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Surface silanols (SiOH) are important moieties on glass surfaces. Here we present a tag-and-count approach for determining surface silanol densities, which consists of tagging surface silanols with Zn via atomic layer deposition (ALD) followed by detection of the zinc by high sensitivity-low energy ion scattering (HS-LEIS). Shards of fused silica were hydroxylated with aqueous hydrofluoric acid (HF) and then heated to 200, 500, 700, or 900 °C. These heat treatments increasingly condense and remove surface silanols. The samples then underwent one ALD cycle with dimethylzinc (DMZ) or diethylzinc (DEZ) followed by water. As expected, fused silica surfaces heated to higher temperatures showed lower Zn coverages. When fused silica surfaces treated at 200 °C were exposed to DMZ for two different dose times, the same sub-monolayer quantity of Zn was obtained by X-ray photoelectron spectroscopy (XPS). Surface cleaning/preparation immediately before HS-LEIS, including atomic oxygen treatment and annealing, played a critical role in these efforts. Surfaces treated with DMZ generally showed slightly higher Zn signals by LEIS. Using this methodology, a value of 4.59 OH/nm2 was found for fully hydroxylated fused silica. Both this result and those obtained at 500, 700, and 900 °C are in very good agreement with literature values.

This work aimed to comprehensively assess the influence of various surface modifications on the formation of apatite ability for EBM Ti-6Al-4V alloy. Sandblasting (S), acid-etching (E), sandblasting and acid-etching (SE), anodization (NA), micro-arc oxidations in 1M H2SO4solution (SM) and 1M H3PO4solution (PM) methods were applied to modify electron beam melted (EBM) Ti-6Al-4V surface. The α/α’-Ti structures and TiO2phases were detected by XRD. The surface roughness (Ra) values ranged from 0.25 μm and 2.86 μm. The wettability of samples was between around 25° and 104°. The SM sample possessed the lowest contact angle. In vitro tests were employed in the simulated body fluid (SBF) solution for 28 days. The samples with different surface textures demonstrated bioactive behaviors. In vitro test results showed that apatite layers formed on the surfaces. The SM sample exhibited good apatite formation ability when the Ca/P ratios were considered. The apatite formation for the SM sample might derive from high roughness, low contact angle value, the existence of Ti-OH groups, and anatase and rutile phases. The SM can be implemented to boost bioactivity on EBM Ti-6Al-4V alloys.

ispartof: SURFACE ENGINEERING vol:38 issue:4 pages:430-439 status: published

Nowadays, the need for papers and cardboards with improved surface properties is increasing with the development of the packaging industry. The improvements made are not only limited to the paper and paper surface, but also environmentalist approaches are exhibited in printing ink. For this purpose, the use of water-based ink tends to become widespread, especially in food packaging. In this study, five different paper coating formulations were prepared using different proportions of precipitated calcium carbonate (PCC) and kaolin pigments. Latex (Acronal S360D) was used as a binder. All prepared coating mixes were applied onto the base paper surface. All coated papers were also subjected to the calendering process. In addition, three different dyestuffs (14, 17, 20%) concentrations of water-based printing inks were prepared. Prints were made by the silk screen printing technique on the calendered-coated papers. The optical and physical properties (roughness, air permeance, paper gloss and printing gloss, contact angle and surface energy) of all papers were measured according to the standards. Paper gloss, print gloss, Delta E-00 color differences, contact angles and surface energy measurements were made, and the effects of dye ratio on printing and gloss in water-based inks and coating type suitable for printability were investigated. As a result, papers can be coated and even calendered to achieve better paper surface properties and printability. In the case of printing with water-based inks, better printability properties are obtained by choosing PCC pigmented coated papers.

The etching of HfO[Formula: see text] and ZrO[Formula: see text] high-k dielectrics is studied using plasma enhanced atomic layer etching. The etching method relies on a continuous argon inductively coupled plasma discharge in which reactive gases are pulsed, followed by substrate biasing; both steps are separated by purge periods. It is found that pure BCl[Formula: see text] is too chemically active while a Cl[Formula: see text]–BCl[Formula: see text] allows a high process synergy; in addition, the latter gives a high selectivity to SiO[Formula: see text]. The optimal etch conditions are applied to high-k layers deposited on top of WS[Formula: see text] transition metal dichalcogenide. Postetch analysis shows negligible tungsten and sulfur depletion as well as negligible change in optical (Raman) response of the 2D layer, indicating that atomic layer etching concepts allows us to prevent WS[Formula: see text] material loss or damage.

