Neutron Researches https://wigner.hu/en en Research - Nanostructure Research https://wigner.hu/hu/node/961 <span class="field field--name-title field--type-string field--label-hidden">Research - Nanostructure Research</span> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><h4><strong>2018</strong></h4> <p>The research group has been involved in several research projects and various user measurements performed at the neutron scattering instruments operated by the members of the Group: Small Angle Neutron Scattering instrument, Time of Flight spectrometer, Three-axis spectrometer, Reflectometer and PSD Diffractometer. Some of the results are specified below.<br /> <br /> <strong>A novel approach in the mineralogy of Carpathian mahogany obsidian using complementary methods</strong><br /> The study of Carpathian obsidians has been performed with the aid of multidisciplinary approach. Carpathian obsidians have various macroscopic features. They are typically black or grey and their transparency ranges from clear to opaque. The Tolcsva source, very rarely, can yield brown or red (‘mahogany’ type) obsidian. In 2007, the exact location of the red variant's outcrop was identified on the Szokolya hill (Tolcsva). In order to understand the possible reasons for the colouring of red obsidian a multiple methods approach has been used for the analysis of the samples. For comparison, other Carpathian type, namely black obsidian from Tolcsva, and red obsidian from Bogazkoy (Anatolia) were also studied. The measurements were carried out in collaboration with the MTA Centre for Energy Research groups and the Hungarian National Museum PGAA measurements of the bulk elemental composition. Mössbauer spectroscopy and transmission electron microscopy (TEM) were used to identify the presence of ferrous or ferric iron. We used small angle neutron scattering (SANS) for characterization of the nanostructure, measuring their anisotropy and surface or volume fractal dimensions. Black obsidians showed isotropy, while mahogany samples displayed a considerable anisotropy in the bulk pore orientation (Figure 1). According to our results, a large amount of the iron is dominantly located in different phases in the case of mahogany and black obsidians. The differences between the red and black variants could be also explained by the different oxidation states of the Fe-ions, which may explain the colour difference.<br /> <br /> <img alt="dz1" data-entity-type="file" data-entity-uuid="e45ad334-cafb-4925-ac0e-547c6583d82a" height="249" src="https://wigner.hu/sites/default/files/inline-images/DZ1.jpg" width="623" /><br /> <br /> <em><strong>Figure 1.</strong> 2D scattering pattern of Tolcsva mahogany (a) and Bogazkoy mahogany (b) samples, measured on the FSANS instrument.</em></p> <p><strong>Study on polyester - carbon nanotube – graphite composites by small angle neutron scattering.</strong> - Polymer nanocomposites prepared by carbon nanotube (CNT) addition were first reported in 1990’s. Since then a great number of scientific papers have been published on this topic, however the great differences between the CNT’s produced by different companies, the aggregation and surface characteristics of the CNT fillers, the amount of impurities and defects makes the comparison of the results difficult. The fractal dimension of fracture surfaces or of the bulk volume of prepared nanocomposites is linked to the strength, thermal and electrical conduction properties etc. of them. The studies carried out and the description of physical characteristic of the polymer composites lead to a better understanding of the relation between the nano- and macro-characteristics, and to a more relevant comparison of the composites prepared by different laboratories and companies.<br /> Samples with various MWCNT and graphite additives were prepared in collaboration with a research group from Morocco, with the aid of a clean, economical and environmental friendly method. Small angle neutron scattering experiments on the samples were carried out at Yellow Submarine and FSANS instruments located at the Budapest Research Reactor. Nanostructural characteristics of the prepared ternary composites (such as the size distribution and agglomeration of the additives, and their fractal characteristics) were determined, that contributed to the better understanding of macroscopical characteristics of these composites.<br /> <br /> <strong>Synthesis and characterization of a polyurethane carrier used for a prolonged transmembrane transfer of a chili pepper extract. </strong>- Red chili peppers have been highly valued in gastronomy and traditional medicine since ancient times. In collaboration with the University of Medicine and Pharmacy, Timisoara a complex study on the characterization of a new carrier used for encapsulated extract has been performed.