higher magnetic moments in amorphous films compared to the epitaxial ones due to decreasing the number of iron-atoms in the next nearest environment. Both our model and ab initio calculations confirm existence of known spin crossover with pressure and predict second crossover at higher pressure.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zamkova N.G., Zhandun V.S., Zinenko V.I.
Заглавие : Effect of Sr2+ ion substitution by the triva- lent ions (Sc3+,In3+,La3+,Bi3+) on the ferroelectric instability in SrTi03
Коллективы : European Meeting on Ferroelectricity
Место публикации : 12th European Meeting on Ferroelectricity: Abstracts. - 2011. - Ст.1-4
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Zinenko V. I.
Заглавие : Effect of Sr2+ Ion Substitution with Trivalent Ions (Sc3+, In3+, La3+, Bi3+) on Its Ferroelectric Instability in SrTiO3
Разночтения заглавия :авие SCOPUS: Effect of Sr 2+ ion substitution with trivalent ions (Sc 3+, In 3+, La 3+, Bi 3+) on its ferroelectric instability in SrTiO 3
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 53, Is. 11. - P2290-2299. - ISSN 1063-7834, DOI 10.1134/S1063783411110345
Примечания : Cited References: 14. - This study was supported by the Russian Foundation for Basic Research (project no. 09-02-00067), the Federal Program of Support for Leading Scientific Schools (project no. NSh-4645.2010.2).
Предметные рубрики: BEHAVIOR
RELAXOR
Аннотация: The vibration frequencies of unstable ferroelectric and antiferrodistortion modes and the dependences of the energy on the ion displacement amplitude have been calculated within the generalized Gordon-Kim model for distortions along eigenvectors of these modes in the mixed compounds Sr(1-x)A(x)Ti(1-x/4)square O-x/4(3) and Sr(1-y)A(2y/3)square y/3TiO3 (A = Sc3+, In3+, La3+, Bi3+; square is the vacancy). To compensate an excess positive charge, vacancies are introduced into the Ti4+ or Sr2+ site. Calculations have been performed in the "average" crystal approximation for impurity concentrations of 0.25 and 0.50. To this end, a set of 40 atomic superlattices with various orderings of heterovalent ions Sr2+ and impurity A(3+) has been considered. It has been found that each impurity type, independently of charge balance, induces ferroelectric instabilities in doped compounds. In the case of doping with In3+ and La3+ for concentration x = 0.25, the possibility of rotating the polarization vector has been shown.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zamkova N. G., Zhandun V. S.
Заглавие : Effect of substitution of Mn and Ga atoms by Fe atom in the Mn2GaC MAX phase
Место публикации : J. Magn. Magn. Mater. - 2022. - Vol. 563. - Ст.169860. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2022.169860
Примечания : Cited References: 40. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project № 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic M n+1 AX n (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1-3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” ( http://ckp.urcki.ru ). The ternary phase diagrams for the calculation of formation enthalpies were taken from Materials Project ( https://materialsproject.org ) and OQMD ( https://oqmd.org/ ) databases
Аннотация: The magnetic properties of ordered and disordered MAX-phase Mn2-xFe2xGaC and Mn2Ga1-xFexC (x = 12.5, 25, and 50 at.%) have been studied within DFT-GGA. The investigation of phase stability of M2AX phases is performed by comparing the total energy of MAX phases to that of the set of competitive phases for calculation of the phase formation enthalpy. At the small concentration of Fe atoms (x = 12.5 %) compound remains stable. We have found that introducing Fe atom at A-site leads to the forming of ferromagnetic phase with large magnetic moments on magnetic atoms and magnetization. Through detailed group-theoretical analysis we have obtained that only ferromagnetic ordering is possible when Fe atom ordering over Ga sites. The study of exchange constants shows that the out-of-plane Fe-Mn exchange gives the main contribution in appearance of ferromagnetic phase. The temperature dependences of magnetization reveal the increase of Curie temperature in Mn2GaC with Fe atom incorporated into Ga-site.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zhandun V. S., Zamkova N. G.
Заглавие : Effect of the Local Environment on the Magnetic Properties of Mn3Si: Hybrid Ab Initio and Model Study
Место публикации : Phys. Status Solidi B. - 2019. - Vol. 256, Is. 12. - Ст.1900228. - ISSN 03701972 (ISSN), DOI 10.1002/pssb.201900228
Примечания : Cited References: 34. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research Project No. 18‐42‐243019: “First‐principles studies of the polarization, magnetic, electronic, and magnetoelectric properties of functional compounds with a spinel structure containing 3d and 4f ions.”
