Main achievements in 2025

approved by ISSP RAS Academic Board on December, 15, 2025
(protocol № 26)

1. Металл-поддерживаемые твердооксидные топливные элементы с единственным низкотемпературным insitu обжигом

И.С. Ерилин , И.Н. Бурмистров , Д.А. Гайнуллина , Е.А. Агаркова , С.И. Бредихин 
(с соавторами)

В работе демонстрируется технологический маршрут изготовления металл-поддерживаемых твердооксидных топливных элементов (МП-ТОТЭ) с единственным обжигом при температуре 1000°С в составе стенда, имитирующего условия в батареях ТОТЭ. Разработанные МП-ТОТЭ продемонстрировали удельную мощность близкую к рекордным мировым показателям, с наибольшим преимуществом в области более низких температур и более высоких КПД (напряжений).

Представленная концепция МП-ТОТЭ была разработана и изготовлена впервые в мировой практике. Основная новизна связана с использованием метода осаждения слоев из сухого порошка, который позволил изготовить высокоактивный анод с температурами консолидации 950 – 1000°С достаточными для отсутствия значительного окисления стальных токосъемов и подложки, а также с адгезионной прочностью достаточной для осаждения электролитной мембраны магнетроном без промежуточных обжигов, что в конечном итоге позволило проводить единственный обжиг с разделенными газовыми пространствами анод-катод. Впервые в мировой практике промышленно-ориентированным методом был изготовлен анод для МП-ТОТЭ, внедренный в поры подложки почти на всю толщину, что обеспечивает невозможность его деламинации в процессе быстрых нагревов и охлаждений. Анализ спектров импеданса (Рис. 1) изготовленных МП-ТОТЭ и анод-поддерживаемых ТОТЭ (АП-ТОТЭ) на основе коммерческой подложки показал, что при температурах 600–650°С основной вклад в сопротивление в случае МП-ТОТЭ вносит катод, а в случае АП-ТОТЭ анодный и катодный вклад примерно равен, что продемонстрировало важность высокой активности анода при температурах 600–650°С.

Публикация: Erilin, I.S. Metal-supported solid oxide fuel cell with low temperature single in situ firing: fabrication, analysis, perspectives / I.S. Erilin, I.N. Burmistrov, E.A. Smolyanskiy, A.A. Solovyev, D.A. Gaynullina, E.A. Agarkova, S.I. Bredikhin // Journal of Power Sources. – 2025. – Vol. 659. – P. 238430. – DOI:10.1016/j.jpowsour.2025.238430

Уровень готовности технологии – второй УГТ

Полученный результат соответствует приоритетному направлению научно-технического развития Российской Федерации, утвержденным Указом Президента Российской Федерации от 18.06.2024 №529 – 1. Высокоэффективная и ресурсосберегающая энергетика.

Государственное задание ИФТТ РАН: «Фундаментальные исследования и проблемно-ориентированные разработки по созданию макетных образцов энергетических установок на базе твердооксидных топливных элементов (ТОТЭ)», №125032804581-9

Энергетика и рациональное природопользование, направление 2.5.1.7. Альтернативные источники энергии, технологии, производство и преобразование энергии на основе возобновляемых источников.

2. Spin valve for surface states in topological semimetals

A.A. Avakyants, V.D. Esin, D. Yu. Kazmin, N.N. Orlova, N.N. Kolesnikov, A.V. Timonina, E.V. Deviatov

Recently, serious interest is attracted by the spin valve as a key element for various implementations of magnetic memory. A spin valve is typically a multilayer structure consisting of several ferromagnetic layers which are separated by the normal metal layer or tunneling distance. The electrical resistance of this structure depends on the mutual orientations of the layers’ magnetizations due to the spin-dependent scattering of charge carriers. As a result, the resistance of the spin valve can be controlled by the external magnetic field due to the alignment of layer magnetizations in parallel or antiparallel configurations.

