Austrian Centre for Electron Microscopy and Nanoanalysis

Aging processes at the anode–separator contact surface (“interface”) critically affect the lifetime and safety of lithium-ion batteries. Nevertheless, the role of the important fluorine–containing anode passivation layers (“solid electrolyte interphases”, SEI) under application-oriented conditions remains insufficiently understood. In this study, industrial lithium-ion cells with graphite anodes and NMC 811-based cathodes were subjected to long-term cycling and high charging rates. X-ray computed tomography (CT) combined with post-mortem scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), as well as ion exchange chromatography, Fourier transform infrared spectroscopy (FTIR), and depth-resolved X-ray photoelectron spectroscopy (XPS), was employed to investigate SEI composition as a function of cycling temperature and cycle number. The results demonstrate that cycling temperature has a significantly stronger impact on cell aging than the number of completed cycles. Elevated temperatures promote formation of fluorine containing phases within the SEI, in particular LiF, accompanied by very likely dendrite-induced blocking of electrolyte transport pathways at the anode–separator interface. Furthermore, the fraction of irreversible capacity associated with fluorine–containing SEI-compounds (LiF and Li x PO y F z ) was quantified, revealing a temperature-dependent contribution to interfacial degradation. These findings provide mechanistic insight into temperature-driven SEI evolution and highlight the critical role of LiF in aging processes of industrial lithium-ion batteries. • Cycling temperature has a stronger impact on aging than cycle number. • Elevated temperatures promote formation of fluorine-containing SEI. • Fluorine-containing SEI accumulates at the anode–separator interface. • Fluorine-containing SEI formation correlates with cumulative irreversible capacity rise. • Interfacial fluorine-containing SEI contributes to charge transport limitation and impedance growth.

Microplastics are of growing concern due to their ubiquity and potential risks to ecosystems and human health. Their small size, chemical diversity, and coexistence with natural colloids make comprehensive analysis difficult. Here, we evaluate two emerging single particle techniques, single particle inductively coupled plasma-mass spectrometry (SP ICP-MS) and optofluidic force induction coupled with Raman spectroscopy (OF2i-Raman), for their ability to provide complementary information at single microplastic resolution. SP ICP-MS determined carbon mass per particle and enabled detection of degradation-induced trends in size and abundance, while OF2i-Raman identified polymer type and molecular changes via optical trapping and inelastic light scattering. OF2i-Raman is a novel method in the field of microplastic research and was therefore first benchmarked by analysing mixed suspensions of polymethylmethacrylate (PMMA), polystyrene (PS), and polyamide-6 (PA-6), as well as PA-6 in a soil extract to assess selectivity under complex matrix conditions. Subsequently, both techniques were applied in parallel to study the UV-induced degradation of PA-6 and low-density polyethylene (LDPE) as relevant industrial polymers. SP ICP-MS detected longitudinal carbon loss and relative changes in particle sizes and numbers, while OF2i-Raman revealed polymer-specific structural alterations and detected spectral fingerprints even after extended irradiation. Together, SP ICP-MS and OF2i-Raman link elemental mass with molecular identity, providing complementary insights into microplastic degradation. While SP ICP-MS remains confined to controlled laboratory experiments due to its limited selectivity and size range, OF2i-Raman extends the analytical window to complex matrices and mixed polymer systems.

The study investigates the microstructure evolution in the stir zone produced by the friction stir processing (FSP) of a heat-treated microalloyed Al-Mn-Cu alloy in the area subjected to the highest temperature, strain, and strain rate. The samples were studied using electron microscopy and atom probe tomography (APT) to obtain structural and chemical information from the macro to the nano scale. FSP refines the dendritic Al-rich solid solution grains through dynamic recrystallisation in the range of a few micrometres. The primary intermetallic phases were dispersed to the particles in the 0.5–3 µm range and transformed mainly into a more stable τ1-Al29Mn6Cu4 phase. The fraction of dispersed particles after FSP increased due to the precipitation from the solid solution during cooling. The nanoscale quasicrystalline precipitates in the matrix, formed upon heat treatment, dissolved entirely during FSP, while the strong coarsening of the L12 precipitates occurred due to high temperatures in the stir zone. After FSP, the hardness of the stir zone was nearly identical for specimens in the as-cast and heat-treated conditions.

Tuberculosis (TB),caused by Mycobacterium tuberculosis (Mtb), remains one of the leading causes of mortalityfrom infectious diseases worldwide. So, this study investigates theantimicrobial potential of [Fe­(phen)3]2+ (FEP)and FEP-loaded nanostructured lipid systems (NLS@FEP) as an innovativetherapeutic approach for TB. The FEP showed promising antimycobacterialactivity in simulated physiological environments, with minimum inhibitoryconcentrations (MIC90) from 3.92 to 0.98 μg mL–1. FEP combination with rifampicin or pretomanid significantlyreduced the MIC90, with fractional inhibitory concentrationindex (FICI) of 0.27 and 0.103, respectively. Field emission scanningelectron microscopy (FE-SEM) analysis revealed significant structuralalterations in the Mtb cell wall, suggesting thatFEP interferes with its synthesis. In silico analysesand whole-genome sequencing (WGS) supported these findings, identifyingmutations in key genes, such as ponA1, which encodesa penicillin-binding protein involved in peptidoglycan synthesis. In silico modeling predicted high FEP affinity for PonA1,in line with FE-SEM observations; however, these predictions are hypothesis-generatingand require functional validation. FEP-loaded nanostructured lipidsystem (NLS@FEP) was designed to optimize FEP activity, which improvedits stability and bioavailability. In a murine model infected with Mtb H37Rv, free FEP and NLS@FEP achieved complete eliminationof pulmonary infection.

