2026-06-13
00:01 |
Thermally Induced Transformation of Nickel-Fullerene Hybrid Assembly
Vacík, Jiří ; Ceccio, Giovanni ; Lavrentev, Vasyl ; Lavrenteva, Inna ; Takahashi, K.
Metal-fullerene composites represent a specific class of materials exhibiting interesting properties. However, the thin hybrid assemblies are thermodynamically unstable, thus the destructive processes such as thermal annealing can change their structure and properties.In this work, the thermal stability of nickel-fullerene composites was investigated over a broad temperature range. The evolution of the samples was monitored using Neutron Depth Profiling, Rutherford backscattering, micro-Raman spectroscopy and Scanning Electron Microscopy. The results showed that the hybrid films exhibit phase transformation upon heating, which leads to a dramatic change in their structure and in formation of a new self-assembled material.
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2026-06-13
00:01 |
Synthesis and Modification of Thin NaSICON Solid Electrolytes Using Ion Beams
Ceccio, Giovanni ; Vacík, Jiří ; Mastronardo, I. ; D'Urso, C. ; Štěpanovská, Eva ; Mikšová, Romana
Solid electrolytes (SEs) for sodium-based superionic conductors (NaSICON) were first introduced in 1976 and quickly recognized for their excellent ionic conductivity. While considerable effort has been made to develop thin electrolytes for all-solid-state batteries (ASSBs), only a few sodium-based SEs have been successfully fabricated as thin films. These thin films are particularly desirable for their reduced electrical resistance, which typically increases with the thickness of the SE. By reducing the thickness of the SEs to the nanometer scale, their ionic conductivity can be significantly enhanced.In this study, the NASICON composite was initially prepared in the form of pellets using the mixed oxide technique with a planetary ball mill and synthesized by the solid-state method at 1300 °C. The resulting pellets were used as sputtering targets in a low-energy ion facility to prepare continuous NASICON nanofilms. To explore the effect of ion implantation on the electrical properties of NASICON, the prepared films were bombarded with Ni ions at 1.1 MeV and varying fluences, using the Tandetron accelerator at the CANAM infrastructure (NPI Řež). The electrical properties of both the synthesized and implanted films were analyzed through electrochemical impedance spectroscopy (EIS). The results, describing the impact of irradiation on NASICON's properties, are presented here.
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2026-06-13
00:01 |
Physical principles of Crosslinking of Water-Soluble Polymers for Tissue Engineering
Strnadová, K. ; Lisnenko, M. ; Agazarian, A. ; Chvátil, David ; Matějů, Š. ; Mikule, J. ; Jenčová, V.
hysical crosslinking of water-soluble polymers is a promising route for creating highly pure and biocompatible hydrogel scaffolds, offering an advantage over methods that use potentially cytotoxic chemical reagents. This study investigated the effectiveness of heat treatment and β-electron irradiation for the physical crosslinking of electrospun nanofibrous scaffolds / hydrogel disks derived from synthetic polymer - polyvinyl alcohol (PVA) and natural polymer - gelatin (GEL), focusing on material stability and cytocompatibility. PVA and GEL samples were fabricated and subsequently subjected to either heat treatment or β-electron irradiation before being characterized for morphology, water-solubility, and cytotoxicity (ISO 10993). Both physical methods were found not to significantly alter the nanofiber morphology. Crucially, β-electron irradiation failed to crosslink dry samples, which immediately dissolved, revealing that the presence of water is essential for this crosslinking mechanism. Biologically, physically crosslinked GEL nanofibers demonstrated excellent cell viability, while irradiated PVA nanofibers exhibited unexpected cytotoxicity. Otherwise, cell proliferation with PVA samples was unaffected, compared to GEL samples. Cell adhesion assays were inconclusive and require further investigation. These findings highlight that while physically crosslinked water-soluble polymers are good scaffold candidates, optimizing irradiation conditions, particularly by ensuring proper hydration, is critical for developing stable and functional scaffolds for tissue engineering applications.