On the other hand, the spin valve can be realized for spin-polarized topological surface states in topological semimetals. In addition to purely scientific interest, this device can be expected to exhibit highly efficient spin-to-charge conversion due to the strong spin-momentum locking. In this case, topological semimetal α-GeTe is of particular interest since its topological properties can be observed from cryogenic to room temperatures.

Here, we experimentally investigate the magnetoresistance of a single GeTe–Ni heterojunction between the topological semimetal α-GeTe and a thick nickel film. We demonstrate characteristic spin-valve hysteresis with mirrored differential resistance dV/dI peaks at room and liquid helium temperatures (Fig. 1). From the magnetic field anisotropy, observation of the similar effect for another topological semimetal Cd₃As₂, and strictly flat dV/dI(H) magnetoresistance curves for the reference GeTe-Au junction, we connect the observed spin-valve effect with the spin-dependent scattering between the spin textures in the topological surface states and the ferromagnetic nickel electrode. For the fundamental research, we show the influence of topological spin textures on charge carrier transport in heterostructures, while the efficient spin-to-charge conversion at room temperature could be important for potential applications.

Publication: Avakyants, A.A. Spin-valve effect for spin-polarized surface states in topological semimetals / A.A. Avakyants, V.D. Esin, D.Yu. Kazmin, N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov // JETP Letters. – 2025. – Vol. 121, Iss. 9. – DOI:10.1134/S0021364025606293

3. Spectrum of plasma excitations in a plasmonic crystal based on an AlGaAs/GaAs heterostructure

A.A. Zabolotnykh, A.S. Astrakhantseva, I.V. Kukushkin, V.M. Muravev et al.

A comprehensive study of the spectrum and relaxation of plasma excitations in a plasmonic crystal fabricated from the two-dimensional electron system in an AlGaAs/GaAs semiconductor heterostructure was carried out (Fig. 1). A key feature of the experiment was the use of terahertz time-domain spectroscopy to directly observe the evolution of the fundamental plasma mode with a systematic variation of the width of the metal gate strips (the filling factor) at fixed grating periods of 8 and 12 μm. To explain the observed phenomena, the authors developed a new analytical approach based on the solution of Maxwell’s equations for space harmonics. This approach proved to be significantly more accurate than the widely used phenomenological Kronig–Penney model. The theoretical analysis confirmed that the plasma modes in this crystal have a delocalized superlattice nature and are a hybridization of multiple space harmonics, rather than a simple alternation of modes in screened and unscreened regions. Another key result of the study was the identification of the decay mechanisms of plasma oscillations. It was found that the resonance linewidth is not constant. For low filling factors, it is determined by classical single-particle scattering (collisions with impurities and phonons), which correlates with the measured electron transport mobility. However, a sharp broadening of the line occurs with an increase in the gate width, which results from radiative decay effects. This indicates that the metal gate grating performs as an efficient antenna that couples plasmons to the external electromagnetic field. These results provide new insights into the physics of plasmonic crystals and create a scientific basis for engineering of new terahertz devices, such as detectors, generators, and phase shifters.

Publication: Khisameeva A. R. Spectrum of plasma excitations in a plasmonic crystal fabricatedin an AlGaAs/GaAs heterostructure / A.R. Khisameeva, A. Shuvaev, A.A. Zabolotnykh, A.S. Astrakhantseva, D.A. Khudaiberdiev, A. Pimenov, I.V. Kukushkin, V.M. Muravev // Physical Review Research. – 2025. – Vol. 7, Iss. 3. – P. 033224. – DOI:10.1103/3gnt-w1zj

RSF project no. 19-72-30003

4. Plasma excitations in the superconducting electron system in NbN thin films

S.A. Andreeva, A.V. Shchepetilnikov, K.R. Dzhikirba, V.V. Solovyev, I.V. Kukushkin

The main challenge in detecting plasma excitations in a three-dimensional superconducting electron system is an extremely high electron density compared to semiconductor systems. This results in a high frequency of plasma excitations that significantly exceeds the superconducting gap energy. Under these conditions, plasma excitations are strongly damped and cannot be observed. Since the plasma excitation spectrum in two-dimensional electron systems is gapless, the plasma frequency can always be reduced down to zero by decreasing the excitation wave vector (e.g., by increasing the sample size) and, thereby, be made significantly lower than the superconducting gap.

