The functionality of common organic semiconductor materials is determined by their chemical structure and crystal modification. While the former can be fine-tuned via synthesis, a priori control over ...the crystal structure has remained elusive. We show that the surface tension is the main driver for the plate-like crystallization of a novel small organic molecule n-type semiconductor at the liquid–air interface. This interface provides an ideal environment for the growth of millimeter-sized semiconductor platelets that are only few nanometers thick and thus highly attractive for application in transistors. On the basis of the novel high-performance perylene diimide, we show in as-grown, only 3 nm thin crystals electron mobilities of above 4 cm2/(V s) and excellent bias stress stability. We suggest that the established systematics on solvent parameters can provide the basis of a general framework for a more deterministic crystallization of other small molecules.
Bottom-up self-assembly of simple molecular compounds is a prime pathway to complex materials with interesting structures and functions. Coupled reaction systems are known to spontaneously produce ...highly ordered patterns, so far observed in soft matter. Here we show that similar phenomena can occur during silica-carbonate crystallization, the emerging order being preserved. The resulting materials, called silica biomorphs, exhibit non-crystallographic curved morphologies and hierarchical textures, much reminiscent of structural principles found in natural biominerals. We have used a fluorescent chemosensor to probe local conditions during the growth of such self-organized nanostructures. We demonstrate that the pH oscillates in the local microenvironment near the growth front due to chemical coupling, which becomes manifest in the final mineralized architectures as intrinsic banding patterns with the same periodicity. A better understanding of dynamic autocatalytic crystallization processes in such simple model systems is key to the rational development of advanced materials and to unravel the mechanisms of biomineralization.
Nucleation is a unique process with broad relevance across a wide range of scientific disciplines and applications. While considerable progress in the understanding of the mechanisms underlying the ...nucleation of minerals from solution has been made for popular model systems such as calcium carbonate, corresponding detailed insights are still missing for other, less prominent minerals. Here, we present a potentiometric titration-based method that allows the early stages of the crystallisation of brucite, Mg(OH) 2 , to be monitored and quantified. Together with complementary characterisation provided by (cryogenic) transmission electron microscopy, the collected data shed novel light on the species occurring prior to, during, and after nucleation of brucite. In the second part of the work, the newly developed approach was applied to investigate the effects of added poly(acrylic acid) on the different stages of the crystallisation process. The polymer is found to stabilise brucite nanoplatelets and co-precipitate with the inorganic phase, yielding a composite material. The methodology established in this study can readily be used to screen other chemistries for their ability to prevent magnesium hydroxide scaling and/or afford brucite nanomaterials with tailored properties.
Silica gardens are tubular structures that form along the interface of multivalent metal salts and alkaline solutions of sodium silicate, driven by a complex interplay of osmotic and buoyant forces ...together with chemical reaction. They display peculiar plant-like morphologies and thus can be considered as one of the few examples for the spontaneous biomimetic self-ordering of purely inorganic materials. Recently, we could show that silica gardens moreover are highly dynamic systems that remain far from equilibrium for considerable periods of time long after macroscopic growth is completed. Due to initial compartmentalisation, drastic concentration gradients were found to exist across the tube walls, which give rise to noticeable electrochemical potential differences and decay only slowly in a series of coupled diffusion and precipitation processes. In the present work, we extend these studies and investigate the effect of the nature of the used metal cations on the dynamic behaviour of the system. To that end, we have grown single macroscopic silica garden tubes by controlled addition of sodium silicate sol to pellets of iron(
ii
) and iron(
iii
) chloride. In the following, the concentrations of ionic species were measured as a function of time on both sides of the formed membranes, while electrochemical potentials and pH were monitored online by immersing the corresponding sensors into the two separated solution reservoirs. At the end of the experiments, the solid tube material was furthermore characterised with respect to composition and microstructure by a combination of
ex situ
techniques. The collected data are compared to the previously reported case of cobalt-based silica gardens and used to shed light on ion diffusion through the inorganic membranes as well as progressive mineralisation at both surfaces of the tube walls. Our results reveal important differences in the dynamics of the three studied systems, which can be explained based on the acidity of the metal cations and the porosity of the membranes, leading to substantially dissimilar time-dependent solution chemistry as well as distinct final mineral structures. The insight gained in this work may help to better understand the diffusion properties and precipitation patterns in tubular iron (hydr)oxide/silicate structures observed in geological environments and during steel corrosion.