<br /> Chili pepper extract was obtained and was physically entrapped inside polyurethane microparticles in order to diminish the irritative potential of this extract. The particles morphology was evaluated by various methods, among them small-angle neutron scattering and scanning electron microscopy (SEM) were performed by our group. SEM images indicated no difference between the capsaicin loaded and capsaicin free samples; in both cases the formation of 50–100 µm clusters was visible (Figure 2), and SANS indicated no differences in the nanometer scale either. <br /> <br /> <img alt="dz2" data-entity-type="file" data-entity-uuid="f5b8d1b5-276a-4bc3-a1f2-098cb455a00f" height="560" src="https://wigner.hu/sites/default/files/inline-images/DZ2.jpg" width="579" /><br /> <br /> <em><strong>Figure 2. </strong>SEM images of capsaicin loaded (right) and capsaicin free (left) samples.</em><br /> <br /> The encapsulation efficacy and the drug release profile were assessed by UV-Vis spectroscopy. Bioevaluations on mice skin were performed to predict the irritative potential of the samples. The encapsulation of a chili pepper extract inside polyurethane microparticles lead to a non-irritative product with a prolonged release: ~30% of encapsulated extract is released within the first 8 days and a maximum 45% is reached in 2 weeks.<br /> <br /> <strong>Mesoporous silica materials for different applications.</strong> - Various types of templated silica materials have been synthesized and studied by small-angle neutron and X-ray scattering methods. Functionalization of the pore surfaces has been achieved using simple co-condensation of two precursors, with variation of the reaction conditions, or in multistep method by subsequent treatment of the templated porous silica by organic precursors. The method of preparation, and the type of additives determine the performance of the materials in different applications. Sorption studies of guest molecules and heavy metals have been performed and the performance of the materials have been optimized for achieving maximal adsorbance, and for the control of the release rate of drug molecules.<br /> Silica based aerogels hybridized with biomolecules (proteins or polysaccharides) are also promising platforms for drug delivery applications. The composition, the pore structure and the hydrophobicity of the biopolymer aerogel predetermines the main properties, each fundamental in drug delivery applications. These properties will determine the release profile (desorption kinetics) of the drugs from the delivery system. By understanding the key factors which connect the structure to the application, a systematic approach has been developed in designing and fine-tuning hybrid aerogel based drug delivery systems. SANS measurements monitored the deformation and the hydration of the aerogel structure upon interaction with water. In order to visualize the silica matrix and the gelatin phase the samples were measured in various H<sub>2</sub>O/D<sub>2</sub>O concentrations, in order to match the silica or the gelatin content. The measurements on half and fully saturated samples proved that the hydration of the samples did not affect the silica skeleton, and the pore structure.<br /> <br /> <strong>Structural characterization of chalcogenide systems. </strong>- Neutron- and X-ray diffraction techniques were used to study the atomic glassy structure and Reverse Monte Carlo simulations were applied to model the 3-dimensional atomic configurations and thorough mapping of the atomic parameters, of the 3-components Ge-Sb-Se and 4-components As-Se-Sb-Te chalcogenides. We determined the short-range order of the amorphous Ge-Sb-Se system.  From diffraction measurements it was revealed that the short-range order is formed by the fulfillment of the 8-N1 rule (germanium has 4, antimony has 3 and selenium has 2 neighbors) and the presence of the chemical order (germanium and antimony bonds primarily to the selenium atom). We found that in case of the As-Se-Sb-Te system, the 8-N rule is not fulfilled for all atoms. The As and Sb atoms have three neighbors, connected to the mixed Te and Se atoms. The glassy network builds up from pyramid units, connected through 2-coordinated Se and Te atoms.<br /> <br /> <strong>Interfacial roughness correlation in multilayers.