In this study, we observed two-dimensional plasma waves in a superconducting electron system in thin NbN films for the first time (Fig. 1) and measured their dispersion (Fig. 2). We used very thin NbN films, in which the superconducting electron density was considerably reduced compared to the total electron density. Under these conditions, we discovered features in the resonant transmission of THz radiation that depended on the size of the electron system. It was found that these resonances vanished at temperatures above the critical temperature (Tc). Furthermore, it was shown that, with an increase in the temperature up to Tc, a shift in the resonant frequency to lower frequencies (due to a decrease in the density of superconducting electrons) and a significant broadening of the resonance features were observed. The dispersion of plasma excitations was measured, and the plasma frequency was shown to depend linearly on the wave vector.

Publication: The article is published as Letter in Physical Review B (Phys. Rev. B 113, L100503 – Published 31 March, 2026, DOI: https://doi.org/10.1103/crcr-w98q)

5. Prospects for using solid oxide fuel cells to generate energy from low-calorific waste gases

A.U. Sharafutdinov, E.V. Tsipis, D.V. Matveev, N.V. Demeneva, M.S. Dyakina, S.D. Rodionova, V.V. Kharton, S.I. Bredikhin

This study aims to solve the problem of utilization of low-calorific waste gases from coal mines and solid waste landfills. The main components of landfill and mine gases are CH₄, CO₂, and N₂. The low concentration of methane in these gases complicates their utilization in gas reciprocating internal combustion engines and gas turbines. Solid oxide fuel cell (SOFC) technologies are characterized by record efficiency (up to 65 %), the ability to use various types of fuel, environmental safety, long service intervals, and good scalability. Therefore, the use of waste gases in SOFCs to produce electricity and heat will significantly reduce the environmental impact. The performance and limitations of SOFCs operating on model fuel gases containing 25–100 % methane, with and without external pre-reforming, have been evaluated using electrochemical testing and modeling. The experimental results (Fig. 1) show that the developed SOFC configuration with industrial-scale cells (10×10 cm²) enables gas mixtures with relatively low methane concentrations to be used as fuel while still maintaining sufficiently high energy conversion efficiency. This is confirmed by the results of modeling showing that the stable operation of SOFCs at acceptable power levels is possible even with significant methane dilution (up to 10 %), while the efficiency decreases only slightly (from 59 % to 44 %).

Publication: Sharafutdinov, A.U. Performance of SOFCs using waste gases: Effects of CH4/CO2/H2O ratio / A.U. Sharafutdinov, E.V. Tsipis, D.V. Matveev, N.V. Demeneva, M.S. Dyakina, S.D. Rodionova, V.V. Kharton, S.I. Bredikhin // Chemical Engineering Journal. – 2025. – Vol. 512. – P. 162725. – DOI:10.1016/j.cej.2025.162725

The priority area of scientific and technological development of the Russian Federation: “Highly efficient and resource-saving energy”

RSF project no. 20-19-00478-П

Branch 2.5.1. “Power industry and rational use of natural sources”

Branch 1.4.4.2. “Scientific basis for fuel cells”

Branch 1.4.4.4. “Materials science of energy generation and energy storage devices, apparatus, and energy transmission and conversion systems”

6. Composite of silica and detonation nanodiamonds with partially removed shells

M.A. Korotkova, V.S. Efimchenko, V.E. Antonov, O.I. Barkalov, T.N. Fursova, K.A. Gavrilicheva, S.V. Zaitsev et al.