The time-dependent dynamic evolution of macroscopic silica garden tubes is shown to strongly depend on the used metal cations.
Abstract
ARES is an electron linear accelerator at the SINBAD facility at DESY. It aims to deliver reliable high-brightness beams with an energy in the range of 50 MeV to 150 MeV with fs to sub-fs ...bunch lengths. This is ideal for injection into novel high-gradient acceleration devices, such as dielectric laser accelerators (DLA), accelerator components R&D and medical applications. The ARES linac has been recently commissioned. Here we report the results of beam based alignment of focusing solenoids of ARES. The alignment is an important part of commissioning and is crucial for the beam quality.
Bassanite is a metastable but industrially important form of calcium sulfate, which is commonly produced by heating of gypsum. Here we show that pure bassanite can also be obtained at ambient ...conditions by quenching aqueous CaSO sub(4) solutions in ethanol. This highlights that organic solvents can actually induce the formation of metastable phases rather than freezing precipitation processes.
Abstract The undesired precipitation of minerals from solution poses challenges in various industrial and domestic applications, including water treatment, desalination, dishwashers and boilers. To ...mitigate this, threshold inhibitors - small quantities of water-soluble additives—are commonly employed to inhibit the precipitation of inorganic phases. However, concerns about the persistence of traditional additives like phosph(on)ates) in natural environments and stricter regulations warrant the development of more sustainable alternatives. We present a high-throughput approach using a UV-Vis spectrophotometer and automated data analysis to assess the scale inhibiting potential of numerous candidates and their combinations. The robustness and versatility of this method were validated by measuring the kinetics of alkaline-earth metal carbonates precipitating from simulated hard waters and seawaters across an extended range of experimental parameters. This approach allows for straightforward evaluation and quantification of each antiscaling additive’s effectiveness and operational range, enabling direct comparison of different additives and blends of additives. Moreover, it facilitates the study of scaling processes in both bulk solutions and at liquid/solid interfaces. By providing a rapid and reliable means of screening potential additives and formulations, our versatile toolbox will expedite the identification of effective scale inhibitors, thereby contributing to the advancement of sustainable practices in various industries reliant on water treatment and mineral precipitation control.
Emerging high-frequency accelerator technology in the terahertz regime is promising for the development of compact high-brightness accelerators and high resolution–power beam diagnostics. One ...resounding challenge when scaling to higher frequencies and to smaller structures is the proportional scaling of tolerances which can hinder the overall performance of the structure. Consequently, characterizing these structures is essential for nominal operation. Here, we present a novel and simple self-calibration technique to characterize the dispersion relation of integrated hollow THz waveguides. The developed model is verified in simulation by extracting dispersion characteristics of a standard waveguide a priori known by theory. The extracted phase velocity is in good agreement with the true value. In experiments, the method demonstrates its ability to measure dispersion characteristics of nonstandard waveguides embedded with their couplers with an accuracy due to systematic errors of≈0.5%. Equipped with dielectric lining, the metallic waveguides act as slow wave structures, and the dispersion curves are compared without and with dielectric. A phase synchronous mode, suitable for transverse deflection, is found at 275 GHz.
Biomorphs are a unique class of self-organised silica-carbonate mineral structures with elaborate shapes. Here we report first approaches to modify these complex inorganic architectures through ...silane chemistry, binding of nanoparticles, and organic polymerisation. This leads to functional nanostructures in which the complexity of the originally inorganic template is preserved, and offers new diagnostic tools to study the mechanisms underlying their formation.
PDF