Аннотация: The effect of the local environment on the formation of magnetic moments on Mn atoms in manganese silicide Mn3Si is studied by the combination of ab initio calculations and the model analysis. The suggested approach is related to the self-consistent mapping of the results of ab initio calculations to a multiorbital model. The model analysis allows to reveal the role played by the local environment of the transition metal atoms on the magnetic moments formation. It is found that the formation of the magnetic moment is controlled rather by hopping parameters between Mn atoms, not by the number of Mn–Si nearest neighbors. Particularly, the formation of magnetic moment on MnI atom is mainly controlled by the hopping parameter between nearest Mn atoms, while the magnetic moment on MnII atom is primarily determined by the hoppings between next-nearest Mn atoms. The obtained phase diagrams of the magnetic state show the presence of a sharp boundary with respect to the hopping between Mn atoms. This opens the opportunity to turn on or turn off the magnetic state by the external impacts. The ab initio calculations of Mn3Si well agree with the results of model consideration and confirm the model conclusions.
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14.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Zhandun V. S., Zamkova N. G., Maximova O. A., Lyashchenko S. A., Vysotin M. A., Sandalov I. S.
Заглавие : Electronic structure and magnetic properties of iron silicides
Коллективы : Asian School-Conference on Physics and Technology of Nanostructured Materials, Азиатская школа-конференция по физике и технологии наноструктурированных материалов
Место публикации : The Fifth Asian School-Conference on Physics and Technology of Nanostructured Materials: Proceedings. - VLadivostok: Dalnauka Publishing, 2020. - Ст.PS.03.04i. - P.26. - ISBN 978-5-8044-1698-1
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15.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Tarasov I. A., Yakovlev I. A., Volochaev M. N., Kuzubov A. A., Zamkova N. G., Kosyrev N. N., Velikanov D. A., Shemukhin A. A., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Examination of structure, optical and magnetic properties of epitaxial Fe1–xSix/Si(111) alloy films
Коллективы : Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : VI Euro-Asian Symposium "Trends in MAGnetism" (EASTMAG-2016): abstracts/ ed.: O. A. Maksimova, R. D. Ivantsov. - Krasnoyarsk: KIP RAS SB, 2016. - Ст.O10.20. - P.464. - ISBN 978-5-904603-06-9 (Шифр -478014040)
Примечания : References: 1. - The work was supported by State contract No. 02.G25.31.0043, State task No.16.663.2014К, the Complex program of SB RAS № II.2P, project 0358-2015-0007
Ключевые слова (''Своб.индексиров.''): epitaxy--iron silicides--optical and magnetic properties--structure, defects
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zinenko V. I., Zamkova N. G., Zhandun V. S., Pavlovskii M. S.
Заглавие : Ferroelectric and structural instability in double perovskites Me1+Bi3+Me3+Nb5+O6 (Me1+ = Na, K, Rb; Me3+ = Sc, Ga, In, Lu)
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 114, Is. 6. - P.955-962. - ISSN 1063-7761, DOI 10.1134/S1063776112040188
Примечания : Cited References: 7. - This work was supported by the Russian Foundation for Basic Research (project no. 09-02-00067) and by the program for the support of leading scientific schools (project no. NSh-4645.2010.2).
Аннотация: Within the Gordon-Kim generalized model with regard to the polarizabilities of ions, the lattice constants, the high-frequency permittivity, the Born dynamic charges, and the vibration constants of the crystal lattice are calculated for cation-ordered double perovskites Me1+Bi3+Me3+Nb5+O6. The vibration spectra of all the compounds exhibit two types of instabilities: instability associated with the rotation of the oxygen octahedron and ferroelectric instability. Various combinations of distortions with respect to the rotation mode yield five energetically most favorable distorted phases. The symmetry and the energy characteristics of these phases are discussed. In four of the five phases, the distortions associated with the oxygen octahedron rotation lead to polar phases, thus allowing one to speak of improper ferroelectricity in these compounds. One phase turns out to be nonpolar; however, it contains unstable polar modes such that a displacement along the eigenvectors of these modes gives rise to polarization in the crystal.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zamkova N. G., Zhandun V. S., Zinenko V. I.
Заглавие : First-principles calculations of ferroelectric properties in AA`BB`O6 double perovskites with different types of cation ordering
Место публикации : Phys. status solidi B. - 2013. - Vol. 250, Is. 9. - P.1888-1897. - ISSN 0370-1972, DOI 10.1002/pssb.201349084
Ключевые слова (''Своб.индексиров.''): density functional theory--double perovskites--ferroelectrics--polarization
Аннотация: First-principles calculations of lattice dynamics and polarization properties have been performed for double perovskite ABiBNbO6 (A - alkali metal Na, Rb, and B - trivalent metal Sc, Lu). Three possible types of A- and B-site cation ordering are studied: layer and columnar ordering of A-site cations with rocksalt ordering of B-site cations, and layer ordering of both cations. The ground state of all compounds is polar with a large value of polarization for all types of cation ordering. For some compounds we obtain spontaneous polarization of 0.7-1.0Cm-2 that is twice the BaTiO3 value. For RbBiScNbO6 the lowest-energy state has layer ordering of both A- and B-site cations, which is rare for compounds with double-perovskite structure.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Draganyuk O. N., Zhandun V. S., Zamkova N. G.