ε-Fe3N nanoparticles were produced in gram-scale quantities using a one-pot thermal decomposition route, yielding monodisperse particles with an average diameter of 13.5 nm. We thoroughly investigated the structure, surface chemistry, size distribution, and magnetism using in situ high-temperature X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution TEM, Mössbauer spectroscopy, dynamic light scattering, AC magnetometry, and temperature-dependent magnetometry. The room-temperature saturation magnetization of 128 A·m2/kg significantly exceeds that of conventionally used iron oxides and results in an impressive heating performance reaching a specific absorption rate of several kW/g with 508 W/g within biological safety limits which are the highest values reported to-date for iron nitride nanoparticles. The measured magnetocrystalline anisotropy constant of 133.9 kJ/m3 is in very good agreement with density functional theory calculations demonstrating the quality and convergence of the experimental and theoretical results. This work positions ε-Fe3N nanoparticles as a potential sustainable material without critical or toxic elements for magnetic fluid hyperthermia and other applications that would benefit from much increased magnetization.

AlScN-based bulk acoustic wave resonators with enhanced performance have become attractive for meeting the demanding requirements of the 5G telecommunication industry. For resonators to have better performance, AlScN films exhibiting epitaxy, high crystalline quality, high electric insultation, and low number of abnormally oriented grains are desired. In this study, we systematically change the total sputter power and investigate the structural, optical, and electrical properties of the resulting Al1−xScxN films. Our findings demonstrate that increasing the total sputter power results in Al1−xScxN films with low abnormally oriented grains, reduced sub-bandgap absorption, and lower leakage currents—predominantly due to reduced nitrogen vacancies. Based on these results, we argue that a higher growth rate promotes the growth of Al1−xScxN with reduced impurity levels. Furthermore, by depositing Al0.7Sc0.3N on epitaxial AlN, we demonstrate that epitaxial AlScN can be achieved while improving its crystal quality by ≈36%.

Molybdenum components manufactured using Powder Bed Fusion-Laser Beam (PBF-LB) currently cannot achieve the mechanical properties and quality of powder-metallurgically produced parts. This is a result of the process characteristics of steep thermal gradients and high solidification rates in PBF-LB, which promote the development of a coarse-grained, columnar microstructure. It has been observed that segregated oxygen impurities have a negative impact grain boundary cohesion, resulting in intergranular cracking and pore formation. This study aims to investigate the effect of a grain boundary and segregation engineering alloying approach for molybdenum using boron and lanthanum additions, and simultaneous adjustment of the PBF-LB process conditions. Mo-B-La alloy specimens were manufactured from a Mo-1.5 wt% LaB 6 powder blend by in-situ alloying in PBF-LB using varying substrate plate temperatures of 200 °C, 500 °C and 800 °C. The results show that all specimens exhibit a fine-grained microstructure. A grain size of between 15 and 21 μm was achieved owing to the solute rejection effect of B and La during solidification. The specimens exhibit a mixed cellular and columnar dendritic subgrain structure of α-Mo cells or dendrites surrounded by intercellular or interdendritic Mo 2 B filaments. La is found to support grain boundary purification from oxygen impurities owing to the formation of nanometer sized oxidic particles located at the interface between α-Mo and Mo 2 B. 60–80 % of the added La evaporates during the process, which leads to the formation of spherical gas pores with a size <Ø30 μm and limits the specimen's density to a maximum of 98.4 ± 0.4 %. The formation of cracks is significantly affected by the substrate plate temperature during the manufacturing process. Specimens manufactured at ≥500 °C are crack-free, while those produced at 200 °C exhibit cold cracks. Therefore, the bending strength of specimens manufactured at 200 °C is limited to 445 MPa, whereas those manufactured at 500 °C and 800 °C reach a bending strength of 1107 ± 117 MPa and 1210 ± 125 MPa, respectively, at room temperature. At elevated test temperatures, specimens demonstrate excellent properties, with bending strengths of 2151 ± 272 MPa and 1954 ± 510 MPa achieved at 400 °C and 600 °C, respectively. The study concludes that the grain boundary and segregation engineering approach by alloying Mo with B and La, along with the simultaneous optimization of the process conditions by substrate plate heating, makes it possible to suppress the formation of the main quality inhibiting defects and to produce specimens with excellent mechanical properties in PBF-LB. • Molybdenum alloy tailored for powder bed fusion-laser beam with boron and lanthanum enables grain boundary and segregation engineering. • Solute rejection during solidification leads to the formation of a fine-grained microstructure with a honeycomb-like cellular subgrain structure. • Lanthanum effectively scavenges oxygen impurities, enhancing grain boundary purity. • Crack-free specimens with excellent bending strength at room temperature and elevated temperatures.