Single detonation nanodiamonds (DNDs) with nitrogen-vacancy (NV) centers have attracted interest as single-photon emitters. This study proposes a method to overcome two main problems of DNDs: the tendency to agglomerate and the presence of a graphite-like carbon shell. After compression at 75 kbar and 250 °C, the initial SiO2 aerogel containing single DND particles irreversibly transforms into a dense and chemically inert material that prevents their agglomeration. Subsequent hydrogenation of this material at P = 75 kbar and T = 600 °C partially removes the DND shell (Fig. 1, left panel) and, thus, activates the luminescence of negatively charged NV– centers without using low temperatures (Fig. 1, right panel).

Publication: Korotkova, M.A. Bulk composite of silica and detonation nanodiamonds with partially removed sp2 shells / M.A. Korotkova, V.S. Efimchenko, V.E. Antonov, O.I. Barkalov, I.G. Fomina, T.N. Fursova, K.A. Gavrilicheva, S.V. Zaitsev, I.O. Gozhikova, A.Ya. Vul', S.A. Lermontov // CeramicsInternational. – 2025. – Vol. 51, Iss. 18, № Part 1. – P. 25160–25168. – DOI:10.1016/j.ceramint.2025.03.197

State task of ISSP RAS: “Structure, phase transitions, and properties of liquids and solids”, no. 125031904202-5

Physical sciences, branch 1.3.2.2. “Structural studies of condensed media, relationship between the structure and properties”

7. Lattice dynamics, compressibility, thermal expansion, and heat capacity of multilayer graphane

V.E. Antonov, V.S. Efimchenko, V.I. Kulakov, R.I. Usmanov et al.

Multilayer graphane (hydride of graphite) is a new crystalline hydrocarbon of the composition CH, first synthesized at ISSP RAS [1]. This is one of the theoretically predicted [2] phases of 3D graphane, the “graphane II” phase consisting of corrugated layers of 2D graphane in the “chair” conformation stacked along the hexagonal axis in the -ABAB- sequence, space group P6_3mc (Fig. 1). The crystal structure of graphane was unambiguously established in this work by the presence of a gap near 100 meV in the vibrational spectrum G(E) studied at T = 7 K by inelastic neutron scattering (Fig. 1) on an almost single-phase sample. The sample was synthesized at T = 870 K and a hydrogen pressure of 7.4 GPa. The almost complete hydrogenation of the sample was achieved by pre-activating the surface of graphite particles through ball milling under mild conditions in a hydrogen atmosphere at a pressure of 1 MPa. Сalorimetric measurements at 120–673 K confirmed the good accuracy of determination of the vibrational spectrum.

An X-ray diffraction study in diamond anvil cells revealed that the graphane II phase is stable in a hydrogen atmosphere at pressures up to 53 GPa and temperatures up to 1500 K. This characterizes the synthesized exotic compound as one of the most chemically, barically, and thermally stable hydrocarbons and makes it an important part of the C-H system. Remarkably, all phases of multilayer graphane, including graphane-II, should have been thermodynamically unstable in a hydrogen atmosphere at T > 0 K and pressures up to 400 GPa according to first-principles calculations [3].

[1] V.E. Antonov, I.O. Bashkin, A.V. Bazhenov et al., Carbon 100 (2016) 465–473.

[2] X.-D. Wen, L. Hand, V. Labetetal., PNAS 108 (2011) 6833–6837.

[3] A.S. Naumova, S.V. Lepeshkin, A.R. Oganov, J. Phys. Chem. C 123 (2019) 20497–20501.

