Kristina Kvashnina

Kristina Kvashnina
Helmholtz-Zentrum Dresden-Rossendorf | HZDR · Institute of Resource Ecology

Doctor of Philosophy
Electronic structure of actinide and lanthanide nanomaterials

About

232
Publications
37,551
Reads
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3,751
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Introduction
We study fundamental physical and chemical properties of the f-electron systems (actinides and lanthanides) using variety of synchrotron based experimental methods and theoretical calculations. We are always looking for a PhD and MS students, postdocs, trainees to join our group. Are you interested in getting involved in our research? Do not hesitate to contact us. TOP group website https://www.hzdr.de/db/Cms?pNid=787
Additional affiliations
September 2015 - present
Helmholtz-Zentrum Dresden-Rossendorf
Position
  • Group Leader
Description
  • Beamline BM20
November 2010 - September 2015
European Synchrotron Radiation Facility
Position
  • Researcher
Description
  • Beamline ID26
September 2008 - November 2010
European Synchrotron Radiation Facility
Position
  • PostDoc Position
Description
  • Beamline ID26
Education
June 2015 - February 2017
Université Grenoble Alpes
Field of study
  • Physics
September 2001 - September 2006
Uppsala University
Field of study
  • Physics

Publications

Publications (232)
Article
High Surface Area “3D Graphene Oxide” In article number 2200510, Nicolas Boulanger, Alexandr V. Talyzin, and co‐workers apply surface oxidation to carbon material with extremely high surface area to produce “3D graphene oxide”. This material has high oxidation degree typical for graphene oxide but also a rigid 3D structure. Hydrophilic nature, high...
Article
Here preparation of high surface area activated reduced graphene oxide (arGO) oxidized into a 3D analogue of defect‐rich GO (dGO) is reported. Surface oxidation of arGO results in carbon to oxygen ratio C/O = 3.3, similar to the oxidation state of graphene oxide while preserving high BET surface area of about 880 m2 g−1. Analysis of surface oxidize...
Article
Correction for ‘Formation of plutonium( iv ) silicate species in very alkaline reactive media’ by Paul Estevenon et al. , Dalton Trans. , 2021, 50 , 12528–12536, DOI: 10.1039/D1DT02248B.
Article
The aim of this study is to synthesize PuO2 nanoparticles (NPs) at low pH values and characterize the materials using laboratory and synchrotron-based methods. Properties of the PuO2 NPs formed under acidic conditions (pH 1-4) are explored here at the atomic scale. High-resolution transmission electron microscopy (HRTEM) is applied to characterize...
Article
Full-text available
Extended X-ray absorption fine structure (EXAFS) is a comprehensive and usable method for characterizing the structures of various materials, including radioactive and nuclear materials. Unceasing discussions about the interpretation of EXAFS results for actinide nanoparticles (NPs) or colloids were still present during the last decade. In this stu...
Article
Full-text available
Reaction of the N ‐heterocylic carbene ligand iPrIm (L1) and lithium bis(trimethylsilyl)amide (TMSA) as a base with UCl4 resulted in U(IV) and U(V) complexes. Uranium’s +V oxidation state in (HL1)2 [U(V)(TMSI)Cl5] (TMSI = trimethylsilylimido) (2) was confirmed by HERFD‐XANES measurements. Solid state characterization by SC‐XRD and geometry optimisa...
Article
Full-text available
We performed a systematic study of the complexes of trivalent lanthanide cations with the hydridotris(1-pyrazolyl)borato (Tp) ligand (LnTp3; Ln = La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu) using both high-energy-resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) and resonant inelastic X-ray scattering (...
Article
Full-text available
The uranium valence electronic structure in the prototypical undistorted perovskite KUO3 is reported on the basis of a comprehensive experimental study using multi-edge HERFD-XAS and relativistic quantum chemistry calculations based on density functional theory. Very good agreement is obtained between theory and experiments, including the confirmat...
Article
Full-text available
In recent years, scientists have progressively recognized the role of electronic structures in the characterization of chemical properties for actinide containing materials. High-energy resolution X-ray spectroscopy at the actinide M4,5 edges emerged as a promising direction because this method can probe actinide properties at the atomic level thro...
Article
Pyrrhotite Fe 1– x S is the main sulfide component of platinum-group element (PGE) ores and commonly contains from a few tenths to a few dozen ppm of disseminated Pt. Here we report an X-ray absorption spectroscopy investigation into the state of Pt in synthetic pyrrhotite in combination with theoretical spectra modelling. The pyrrhotite crystals w...