To realise the promise of solid-state batteries, negative electrode materials exhibiting large volumetric expansions, such as Li and Si, must be used. These volume changes can cause significant mechanical stresses and strains that affect cell performance and durability, however their role and nature in SSBs are poorly understood. Here, a 2D electro-chemo-mechanical model is constructed and experimentally validated using steady-state, transient and pulsed electrochemical methods. The model geometry is taken as a representative cross-section of a non-porous, thin-film solid-state battery with an amorphous Si (a-Si) negative electrode, lithium phosphorous oxynitride (LiPON) solid electrolyte and LiCoO2 (LCO) positive electrode. A viscoplastic model is used to predict the build-up of strains and plastic deformation of a-Si as a result of (de)lithiation during cycling. A suite of electrochemical tests, including electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique and hybrid pulse power characterisation are carried out to establish key parameters for model validation. The validated model is used to explore the peak interfacial (a-Si∣LiPON) stress and strain as a function of the relative electrode thickness (up to a factor of 4), revealing a peak volumetric expansion from 69% to 104% during cycling at 1C. The validation of this electro-chemo-mechanical model under load and pulsed operating conditions will aid in the cell design and optimisation of solid-state battery technologies.

The use of metal-free click reactions for the design and synthesis of novel flame retardant reactive monomers for thiol-ene photopolymerization is an intriguing area of research. In this study, we have prepared a new, 9,10-dihy-dro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based, P-and N-containing reactive flame retardant via the metal-free azide-alkyne click reaction. For this purpose, first, azide-functionalized DOPO (DOPO-N-3) has been synthesized via Atherton-Todd reaction, and then this compound has been reacted with acetylene dicar-boxylic acid diallyl ester (ACDAE) to give the flame retardant monomer, namely DOPO-triazole diallyl ester (DTDAE). As prepared flame retardant monomer was characterized by nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) spectroscopies. Thermoset materials prepared by using DTDAE displayed over 90% gel content values. Polar triazole and phosphorous units rendered the surface of the ther-mosets hydrophilic. The thermal stability of the networks was enhanced, char yields increased and the glass transition temperatures (T(g)s) were increased. The limiting oxygen index (LOI) values of the crosslinked materials increased up to 27.8% as the DTDAE content was increased in the formulations. The synthetic method described in this study provides a practical approach for the synthesis of a P-and N-containing flame retardant through a metal-free azide-alkyne click reaction Also, the fact that DTDAE is in a liquid state makes this study valuable as it indicates that it can be easily dispersed. It is also believed this promising compound can be used in different polymer structures and formulations to develop new flame retardants in future studies to be applied in industrial applications.

Gloss is one of the main attributes to describe the appearance of surfaces and objects, as it contributes to the general quality perception. Gloss is a multidimensional quantity of which ‘specular gloss’ is the most commonly applied attribute. Specular gloss meters are standardized and widely used in industry. However, their readings correlate only partially to the general visual gloss impression, which also comprises distinctness-of-the-reflected-image (DOI), haze, contrast and surface-uniformity attributes. This study presents a more profound image-based gloss meter (iGM) which incorporates a CMOS camera detector. This concept is not new, but limited research has been conducted on the inclusion of various image processing evaluations for gloss attributes. The designed iGM is compatible to 60° specular gloss meter standards. The CMOS detector captures the reflected source image, which is processed to measure four perceptual attributes of surface gloss. The obtained results validate the 60° specular gloss evaluation and indicate a promising capability in characterizing DOI, haze, and contrast. Contrast is an important attribute that is not available yet in industrial gloss meters. It is measured using a diffuse aspecular light source. Generally, this iGM maintains the hardware principles of specular gloss meters, while evolving toward a representative gloss perception meter.

