Time-of-flight modulated intensity small-angle neutron scattering measurement of the self-diffusion constant of water

The modulated intensity by zero effort small-angle neutron scattering (MI-SANS) technique is used to measure scattering with a high energy resolution on samples normally ill-suited for neutron resonance spin echo. The self-diffusion constant of water is measured over a q-t range of 0.01-0.2Å-1 and 70-500ps. In addition to demonstrating the methodology of using time-of-flight MI-SANS instruments to observe diffusion in liquids, the results support previous measurements on water performed with different methods. This polarized neutron technique simultaneously measures the intermediate scattering function for a wide range of time and length scales. Two radio frequency flippers were used in a spin-echo setup with a 100kHz frequency difference in order to create a high-resolution time measurement. The results are compared with self-diffusion measurements made by other techniques and the general applicability of MI-SANS at a pulsed source is assessed.Accepted Author ManuscriptInstrumenten groe

VC-precipitation kinetics studied by Small-Angle Neutron Scattering in nano-steels

Nanosteels are used in automotive applications to accomplish resource-efficiency while providing high-tech properties. Quantitative data and further understanding on the precipitation kinetics in Nanosteels can contribute to fulfil this goal. Small-Angle Neutron Scattering measurements are performed on a Fe-C-Mn-V steel, previously heat-treated in a dilatometer at 650°C for several holding times from seconds to 10 hours. The evolution of the precipitate volume fraction, size distribution and number density is calculated by fitting the experimental Small-Angle Neutron Scattering curves. The effect of phase transformation on precipitation kinetics is also discussed. Complementary Transmission Electron Microscopy, Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy measurements are performed to support the Small-Angle Neutron Scattering data analysis.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.(OLD) MSE-1RST/Neutron and Positron Methods in Material

Different agglomeration properties of PC₆₁BM and PC₇₁BM in photovoltaic inks-a spin-echo SANS study

Fullerene derivatives are used in a wide range of applications including as electron acceptors in solution-processable organic photovoltaics. We report agglomeration of fullerene derivatives in optically opaque solutions of PC61BM and PC71BM, with concentrations ranging from 30 mg mL-1 up to 90 mg mL-1, in different solvents with relevance to organic photovoltaics, using a novel neutron scattering technique, Spin-Echo Small Angle Neutron Scattering (SESANS). From SESANS, agglomerates with correlation lengths larger than 1 μm are found in some PC61BM solutions, in contrast no agglomerates are seen in PC71BM solutions. These results clearly show that PC71BM is fundamentally more soluble than PC61BM in the solvents commonly used in photovoltaic inks and corroborating similar observations previously achieved using other experimental techniques. Computer models are presented to study the energetics of solution and agglomeration of both species, ascribing the difference to a kinetic effect probably related to the larger anisotropy of PC71BM. Also, this work showcases the power of SESANS to probe agglomerates of fullerene derivatives in completely opaque solutions for agglomerates of the order of one to several microns.Instrumenten groe

Ionizing Radiation-Induced Release from Poly(ϵ-caprolactone- b-ethylene glycol) Micelles

Polymeric micelles, due to their easy preparation and versatile properties, have been widely applied as one of the most popular carriers for chemotherapeutic agents. Such micelles primarily prevent the leakage of drugs during transportation and thus protect healthy tissue. Controlled drug release, which releases the drugs at the site of interest using internal or external stimuli as triggers, can further improve the safety of the drug delivery process. In this paper, we investigate whether ionizing radiation can be used to initiate release, focusing on using Cerenkov light as a possible trigger. For this purpose, micelles composed of the degradable polymer poly(ϵ-caprolactone-b-ethylene glycol) (PCL-PEO) were first loaded with the photosensitizer chlorin e6 (Ce6) and subsequently exposed to gamma or X-ray radiation of varying radiation doses. The results reveal that Ce6 was released from the micelles under radiation, regardless of the energy of incident photons, showing that Cerenkov light was not the driving force behind the observed release. SANS measurements showed that the volume fraction of the micelles containing Ce6 was reduced after exposure to radiation. This change in volume fraction suggests that the number of micelles was reduced, which was probably responsible for the release of Ce6. The exact mechanism, however, remains unclear. Subsequently, the PCL-PEO micelles were loaded with Ce6 and one of the following drugs: doxorubicin (Dox), docetaxel (DTX), and paclitaxel (PTX). Under radiation exposure, Dox, which is quite stable in single-loaded micelles, shows an enhanced release profile in the presence of Ce6, while DTX and PTX remained in the micelles, regardless of the presence of Ce6. RST/Applied Radiation & IsotopesRST/Technici PoolInstrumenten groepChemE/Advanced Soft Matte

1.5 GPa compact double-wall clamp cell for SANS and NSE studies at low temperatures and high magnetic fields

We have developed and realised a compact high-pressure clamp cell of the piston-cylinder type for Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectroscopy measurements. The cell can pressurise φ5 mm samples up to 1.5 GPa. It is non-magnetic, produces a sufficiently low and flat SANS background with a relatively good neutron transmission and can be used in combination with polarised neutrons. The cell accommodates samples of up to 55 mm3 in volume and adopts a two-layer geometry: a TiZr body (outer layer) and a CuBe2 insert (inner layer). Its design is very compact and can be employed inside cryomagnets featuring a sample bore greater than φ30 mm. We present the cell and illustrate its performances with a series of neutron scattering experiments performed on single-crystalline MnSi.RST/Neutron and Positron Methods in Material

Probing magnetic correlations with spin-echo modulated small angle neutron scattering (SEMSANS)