</strong> – Interface roughness and correlation properties of magnetron sputtered Ni-Ti multilayers were investigated by off-specular x-ray and neutron scattering. GISAS (Grazing Incidence Small Angle Scattering) measurements were performed in order to complement our reflectometry results. The aim of the experiments was to check whether the interface roughness auto- and cross-correlation can be described by the in-plane and out-of-plane correlation lengths and Hurst-exponent. In the case of X-ray GISAS on periodic samples we had to modify the linear approximation in the frames of Distorted Wave Born Approximation for large scattering angles and roughness. Taking into account the non-linear terms we showed the limitations of the linear approximation which can lead to erroneous interpretation of experimental results in respect to the value of the in-plane correlation length and the wavelength dependence of roughness replication. Neutron GISAS experiments (Garching, FRM II) revealed non-isotropic roughness in neutron supermirrors and presence of two different length scale roughness components. Consequently we have to modify the roughness models generally used for mirror analyses.). <br /> <br /> <strong>Investigation of Willemite with different ions added.</strong> - Zn<sub>2</sub>SiO<sub>4</sub>, trigonal, R3, with hexagonal axes: a =13.948 (2), c = 9.315 (2)A, Z= 18, Dx = 4.224 gcm -3,st(Cu K<t) = 197.3 cm-L The structure of Willemite has been refined by Rietveld method  to an R value of 0.032 for a powder samples was achieved.<br /> The addition of different ions creates color centers in Willemite, making it a good luminophore powder. The treatment of addition of ions can be processed by a high temperature thermal dry way or a newly discovered low temperature wet treatment. One of the goals was the check the result of the new treatment and to obtain accurate atomic parameters in order to provide a structural basis for the evaluation of the optical properties of Willemite. <br /> By combined use of neutron and X-ray diffraction we could determine that the different metallic ions are built in different way. Some of them created a separate phase, (Ce, Eu) some of them could to built in the original Willemite structure (Mn, Tb).<br /> <br /> <strong>Characterisation of forming techniques and firing temperatures of archaeological ceramic artefacts. </strong>- Neutron tomography experiments on archaeological and experimental reference samples have been performed at the RAD instrument of the Budapest Neutron Centre. The aim of the project was to investigate the suitability of non-destructive neutron computer tomography as a means for identifying the forming techniques used in the production of ancient organic-tempered pottery. Specifically, it aimed to create a three-dimensional (3D) model of the distribution of the voids/carbonised particles left within the ceramic matrix resulting from the complete or partial combustion of organic fibres within samples of ancient pottery and modern replicas. Through statistical analysis of the orientation of these fibrous voids/particles in 3D space the preferential alignments were detected, which in turn correlates with suspected or known forming techniques. This information can be used to further refine the detection of preferential particle alignments by more conventional and cheaper methods, in particular by petrographic analysis of ceramic thin sections.<br /> <br /> A new, systematic and larger set of investigated samples (36 samples from 3 geological sources, 12 different firing temperatures between 500°C and 1000°C) and archaeological samples (12 samples from Keszthely, Hungary) have been measured at the Yellow Submarine and F-SANS instruments of the Budapest Neutron Centre in order to determine the correlation between the maximum firing temperature of the ceramic materials and the Porod exponent gained from the SANS measurements. Previous experiments on a smaller set of samples had already shown linear dependency between the maximum firing temperature and the SANS curves, therefore, the main objective of the new experiments were to 1) examine whether the aforementioned linear dependency only applies to a certain range of firing temperatures and 2) how clays from different geological sources correlate to each other. Our results show that the linear dependency can be observed between 550°C and 950°C, which might be explained by the mineral phase transitions and vitrification occurring in this range of temperatures. Clays from different geological origins, while displaying linear temperature dependency, show different levels of the power exponent – firing temperature master curves. These findings reveal the possibility to identify the characteristic processing temperatures at different provenances of the clay artifacts, after performing an extensive calibration of the SANS data using local reference samples.</p> <p><strong>Time of flight neutron diffraction (TOF-ND) analysis of Late Bronze Age metallic artifacts:</strong><br /> <br /> As a member of "Momentum Mobility research team" (From bones, bronzes and sites to society: Multidisciplinary analysis of human mobility and social changes in Bronze Age Hungary (2500–1500 BC), <a href="http://mobilitas.ri.btk.mta.hu">http://mobilitas.ri.btk.mta.hu</a>) György Káli has investigated several sets of finds, especially bronze weapons and jewelry items from the Carpathian Basin. The tests covered the phase compositions, chemical distributions, preferred orientations and dislocation densities of the alloys to unfold the manufacturing techniques. These pieces of information are great help for the archeology and historical sciences to determine the social, cultural and trade links between distant regions of the given period.