Mikhail Feygenson

• PhD
• Neutron Diffraction Scientist at European Spallation Source ERIC

Due to their high potential energy storage, magnetite (Fe3O4) nanoparticles have become appealing as anode materials in lithium-ion batteries. However, the details of the lithiation process are still not completely understood. Here, we investigate chemical lithiation in 70 nm cubic-shaped magnetite nanoparticles with varying degrees of lithiation,...

The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented , while their influence on sp...

The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size.

Due to their high potential energy storage magnetite (Fe3O4) nanoparticles have become appealing for anode materials in lithium-ion batteries. However, the details of the lithiation process are still not completely understood. Here, we investigate chem- ical lithiation in 70 nm cubic shaped magnetite nanoparticles with varying degree of lithiation...

We have investigated the chemical lithiation in 70 nm cubic-shaped magnetite nanoparticles with varying degree of lithiation x = 0, 0.5, 1, 1.5. The induced changes on structure and magnetic properties were investigated with X-ray scattering techniques along with electron microscopy and magnetic measurements. The results indicate that a structural...

To meet the ever-increasing user demand, eleven of the fifteen European Spallation Source (ESS) instruments under construction aim to offer polarised neutrons for user experiments. They include an imaging instrument, a SANS instruments, two reflectometers, three diffractometers, and four spectrometers. In conjunction with in-kind contributions and...

Small-angle scattering (SAS) experiments are a powerful method for studying self-assembly phenomena in nanoscopic materials because of the sensitivity of the technique to structures formed by interactions on the nanoscale. Numerous out-of-the-box options exist for analysing structures measured by SAS but many of these are underpinned by assumptions...

Displacive and diffusional transformations are the main processes during solid-state phase transformations, which have formed the basis of applied physics and materials technology for centuries. However, the relationship between diffusional and displacive transformations has remained elusive, which significantly hinders the fundamental understandin...

We studied structural and magnetic phase transitions under applied pressure for the doped cobaltite La0.75Ba0.25CoO2.9. Neutron and x-ray diffraction experiments established the coexistence of rhombohedral and cubic phases in the sample. The magnetic state at 2 K is best described as a long-range ordered antiferromagnet (AFM) with small ferromagnet...

Spherical iron oxide nanoparticles in dispersion are controlled by external magnetic fields to form flexible and reversible chains for biomedical applications. In article number 2008683, Mikhail Feygenson and co‐workers combine the advanced scattering methods and reverse Monte Carlo simulations to directly visualize the chain formation in real spac...

Self‐assembly of iron oxide nanoparticles (IONPs) into 1D chains is appealing, because of their biocompatibility and higher mobility compared to 2D/3D assemblies while traversing the circulatory passages and blood vessels for in vivo biomedical applications. In this work, parameters such as size, concentration, composition, and magnetic field, resp...

Self‐assembly of iron oxide nanoparticles (IONPs) into 1D chains is appealing, because of their biocompatibility and higher mobility compared to 2D/3D assemblies while traversing the circulatory passages and blood vessels for in vivo biomedical applications. In this work, parameters such as size, concentration, composition, and magnetic field, resp...

Low Energy accelerator-driven Neutron Facilities have the potential to become competitive to research reactors and spallation sources to generate neutron beams for scattering experiments. A low energy accelerator-driven neutron facility is developed at the Jülich Centre for Neutron Science. This source is expected to provide thermal and cold neutro...

Iron oxide nanoparticles are presently considered as main work horses for various applications including targeted drug delivery and magnetic hyperthermia. Several questions remain unsolved regarding the effect of size onto their overall magnetic behavior. One aspect is the reduction of magnetization compared to bulk samples. A detailed understandin...

An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of theEuropean Spallation Source (ESS), and being made available to the neutron user community. The ESS neutronsource consists of a high-power accelerator and target station, providing a unique long-pulse time structureof slow neutrons. The design cons...

The local atomic and magnetic structures of the compounds AMnO2 (A = Na, Cu), which realize a geometrically frustrated, spatially anisotropic triangular lattice of Mn spins, have been investigated by atomic and magnetic pair distribution function analysis of neutron total scattering data. Relief of frustration in CuMnO2 is accompanied by a conventi...