The first measurements of magnetic correlation functions are presented using time-of-flight Spin-echo modulated small angle neutron scattering (SEMSANS) on the Larmor instrument at the ISIS pulsed neutron source. The accessible length scale is beyond that of the conventional SANS. A simplified model is presented to calculate the expected correlation functions for various magnetisation fields applied to the sample. As an example, we present the experimental data of a soft iron sample at various configurations of magnetisation field.Instrumenten groe

SANS and SAXS: A Love Story to unravel structural evolution of soy proteins and polysaccharide fibres during high moisture extrusion for meat alternatives

Plant-based meat alternatives are seeing considerable interest due to their potential to reduce environmental burden and enhance population health. The food industry, therefore, seeks routes to provide the consumer with whole-cut plant-based products that closely resemble meat products. High-moisture extrusion (HME) of plant proteins enables the industrial manufacturing of meat-like products with highly hierarchical structural organisation of fibres. The major bottleneck in serving the growing market for these products is a lack of insight intohow multiscale structures evolve during shear processing. Furthermore, it remains an open question of how two biopolymers, one being a plant protein and the other being a polysaccharide, contribute to the anisotropic structure formation during HME. This study shows how the complementary use of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) can add clarity to these matters, benefiting from the different contrasts in scattering length density (SLD) encountered with each of these methods. It is demonstrated that twobiopolymers have differences in the development of structural anisotropy. The protein fibril alignment starts in the extruder section with its further development along the cooling die. On the other hand, for polysaccharide fibres, the strongest local alignment has been found in the transition zone. RST/Neutron and Positron Methods in Material

Systematically quantifying oil–water microemulsion structures using (spin-echo) small angle neutron scattering

Microemulsion systems consisting of D2O, an alkane, an anionic internal olefin sulfonate surfactant, salt and secondary butyl alcohol (SBA) as co-solvent are studied in a systematic way. In four different sample sets, either the salt content, SBA content or alkane carbon number was varied in order to study the effects of the individual compounds on the structure sizes making up the microemulsion. Using complementary small-angle neutron scattering techniques SANS and Spin-Echo SANS, it was found that the microemulsion systems exhibit the largest structures in the optimum state (domain size of d/2 =144 nm in the model by Teubner and Strey), where the structure is considered bicontinuous. In comparison, at under- and over-optimum states where the structures consist of emulsified spherical droplets, the smallest measured diameter was 2R = 44 nm. Furthermore, the structure sizes in bicontinuous microemulsions decrease exponentially (down to d/2 =15 nm for pentadecane and 5 wt% SBA) as function of both SBA content and alkane carbon number. The observed trends in structure sizes combined with the trends observed in the area per surfactant molecule, are qualitatively explained with the extended Winsor R-ratio, the HLD-NAC model and surfactant film flexibility arguments.ImPhys/OpleidingTechnische NatuurkundeRST/Neutron and Positron Methods in Material

Evolution of the precipitate composition during annealing of vanadium micro-alloyed steels by in-situ SANS

In-situ Small-Angle Neutron Scattering (SANS) is used to determine the time evolution of the chemical composition of precipitates at 650 °C and 700 °C in three micro-alloyed steels with different vanadium (V) and carbon (C) concentrations. Precipitates with a distribution of substoichiometric carbon-to-metal ratios are measured in all steels. The precipitates are initially metastable with a high iron (Fe) content, which is gradually being substituted by vanadium during isothermal annealing. Eventually a plateau in the composition of the precipitate phase is reached. Faster changes in the precipitate chemical composition are observed at the higher temperature in all steels because of the faster vanadium diffusion at 700 °C. At both temperatures, the addition of more vanadium and more carbon to the steel has an accelerating effect on the evolution of the precipitate composition as a result of a higher driving force for precipitation. Addition of vanadium to the nominal composition of the steel leads to more vanadium rich precipitates, with less iron and a smaller carbon-to-metal ratio. Atom Probe Tomography (APT) shows the presence of precipitates with a distribution of carbon-to-metal ratios, ranging from 0.75 to 1, after 10 h of annealing at 650 °C or 700 °C in all steels. These experimental results are coupled to ThermoCalc equilibrium calculations and literature findings to support the Small-Angle Neutron Scattering results.(OLD) MSE-1(OLD) MSE-3RST/Neutron and Positron Methods in MaterialsMaterials Science and EngineeringBedrijfsondersteunin

Phase-transformation and precipitation kinetics in vanadium micro-alloyed steels by in-situ, simultaneous neutron diffraction and SANS

In-situ Neutron Diffraction and Small-Angle Neutron Scattering (SANS) are employed for the first time simultaneously in order to reveal the interaction between the austenite to ferrite phase transformation and the precipitation kinetics during isothermal annealing at 650 and at 700 °C in three steels with different vanadium (V) and carbon (C) concentrations. Austenite-to-ferrite phase transformation is observed in all three steels at both temperatures. The phase transformation is completed during a 10 h annealing treatment in all cases. The phase transformation is faster at 650 than at 700 °C for all alloys. Additions of vanadium and carbon to the steel composition cause a retardation of the phase transformation. The effect of each element is explained through its contribution to the Gibbs free energy dissipation. The austenite-to-ferrite phase transformation is found to initiate the vanadium carbide precipitation. Larger and fewer precipitates are detected at 700 than at 650 °C in all three steels, and a larger number density of precipitates is detected in the steel with higher concentrations of vanadium and carbon. After 10 h of annealing, the precipitated phase does not reach the equilibrium fraction as calculated by ThermoCalc. The external magnetic field applied during the experiments, necessary for the SANS measurements, causes a delay in the onset and time evolution of the austenite-to-ferrite phase transformation and consequently on the precipitation kinetics.Team Erik OffermanTeam Jilt SietsmaRST/Neutron and Positron Methods in MaterialsInstrumenten groe