Publication: Yartys, V.A. Reversible hydrogen storage in multilayer graphane: Lattice dynamics, compressibility, and heat capacity studies / V.A. Yartys, V.E. Antonov, B.M. Bulychev, V.S. Efimchenko, V.I. Kulakov, M.A. Kuzovnikov, R.T. Howie, H.A. Shuttleworth, M. Holin, R. Rae, M.B. Stone, B.P. Tarasov, R.I. Usmanov, A.I. Kolesnikov // Materials Chemistry and Physics. – 2025. – Vol. 332. – P. 130232. – DOI:10.1016/j.matchemphys.2024.130232

RSF project no. 23-22-00361

Physical sciences, branch 1.3.2. “Condensed matter physics and physical materials science”

8. Purification of raw materials and growth of CaF₂ crystals by vertical zone melting

N.N. Kolesnikov, A.V. Timonina, A.S. Azhgalieva

CaF₂ crystals are a key material for far-ultraviolet laser lithography, especially in 193-nm excimer lasers, where they are used for both transmissive and focusing optics. This application requires the production of large, high-purity crystals. We have developed a method for purifying CaF₂ raw materials and growing crystals by vertical zone melting. The purification of CaF₂ by multiple-pass zone melting can be demonstrated as follows. The raw material is CaF₂ (GOST 7167-54) with a CaF₂ content of ​​98 %. The main impurities are SO₄ (0.15 %), Fe (0.025 %), Pb (0.01 %), and Si (0.04 %). With five passes of the zone, the process allows for the removal of all main impurities (within the accuracy of X-ray microanalysis), except for Fe (Figs. 1-2). We have also developed a set of effective measures to reduce the Fe content in crystals.

Based on the results of the study, an application for a patent for invention has been filed [1].

[1] Patent: N.N. Kolesnikov, A.V. Timonina, A.M. Khamidov, A.S. Azhgalieva. A method for purifying and producing CaF₂ crystals. Application for a patent for invention, registration no. 2025130063, Russian Federation.

Technology Readiness Level: TRL 2

The priority area of scientific and technological development of the Russian Federation: “Security of obtaining, storing, transferring, and processing information”

State task of ISSP RAS: “Physics, physical materials science, and technologies of novel inorganic materials and functional structures”, no. 125032804582-6

Physical sciences, branch 1.3.5.5. “Physics of lasers and laser materials; non-linear optical phenomena”

9. Local thermometry of NbSe₂ flake with delta-T noise measurements

M.G. Prokudina, A.F. Shevchun, V.S. Khrapai, E.S. Tikhonov

Understanding of the dynamics of quasiparticles in superconductors is essential for improving the operation of superconductor-based electronic microrefrigerators, photon detectors, kinetic inductance elements, and qubits. In this study, we implemented an approach for local thermometry of electronic states in a non-equilibrium superconductor (an NbSe2 flake) based on the noise measurements of a weakly coupled tunnel probe. A similar approach was previously employed for local thermometry of electronic states in diffusive metallic conductors using an InAs semiconductor nanowire with negligible electron-phonon scattering as a sensor. Later, the same approach, but with a tunnel junction probe, provided energy resolution of electronic states in diffusive metallic wires. However, up to now, this approach has never been applied to superconductors. It should be noted that it does not rely on any spectral characteristics of the superconductor or sensor. Therefore, its applicability is not limited to low temperatures or zero magnetic field, as in tunnel conductance spectroscopy experiments. This approach can be used to characterize not only other superconductors from the transition-metal dichalcogenide family down to the 2D limit but also bulk superconductors. Figure 1 shows the sample and measurement scheme. The right panel displays the main result: the local electronic temperature in the NbSe₂ flake in the vicinity of the tunnel junction (the red dot in the central panel) in the normal (yellow symbols) and superconducting (blue symbols) states. These measurements allow extraction of the electron-phonon scattering length in NbSe₂ of le-ph=0.8/T1.1 μm K1.1.

Publication: Prokudina, M.G. Local Thermometry of NbSe2 Flake with Delta-T Noise Measurements / M.G. Prokudina, A.F. Shevchun, V.S. Khrapai, E.S. Tikhonov // JETP Letters. – 2025. – Vol. 122, Iss. 4. – P. 250–258. – DOI:10.1134/S0021364025607869

State task of ISSP RAS: “Collective phenomena in transport and optical properties of nanostructures, including hybrid nanostructures”, no. 125032704559-9

Physical sciences, branch 1.3.2.5. “Physics of nano- and heterostructures, mesoscopic physics”

10. Light-induced ordering of skyrmions with the formation of a cubic phase in cholesteric liquid crystals

P.V. Dolganov, E.A. Maksimov, V.K. Dolganov et al.