The local atomic and magnetic structures of the compounds $A$MnO$_2$ ($A$ = Na, Cu), which realize a geometrically frustrated, spatially anisotropic triangular lattice of Mn spins, have been investigated by atomic and magnetic pair distribution function analysis of neutron total scattering data. Relief of frustration in CuMnO$_2$ is accompanied by...

Birnessite is a low-cost and environmentally friendly layered material for aqueous electrochemical energy storage; however, its storage capacity is poor due to its narrow potential window in aqueous electrolyte and low redox activity. Herein we report a sodium rich disordered birnessite (Na0.27MnO2) for aqueous sodium-ion electrochemical storage wi...

A detailed account of the local atomic structure and disorder at 5 K across the phase diagram of the high-temperature superconductor KxFe2−ySe2−zSz (0≤z≤2) is obtained from neutron total scattering and associated atomic pair distribution function (PDF) approaches. Various model-independent and model-dependent aspects of the analysis reveal a high l...

The unconventional transport and magnetic properties of perovskitelike lanthanum cobalt oxide LaCoO 3 have been studied for more than five decades. This highly correlated electron system exhibits a variety of peculiar properties that are desirable for environmentally friendly energy solutions, fuel cell technologies, novel diesel engines, and oxyfu...

The improper ferroelectricity in YMnO_{3} and other related multiferroic hexagonal manganites is known to cause topologically protected ferroelectric domains that give rise to rich and diverse physical phenomena. The local structure and structural coherence across the ferroelectric transition, however, were previously not well understood. Here, we...

The detailed account of the local atomic structure and structural disorder at 5~K across the phase diagram of K$_x$Fe$_{2-y}$Se$_{2-z}$S$_z$ $(0 \leq z \leq 2)$ high temperature superconductor is obtained from neutron total scattering and associated atomic pair distribution function (PDF) approach. Various model independent and model dependent aspe...

Crystal structure of hydrothermally synthesized BiEuWO6 and BiTbWO6 nanomaterials is deduced for the first time by combined Rietveld refinement of Neutron and Synchrotron data using the ordered and disorder models available in literature. The ordered model is validated for the average structure of these nanomaterials and it is further supported by...

Materials with the pyrochlore/fluorite structure have diverse technological applications, from magnetism to nuclear waste disposal. Here we report the observation of structural instability present in the pyrochlores A2Zr2O6O' (A = Pr, La) and Yb2Ti2O6O', that exists despite ideal stoichiometry, ideal cation-ordering, the absence of lone pair effect...

Comparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas KxFe2−ySe2 is a superconductor with a transition temperature of about 32 K, the isos...

BaSnO3 has attracted attention as a transparent conducting oxide with high room temperature carrier mobility. We report a series of measurements that were carried out to assess the structure of BaSnO3 over a variety of length scales. Measurements included single crystal neutron and x-ray diffraction, Rietveld and pair distribution analysis of neutr...

As a generic property, all substances transfer heat through microscopic collisions of constituent particles 1 . A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations2,3. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such...

The present work verifies the existence of chemical short-range orders (CSROs) in high-entropy alloys (HEAs) using a cluster-plus-glue-atom model. Two HEAs with a composition of Al2M14 (M = Ni4Co4Fe3Cr3 or Ni1Co1Fe2Cr1) are designed, which is derived from the cluster model of [Al-M12](M2Al1) in face-centered-cubic structure or [Al-M14]Al1 in body-c...

Manganese-based metal oxide electrode materials are of great importance in electrochemical energy storage for their favorable redox behavior, low cost, and environmental friendliness. However, their storage capacity and cycle life in aqueous Na-ion electrolytes is not satisfactory. Herein, the development of a biphase cobalt–manganese oxide (CoMnO)...

Herein we report a new Na-insertion electrode material, Na2Ti9O19, as a potential candidate for Na-ion hybrid capacitors. We study the structural properties of nanostructured Na2Ti9O19, synthesized by hydrothermal technique, upon electrochemical cycling vs. Na. Average and local structure of Na2Ti9O19 are elucidated from neutron Rietveld refinement...

The key design parameters for the ESS provide new opportunities in neutron diffraction. The long pulse at 5 MW is most intense and about two orders of magnitude larger than the neutron flux of today’s leading pulsed sources. The peak brightness clearly exceeds those of the existing short pulse spallation sources. Tailoring the pulse with fast chopp...

