Amorphous Research Articles

Effect of physical aging on scratch behavior of polycarbonate

AbstractPhysical aging refers to relaxation of the polymer glassy state toward the amorphous state and this phenomenon affects their physical‐mechanical properties. This work investigates the effect of physical aging on polymer scratch behavior and visibility. It was shown that mechanical properties were significantly modified over the aging time, especially the yield stress, in turn affecting polymer scratch behavior. As a matter of fact, the critical load for the onset of scratch visibility was shown to increase with the aging, thus improving sensitivity of polymer to scratches. Such behavior was strictly related to the yield stress increase with the aging time. The usefulness of the present work is highlighted, and some future perspectives are discussed.

Influence of HfO2 oxide layer on crystallization properties of In3SbTe2 phase change material

Phase Change Memory (PCM) represents a potential paradigm in the realm of non-volatile memory technologies, and several phase change materials are studied for utilization in PCM devices. This work employs a less explored In3SbTe2 (IST) phase change material (active layer) integrated with an oxide (HfO2) layer and investigates the influence of the oxide layer on the active layer. The oxide layer remains amorphous when annealed at 400 °C, and it doesn’t alter the crystallization temperature (290 °C) of the active layer in IST with HfO2 thin-film. However, after crystallization, the grain size of the active layer is reduced to ∼8.23 nm in IST with HfO2 thin-film, compared to only IST thin-film. XPS core-level spectra (In 3d, Sb 3d, Te 3d) of IST active layer reveal the peak shifting towards higher binding energy at 300 °C and 400 °C annealed films, implying bond energy increase with crystallization and film stability improves. The Hf or O atoms of the oxide layer don’t diffuse into the active layer with annealing, suggesting no interference with the phase switching property of IST. A higher optical bandgap of 1.154 eV in as-deposited IST with HfO2 thin-film compared to the only IST thin-film illustrates better stability of the amorphous state in the film with the oxide layer. In addition, the fabricated PCM device using the IST with the oxide layer demonstrates phase switching at a lower threshold voltage of (2.1 ± 0.1) V, compared to the IST-based device. The findings indicate that the enhanced structural and electrical switching characteristics of IST phase change layer coupled with an oxide layer make it beneficial for data storage PCM applications.

Achieving Non-Interfacial Blocking Zinc Ion Transport Based on MOF Derived Manganese Oxides and Amorphous Carbon Hybrid Materials.

How to coordinate electron and ion transport behavior across scales and interfaces within ion battery electrodes? The exponential increase in surface area observed in nanoscale electrode materials results in an incomprehensibly vast spatial interval. Herein, to address the problems of volume expansion, dissolution of cathode material, and the charge accumulation problem existing in manganiferous materials for zinc ion batteries, metal organic framework is utilized to form the architecture of non-interfacial blocking ~10 nm Mn2O3 nanoparticles and amorphous carbon hybrid electrode materials, demonstrating a high specific capacity of 361 mAh g-1 (0.1 A g-1), and excellent cycle stability of 105 mAh g-1 after 2000 cycles under 1 A g-1. The uniform and non-separated disposition of Mn and C atoms constitutes an interconnected network with high electronic and ionic conductivity, minimizing issues like structural collapse and volume expansion of the electrode material during cycling. The cooperative insert mechanism of H+ and Zn2+ are analyzed via ex-situ XRD and in-situ Raman tests. The model battery is assembled to present practical possibilities. The results indicate that MOF-derived carbonization provides an effective strategy for exploring Mn-based electrode materials with high ion and electron transport capacity.

Crystalline and Amorphous Interface Simulations of Donor-Acceptor Blends.

In an organic solar cell, exciton dissociation and charge transport to generate current depend on interface and bulk morphology, respectively, and their rates dictate device performance. Blend miscibility and processing determine the final morphology. We investigate the blend miscibility of P3HT and O-IDTBR, employing our recently developed "push-pull" computational technique, and explore its effect on nanoscale morphology. The resulting Flory-Huggins χ parameter is primarily enthalpic, and the blend exhibits UCST behavior. To directly simulate an equilibrated morphology in such a blend requires large (30 nm) systems and long (10 μs) simulations, which we attain with our virtual site coarse graining technique. In the resulting amorphous phase-separated state, O-IDTBR swells P3HT by about 15%, but does not percolate within the P3HT-rich phase. The interfacial profile depends on crystallinity: the amorphous interface is several nanometers wide, whereas an acceptor crystal induces order in the adjacent donor polymer, forming a sharp interface quite similar to a crystal-crystal interface. The wide amorphous interface promotes more donor-acceptor contacts with a wide range of relative orientations; however, the acceptors do not form a percolating network, which will likely lead to charge recombination. A crystal interface exhibits fewer donor-acceptor contacts with primarily face-on orientation that are more likely to charge-separate because of instant access to the preferred domain.