We investigated the benzotriazole enabled growth of low Ni content (5–15 at.%) CuNi alloy deposits by characterisation of its morphology and elemental composition as a function of substrate metal (Cu and Ni), charge density, current density, and potential-time response measured during electrodeposition. Alloy deposition starts in favor of Cu, forming a Cu-rich layer on a Ni substrate and Cu-rich islands on a Cu substrate after which aggregates only form on a Cu substrate, due to the ability of benzotriazole (BTAH) to chemically bond to Cu but not to a Ni surface. Furthermore, Ni deposits preferably on grain boundaries, BTAH gets incorporated in the deposit and forms a thin layer between the Cu substrate and the alloy deposit. Based on our findings a growth model for BTAH enabled CuNi growth is proposed which describes that the BTAH working mechanism is twofold. First, the additive shifts the onset potential of Cu2+ reduction closer to the Ni2+ reduction potential by forming a chemisorbed BTAH layer, thereby enabling Cu and Ni co-deposition and, secondly, during deposition it specifically interacts with Cu, thus inhibiting Cu dendrite formation.

High voltage cathodes suffer from degradation phenomena that are challenging to be observed and identified during cell operation. Dense and smooth sputtered thin films electrodes with absence of binders and conductive additives allow a direct study of the active material upon Li insertion and extraction at surface and bulk. Using an operando spectroscopic ellipsometry set-up combined with a customized electrochemical-optical cell (EC-SE), the evolution of the optical absorption and thickness of LiMn2O4 and LiNi0.5Mn1.5O4 thin-film electrodes was monitored upon cycling. Mixed Mn3+/4+ valence in the electrodes and evident layer dissolution associated to Transition Metal (TM) dissolution in the non-aqueous electrolyte at the applied polarization potentials was observed. Our results reaffirm EC-SE as a convenient method to study degradation phenomena in cobalt-free transition metal oxide electrodes.

Nanoelectronics holds significant promise for two-dimensional (2D) semiconducting transition metal dichalcogenide (TMD) applications. On a polycrystalline WS2 monolayer created by metal-organic chemical vapor deposition (MOCVD) at 950 °C, we studied the nucleation, growth, and development of Al2O3 atomic layer deposition (ALD) on a SiO2/Si substrate. In this investigation, we used various complementary characterization methods, such as Raman spectroscopy, elastic recoil detection, atomic force microscopy, and time-of-flight secondary ion mass spectrometry, to understand thoroughly the intrinsic reactivity of WS2. Strong peak intensity changes at the interfaces in the Raman line scans of the SiO2/Si patterns suggest extremely crystalline WS2. After multiple ALD cycles, triangular WS2 crystals were decorated to provide a two-dimensional growth mode with a great selectivity for grain boundaries and step edges. The results of this work can be used for further exploration of the TMD monolayer structure and properties, which is essential for tailoring 2D materials for a specific application in devices.

In this study, we explored the key properties and functionalities of plasma enhanced atomic layer deposition (PEALD) SiNx films, synthesized using different deposition temperatures (500–550 °C) and plasma conditions (lower and higher), both on 300 mm blanket Si and on several integrated 3D topology substrates, at the thicknesses relevant for diverse nanoscale applications. Our study shows that with an increase of temperature (500–550 °C), a small reduction in HF wet etch rate (1.1–0.69 nm/min), and H content (9.6% vs 7.4%) was observed. When using higher plasmas, significant improvements in blanket properties were observed. The films were denser (2.95 g/cm3), exhibited lower H content (2.4%), showed better etch rates (0.39 and 0.44 nm/s for HF and CF4 based), and SiNx grew without any nucleation delay on alternative Si1−xGex channel surfaces. The vertical and lateral conformality was found to be similar and appears not to be impacted with the plasma conditions. Extensive steam oxidation barrier studies performed at the sidewalls of different aspect ratio lines showed the PEALD SiNx liner scaling potentiality down to 1 nm when deposited using higher plasma. In addition, the outer gate and inner spacer properties were found to be superior (with lower loses) for higher plasma films when subjected to several dry etch, strips, and H3PO4 chemistries. The outstanding conformality (90%–95% on aspect ratios ≤10:1) combined with excellent high end material properties in the ultrathin regimes (1–10 nm) corroborate the virtue of PEALD SiNx toward integration in scaled down and advanced nanoelectronics device manufacturing.