A major challenge to understanding the response of materials to extreme environments (e.g., nuclear fuels/waste forms and fusion materials) is to unravel the processes by which a material can incorporate atomic-scale disorder, and at the same time, remain crystalline. While it has long been known that all condensed matter, even liquids and glasses,...

Two phase transitions in the tetragonal strongly correlated electron system CeNiAsO were probed by neutron scattering and zero field muon spin rotation. For $T <T_{N1}$ = 8.7(3) K, a second order phase transition yields an incommensurate spin density wave with wave vector $\textbf{k} = (0.44(4), 0, 0)$. For $T < T_{N2}$ = 7.6(3) K, we find co-plana...

The improper ferroelectricity in YMnO$_3$ and related hexagonal manganites is known to cause topologically protected ferroelectric domains that give rise to rich and diverse physical phenomena. The local structure and structural coherence across the transition, however, are not well understood. Here we reveal the evolution of the local structure in...

Two phase transitions in the tetragonal strongly correlated electron system CeNiAsO were probed by neutron scattering and zero field muon spin rotation. For $T <T_{N1}$ = 8.7(3) K, a second order phase transition yields an incommensurate spin density wave with wave vector $\textbf{k} = (0.44(4), 0, 0)$. For $T < T_{N2}$ = 7.6(3) K, we find co-plana...

A combined diffraction and EXAFS study of LaCoO3 and La0.5Sr0.5Co0.75Nb0.25O3 powders — CORRIGENDUM - E. A. Efimova, V. V. Sikolenko, D. V. Karpinsky, I. O. Troyanchuk, S. Pascarelli, C. Ritter, M. Feygenson, S. I. Tiutiunnikov, V. Efimov

Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because the large ionic radius of potass...

Supplementary Figures, Supplementary Tables and Supplementary Notes

A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. Here, we report that the crystalline solid AgCrSe2 has liquid-like thermal conduction. In this compound, Ag atoms exhibit a dynamic duality that they are exclusively involved in intense low-lying transverse acoustic ph...

The average structure, local structure, and band structure of nanoparticles of photocatalyst Bi4TaO8Cl, an Aurivillius-Sillen layered material, has been studied by powder neutron Rietveld refinement, neutron pair distribution function technique, Raman scattering, and density functional theory calculations. A significant local structural deviation o...

A combination of neutron diffraction, synchrotron X-ray diffraction, and high-resolution extended X-ray absorption fine structure measurements has been used to clarify the correlations between long- and local-range structural distortions across the spin-state transition in powders of LaCoO 3 and La 0.5 Sr 0.5 Co 0.75 Nb 0.25 O 3 . The analysis of t...

Transition metal arrangement impacts electrochemical behaviors of high-voltage electrodes for Li-ion batteries. In article number 1601950, Ke An and co-workers report a new lattice-cell orientation disorder model as the local ordering mechanism, which explains the difference between global and local structures of LiNi0.5Mn1.5O4. The cover picture s...

A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. Here, we report that the crystalline solid AgCrSe2 has liquid-like thermal conduction. In this compound, Ag atoms exhibit a dynamic duality that they are exclusively involved in intense low-lying transverse acoustic ph...

Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite—a metastable polymorph of CaCO3. Vateri...

Supplementary Figures 1-17, Supplementary Tables 1-3, Supplementary Notes 1-2, Supplementary Methods and Supplementary References

Transition metal (TM) substitution has been widely applied to change complex oxides crystal structures to create high energy density electrodes materials in high performance rechargeable lithium-ion batteries. The complex local structure in the oxides imparted by the TM arrangement often impacts their electrochemical behaviors by influencing the di...

Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (1/41.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn 5...

Transformation between different types of carbon–carbon bonding in carbides often results in a dramatic change of physical and chemical properties. Under external pressure, unsaturated carbon atoms form new covalent bonds regardless of the electrostatic repulsion. It was predicted that calcium acetylide (also known as calcium carbide, CaC2) polymer...

We have studied the atomic and magnetic structure of the dilute ferromagnetic semiconductor system (Ba,K)(Zn,Mn)$_2$As$_2$ through atomic and magnetic pair distribution function analysis of temperature-dependent x-ray and neutron total scattering data. We detected a change in curvature of the temperature-dependent unit cell volume of the average te...