Amorphous CoSx in heterogeneous electro-Fenton: A 1O2-mediated system for efficient and selective water decontamination

Heterogeneous electro-Fenton (hetero-EF) technology represents a promising and safe approach to water treatment. However, conventional hetero-EF catalysts still face the challenges of removing contaminants selectively and operating efficient in complex water quality. We proposed a novel system utilizing amorphous CoSx (A-CoSx) that overcame these limitations. This material generated only singlet oxygen (1O2), a highly specific oxidant, for contaminants degradation. Unlike traditional crystalline catalysts, A-CoSx efficiently utilized hydrogen peroxide (H2O2) to directly produce 1O2, exhibiting high catalytic activity across a wide pH range (3.0–11.0). The formation mechanism of 1O2 was confirmed through experimental investigations, density functional theory (DFT) calculations, and advanced characterization techniques. This system effectively degraded contaminants even in complex water with interferences and enabled selective targeting of pollutants with electron-donating groups. This innovative approach using amorphous materials offers a promising strategy for the regulation of ROS and enabling selective contaminant removal in water treatment.

Heating Rate Sensitive Polyethylene Terephthalate.

Smart materials react to external triggers by changing size, color, mechanical properties, or permeability. The next generation of smart materials will be able to not only recognize and react to external triggers but also to their dynamics. The only existing example of such a material is heating rate-sensitive polymorphous cross-linked syndiotactic polypropylene. This study presents a new principle of a heating rate-sensitive material on the example of cross-linked and fully amorphous quenchable semi-crystalline polyethylene terephthalate (x-PET). The x-PET is stretched to high elongation above its melting temperature and constrained quenched to a fully amorphous state. Then the polymer is heated to 120-170°C with different heating rates. Due to its heating-rate sensitivity, x-PET shrinks to different stabilized lengths dependent on the heating rate. The new length can be used to read out the heating rate and to specifically answer to this by mechanically switching a process. Detailed analytics of this process reveal that amorphous stretched x-PET is starting the retraction above Tg and simultaneously stopping it by crystallization. The different rates of these processes result in the heating rate sensitivity of x-PET.

OLEOPHILIC SORBENTS BASED ON GRANULAR FOAMED SILICATE: PROPERTIES AND FEATURES OF REGENERATION

The solution to the problems of ecological safety when cleaning water objects from organic pollutants is indissolubly related to developing new sorbents and improving the technologies of their synthesis. Various materials in dispersed and granulated forms are successfully used in the production of sorbents. This article deals with the development and improvement of the technologies for producing the sorbents of petroleum and petroleum products. As a basis for the development of new sorbents, the properties of the granular foamed silicate obtained from the siftings of waste products from mining and processing plants were studied. The trial batches of oleophilic sorbents were obtained through thermochemical modification of hydrocarbons in the gas-vapour phase. It has been established that foamed silicate does not change its porous structure and amorphous state after thermo-chemical modification, retaining the high sorption activity. The nature of the porous structure of sorbents and the influence of porosity on their key properties, such as oil capacity, water absorption, and buoyancy, are investigated. The studies of the fractions of modified foamed silicate revealed low water-absorption capacity of the coarse- and middle-sized fractions. The minimum water absorption was determined for the fine fraction of the modified material, which is related to the absence of pores in these samples. Determination of oil capacity characteristics provides evidence of high oil receptivity and sorption capacity of the modified foamed silicate with respect to petroleum products. The results of experiments on sorbent regeneration after the end of its service life are presented. The developed semi-production experimental plant for the modification and regeneration of porous loose materials in the fixed bed is presented. The technological scheme of regeneration is proposed, allowing for regeneration and repeated modification of the used sorbent during one processing stage without any decrease in its sorption properties. The advantage of the developed technology of sorbent properties recovery is in the implementation simplicity and economic rationality. The repeatedly modified sorbent retains its characteristics and, first of all, sorption properties with respect to petroleum products. The practicability of developing new sorbents of petroleum products based on granular foamed silicate is demonstrated.