A method for forming electromagnetic waves with a tunable nonzero orbital angular momentum (OAM) is proposed. The approach is based on transforming an incident plane wave into a helical one using an electrically tunable ferroelectric lens. It uses high-resistive thin/thick film electrodes with a special discrete topology. The correlation between film electrodes topology and the highest order of OAM modes that the lens can form is described. A lens prototype based on Ba0.55Sr0.45TiO3 ferroelectric material and operating at a frequency of 60 GHz was designed, manufactured, and tested. The amplitude and phase distribution of the OAM wave with l = +1 formed by prototype were measured to confirm the effectiveness of the proposed method. The proposed lens has a combination of advantages such as low dimensions, electrical control over the OAM modes, and the possibility to operate in the millimeter wavelength range.

It is well-known that the crystallographic texture of a polycrystalline aggregate can be represented by the Orientation Distribution Function (ODF). A similar statistical approach can be extended to other microstructural state variables that are of relevance in the context of obtaining microstructurally based and quantitatively accurate structure-properties relations. In principle such statistical representations are of a non-topological nature, in contrast to an RVE (Representative Volume Element) description of the microstructure. However, by including additional variables to the statistical descriptor specific features of the topology may be taken into account. In this paper the example will be shown on how the plastic anisotropy simulation of a conventional deep drawing grade of Interstitial Free (IF) steel can be improved by considering the crystallographic misorientation of pairs of neighboring crystals, which represent the basic structural units of the 2-point mean field ALAMEL crystal plasticity model. In another example it will be shown how the recrystallization texture of the same deep drawing IF steel can be modelled with improved accuracy if the Strain Induced Boundary Mechanism (SIBM) is taken into account whereby a crystal orientation of low stored energy grows into a neighboring orientation of high stored energy.

This work reports on sputter depositions carried out from a compound (Ti,Zr)(2)AlC target on Al2O3(0 0 0 1) substrates at temperatures ranging between 500 and 900 degrees C. Short deposition times yielded 30-40 nm-thick Al-containing (Ti,Zr)C films, whereas longer depositions yielded thicker films up to 90 nm which contained (Ti,Zr)C and intermetallics. At 900 degrees C, the longer depositions led to films that also consisted of solid solution MAX phases. Detailed transmission electron microscopy showed that both (Ti,Zr)(2)AlC and (Ti,Zr)(3)AlC2 solid solution MAX phases were formed. Moreover, this work discusses the growth mechanism of the thicker films, which started with the formation of the mixed (Ti,Zr)C carbide, followed by the nucleation and growth of aluminides, eventually leading to solid state diffusion of Al within the carbide, at the highest temperature (900 degrees C) to form the MAX phases. Funding Agencies|Swedish research council VR-RFISwedish Research Council [2017-00646_9]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIF14-0053]; Euratom research and training programme 2014-2018 [740415]; Stiftelsen Olle Engkvist ByggmastareSwedish Research Council [184-561]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-MatLiU) [2009 00971]; Research Foundation FlandersFWO [AKUL/1319]

ispartof: THIN SOLID FILMS vol:732 status: published

Product water accumulations in polymer electrolyte fuel cells can cause performance losses and reactant starvation leading to cell degradation. Liquid water removal in the form of droplets, fed by percolation networks in the gas diffusion layer (GDL), is one of the main transport mechanisms by which the water is evacuated from the GDL. In this study, the effect of droplet detachment in the gas channel on the water cluster inside the GDL has been investigated using X-ray tomographic microscopy and X-ray radiography. The droplet growth is captured in varying stages over a sequence of consecutive droplet releases, during which an inflation and deflation of the gas-liquid interface menisci of the percolating water structure in the GDL has been observed and correlated to changes in pressure fluctuations in the water phase via gas-liquid curvature analysis., Journal of the Electrochemical Society, 167 (8), ISSN:0013-4651, ISSN:1945-7111

Cooling electrical tabs of the cell instead of the lithium ion cell surfaces has shown to provide better thermal uniformity within the cell, but its ability to remove heat is limited by the heat transfer bottleneck between tab and electrode stack. A two-dimensional electro-thermal model was validated with custom made cells with different tab sizes and position and used to study how heat transfer for tab cooling could be increased. We show for the first time that the heat transfer bottleneck can be opened up with a single modification, increasing the thickness of the tabs, without affecting the electrode stack. A virtual large-capacity automotive cell (based upon the LG Chem E63 cell) was modelled to demonstrate that optimised tab cooling can be as effective in removing heat as surface cooling, while maintaining the benefit of better thermal, current and state-of-charge homogeneity. These findings will enable cell manufacturers to optimise cell design to allow wider introduction of tab cooling. This would enable the benefits of tab cooling, including higher useable capacity, higher power, and a longer lifetime to be possible in a wider range of applications.