We have studied the atomic and magnetic structure of the dilute ferromagnetic semiconductor system (Ba,K)(Zn,Mn)$_2$As$_2$ through atomic and magnetic pair distribution function analysis of temperature-dependent x-ray and neutron total scattering data. We detected a change in curvature of the temperature-dependent unit cell volume of the average te...

Hollandite solid solutions along the A-site compositional range from the pure barium end-member Ba1.33Ga2.66Ti5.34O16 to the pure cesium end-member Cs1.33Ga1.33Ti6.67O16 have been synthesized using a solid-state reaction technique. The crystal structure of the hollandite across the entire compositional range remained in the I4/m space group. Struct...

Acetonitrile (CH3CN) is the simplest and one of the most stable nitriles. Reactions usually occur on the C≡N triple bond, while the C−H bond is very inert and can only be activated by a very strong base or a metal catalyst. It is demonstrated that C−H bonds can be activated by the cyano group under high pressure, but at room temperature. The hydrog...

Acetonitrile (CH3CN) is the simplest and one of the most stable nitriles. Reactions usually occur on the C≡N triple bond, while the C−H bond is very inert and can only be activated by a very strong base or a metal catalyst. It is demonstrated that C−H bonds can be activated by the cyano group under high pressure, but at room temperature. The hydrog...

This study sought to resolve whether sturgeon (Acipenseridae) sagittae (otoliths) contain a non-vaterite fraction and to quantify how large a non-vaterite fraction is using neutron diffraction analysis. This study found that all otoliths examined had a calcite fraction that ranged from 18 ± 6 to 36 ± 3% by mass. This calcite fraction is most probab...

Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury b...

Despite kerogen’s importance as the organic backbone for hydrocarbon production from source rocks such as gas shale, the interplay between kerogen’s chemistry, morphology and mechanics remains unexplored. As the environmental impact of shale gas rises, identifying functional relations between its geochemical, transport, elastic and fracture propert...

As a compelling case of sensitive structure-property relationship, an odd-even effect refers to the alternating trend of physical or chemical properties on odd/even number of repeating structural units. In crystalline or semicrystalline materials, such odd-even effects emerge as manifestations of differences in the periodic packing patterns of mole...

Due to limitations on the availability of rare earth elements it is imperative that new high energy product rare earth free permanent magnet materials are developed for the next generation of energy systems. One promising low cost permanent magnet candidate for a high energy magnet is α″-Fe16N2, whose giant magnetic moment has been predicted to be...

There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under ex...

A combination of Rietveld refinement and pair distribution function analysis of total neutron scattering data are used to provide insight into the negative thermal expansion mechanism of siliceous faujasite. The negative thermal expansion mechanism of siliceous faujasite is attributed to the transverse vibrations of bridging oxygen atoms resulting...

Despite kerogen’s importance as the organic backbone for hydrocarbon production from source rocks such as gas shale, the interplay between kerogen’s chemistry, morphology and mechanics remains unexplored. As the environmental impact of shale gas rises, identifying functional relations between its geochemical, transport, elastic and fracture propert...

A spin-orbital quantum liquid state is theoretically proposed in the honeycomb lattice of Ba3CuSb2O9, enabled by dynamic short-range correlations between the spin and orbital degrees of freedom. Using neutron diffraction, the local atomic structure of Ba3Cu1+xSb2−xO9 at x=0 and 0.1 is obtained via the pair density function analysis. The results ind...

Otoliths, calcium carbonate (CaCO 3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO 3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite—a metastable polymorph of CaCO 3. Vat...

It has recently been demonstrated that dynamical magnetic correlations measured by neutron scattering in iron chalcogenides can be described with models of short-range correlations characterized by particular {choices of four-spin plaquettes, where the appropriate choice changes as the} parent material is doped towards superconductivity. Here we ap...

It has recently been demonstrated that dynamical magnetic correlations measured by neutron scattering in iron chalcogenides can be described with models of short-range correlations characterized by particular {choices of four-spin plaquettes, where the appropriate choice changes as the} parent material is doped towards superconductivity. Here we ap...

Supplementary Figures 1-4, Supplementary Note 1 and Supplementary References

Pressure-induced polymerization of charged triple-bond monomers like acetylide and cyanide could lead to formation of a conductive metal-carbon network composite, thus providing a new route to synthesize inorganic/organic conductors with tunable composition and properties. The industry application of this promising synthetic method is mainly limite...