Article
Full-text available
Implantation and subsequent behaviour of heavy noble gases (Ar, Kr, Xe) in few-layer graphene sheets and in nanodiamonds is studied both using computational methods and experimentally using X-ray absorption spectroscopy. X-ray absorption spectroscopy provides substantial support for the Xe-vacancy (Xe-V) defect as a main site for Xe in nanodiamond....
Article
Yb3Co4Ge13 is the first example of a Remeika phase with a 3D + 3 [space group P4̄3n(α,0,0)000(0,α,0)000(0,0,α)000; a = 8.72328(1) Å, α = 0.4974(2)] modulated crystal structure. A slight shift of the composition towards higher Yb-content (i.e. Yb3.2Co4Ge12.8) leads to the disappearance of the satellite reflections and stabilization of the disordered...
Preprint
Implantation and subsequent behaviour of heavy noble gases (Ar, Kr, Xe) in few-layer graphene sheets and in nanodiamonds is studied both using computational methods and experimentally using X-ray absorption spectroscopy. X-ray absorption spectroscopy provides substantial support for the Xe-vacancy (Xe-V) defect as a main site for Xe in nanodiamond....
Article
Full-text available
Unusually high uranium (U) concentrations (up to 175 μg/L) have been measured in groundwater at depths between 400 and 650 m at the Forsmark site, eastern Sweden. Since it is unlikely that such high concentrations formed under the stagnant and low redox groundwater conditions that currently prevail, this study employs U-series isotopes to understan...
Article
Studying the speciation of Pu(IV) in very alkaline and silicate ions rich reactive media allowed identifying the formation of plutonium (IV)-silicate colloidal suspensions which were stable for months. These colloids were stabilized in aqueous solution for pH > 13 and for concentrations around 10-2 mol·L-1. Successive filtration process allowed eva...
Article
Full-text available
The key to fabricating complex, hierarchical materials is the control of chemical reactions at various length scales. To this end, the classical model of nucleation and growth fails to provide sufficient information. Here, we illustrate how modern X-ray spectroscopic and scattering in situ studies bridge the molecular- and macro- length scales for...
Article
Boron-rich materials combine chemical stability with refractory properties and, consequently, are interesting for high-temperature thermoelectric applications. Therefore, the magnetic, electrical, and thermal transport properties of the Y1−xCexCrB4 series have been investigated here to employ the concept of correlation-enhanced thermoelectric prope...
Article
Geological disposal is the globally preferred long-term solution for higher activity radioactive wastes (HAW) including intermediate level waste (ILW). In a cementitious disposal system, cellulosic waste items present in ILW may undergo alkaline hydrolysis, producing significant quantities of isosaccharinic acid (ISA), a chelating agent for radionu...
Preprint
Full-text available
Highly crystalline UO2 nanoparticles (NPs) with sizes of 2-3 nm were produced by fast chemical deposition of uranium(IV) under reducing conditions at pH 8-11. The particles were then characterized by microscopic and spectroscopic techniques including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), high-energy reso...
Article
Full-text available
ROBL-II provides four different experimental stations to investigate actinide and other alpha- and beta-emitting radionuclides at the new EBS storage ring of ESRF within an energy range of 3 to 35 keV. The XAFS station consists of a highly automatized, high sample throughput installation in a glovebox, to measure EXAFS and conventional XANES of sam...
Article
Highly crystalline UO2 nanoparticles (NPs) with sizes of 2-3 nm were produced by fast chemical deposition of uranium(IV) under reducing conditions at pH 8-11. The particles were then characterized by microscopic and spectroscopic techniques including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), high-energy reso...
Article
Pd(II) chloride complexes were anchored using magnesium-aluminum layered double hydroxides (LDHs) with interlayer anions (CO32– and OH–), which possess different exchange properties, and MgAl mixed oxide during its rehydration. It was shown that the catalysts of the same chemical composition with different size, morphology and electronic state of s...
Article
Invited for the cover of this issue is Lucia Amidani and co‐workers from the The European Synchrotron, Helmholtz Zentrum Dresden‐Rossendorf, Lomonosov Moscow State University, Kurchatov Institute, and the Université Grenoble Alpes. The image depicts the atomic structure of the sample being viewed through “atomic googles”, which represent the X‐ray...
Article
Oh, now I see! The precipitates formed during ThIV hydrolysis are ThO2 nanoparticles, which in their initial stages of formation are a mixture of ultra‐small nanoparticles and Th hexamer clusters. This new structural insight is made possible by the combined use of two synchrotron techniques: HEXS and XANES in HERFD mode, which probe short‐ and medi...