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2026-06-13
00:01 |
Study of LAGP Coating on Polythylene Separator for Polysulfide Suppression in Thin Li-S Batteries
Ceccio, Giovanni ; Vacík, Jiří
The use of a thin solid electrolyte layer on polyethylene (PE) separators has been explored as a potential strategy to mitigate the polysulfide shuttle effect in lithium-sulfur (Li-S) batteries, a phenomenon responsible for significantly reducing their lifespan. While some solid electrolytes, such as LAGP (Li1+xAlₓGe2-x(PO4)3), have demonstrated the ability to effectively suppress the shuttle effect, their brittle ceramic nature limits their application, particularly in flexible electronics. Coating PE separators with LAGP nanofilms offers a promising solution by combining the mechanical flexibility and thinness of polymer separators with the electrochemical advantages of LAGP, due to its NASICON-like structure and high ionic conductivity. In this study, PE separators were coated with LAGP nanofilms using the ion sputtering technique and further modified with ferroic elements such as Ni and Co. The surface morphology of the coated separators was analyzed using scanning electron microscopy (SEM), and staircase voltammetry was employed to evaluate the electrochemical performance and modifications induced by the coatings. The results demonstrate that the use of PE separators with a thin LAGP layer significantly influences polysulfide diffusion and suppresses the shuttle effect, thereby reducing unwanted processes in Li-S batteries.
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2026-06-13
00:01 |
Rutherford Backscattering for Evaluation of Porosity Distribution in Thin Black Silver Film
Havránek, Vladimír ; Kejzlar, J. ; Vacík, Jiří ; Ceccio, Giovanni ; Mikšová, Romana ; Fink, Dietmar ; Vrňata, M.
The determination of porosity in thin, highly porous films is essential for many technological applications. For evaluating the porosity of materials, various methods have been developed. In this study, Rutherford Backscattering was used to analyze a thin layer of black silver at several angles of the probing beam. Through careful simulation of the energy spectra using a MC SIMNRA code, depth profiles of the constituent atoms were determined, enabling the quantification of both the total and directional relative occupancy of Ag in the layer. This provided a new (albeit simplified) perspective on the porous structures, allowing for the evaluation of Ag porosity distribution within the layer. The samples were prepared at the University of Chemistry and Technology in Prague (UCT Prague) by evaporating silver in an Ar ambient atmosphere, while the RBS analyses were conducted at the Tandetron accelerator at the Nuclear Physics Institute in Řež using a 2 MeV alpha particle beam.
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2026-06-13
00:01 |
Study of Li Behaviour in All Solid-State Li-S Half Cell
Vacík, Jiří ; Ceccio, Giovanni ; Mikšová, Romana
The effect of a thin Ni barrier layer on Li diffusion - deposited between the solid electrolyte and the cathode - was investigated using Neutron Depth Profiling (NDP) and complemented by Rutherford Backscattering Spectrometry (RBS) for elemental depth distribution analysis. Half-cells consisting primarily of a LiPON solid-state electrolyte, MoS₂ cathode, and a top Au current collector were fabricated on Ti substrates via ion beam sputtering. Selected samples were prepared specifically to examine the potential impact of the Ni barrier on Li transport. While Ni is often proposed to suppress the shuttle effect in Li–S batteries, its influence on Li⁺ ion diffusion remains poorly understood. The study showed that the Ni interlayer may hinder the diffusion of Li - S complexes between electrodes, suggesting a potential strategy to mitigate the shuttle effect and enhance Li - S battery performance. However, the observed effects are not yet conclusive and require further experimental validation.
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2026-05-09
00:01 |
On a Possibility of High-Resolution Neutron Diffraction Studies of High-Entropy Ceramics Substructure
Mikula, Pavol ; Ryukhtin, Vasyl ; Dusza, J.