Oxygen is often detected as an impurity in III-nitride films deposited by atomic layer deposition (ALD). The presence of oxygen has deep and unfavorable influences on the structural and optical properties of AlN. We have studied the oxygen incorporation in AlN films prepared by hollow cathode plasma-assisted ALD by alternating H-2 plasma. We report a decrease in the O concentration in the film upon the addition of H-2 plasma flow. However, increasing the H-2 plasma flow does not further decrease the O incorporation. Film composition became almost constant at the surface and beneath the surface of AlN films deposited using N-2/H-2 plasma. Only samples grown with N-2/H-2 plasma showed decreases in oxygen concentration from the surface to the bulk film. Oxygen produces important modifications in the structural, chemical, and electrical properties. The Al 2p, N 1s, and O 1s high-resolution x-ray photoelectron spectra represent that AlN films are composed of Al-N, Al-O, and N-Al-O bonds. X-ray photoelectron spectroscopy data suggest that the composition of the AlN film changes to AlON + AlN when N-2 plasma is used. The valence band maximum position of the AlN film is found to be at & SIM;1.7 eV for oxygen atomic concentration & SIM;20 at. %. The TO and LO phonon modes are present in AlN films with oxygen contamination & SIM;20 at. % and disappear at high oxygen contamination (& SIM;55 at. %).

© 2018 Elsevier B.V. Retrieving molecular information by sputtering of organic systems has been concretized in the last years due to the introduction of sputtering by large gas clusters which drastically eliminated the compound degradation during the analysis and has led to strong improvements in depth resolution. Rapidly however, a limitation was observed for heterogeneous systems where inorganic layers or structures needed to be profiled concurrently. As opposed to organic material, erosion of the inorganic layer appears very difficult and prone to many artefacts. To shed some light on these problems we investigated a simple system consisting of aluminum delta layer(s) buried in a silicon matrix in order to define the most favorable beam conditions for practical analysis. We show that counterintuitive to the small energy/atom used and unlike monoatomic ion sputtering, the information depth obtained with large cluster ions is typically very large (∼10 nm) and that this can be caused both by a large roughness development at early stages of the sputtering process and by a large mixing zone. As a consequence, a large deformation of the Al intensity profile is observed. Using sample rotation during profiling significantly improves the depth resolution while sample temperature has no significant effect. The determining parameter for high depth resolution still remains the total energy of the cluster instead of the energy per atom in the cluster. ispartof: Applied Surface Science vol:444 pages:633-641 status: published

To prolong the lifetime of hydraulic cylinders, a wear-resistant low-friction surface is required. Until now, hard Cr coatings were the best materials for this. However, in recent years, there has been an increasing pressure on the manufacturing of hard Cr plating and plated products, because of environmental and health hazards. The replacement of these coatings by alternatives has not been highly successful yet, because it requires extensive component testing, which is costly and time-consuming and thus not appropriate for material development. For this reason, there is a high need to develop tribological methods that simulate hydraulic cylinders’ component-testing closely. In addition, these new methods should also provide additional information (e.g., friction evolution) that can assist in the further development and optimization of alternative coatings. Having the above in mind and building on an existing method from the American Society for Testing and Materials (ASTM G133), a new test method that allows users to test directly on hydraulic cylinders was developed. This method can provide a relative ranking of both the wear resistance and frictional performance of alternative coatings in direct comparison to state-of-the-art hard Cr. Importantly, the method is repeatable and has a much shorter test duration than full-scale component tests, thereby accelerating material development significantly. ispartof: Coatings vol:11 issue:12 status: published