Preprint
A general strategy for the determination of Tc oxidation state by new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3 edge is shown. A comprehensive series of 99Tc compounds, ranging from oxidation states I to VII, was measured and subsequently simulated within the framework of crystal-field multiplet theory. The obs...
Preprint
Full-text available
Understanding the complex chemistry of functional nanomaterials is of fundamental importance. Controlled synthesis and characterization at the atomic level is essential to gain deeper insight into the unique chemical reactivity exhibited by many nanomaterials. Cerium oxide nanoparticles have many industrial and commercial applications,resulting fro...
Preprint
Developing characterization techniques and analysis methods adapted to the investigation of nanoparticles (NPs) is of fundamental importance considering the role of these materials in many fields of research. The study of actinide based NPs, despite their environmental relevance, is still underdeveloped compared to that of NPs based on stable and l...
Preprint
Structural characterization of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non-homogeneous samples with NPs below 3 nm. By combining High Energy X-ray Scattering (HEXS) and High-Energy-Resolution Fluorescence Detected X-ray Near-Edge Structure (HERFD XANES), we characterized for the first time both shor...
Preprint
Full-text available
Valence band electronic structure of mixed uranium oxides (UO2, U4O9, U3O7, U3O8, UO3) has been studied by the resonant inelastic X-ray scattering (RIXS) technique at the U M5 edge and by computational methods. We show here that the RIXS technique and recorded U 5f-O 2p charge transfer excitations can be used to proof the validity of theoretical ap...
Preprint
Full-text available
The nanoscience field often produces results more mystifying than any other discipline. It has been argued that changes in the plutonium dioxide (PuO2) particle size from bulk to nano can have a drastic effect on PuO2 properties. Here we report a full characterization of PuO2 nanoparticles (NPs) at the atomic level and probe their local and electro...
Preprint
Full-text available
Eu$^{2+}$ is used to replace toxic Pb$^{2+}$ in metal halide perovskite nanocrystals (NCs). The synthesis implies injection of cesium oleate into a solution of europium (II) bromide at an experimentally determined optimum temperature of 130C and a reaction time of 60s. Structural analysis indicates the formation of spherical CsEuBr$_3$ nanoparticle...
Preprint
Full-text available
The chemical properties of actinide materials are often predefined and described based on the data available for isostructural species. This is the case for potassium plutonyl (PuVI) carbonate, K4PuVIO2(CO3)3(cr), a complex relevant for nuclear technology and the environment, of which the crystallographic and thermodynamic properties of which are s...
Preprint
Full-text available
Intrinsic properties of a compound (e.g., electronic structure, crystallographic structure, optical and magnetic properties) define notably its chemical and physical behavior. In the case of nanomaterials, these fundamental properties depend on the occurrence of quantum mechanical size effects and on the considerable increase of the surface to bulk...
Preprint
Full-text available
We investigate the origin of satellite features that appear in the high-resolution x-ray absorption spectra measured at the uranium M 4 edge in compounds where the uranium atoms are in the U 6+ oxidation state. We employ a material-specific Anderson impurity model derived from the electronic structure obtained by the density-functional theory.
Preprint
Full-text available
Herein, a multi-technique study was performed to reveal the elemental speciation and microphase composition in altered granitic rock collected from the Krunkelbach Valley uranium (U) deposit area near an abandoned U mine, Black Forest, Southern Germany.
Preprint
Full-text available
Computational modeling is an important aspect of the research on nuclear waste materials. In particular, atomistic simulations, when used complementary to experimental efforts, contribute to the scientific basis of safety case for nuclear waste repositories. Here we discuss the state-of-the-art and perspectives of atomistic modeling for nuclear was...
Preprint
Full-text available
The facile chemical precipitation method and subsequent thermal treatment were shown to be suitable for preparation of crystalline ThO2 nanoparticles(NPs) in a wide range of particle sizes (from 2.5 to 34.3 nm). The obtained NPs were investigated with X-ray diffraction, high-resolution transmission electron microscopy, and X-ray absorption techniqu...
Preprint
Full-text available
The sorption of radionuclides by graphene oxides synthesized by different methods was studied through a combination of batch experiments with characterization by microscopic and spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), attenuated total reflection fourier-transform infrared spectroscopy (ATR-FTIR), high-energy resolut...
Article
Full-text available
The distortion of atomic structure around In and Cu dopants in sphalerite ZnS was explored by extended X-ray absorption fine structure (EXAFS) spectroscopy enhanced by reverse Monte Carlo (RMC) simulation (RMC-EXAFS method). These data were complemented with quantum chemical Density Functional Theory (DFT) calculations and theoretical modeling of X...