In our contribution we present the methodology results of the feasibility of using high-resolution neutron scattering for studies of some additional substructure parameters of the samples of H-E (High-Entropy) ceramics in relation to their technological preparation. For demonstration we used 4 different samples, namely, 2 monocarbides HfC and TAC and 2 H-E carbides HEC1-(Hf-TaZr-Nb)C and HEC2-(Mo,Nb,Ta,V,W)C. The neutron diffraction results could be used in some special studies exploiting diffraction line profile analysis for e.g. micro-strain/micro-stress analysis of plastically deformed samples, determination of possible phases having very close values of the lattice spacings. On the other hand, the small-angle scattering provides the results e.g. mean radius of pores, size distribution of inhomogeneities in the homogeneous matrix. The samples were of the half-moon disc of the diameter of ϕ = 15 mm and the thickness from 1.1 mm to 1.7 mm.
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2025-12-16
16:40 |
The Effects of β-irradiation on Electrospun Polycaprolactone Fibres
Mikule, J. ; Sivan, M. ; Madheswaran, D. ; Chudobová, E. ; Hauzerová, Š. ; Chvátil, David ; Olšanský, Václav ; Běhálek, L. ; Kuželová Košťáková, E. ; Lukáš, D.
Microplastics originating from the degradation of plastic waste are considered a global concern for the environment, with microplastic fibres from synthetic textiles being responsible for the majority of microplastic pollution. Over the past few decades, there has also been a notable increase in the production of synthetic polymeric materials in the form of nanofibers for various applications. Despite this fact, knowledge in the field of aging of nanofibrous materials is very limited. To evaluate the effects of polymer aging, accelerated aging techniques involving high-energy irradiation are commonly used. This work focuses on the impact of β-irradiation on electrospun polycaprolactone nanofibers. Polycaprolactone (PCL) is a semicrystalline biodegradable polyester widely used in medical applications. Thus, any potentially formed fiber fragments pose less risk to the environment and health compared to non-biodegradable counterparts. The impact of irradiation was evaluated in terms of the mechanical properties of the prepared nanofibrous mats. Additionally, the effects on fibre morphology and crystallinity were assessed, as well as the impact of irradiation on the biocompatibility of the material.
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2025-12-16
16:40 |
Comparison of Lu.sub.3./sub.Al.sub.5./sub.O.sub.12./sub.:Ce(Er) Bulk and Nono Single Crystals
John, David ; Volf, J. ; Bartosiewicz, K. ; Horiai, T. ; Kamada, K. ; Yoshikawa, A. ; Remeš, Z. ; Landová, L. ; Ledoux, G. ; Houel, J. ; Prokhorov, Andriy ; Buryi, Maksym
Lutetium aluminum garnet (LuAG) is a crystal well known for being extraordinarily useful for building highly efficient laser devices or ionizing radiation detectors. To design the most favourable physical properties, different dopants and synthesis methods are constantly developed, primarily focused on the advantages of single crystals. However, the downscaling of the luminescent materials to nanosize also creates additional benefits of increased surface to volume ratio and thus, the efficiency of luminescence or doping can be improved. Therefore, the aim of this work is to compare the single crystals and nanogarnets under the influence of Ce and Er doping. Optical properties of the garnet single crystals are very well known while the nanocrystals should have been studied first. Synergy methods like X-ray diffraction (XRD), photoluminescence (PL), photothermal deflection spectroscopies (PDS) were applied to the LuAG:Ce(Er) nanocrystals whereas the electron paramagnetic resonance (EPR) measurements were carried out in both single and nanocrystals. The main conclusion is that cerium enters nanocrystalline lattice becoming Ce4+ compensated by the Cr2+, Fe2+ ions (accidental impurities) whereas it is also Ce3+ in the single crystal. About one order of magnitude larger Er3+ content was observed in the case of nanocrystals as compared to single crystals.
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2025-03-02
00:01 |
High-resolution neutron diffraction for finer studies of powder diffraction lines
Mikula, Pavol ; Ryukhtin, Vasyl
Feasibility of focusing high-resolution three axis diffractometer with the polycrystalline sample between the monochromator and the analyzer for studies of finer effects of diffraction lines is routinely used at the medium-power reactor LVR-15 in Řež. The focusing three-axis set-up equipped with bent perfect crystal monochromator and analyzer exploits both focusing in real and momentum space and provides the intensity and resolution parameters for measurements within a reasonable measurement time.
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