Alternating-bias assisted annealing of amorphous oxide tunnel junctions

Superconducting quantum bits (qubits) rely on ultra-thin, amorphous oxide tunneling barriers that can have significant inhomogeneities and defects as grown. This can result in relatively large uncertainties and deleterious effects in the circuits, limiting the scalability. Finding a robust solution to the junction reproducibility problem has been a long-standing goal in the field. Here, we demonstrate a transformational technique for controllably tuning the electrical properties of aluminum-oxide tunnel junctions. This is accomplished using a low-voltage, alternating-bias applied individually to the tunnel junctions, with which resistance tuning by more than 70% can be achieved. The data indicates an improvement of coherence and reduction of two-level system defects. Transmission electron microscopy shows that the treated junctions are predominantly amorphous, albeit with a more uniform distribution of alumina coordination across the barrier. This technique is expected to be useful for other devices based on ionic amorphous materials.

Sub-10 μm Soft Interlayers Integrating Patterned Multivalent Biomolecular Binding Environments.

Designing surfaces that enable controlled presentation of multivalent ligand clusters (e.g., for rapid screening of biomolecular binding constants or design of artificial extracellular matrices) is a cross-cutting challenge in materials and interfacial chemistry. Existing approaches frequently rely on complex building blocks or scaffolds and are often specific to individual substrate chemistries. Thus, an interlayer chemistry that enabled efficient nanometer-scale patterning on a transferrable layer and subsequent integration with other classes of materials could substantially broaden the scope of surfaces available for sensors and wearable electronics. Recently, we have shown that it is possible to assemble nanometer-resolution chemical patterns on substrates including graphite, use diacetylene polymerization to lock the molecular pattern together, and then covalently transfer the pattern to amorphous materials (e.g., polydimethylsiloxane, PDMS), which would not natively enable high degrees of control over ligand presentation. Here, we develop a low-viscosity PDMS formulation that generates very thin films (<10 μm) with dense cross-linking, enabling high-efficiency surface functionalization with polydiacetylene arrays displaying carbohydrates and other functional groups (up to 10-fold greater than other soft materials we have used previously) on very thin films that can be integrated with other materials (e.g., glass and soft materials) to enable a highly controlled multivalent ligand display. We use swelling and other characterization methods to relate surface functionalization efficiency to the average distance between cross-links in the PDMS, developing design principles that can be used to create even thinner transfer layers. In the context of this work, we apply this approach using precision glycopolymers presenting structured arrays of N-acetyl glucosamine ligands for lectin binding assays. More broadly, this interlayer approach lays groundwork for designing surface layers for the presentation of ligand clusters on soft materials for applications including wearable electronics and artificial extracellular matrix.

R-Q@P-D nanoparticle for improving the oral bioavailability and therapeutic efficacy: A novel reversible dual-target-mild-inhibition intestinal metabolic enzymes strategy for resveratrol delivery

The low bioavailability of polyphenols, such as resveratrol (RES), is typically caused by the poor solubility and first-pass effect. To improve bioavailability and reduce adverse effects, an oral reversible UDP-glucuronosyltransferases (UGTs) and sulfotransferases (SULTs) dual-target-mild-inhibition strategy was designed, and a proof-of-concept was studied. This R-Q@P-D nanoparticle for the codelivery of RES and quercetin (QUE) was constructed using pea protein isolate and dipotassium glycyrrhizinate (DG) as nanocarriers. These nanoparticle ingredients were all plant extracts approved by the FDA, and the fabrication process was a simple but novel pH-ultrasonic-shifting method in water conditions. R-Q@P-D exhibited high encapsulation efficiency of RES (97.25 ± 1.13 %) and QUE (94.21 ± 0.62 %), with a uniform nanosize (147.73 ± 1.85 nm). Characterizations implied that RES and QUE could be successfully encapsulated in nanoparticles in amorphous states, and the self-assembly binding between them was non-covalent bonds. Moreover, the in-silicon simulation and experimental results verified interactions between RES and DG, while there was no interaction between QUE and DG. In vivo evaluations showed that R-Q@P-D increased the bioavailability of RES by mildly and reversibly inhibiting intestinal UGTs and SULTs, but without inhibiting hepatic UGTs and SULTs. Moreover, molecular simulations showed that QUE and RES are competitively bound to SULTs but not UGTs. R-Q@P-D had significant therapeutic efficacy and excellent safety performance for its oral application. The tremendous safety and simple fabrication benefited the clinical translation. Together, R-Q@P-D based on reversible UGTs and SULTs dual-target-mild-inhibition strategy might be a promising nano-platform for improving the bioavailability and efficacy of hydrophobic polyphenols.