<br /> <br /> <strong>Other archaeometric investigations:</strong> As participants of the IPERION CH (Integrated Platform for the European Research Infrastructure ON Cultural Heritage) project we have performed a large set of neutron diffraction studies in various fields (ancient metal, ceramic and other objects). <br /> <strong>Study of oriental and European carbon steel swords (Iperion)</strong>: Earlier we have shown that the oriented distribution of cementite inclusions is a very efficient resource for the sorting of steels produced by different forging techniques. Besides that, texture and stress analyses have been performed on the ferrite phase as well on a large set of samples from several European collections. These non-destructively gained results on the sample bulk are very helpful to the archaeo-metallurgists to unfold the medieval steel production techniques.<br /> <strong>The 'Budapest Horse':</strong> A comprehensive technical investigation has been performed on the world-famous statuette called Budapest Horse and Rider attributed to Leonardo da Vinci. This small bronze of the Budapest Museum of Fine Arts was taken first in 2017 to the BNC to carry out non-destructive experiments to collect new information on the inside of both parts. Now PGAA and widespread neutron diffraction analyses have been performed. For that, two new detector banks have been installed to the TOF beam. A normal (90°) and a reversed one on the opposite side, for diffraction tomography. Our results – of major international interest in the light of the investigations performed in the Washington National Gallery of Art in 2009 – will be published soon.</p> <p> </p> <h4><strong>2018</strong></h4> <p><strong>Neutron instrumentation development </strong>—Our group contributes to the Europen Spallation project by designing and delivering neutron optical components for the instruments. The NMX instrument is one ot those instruments where significant Hungarian contribution was delivered. The NMX instrument is a macromolecular single crystal time of flight diffractometer. The instrument has the length of 160m to be able to use the full pulse of ESS (2.76ms). The neutron guide system of the instrument has to transport the "useful" neutrons - reaching the maximum 0.5cm large sample within 0.4o  total divergence - with high efficiency. In order to avoid the background caused by the fast neutrons, and to decrease the cost of shielding the beam has to go out of line of sight within 24.5m i.e. before the inner surface of the bunker built to stop the energetic neutrons (up to 2GeV). The original guide design of NMX consisted of a curved part until 24.5m, and a straight one with the cross section of 3X3 cm<sup>2</sup>. We developed a calculation method for the loss due to the imperfectness of the neutron guide system - waviness and the misalignments of the mirrors. The results show that almost half of the beam will be lost in the original guide. The neutron loss can be avoided by applying the so called ballistic guide i.e. a guide system with  diverging - straight - focusing sections. After the curved section the divergence of the neutron beam is decreased with a diverging segment, then a long, ~100m straight guide with larger (4.5X4.5 cm<sup>2</sup>) cross section results more than two times less reflection in the guide, finally a parabolic focusing section focuses the beam onto the small sample. Since the curvature of the guide is horizontal, vertically the diverging section is already at the beginning of the guide system. To decrease the effect of the inhomogeneity and position dependent divergence caused by the simple curved guide, the horizontal diverging part is asymmetric, the the outer side (convex side in the curved region) of the guide after the curved section is diverging while the inner part goes parallel with the main beam in the first 3.5m and then starts to diverge. With these modifications the transmission of the guide increased over 85%.<br /> <br /> Beside the NMX instrument we took part in the design of two other instruments at ESS: the BIFROST instrument is an indirect geometry inelastic spectrometer optimized for extreme environment (high fields, low temperature, high pressure etc.) where the vertical divergence of the scattered neutrons is limited by the sample environment. We took part in the optimization of the chopper and analyser system of the instrument. The MIRACLES instrument is also an indirect geometry inelastic spectrometer, a so called time of flight backscattering spectrometer for investigation of slow changes like diffusion, low energy excitations etc. We took part in the design of the radial collimator system (around the sample) which reduces the background of the measurement.