Lithium ion batteries are increasingly important in large scale applications where thermal management is critical for safety and lifetime. Yet, the effect of different thermal boundary conditions on the performance and lifetime is still not fully understood. In this work, a two-dimensional electro-thermal model is developed to simulate cell performance and internal states under complex thermal boundary conditions. Attention was paid to model, not only the electrode stack but also the non-core components (e.g. tab weld points) and thermal boundaries, but also the experiments required to parameterize the thermal model, and the reversible heat generation. The model is comprehensively validated and the performance of tab and surface cooling strategies was evaluated across a wide range of operating conditions. Surface cooling was shown to keep the cell at a lower average temperature, but with a large thermal gradient for high C rates. Tab cooling provided much smaller thermal gradients but higher average temperatures caused by lower heat removing ability. The thermal resistance between the current collectors and tabs was found to be the most significant heat transfer bottleneck and efforts to improve this could have significant positive impacts on the performance of li-ion batteries considering the other advantages of tab cooling.

The effects of micro-alloying of plain carbon steel with Cr and Mo on the corrosion behavior in CO2-saturated (sweet) brine (0.5 M NaCl, pH 6.6) environment, under hydrodynamic conditions, at 80◦C were investigated. Crystalline siderite/chukanovite scales formed on all the alloys. Analysis of potentiostatic current transient data suggest that there exists a synergistic interaction between Cr and Mo, which induces more rapid crystallization of the scale compared to Mo-free steels. Increasing the Mo content also suppressed the transport-dependent dissolution current passing through the initially-present amorphous surface film. TEM images of the FIB-sectioned corrosion scales confirm that the corrosion scale formed on 1Cr0.7Mo is comparatively thinner and yet offers greater protectiveness when compared to the plain carbon steel.

This paper asserts that the development of continuum-scale mathematical models utilizing John Newman’s BAND subroutine can be simplified through the use of dual number automatic differentiation. This paper covers the salient features of the BAND algorithm as well as dual numbers and how they can be leveraged to algorithmically linearize systems of partial differential equations; these two concepts can be combined to produce accurate and computationally efficient models while significantly reducing the amount of personnel time necessary by eliminating the time-consuming process of equation linearization. As a result, this methodology facilitates more rapid model prototyping and establishes a more intuitive relationship between the numerical model and the differential equations. By utilizing an existing and validated programming module, dnadmod, these advantages are achieved without burdening the general user with significant additional programming overhead.

The main barrier to fast charging of Li-ion batteries at low temperatures is the risk of short-circuiting due to lithium plating. In-situ detection of Li plating is highly sought after in order to develop fast charging strategies that avoid plating. It is widely believed that Li plating after a single fast charge can be detected and quantified by using a minimum in the differential voltage (DV) signal during the subsequent discharge, which indicates how much lithium has been stripped. In this work, a pseudo-2D physics-based model is used to investigate the effect on Li plating and stripping of concentration-dependent diffusion coefficients in the active electrode materials. A new modelling protocol is also proposed, in order to distinguish the effects of fast charging, slow charging and Li plating/stripping. The model predicts that the DV minimum associated with Li stripping is in fact a shifted and more abrupt version of a minimum caused by the stage II-stage III transition in the graphite negative electrode. Therefore, the minimum cannot be used to quantify stripping. Using concentration-dependent diffusion coefficients yields qualitatively different results to previous work. This knowledge casts doubt on the utility of DV analysis for detecting Li plating.

Lithium-sulfur batteries could deliver significantly higher gravimetric energy density and lower cost than Li-ion batteries. Their mass adoption, however, depends on many factors, not least on attaining a predictive understanding of the mechanisms that determine their performance under realistic operational conditions, such as partial charge/discharge cycles. This work addresses a lack of such understanding by studying experimentally and theoretically the response to partial cycling. A lithium-sulfur model is used to analyze the mechanisms dictating the experimentally observed response to partial cycling. The zero-dimensional electrochemical model tracks the time evolution of sulfur species, accounting for two electrochemical reactions, one precipitation/dissolution reaction with nucleation, and shuttle, allowing direct access to the true cell state of charge. The experimentally observed voltage drift is predicted by the model as a result of the interplay between shuttle and the dissolution bottleneck. Other features are shown to be caused by capacity fade. We propose a model of irreversible sulfur loss associated with shuttle, such as caused by reactions on the anode. We find a reversible and an irreversible contribution to the observed capacity fade, and verify experimentally that the reversible component, caused by the dissolution bottleneck, can be recovered through slow charging. This model can be the basis for cycling parameters optimization, or for identifying degradation mechanisms relevant in applications. The model code is released as Supplementary material B.