(Invited) Structural and Dynamics Analysis of Organic Semiconducting Materials by Solid State NMR

Our group have successfully developed several highly efficient blue and green thermally activated delayed fluorescence (TADF) emitters, which show the reverse intersystem crossingfrom triplet to singlet excited states. However the conformation and dynamics of TADF emitters related to RISC process in amorphous states is still unclear, because the experimental approach toward these information is limited due to difficulty of application of diffraction technique . Thus we have carried out multiscale simulations and solid-state NMR (ssNMR) analysis of organic amorphous thin films. The ssNMR is one of the powerful technique to obtain the structural and dynamics information of amorphous aggregated materials. In this presentation, we demonstrate structural and dynamics analysis of amorphous organic semiconducting materials using ssNMR.

(Invited) Comprehensive Analysis of Exciton Diffusion with Time-Resolved Fluorescence Spectroscopy, Anisotropy and Imaging

Excitons produced in materials play a crucial role in photo-energy conversion such as photovoltaics and electroluminescence devices. The temporal and spatial diffusion of excitons is a key factor for dominating the fundamental performance of optoelectronic materials. In this context, analysis of the exciton diffusion dynamics is an important issue for obtaining the rational design of the materials. Excitons diffusing in materials can be characterized by several parameters such as the energy level, orientation of the transition dipole moment and spatial distribution, and the detection of these properties is required for the comprehensive analysis. In the present study, we show time-resolved fluorescence methods for detecting the above relevant properties of excitons.First, time-resolved fluorescence spectroscopy is a basic technique for analyzing the exciton diffusion dynamics. Fluorescence intensity is detected as functions of observation wavelength and time, and the spectral intensity and shift of fluorescence bands provide information on the population of excitons and their energy level. For example, dynamic Stokes shift indicates downhill energy migration and excitons are trapped by the defective site in molecular aggregates. Second, fluorescence anisotropy can be a good indicator for tracking the exciton diffusion in amorphous materials. Fluorescence anisotropy is sensitive to orientation change in transition dipole moments (TDMs) between absorption and fluorescence. In systems where the relative orientation of adjacent molecules is different from each other, such as amorphous solids, the exciton diffusion is accompanied with the change in TDM. Thus, appropriate modeling of molecular alignment enables quantitative estimation of the exciton diffusion coefficient and diffusion length from the anisotropy signal. Finally, time-resolved imaging is a combination of time-resolved spectroscopy and super-resolution microscopy, and an emergent technique for visualizing real-space propagation of excitons in materials. The diffraction-limited excitation beam produces excitons in several hundreds of nanometers and the subsequent exciton diffusion is evaluated by the spatial width of the fluorescence spot. The temporal broadening of the fluorescence spot directly reflects the exciton distribution and we can intuitively obtain the diffusion coefficient and length. Unlike the conventional methods for bulk materials, the advantage of the time-resolved imaging is the applicability to materials with nano- and meso-scale heterogeneous structure and it enables site-selective evaluation of the exciton transport capability. In the conference site, we will also show the application of the above methods to supramolecular polymers and thermally activated delayed fluorescence materials. Figure 1

Hybrid Molecular Layer Deposition of Molybdenum-Aminates as Hydrogen Evolution Reaction Electrocatalysts