<br /> <br /> Members of the group actively contributed to the fulfillment of the EU-H2020 BrightnESS project, including the development of a 2D position sensitive neutron detector with solid boron converter and the main components (bench, choppers, mask with pinhole) of the ESS Test Beam Line, dedicated to energy sensitive imaging of the cold neutron moderator. The chopper of the instrument is shown in Fig. 1. This equipment is expected to be the first instrument to receive neutrons and experimentally assess the performance of the low dimensional moderator, initially proposed by Ferenc Mezei and implemented for the first time at ESS. A prototype of the equipment has been applied to map the energy-dependent brightness of the cold moderator at the Budapest Research Reactor as well as at the JEEP II reactor of IFE at Kjeller, Norway.<br /> <br /> <em><img alt="sza1" data-entity-type="file" data-entity-uuid="0dba39dd-a4b8-413f-b6a2-42297240e24e" height="555" src="https://wigner.hu/sites/default/files/inline-images/SZA1.jpg" width="370" /><br /> <br /> <strong>Figure 1. </strong>The chopper and positioning sytem of the ESS Test Beam Line.</em><br /> <br /> Our group was part of the organizers and lecturers of the 12th Central European Training School on Neutron Techniques (CETS2018), which provided insight into neutron scattering and imaging techniques and their application for studies on structure and dynamics of condensed matter. An important mission of the school is to illustrate the multifarious neutron research potential towards higher education, academy and industry.</p> <p> </p> <h4><strong>2017</strong></h4> <p>The research group has been involved in several research projects and various user measurements performed at the neutron scattering instruments operated by the members of the Group: Small-Angle Neutron Scattering (SANS) instrument, Time of Flight (TOF) spectrometer, Three-axis spectrometer, Reflectometer and PSD Diffractometer. Some of the results are specified below.</p> <p><strong>Study of desiccation-tolerant desert cyanobacterium, Leptolyngbya ohadii by means of small-angle neutron scattering. </strong>— Cyanobacteria (or blue-green algae), the first photosynthetic organisms capable of producing oxygen, the ancestors of chloroplasts of vascular plants, appeared about 3 billion years ago and contributed significantly to the transformation of our globe to a habitable planet. These organisms can be found in the most diverse terrestrial and aquatic habitats – from hot springs to the Antarctic climate and from the oceans and fresh water lakes to only temporarily moistened rocks and <a href="https://en.wikipedia.org/wiki/Desert">desert s</a>oils. In order to acclimate to these different habitats and to adapt to rapidly changing environmental conditions (temperature, illumination intensity, availability of nutrients and water), different cyanobacteria evolved different, multilevel regulatory mechanisms, the details of which are not well understood.</p> <p><img alt="figure01" data-entity-type="file" data-entity-uuid="f6fc7d93-c83f-407f-a116-3679f3c76b76" height="450" src="https://wigner.hu/sites/default/files/inline-images/netron01.png" width="600" /></p> <p><strong>Figure 1.</strong> Hydrated and dry state of the multilamellar thylakoid membrane system.</p> <p>A desiccation-tolerant desert cyanobacterium, Lepto­lyngbya ohadii, a keystone species in desert sand crusts was studied. L. ohadii spends most of the daytime in the desiccated state in strong sunshine, surviving extremely harmful conditions. Recovery of photosynthesis can occur immediately upon the addition of water (in nature, e.g. predawn dew deposition). Desiccation and rehydration in photosynthetic organisms are complex processes; it is important to reveal their structural background. As revealed by small-angle neutron scattering, in the hydrated state, the multilamellar thylakoid membrane system (responsible for the conversion of light energy to chemical energy in the cell) displayed three peaks in the SANS profile: one peak at q=0.072 nm<sup>-1</sup> and two additional, higher harmonic features at 0.139 and 0.221 nm<sup>-1</sup>. These values can be interpreted as the repeat distance (RD) ≈87 nm of thylakoid membranes. In the desiccated state, these peaks were completely lost. The scattering intensity decreased dramatically due to the loss of water and no Bragg peak could be discerned between 0.05 and 0.1 nm<sup>-1</sup>; instead, a broad shoulder emerged between 0.10 and 0.15 nm<sup>-1</sup>, which can be assigned to a 20-30 nm shrinkage in the RD (Fig. 1).