We describe here how the exchange bias effect in Co/CoO nanoparticles depends on the size focusing and temperature treatment of precursor Co nanoparticles before oxidation at ambient conditions. By appealing to magnetization, microscopy, neutron, and synchrotron X-ray measurements, we found that as-synthesized Co nanoparticles readily oxidize in ai...

We report a comprehensive study of the crystal structure of (Ga1−xZnx)(N1−xOx) solid solution nanoparticles by means of neutron and synchrotron X-ray scattering. In our study, we used four different types of (Ga1−xZnx)(N1−xOx) nanoparticles, with diameters of 10−27 nm and x = 0.075−0.51, which show energy band gaps from 2.21 to 2.61 eV. Rietveld an...

The lipid raft hypothesis presents insights into how the cell membrane organizes proteins and lipids to accomplish its many vital functions. Yet basic questions remain about the physical mechanisms that lead to the formation, stability, and size of lipid rafts. As a result, much interest has been generated in the study of systems which contain simi...

The addition polymerization of charged monomers like C≡C2– and C≡N– is scarcely seen at ambient conditions but can progress under external pressure with their conductivity significantly enhanced, which expands the research field of polymer science to inorganic salts. The reaction pressures of transition metal cyanides like Prussian blue and K3Fe(CN...

We have studied the origin of the exchange bias effect in the Au-Fe3O4 dumbbell nanoparticles in two samples with different sizes of the Au seed nanoparticles (4.1 and 2.7 nm) and same size of Fe3O4 nanoparticles (9.8 nm). The magnetization, small-angle neutron-scattering, synchrotron x-ray diffraction, and scanning transmission electron microscope...

The ferrimagnetic spinel $CoV_2O_4$ has been a topic of intense recent interest, both as a frustrated insulator with unquenched orbital degeneracy and as a near-itinerant magnet which can be driven metallic with moderate applied pressure. Central outstanding questions include the number and form of magnetic transitions in this material, and the abs...

Synchrotron X-ray diffraction and neutron scattering studies are performed on As-Se glasses in two states: as-prepared (rejuvenated) and aged for ∼27 years. The first sharp diffraction peak (FSDP) obtained from the structure factor data as a function of composition and temperature indicates that the cooperative processes that are responsible for st...

A new ternary compound, Li1-xSn2+xAs2, 0.2 < x < 0.4, was synthesized via solid-state reaction of elements. The compound crystallizes in a layered structure in the R-3m space group (No. 166) with Sn-As layers separated by layers of jointly occupied Li/Sn atoms. The Sn-As layers are comprised of Sn3As3 puckered hexagons in a chair conformation that...

Poly-L-glutamic acid (PGA) is a widely used biomaterial, with applications ranging from drug delivery and biological glues to food products and as a tissue engineering scaffold. A biodegradable material with flexible conjugation functional groups, tunable secondary structure and mechanical properties, PGA has potential as a tunable matrix material...

The alloy-design strategy of combining multiple elements in near-equimolar ratios has shown great potential for producing exceptional engineering materials, often known as 'high-entropy alloys'. Understanding the elemental distribution, and, thus, the evolution of the configurational entropy during solidification, is undertaken in the present study...

Enhanced coupling of material properties offers new fundamental insights and routes to multifunctional devices. In this context 5d oxides provide new paradigms of cooperative interactions driving novel emergent behavior. This is exemplified in 5d osmates that host a metal-insulator transition (MIT) driven by magnetic order. Here we consider the mos...

Novel lignin-based carbon composite materials have been developed for use as anodes in lithium-ion batteries. The structure of the uncharged anodes has been previously characterized via pair distribution functions (PDFs) obtained from neutron scattering experiments. Computational models of the uncharged composite systems were developed and studied...

In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr56 Cu 36 Al 8, an average glass former, follows continuous nucleation and growth, while...

Novel lignin-based carbon composite materials consisting of amorphous and crystalline domains have been developed for use as anodes in lithium-ion batteries. The performance of these anodes is comparable to conventional anode materials at a significantly reduced manufacturing cost. However, the mechanism behind the performance of these novel materi...

This paper establishes the nanoscale poling mechanism operating in A-site disordered lead-free piezoelectric ceramics. Nanoscale domain maps and quantitative structural changes were obtained by deploying high-resolution transmission electron microscopy, dielectric spectroscopy, Raman spectroscopy and neutron scattering. Based on these results a mic...