The development of high-performance hydrogen evolution reaction (HER) electrocatalysts from noble metal-free materials is critical to achieving cost-effective water splitting and ultimately realizing affordable hydrogen based on renewable energy. Compounds based on earth-abundant transition metals have been the subject of great research interest for this purpose, with metal nitrides gaining recent attention due to their high conductivity and corrosion resistance. Molybdenum nitride-based electrocatalysts have shown particular promise, with many of the best reported activities occurring in composite systems wherein crystalline MoNx domains are embedded in an amorphous N-doped carbon matrix. The present work demonstrates the formation of such uniquely active morphologies in films deposited by organic-inorganic hybrid molecular layer deposition (MLD).Hybrid MLD is a hybridization of other well-established layer-by-layer deposition techniques – namely atomic layer deposition (used to deposit inorganic films) and purely organic MLD. This family of techniques involves the cyclical exposure of a growth surface to alternating vapor-phase chemical precursors which react in a self-limiting fashion to saturate available surface sites, offering atomic- and molecular-level control over the resulting films. This presentation will introduce the successful development of hybrid MLD deposition procedures for new Mo-aminate materials using Mo(CO)6 as a Mo precursor and various amine precursors, including ethylenediamine, p-phenylenediamine, and tris(2-aminoethyl)amine.We will describe how the molecular level of control offered by this technique enables tunable variations in film composition and structure, lending unique insights into how the local bonding environment of Mo active sites affects their catalytic properties towards HER. Increased nitrogen loading in the MLD films was shown to decrease the overpotentials required to drive HER in acidic media (0.5 M H2SO4) and improve film stability. Catalysts with N/Mo ratios above 2 demonstrated the best performance, with overpotentials lower than 400 mV at -10 mA/cm2. By incorporating organic components in the MLD films, it was possible to induce desirable morphological changes in the catalytic material – notably including the development of increased active site density – simply through initial exposure to HER testing conditions. The choice of organic precursor affected the rate and extent of these changes through structural effects like crosslinking and crystallinity, which led to more stable catalysts, slowed the rate of morphological changes, and impacted final film structure.

Large-Scale Exploration of the LiSiPON System Using a High Throughput Experimental Method

Amorphous thin film materials in the LiPON(1) or LiSiPON(2) systems have been prepared for the first time in the early 1990s using magnetron sputtering. Since then, LiPON materials have been used as state-of-the-art solid electrolytes into all-solid-state thin film micro-batteries thanks to their outstanding properties (electrochemical stability vs Li°, wide electrochemical stability window of ~[4-0] V vs. Li+/Li0, isotropic and homogeneous medium, beneficial mechanical properties(3), very low electronic conductivity). The ionic conductivity of LiPON prepared from Li3PO4 targets remains rather moderate, reaching a maximum of 3.10-6 S.cm-1 at room temperature. However, it has recently been demonstrated that the introduction of SiO2 as a second glass former can increase this value up to 2.10-5 S.cm-1, and also that the ionic conductivity of these compounds does not increase steadily with their Li content.(4)This highlights the convoluted effects of mixed formers(5) (Si, P, B...), mixed anions(6) (O, N, S...) and Li concentration on the ionic conductivity. Nevertheless, the latter are usually observed on limited series of compositions, and barely not studied on large sets of samples, which can limit the understanding of composition-structure-conductivity relationships.In this context the aim of our work was to build a High Throughput Screening (HTS) approach to explore the LixSiyPzOuNw system as a case study (Fig.1). Indeed, HTS approaches aim to accelerate material breakthrough discovery, and to understand beyond the material mechanisms. In material science, the goal is to accelerate the discovery of new keys organic, inorganic or composite materials. It may also bring beyond ‘classical’ iterative method regarding the study of complex systems (ternary, quaternary...)(7). To do so, wide ranges of material libraries are synthesized, prior to be tested through an automated characterization workflow.Our specific approach starts with the preparation of material libraries by combinatorial synthesis using magnetron co-sputtering with tilted targets, then goes through automated and fast characterizations targeting specific properties, relevant to its application as ionic conductor.Deposition of thin films displaying composition and thickness gradients at the surface of a 4’’ silicon substrate is achieved by co-sputtering three target materials in a pure Ar or N2 atmosphere. Deposition through a shadow mask allows to discretize the continuum and to prepare a library of 76 separate LixSiyPzOuNw samples in one experiment. Then, by tuning the sputtering parameters (i.e discharge gas, gas pressure, incident power, target tilt, target-to-substrate distance,...) different compositional domains can be explored.Relevant automated characterization techniques are then applied to the material library spread on the 4’’ substrate. For the assessment of these amorphous ionic conducting films, dimensional (thickness), physical-chemical (composition & local structure) and functional properties (ionic/electronic conductivities) are studied.In this sequence, determining the composition of the thin film is a real challenge due to a number of requirements :(i) light elements analysis, especially lithium; (ii) need of localized analysis (mapping) on few mm² over large substrate (4” wafer); (iii) scarce material quantity available (~ μg) and finally (iv) fast analysis. Over lab-scale techniques available, only Laser Induced Breakdown Spectroscopy technique (LIBS) seems to fulfil all these requirements. To this purpose, LIBS is developed as a HTS mapping technique for chemical analysis. A sample calibration approach is implemented through coupling with robust chemical analysis techniques (RBS, NRA, ICP-OES, SEM-EDS).In short, this specific HTS procedure will be discussed and results about composition-structure-conductivity relationships in the LiSiPON system will be presented (Fig.2).References J. B. Bates et al., J. Power Sources. 43, 103–110 (1993).N. J. Dudney, J. B. Bates, J. D. Robertson, J. Vac. Sci. Technol. A. 11, 377–389 (1993).A. S. Westover et al., Chem. Mater. 35, 2730–2739 (2023).T. Famprikis, J. Galipaud, O. Clemens, B. Pecquenard, F. Le Cras, ACS Appl. Energy Mater. 2, 4782–4791 (2019).Y. Su et al., Phys. Status Solidi B. 254, 1600088 (2017).N. Mascaraque, J. L. G. Fierro, A. Durán, F. Muñoz, Solid State Ion. 233, 73–79 (2013).E. J. Amis, X.-D. Xiang, J.-C. Zhao, MRS Bull. 27, 295–300 (2002). Figure 1