</p> <p><strong>Neutron spin echo (NSE) spectrometry using very cold neutrons (VCN). </strong>— The concept of spin echo spectrometer on very cold neutrons (wavelengths  λ ~ 10-30 nm) to provide extra high resolution in energy transfer (ΔE ~ 10<sup>-13</sup> eV) has been proposed. Measurements of spin echo signals at different wavelengths were realized using broadband spin flippers in combination with Fourier-analysis of λ-spectrum. The application of very cold neutrons should extend the spin echo time diapason radically, t ~ 10<sup>-12</sup> -10<sup>-3 </sup>s. This promises to open a set of novel scientific areas including the spectroscopy of chemical reactions and catalytic processes, conformational transitions in polymers and biological molecules, dynamic modes in carbon structures (fullerenes, nanotubes, graphenes) at scales from few nanometers to microns.</p> <p><img alt="figure2" data-entity-type="file" data-entity-uuid="8a20ee35-40d6-4998-9d7b-9004cd32a94f" height="200" src="https://wigner.hu/sites/default/files/inline-images/neutron02.jpg" width="600" /></p> <p><strong>Figure 2.</strong> NSE-VCN-spectrometer: neutron beam (n), polarizer (P), radiofrequency flipper (RF), ±π/2-flippers forming the borders of precession fields (B), sample (S), analyzer(A), detector (D).</p> <p>Spin echo spectrometry based on very cold neutrons promises excellent opportunities in studies of molecular, polymeric, biological objects and systems in extra wide range of times from picoseconds to milliseconds at which their complicated dynamics is revealed. New scientific fields for research open up in comprehensive analysis of chemical reactions and catalysis phenomena, subtle features of conformational and structural transformations in biological molecules and their living structures by using very high energy resolution ~ 10<sup>-13</sup> eV in neutron inelastic scattering experiments based on the proposed principles of wide-band spin-echo technique. The creation of such advanced NSE-instrument (Fig. 2) is considered in connection with the development of intense source of ultra and very cold neutrons on WWR-M reactor at the Petersburg Nuclear Physics Institute using the principles of deep cooling of neutrons in superfluid helium.</p> <p><strong>Stabilization of detonation nanodiamonds (DND) hydrosol in physiological media with poly(vinylpyrrolidone) (PVP). </strong>— A simple method of stabilization of detonation nanodiamonds with negative Ϛ-potential in isotonic aqueous-saline media was realized by means of complex formation with poly(vinylpyrrolidone). The stability conditions of the complexes were defined and their structure was determined by neutron scattering. The obtained hydrosols of nanodiamond particles stable in physiological medium may be used in biological researches and in medicine as drug carriers.</p> <p>The reliable evidences for the formation of stable DND-PVP complexes in hydrosol were obtained with particle sizes 30-35 nm when the ratio of weight concentrations of the component reached r = C<sub>PVP</sub>/CDND ~ 0.5. In the range of r = 0.3÷0.5, complexes with sizes 30-35 nm are formed, stable in isotonic NaCl solution. At lower r, the amount of PVP is not sufficient to form such complexes, and at larger r, PVP forms a more dense shell around DND particles, resulting an increase of their stability in aqueous-saline media. With the use of PVP, the cluster chain structure formed by the DND particles was observed. It was possible to achieve the stability of such structures of DND particles in isotonic solutions for a long period of time (several months) by varying the amount of PVP in the system. The studied systems are promising for use in medicine due to their high stability in isotonic media. The use of PVP will allow to introduce the drugs to DND-PVP complexes, which will be stable drug carriers.</p> <p><strong>Cultural heritage-related studies with the aid of neutrons.</strong> — Firing conditions in old-fired clay bricks were studied by means of small-angle neutron scattering. Masonry and chimney brick samples (Úpice, 1876, Telé, 1950) from Czech Republic, were compared to samples of raw clay from the sites of the original quarries. Bricks produced with different raw materials could be distinguished on the basis of the fractal exponent of the scattering surface of pores.</p> <p>Firing temperature of archaeological pottery wares was determined by means of neutron scattering. A series of control samples with known firing conditions revealed linear correlation between firing temperature and p-exponent of the Porod-approximation of SANS intensity versus momentum transfer curves. Based on this correlation, the firing temperatures of 17 archaeological ceramic samples from the Early Medieval site of Keszthely have been determined in a non-invasive manner.