Article
Full-text available
Structural characterization of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non-homogeneous samples with NPs below 3 nm. By combining High Energy X-ray Scattering (HEXS) and High-Energy-Resolution Fluorescence Detected X-ray Near-Edge Structure (HERFD XANES), we characterized for the first time both shor...
Article
Full-text available
Extremely defect graphene oxide (dGO) is proposed as an advanced sorbent for treatment of radioactive waste and contaminated natural waters. dGO prepared using a modified Hummers oxidation procedure, starting from reduced graphene oxide (rGO) as a precursor, shows significantly higher sorption of U(VI), Am(III) and Eu(III) compared to standard grap...
Article
The chemical properties of actinide materials are often predefined and described based on the data available for isostructural species. This is the case for potassium plutonyl (PuVI) carbonate, K4PuVIO2(CO3)3(cr), a complex relevant for nuclear technology and the environment, of which the crystallographic and thermodynamic properties of which are s...
Article
Full-text available
Uranium (U) is a ubiquitous element in the Earth’s crust at ~2 ppm. In anoxic environments, soluble hexavalent uranium (U(VI)) is reduced and immobilized. The underlying reduction mechanism is unknown but likely of critical importance to explain the geochemical behavior of U. Here, we tackle the mechanism of reduction of U(VI) by the mixed-valence...
Article
Full-text available
The oxidation state and local atomic environment of admixtures of In, Cu, and Ag in synthetic sphalerite crystals were determined by X-ray absorption spectroscopy (XAS). The sphalerite crystals doped with In, Cu, Ag, In-Cu, and In-Ag were synthesized utilizing gas transport, salt flux, and dry synthesis techniques. Oxidation states of dopants were...
Article
Full-text available
A first general strategy for the determination of Tc oxidation state by new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3 edge is shown. A comprehensive series of 99Tc compounds, ranging from oxidation states I to VII, was measured and subsequently simulated within the framework of crystal-field multiplet theory. T...
Article
Full-text available
The nanoscience field often produces results more mystifying than any other discipline. It has been argued that changes in the plutonium dioxide (PuO2) particle size from bulk to nano can have a drastic effect on PuO2 properties. Here we report a full characterization of PuO2 nanoparticles (NPs) at the atomic level and probe their local and electro...
Article
Full-text available
Herein, a multi-technique study was performed to reveal the elemental speciation and microphase composition in altered granitic rock collected from the Krunkelbach Valley uranium (U) deposit area near an abandoned U mine, Black Forest, Southern Germany. The former Krunkelbach U mine with 1–2 km surrounding area represents a unique natural analogue...
Article
In a lithium/sulfur (Li/S) battery, the reduction of sulfur during discharge involves a particular mechanism, where the active material successively dissolves into the electrolyte to form lithium polysulfide intermediate species (Li2S x ), with x being a function of the state of charge. In this work, sulfur K-edge resonant inelastic X-ray scatterin...
Presentation
Full-text available
Invited contribution after selection of the corresponding article as an ACS Editor's Choice on March 11, 2020. The voice-over presentation provides an overview of the main outcomes of the published research. DOI of the corresponding article: 10.1021/acs.inorgchem.9b03702. The presentation can also be viewed directly from the publisher's website: ht...
Article
Intrinsic properties of a compound (e.g., electronic structure, crystallographic structure, optical and magnetic properties) define notably its chemical and physical behavior. In the case of nanomaterials, these fundamental properties depend on the occurrence of quantum mechanical size effects and on the considerable increase of the surface to bulk...
Article
Full-text available
A comprehensive analysis of X-ray absorption data obtained at the U L3-edge for a systematic series of single-valence (UO2 , KUO3 , UO3) and mixed-valence uranium compounds (U4O9 , U3O7 , U3O8) is reported. High-energy resolution fluorescence detection (HERFD) X-ray absorption near-edge spectros-copy (XANES) and extended X-ray absorption fine struc...
Article
Computational modeling is an important aspect of the research on nuclear waste materials. In particular, atomistic simulations, when used complementary to experimental efforts, contribute to the scientific basis of safety case for nuclear waste repositories. Here we discuss the state-of-the-art and perspectives of atomistic modeling for nuclear was...
Article
Full-text available
Rivers discharge a notable amount of dissolved Fe (1.5×109 mol yr−1) to coastal waters but are still not considered important sources of bioavailable Fe to open marine waters. The reason is that the vast majority of particular and dissolved riverine Fe is considered to be lost to the sediment due to aggregation during estuarine mixing. Recently, ho...