Skyrmions, localized topologically stable structures without singularities, are studied in various fields of physics, including condensed matter physics. In cholesteric liquid crystals, skyrmions form ordered cubic structures with periods of several hundred nanometers (crystalline liquids, or so-called blue phases) with phase transitions induced by changes in the temperature. We have implemented for the first time the formation of an ordered skyrmion structure (BPII) upon light irradiation.

We used a liquid crystal material containing a photochromic substance whose molecules change their shape when irradiated with light. It was found that the UV irradiation of the material in the isotropic phase led to the formation of an ordered skyrmion structure with the emergence of a characteristic peak in the reflection spectrum (Fig. 1). The cubic structure was preserved when irradiation was turned off. The photoinduced cubic structure was found to have a finite stability range over the irradiation intensity. Prolonged UV irradiation or visible irradiation resulted in an inverse transition to the isotropic phase.

Publication: Dolganov, P.V. Light-Induced Ordering of Skyrmions with the Formation of a Cubic Phase in Cholesteric Liquid Crystals / P.V. Dolganov, E.A. Maksimov, N.V. Balenko // JETP Letters. – 2025. – Vol. 122, Iss. 5. – P. 315–320. – DOI: 10.1134/S0021364025607936

State task of ISSP RAS: “Structure, phase transitions, and properties of liquids and solids”, no. 125031904202-5

Physical sciences, branches

1.3.2.10. “Physical materials science and physics of defects”

1.3.2.6. “Physics of surfaces, interfaces, and other extended defects”

11. Hollow silica nanospheres with a high content of molecular hydrogen

V.S. Efimchenko, K.P. Meletov, M.A. Korotkova, V.M. Masalov, N.S. Sukhinina, G.A. Emel’chenko, R.I. Usmanov

Hollow silica glass spheres have previously been proposed in various fields of alternative energy as one of the possible materials for storing hydrogen and its isotopes. However, spheres with a diameter of more than 5 µm are collapsed at pressures above 1 kbar, which limits the amount of adsorbed hydrogen. In this study, hollow SiO₂ spheres with a diameter of 289 nm (i.e., 17 times smaller) and a shell thickness of 2 nm were hydrogenated at P = 75 kbar and T = 413 K. The achieved molar ratio of H₂/SiO₂ = 0.94 is the highest hydrogen content reported for silicates. As Figure 1 shows, high pressure did not deform or destroy these spheres, indicating their high strength. According to Raman spectroscopy (Fig. 1), hydrogen molecules formed a gas in the cavities of the nanospheres and a solid solution in their shells. The density of the gas inside the cavity of ρ = 0.016 g/cm³ estimated from these spectra is 52 times higher than its density at ambient pressure. Therefore, the use of hollow spheres with a diameter of 289 nm enables hydrogenation at higher pressures and allows achieving high hydrogen concentrations in their cavity and shell.

Publication: Efimchenko, V.S. Hollow silica nanospheres with a high content of sorbed molecular hydrogen / V.S. Efimchenko, K.P. Meletov, M.A. Korotkova, V.M. Masalov, N.S. Sukhinina, G.A. Emel’chenko, R.I. Usmanov // Fuel. – 2025. – Vol. 385. – P. 134217. – DOI:10.1016/j.fuel.2024.134217

RSF project no. 23-23-00426

Branch 1.3.2.2. “Structural studies of condensed media, relationship between the structure and properties”

Branch 1.4.2.2. “Methods and technologies for production of inorganic, organic, and hybrid nanomaterials and composite nanomaterials for alternative energy”