</p> <p>Scientific analysis of the ceramic artefacts (20 pcs) of the 6th century AD cemetery of Szólád (Hungary) was carried out. During the pottery analysis thin-section petrography (resulting in mineralogical data), Prompt-Gamma Activation Analysis and Neutron Activation Analysis (resulting in major and trace elemental composition) was made. These methods allowed to apply two different statistical models where both types of data (qualitative mineralogical and quantitative chemical) were incorporated into the analysis (“mixed-mode”): multidimensional scaling (MDS) and multifactorial analysis (MFA). They were studied separately, together or weighted. The aim of the analyses was to distinguish different material groups based on their mineralogical and chemical composition which refer either to local or import pottery production. The analyses resulted in two separate material groups, both of local origin, and four individual vessels, which could be defined as import production.</p> <p>Optimization of new borosilicate glasses for conditioning High-Level-Waste (HLW) materials. The immobilization process of HLW materials in borosilicate glasses is generally accepted in the literature. Stable and compact structure, multi-component matrix glasses with a compact structure, namely borosilicate-based glasses doped with 30wt% CeO<sub>2</sub>, Nd<sub>2</sub>O<sub>3</sub> and Eu<sub>2</sub>O<sub>3</sub> lanthanides were investigated. They were used for chemical modelling of the actinides, with the aim to clear up the correlation between structural characteristics and to find answer for a possible incorporation of Ce, Nd and Eu elements. Based on neutron and X-ray diffraction measurements combined with Reverse Monte Carlo simulation, a comprehensive structural study of the glasses was done. The special interest of this system lies in the different glass forming mechanisms of SiO<sub>2 </sub>and B<sub>2</sub>O<sub>3</sub>. The shortest second-neighbour distances obtained for the (Si,B)-Ce, (Si,B)-Nd and (Si,B)-Eu pair correlation functions suggest that lanthanide ions take part partially as network former in the structure. These pronounced correlations show that Ce, Nd and Eu atoms can be incorporated in the matrix glass structure.</p> <p><strong>Hybrid silica materials with ordered pore structure.</strong> — Hybrid silica materials have been synthesized and studied by a variety of experimental methods including scattering techniques. The materials were prepared using organically modified precursors with methyl and aminopropyl functional groups, as well as using templating surfactant molecules with different alkyl tail lengths. These additives influence the pore structure, ordering and the chemical nature of pore surface such as hydrophobicity, which allow to control and tailor the properties of the materials for various applications. The methyl-modified materials were tested for their drug-uptake and -release properties, and a strong correlation between the methyl content and the in vitro dissolution rate of ketoprofen has been achieved, demonstrating the potential applicability of such co-condensation type of synthesis for practical applications.</p> <p>The microstructure of ODS steels processed by friction steel welding (FSW), friction steel welding, has been investigated by methods of small-angle neutron scattering with magnetic contrast variation, and electron microscopy. The particle size distribution of the nano-sized yttrium oxide and its derivatives (Fig. 3) shows a strong change with the parameters of the welding process. The relative number of particles in the range of 2-80 nm decreases, partially dissolves in the stir zone with respect to the base material, and this effect is stronger in the case of higher tool rotation speed, i.e., higher heat input during the welding.</p> <p><img alt="Neutron03" data-entity-type="file" data-entity-uuid="317e6436-a42d-4e39-b44b-5b9ca8c35913" height="300" src="https://wigner.hu/sites/default/files/inline-images/neutron03.jpg" width="600" /></p> <p><strong>Figure 3.</strong> Representative TEM images and the statistically correct size distribution of the ceramic precipitates.</p> <p> </p> <h4><strong>2017</strong></h4> <p><strong>Neutron instrumentation development.</strong> — Members of the group actively participated in the detailed design work of two instruments for the European Spallation Source (ESS) in Lund, Sweden: BIFROST indirect neutron spectrometer and NMX macromolecular single-crystal diffractometer. Both are new type instruments, the first ones in their class. The final design of the neutron optics systems of the instruments (neutron guide systems, choppers and detectors) are finalized by means of analytical calculations completed at our department. Researchers of the Neutron Spectroscopy Department investigated the robustness of the neutron guide system against misalignment and waviness of the neutron mirrors and the movement of the floor, features indispensable both in the optimization of the guide system and in the design of radiological shielding.