Заглавие : Half-metallicity in Fe2MnSi and Mn2FeSi heusler compounds: A comparative ab initio study
Место публикации : Mater. Chem. Phys. - 2021. - Vol. 271. - Ст.124897. - ISSN 02540584 (ISSN), DOI 10.1016/j.matchemphys.2021.124897
Примечания : Cited References: 33. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects No19-42-240016: «Control of structural, magnetic, electronic, and optical properties by pressure and intercalation into functional compounds with a spinel structure containing 3d and 4f ions» and 20-42-240004: “The effect of the composition, pressure, and dimension on the magnetic, electronic, optical, and elastic properties of the magnetic Mn+1AXn (M = Cr, Mn; Fe, A = Al, Ga, Si, Ge, P, In; X = C, N; n = 1–3) MAX-phases”. The calculations were performed with the computer resources of “Complex modeling and data processing research installations of mega-class” SRC “Kurchatovsky Institute” (http://ckp.urcki.ru)
Аннотация: First-principles calculations of the structural, electronic, and magnetic properties of full-Heusler compounds Fe2MnSi and Mn2FeSi in regular L21 and inverse XA structures have been performed using density functional theory (DFT) within generalized gradient approximation (GGA) and SCAN functionals. All compounds indicate half-metallic properties with the minority spin bandgap. The causes for the appearance of half-metallic bandgap and the difference in the electronic and magnetic properties of Heusler compounds were studied and analyzed in terms of the local environment. It is shown, that the half-metallic bandgap determines by the behavior of the t2g-electrons of A- and C-sites atoms. The behavior of the compounds under pressure was also considered. The high sensitivity of the magnetic moments on atoms A, C and the bandgap to pressure is discussed. The transition from regular to inverse structure is predicted at the negative pressure.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vtyurin A. N., Goryainov S. V., Zamkova N. G., Zinenko V. I., Krylov A. S., Krylova S. N., Shefer A. D.
Заглавие : Hydrostatic pressure-induced phase transitions in RbMnCl3: Raman spectra and lattice dynamics
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 7. - P1301-1310. - ISSN 1063-7834, DOI 10.1134/1.1778456
Примечания : Cited References: 16
Предметные рубрики: CRYSTALS
SPECTROSCOPY
Аннотация: Raman scattering spectra of RbMnCl3 are measured at room temperature under high hydrostatic pressure. The results are interpreted based on first principles lattice dynamics calculations. The experimental data obtained correlate with the calculations in the low frequency domain but disagree slightly in the region of high-frequency vibrations. The transition from the hexagonal to the cubic perovskite phase observed earlier (near 0.7 GPa) was confirmed, and new transitions to lower symmetry distorted phases were discovered (at 1.1 and 5 GPa). (C) 2004 MAIK "Nauka / Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhandun V. S., Zamkova N. G., Korzhavyi, Pavel, Sandalov I. S.
Заглавие : Inducing magnetism in non-magnetic α-FeSi2 by distortions and/or intercalations
Коллективы : Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [17-42-240212, 18-42-243019]
Место публикации : Phys. Chem. Chem. Phys. - 2019. - Vol. 21, Is. 25. - P.13835-13846. - ISSN 1463-9076, DOI 10.1039/c9cp02361e. - ISSN 1463-9084(eISSN)
Примечания : Cited References: 27. - The reported study was funded by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research projects No 17-42-240212: "Quantum-mechanical simulation of the physical properties of correlated electron materials to improve their functional characteristics" and No 18-42-243019: "First-principles studies of the polarization, magnetic, electronic, and magnetoelectric properties of functional compounds with a spinel structure containing 3d and 4f ions".
Предметные рубрики: TOTAL-ENERGY CALCULATIONS
WAVE
FeSi2
Аннотация: By means of hybrid ab initio + model approach we show that the lattice distortions in non-magnetic α-FeSi2 can induce a magnetic state. However, we find that the distortions required for the appearance of magnetism in non-magnetic α-FeSi2 are too large to be achieved by experimental fabrication of thin films. For this reason we suggest a novel way to introduce magnetism in α-FeSi2 using “chemical pressure” that is, intercalating the α-FeSi2 films by light elements. Theoretical study of the distortions resulting from intercalation reveals that the most efficient intercalants for formation of magnetism and a high spin polarization are lithium, phosphorus and oxygen. Investigation of the dependency of the magnetic moments and spin polarisation on the intercalation atoms concentration shows that the spin polarization remains high even at small concentrations of intercalated atoms, which is extremely important for modern silicate technology.
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