Exploring Order/Disorder Molecular Networks on Metal Surfaces

Materials featuring disordered structures often exhibit unique properties. Metal-organic frameworks (MOFs) are a class of hybrid materials composed of metal nodes and coordinating organic linkers[1]. Recently, there has been growing interests in MOFs with structural disorder, and the investigations of amorphous structures on surfaces[2]. Herein, we demonstrate a bottom-up method to construct molecular networks on metal surfaces with order-disorder transition by preparing two-component samples with different stoichiometric ratios of two organic molecule linkers sharing the same symmetry but differing in size[3]. We investigate the topological and electronic structures of the order/disorder molecular networks by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) under ultra-high vacuum (UHV). The results may advance our understanding of the formation mechanism and electronic behaviors characteristic of monolayer molecular networks with structural disorders, holding the potential to catalyze advancements in the design and application of new amorphous MOF materials with intriguing properties.[1] L. Dong, et al., Progress in Surface Science, 91, 101–135 (2016).[2] J. Fonseca, et al., Journal of Materials Chemistry A, 9.17, 10562-10611 (2021).[3] J. Lu, et al., ACS Nano, 17, 20, 20194–20202 (2023).

The Effect of Structural Disorder on Li-Ion Transport in the Inorganic Components of the Electrode-Electrolyte Interfaces of Li-Ion Batteries

Conventional organic electrolytes in Li-ion batteries have an electrochemical window that is too narrow, leading to a decomposition at the cathode and anode surfaces, especially at high voltages. The breakdown of the electrolyte leads to the formation of cathode-electrolyte interphase (CEI) and solid-electrolyte interface (SEI) at the anode. These interfaces are a multicomponent, 3-dimensional heterogeneous structures that span from a few nanometers to micrometers. To understand the atomic-scale impact of the interfaces’ structure and chemistry on function we have run molecular dynamics simulations of the Li-ion diffusivity in the most likely components: LiF, Li2CO3, and Li2O. Our work focuses on identifying the effect of local chemistry and lattice structure in disordered or amorphous component materials on Li-diffusivity. We extract Li-ion diffusivity and the activation energy for Li-ion transport from both machine learning force fields and ab-initio molecular dynamics from the individual components of the interface and explicit interfaces. Post analysis establishes the local correlation between atomic structure, chemistry, and Li-ion migration. If well designed, the SEI and CEI can protect the electrolyte and cathode to prevent further degradation during cycling and thus optimization of battery performance.This work was sponsored by the Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

High Throughput Quality Control Tools for Carbon-Related Materials: A Raman Approach

Carbon-based materials play a pivotal role in battery technology, serving as negative electrode materials, conductive additives, and coating layers for both positive and negative electrode materials. Traditional characterization methods, such as transmission electron microscopy (TEM) and X-ray diffraction (XRD), fall short in providing comprehensive quality control, especially when distinguishing the structure of amorphous carbon materials. Raman spectroscopy as a convenient, simple tool is widely used to study the structure of carbon materials. It provides insights into the degree of crystallization, doping degree, and subtle structural differences arising from various preparation processes. By quantifying Raman spectrum testing results through statistical methods and providing relevant statistical outcomes, we demonstrate the potential of Raman spectroscopy as a quality control method for carbon material characterization. With extensive sample testing and automation, along with standardized spectral data processing and analysis software, we propose Raman spectroscopy as a suitable tool for high-throughput quality control in industrial production.