</p> <p>In the frame of the EU-H2020 BrightnESS project, researchers of the group have performed the optimal principial design of the ESS Test Beamline, the first equipment to receive neutrons and produce results at the ESS facility currently being built at Lund.</p> <p><img alt="neutronoptics01" data-entity-type="file" data-entity-uuid="752c845c-1630-4100-8c8e-ffd2084430e8" height="431" src="https://wigner.hu/sites/default/files/inline-images/neutronoptics01.jpg" width="369" /></p> <p><em><strong>Figure 1.</strong> TOF large sample positioning system</em></p> <p>We have developed, successfully tested at the Budapest Research Reactor and applied during an experiment series at the JEEPII reactor of IFE Kjeller, Norway a compact, mobile equipment for energy-sensitive imaging of neutron sources. The key components are the mask with pinhole and chopper unit as well as a four-layer, double-readout solid boron converter neutron detector. Neutron adsorber materials, system geometry and parameters have been optimized to accommodate the high count rate and good resolution specific for the intended application.</p> <p>A further development is the equipment for positioning large samples at the time-of-flight (TOF) diffractometer (Fig. 1), a sample environment equipment indispensable for fulfillment of archeometry tasks in the frame of the EU-H2020 Iperion project.</p> <p>We coordinated the instrumental part of the Hungarian In-Kind contribution to the ESS, including design and production of neutron optical elements and shielding as well as engineer and physicist secondment provisions. </p> <p><strong>Neutron holography.</strong> — In 2017, we continued the research started earlier on the topic of magnetic holography. Neutrons possess magnetic moment, thus they interact with the magnetic moments of the atoms in the sample. The latest investigations revealed the possibility to use this interaction to measure the local magnetic structure around selected atoms in the sample. We described the magnetic hologram previously and showed that the radial component of the atomic magnetic moments can be obtained by applying the Helmholtz-Kirchoff integral transformation to holograms measured in a special experimental arrangement. In 2017, we found a correlation method which can be used to determine the three components of the magnetization vectors. The optimal experimental parameters (neutron spin direction, neutron wavelength and required statistics) were obtained by model calculations (Fig. 2).</p> <p><img alt="figure02" data-entity-type="file" data-entity-uuid="c2e9d89d-5d69-4bbd-9e3d-fd633b5a2ac3" height="377" src="https://wigner.hu/sites/default/files/inline-images/neutronoptics02.png" width="377" /></p> <p><em><strong>Figure 2</strong>.<strong>. </strong>The z-component of the magnetic mo­ments of Cu atoms in CuCr2O4, ob­tained by applying the proposed cor­relation method on the simulated magnetic holo­gram</em></p> <p><strong>Structural investigation of hybrid silica gels.</strong> — The similarities and the differences on the physicochemical characteristics of the organic–inorganic hybrid silica gels derived from two-vinyl substituted (Vinyl – triacetoxy / - triethoxy silica (VTAS/VTES)) precursors were studied. NaF and NH4F catalysts were applied to promote the gelification. For both silica precursors the use of NH4F catalysts resulted in higher specific surface area. Using VTES, higher degree of vinyl substitution could be obtained, but the silica gel specific surface areas are lower compared to the corresponding samples obtained with VTAS. The increasing quantity of the vinyl substituents causes a decrease in primary particle size, pore number and sizes, but an increasing hydrophobicity no matter if VTAS of VTES were used. Further investigation will be made to determine how structural modification of the silica hybrid silica support will influence the activity of immobilized guest molecules (porphyrins, drug or enzymes).</p> <p>An international symposium was organized dedicated to the memory of our passed colleague, László Cser, in the frame of the yearly meeting of the International Scientific Advisory Committee of the Budapest Research Centre. Co-workers, friends, colleagues, former and actual PhD students held lectures to honor his life-long scientific activity.</p> </div> <span class="field field--name-uid field--type-entity-reference field--label-hidden"><span lang="" about="https://wigner.hu/en/user/171" typeof="schema:Person" property="schema:name" datatype="" xml:lang="">Werovszky Veronika</span></span> <span class="field field--name-created field--type-created field--label-hidden">Tue, 11/27/2018 - 13:51</span> Wed, 08 Aug 2018 13:17:06 +0000 Werovszky Veronika 961 at https://wigner.hu