Thermo-Mechanical Properties and Benefits of Borosilicate Glass for SOEC Sealants

Boro-silicate glass materials have ideal properties for sealing oxidizing and reducing environments and electrically insulating solid oxide electrolysis cells (SOEC), while maintaining a glassy phase at high temperatures (750-900°C) to minimize chemo-mechanical degradation and gas permeability 1,2. Glass seals are typically applied as a slurry; hence, they are also expected to have non-wetting properties to prevent glass infiltration into the porous electrode structures during manufacturing 3. During the first startup, the initial temperature ramp serves to evaporate any binder in the slurry and to go through the glass transition phase, which cures the glass and increases hardness to improve resistance to creep. Typical glass materials operate in visco-plastic regimes (i.e., beyond the material’s glass transition temperature) and must be chemically stable while operating in steam-rich and oxygen-rich environments. To fully understand the performance of borosilicate glass seals, optimize the manufacturing, assembly, and maintenance of SOEC, we must be able to measure and analyze the glass material properties (i.e., glass transition temperature, coefficient of thermal expansion, modulus, creep, hardness) at the same operating conditions relevant for SOEC operation. In this work, we characterize the thermo-mechanical properties of borosilicate glass powder and sintered samples at various temperatures (ranging from ambient to 850°C), and at different aging conditions (i.e., atmosphere composition, temperature, and duration). The atmosphere composition is changed between air, steam-N2 mixtures, and H2-N2 mixtures to evaluate the chemical stability of borosilicate glass relating to the possible depletion of boron and silicon via the formation of boron hydroxide and silicon vapor when exposed to steam- and hydrogen-rich environments. The aging temperature and duration is varied to evaluate the crystallization kinetics, particle size growth, and its effect on mechanical properties. We employ a combination of Simultaneous Thermal Analysis - STA (i.e., combined Thermogravimetric Analysis - TGA, Differential Scanning Calorimetry - DSC, Fourier Transform Infrared - FT-IR spectroscopy, and Quadrupole Mass Spectroscopy - QMS), and nanoindentation as characterization techniques, while surface roughness is estimated with a 3D confocal optical microscope.Surface roughness varies between 0.83-1.38 𝜇m ± 1.1-1.76 𝜇m (Sa ± Sq). Both powder and solid samples are analyzed via STA with sequential temperature ramps (constant heating rate at 10 K/min in Ar atmosphere) up to 1500°C to estimate the effect of crystallization and particle size on the glass transition onset. For a sample aged at 850°C for 340 h, the first ramp shows typical DSC exothermic peaks (mW/mg) at around 800°C, with a midpoint glass transition occurring at 900°C. However, on the second ramps, peaks lower to around 500°C and the glass transition is estimated to be around 700°C. Subsequent tests consistently mirrored the trend of the second temperature ramp, showing minimal deviation and influence of crystallization and particle growth. Nanoindentation is performed between room temperature and 600°C to characterize both sintered glass samples “as-received” and aged at temperatures between 750-950°C for 340 h. Comparing a sample aged at 750°C with an “as-received” sample, the elastic moduli equally decreased from 100 GPa at room temperature to 40 GPa at 600°C, with comparable hardness values ranging from 10 GPa at room temperature to 0.5-0.9 GPa at 600°C, respectively. A.G. Sabato, G. Cempura, D. Montinaro, A. Chrysanthou, M. Salvo, E. Bernardo, M. Secco, F. Smeacetto, Journal of Power Sources, 328, 262-270 (2016)Dilshat U. Tulyaganov, Allu Amarnath Reddy, Vladislav V. Kharton, José M.F. Ferreira, Journal of Power Sources, 242, 486-502 (2013)S.-B. Sohn, S.-Y. Choi, G.-H. Kim, H.-S. Song, G.-D. Kim, Stable sealing glass for planar solid oxide fuel cell, J. Non. Cryst. Solids. 297 (2002) 103–112. doi:10.1016/S0022-3093(01)01042-0 Figure 1

Mechanochemical Synthesis of Sodium-Ion Conducting Chloride NaTaCl6

All-solid-state sodium batteries have been attracting attentions owing to their high energy density and safety. Solid electrolytes play a significant role in the electrochemical performances of all-solid-state batteries. Chloride-based solid electrolytes are particularly important for achieving high energy densities because of their high oxidation stability, ionic conductivity, and formability. Fewer sodium-ion conducting chlorides have been developed compared to lithium-ion conducting materials. It is necessary to discover the chlorides as the end-member of sodium-ion conductors. In this study, we report the development of a new NaTaCl6 chloride as an end-member sodium-ion conductor with high ionic conductivity. NaTaCl6 sample was mechanically prepared using a planetary ball mill apparatus. The X-ray diffraction patterns of the obtained sample displayed a broad pattern similar to the reported NaTaCl6 (ICSD#36519), suggesting that the sample contains both amorphous and crystalline phases. The reference intensity ratio method was used to investigate the weight ratios of the amorphous phases in the sample. The ratio was approximately 45 %. Transmission electron microscopy observations suggested that the sample consisted of the amorphous matrix and crystalline with the crystallite size of approximately 20 nm. The electrical conductivities of the pelletized samples were measured using two-terminal AC electrochemical impedance spectroscopy. The sample pellets were prepared by uniaxial pressing at 360 MPa without heat treatment. The pellet sample had the relative density of 85 % (powder density: 3.32 g cm–3, pellet density: 2.83 g cm–3). The sample shows σ 25ºC of 6.2×10–5 S cm–1, and the activation energy of 0.37 eV. To determine the NaTaCl6 onset oxidation voltage (OOV), linear sweep voltammetry measurement was carried out. The OOV of the sample at 60 ºC was 3.8 V vs. Na15Sn4. To demonstrate the high oxidation stability of NaTaCl6 in all-solid-state sodium batteries, it was used in a positive electrode by mixing Na3V2(PO4)3 as the active material and the buffer layer. The cell exhibited an initial reversible capacity of 96 mAh g–1 and stable cycling after 40 cycles with the capacity retention of 99.5 %. A 3.3 V all-solid-state sodium battery without oxide solid electrolytes was successfully operated. In this study, the NaTaCl6 electrolyte was developed with a high ionic conductivity and oxidation stability.Acknowledgement: This work was partly supported by JSPS KAKENHI (Grant Numbers: JP21H04701 and JP19H05816) and MEXT Program: Data Creation and Utilization-Type Material Research and Development Project Grant Number JPMXP1122712807.

Exploring the Efficiency of Magnetic Separation and Gravity Concentration for Valorizing Pb-Zn Smelter Slag in a Circular Economy Framework.

The presented work offers an innovative process scheme for valorizing Pb-Zn slag, which involves crushing, grinding, and separation techniques to concentrate valuable components (non-ferrous metals). This methodology could have a significant impact on the global beneficiation of metallurgical slags since it is significantly more simple, environmentally friendly, and cost-effective than standard pyro- and hydrometallurgical procedures. According to previous physicochemical and mineralogical studies, Pb-Zn slag is a valuable secondary raw material. This inhomogeneous technogenic resource contains substantial amounts of non-ferrous metals (Pb, Zn, Cu, and Ag). However, laboratory tests have indicated that the Pb-Zn slag contains highly uneven amounts of valuable metals, ranging from several g/ton to tens of g/ton. The main issue is that traditional metallurgical procedures for releasing beneficial elements are not commercially viable since the elements are "trapped" within the amorphous aluminosilicates or intergrowths of alloy grains and glassy phases. Gravity concentration (Wilfley 13 shaking table) and magnetic separation (Davis separator and disk separator) were used to obtain the final concentrate following comminution and grindability testing. The gravity concentration proved more effective. Namely, magnetic separators could not process nor adequately separate beneficial non-ferrous elements because they were merged together with iron-bearing minerals and aluminosilicates in amorphous Pb-Zn slag grains. With the gravity concentration approach, 12.99% of the processed slag belonged to ∆T fraction (concentration of non-ferrous metal alloys), while remaining 87% corresponded to the tailings fraction (∆L). The total amounts of recovered Pb, Zn, Cu, and Ag from ∆T and ∆L fractions were 5.28%, 6.69%, 0.58%, and 76.12 ppm and 1.22%, 6.05%, 0.43%, and 15.26 ppm, respectively. This streamlined approach to valorizing Pb-Zn slag can reduce the need for hazardous chemicals used in hydrometallurgical refinement operations, as well as the extremely high temperatures required for pyrometallurgical processing. This is the first study to investigate the viability of this novel methodology, which involves the direct examinations of the Pb-Zn slag feed with various alternative technologies for separation and concentration. After extracting the valuable metals, the amorphous aluminosilicate part of the Pb-Zn slag can be reapplied as an alternative raw material in the building sector, adding to the circularity of the suggested approach.