The mechanisms of friction in natural joints are still relatively unknown and attempts at modelling cartilage-cartilage interfaces are rare despite the huge promise they offer in understanding bio-friction. This article derives a model combining finite strain, porous and thin-film flow theories to describe the lubrication of cartilage-on-cartilage line contacts. The material is modelled as compliant and poroelastic in which the micro-scale fibrous structure is interstitially filled with synovial fluid. This fluid flows over the interface between the bodies and is coupled to pressure generated by relative motion in the thin-film region formed under load. A Stribeck analysis demonstrated that this type of contact is determinable to conventional elastic lubrication but that the friction performance is improved by this interfacial flow. Moreover, the inclusion of periodic flow conditions when contact is onset is a specific novelty which elucidates new observations in the lubrication mechanisms pertaining to natural joints.

The objective of this study was the development of Ag-rich antibacterial coatings on titanium to prevent post-operative infections. A series of Ag-doped TiO2 coatings were synthesized on Ti discs by plasma electrolytic oxidation in an electrolyte containing AgNPs. The incorporation, distribution and chemical composition of the AgNPs on Ti were determined using scanning electron microscopy-energy dispersive spectroscopy. The crystalline structure and wettability of the coating was characterized by X-ray diffraction and water contact angle analysis respectively. Surface roughness and hardness of the coating were examined using surface profilometry and Knoop indentation test respectively, while silver ion release was quantified using inductively coupled plasma-mass spectroscopy. Following PEO, the surface of the Ti substrate was converted to TiO2 composed of anatase and rutile phases. The SEM micrographs showed that the AgNPs were distributed throughout the oxide layer, without changing the morphology of the coating. The coatings also revealed an increased surface roughness, microhardness and improved surface wettability relative to untreated Ti substrates. Furthermore, the incorporation of Ag into the coating did not alter the phase component, roughness, microhardness and wettability. A series of in-vitro antibacterial assays indicated that increasing the number of AgNPs in the electrolyte led to excellent antibacterial activities.

Temperature-dependent nanoindentation testing was employed to investigate the deformation behaviour of magnetron sputtered (100) TiN and Ti1-xAlxN (x = 0.34, 0.52, 0.62) coatings in the temperature range from 295 to 573 K. The maximum temperature is sufficiently below the deposition temperature of 773 K to guarantee for stable microstructure and stress state during testing. The TiN coating displayed the same hardness as bulk single crystal (SC) TiNbulk. The addition of aluminium to TiN (to form single-phase face centred cubic structured Ti1-xAlxN coatings) increased the room temperature hardness due to increased bond strength, lattice strain and higher activation energy for the dislocation slip. For coatings with a low aluminium content, Ti0.66Al0.34N, the decrease in hardness with temperature was similar to the TiN coating and SC-TiNbulk. In contrast, the hardness of coatings with moderate, Ti0.48Al0.52N, and high, Ti0.38Al0.62N, aluminium contents varied little up to 573 K. Thus, the Ti1-xAlxN matrix is mechanically more stable at elevated temperatures than its TiN relative, by providing a lower decrease in lattice resistance to the dislocation flow with increasing temperature. The findings suggest that the addition of Al to TiN (to form Ti1-xAlxN solid solutions) not only improves the hardness but also leads to stable hardness with temperature, and emphasizes the importance of bonding states and chemical fluctuations, next to structure and morphology of the coatings that develop with changing the chemistry.

ispartof: JOURNAL OF THE ELECTROCHEMICAL SOCIETY vol:166 issue:8 pages:D315-D322 ispartof: location:WA, Seattle status: published

In this research, the free surface of micro film of hexyl alcohol on a partially submerged rotating drum has been predicted using CFD (computational fluid dynamics) and compared with experimental data and analytical solution. The trend of has been found very comparable with experimental and analytical solution. A Matlab code was used to model the flow and film dynamics. Computationally it was an unsteady state problem and semi-steady state was achieved. No surfactant was present on the surface. The speed of the moving rotating drum was set a rpm. With the increase of rotating drum, the minimum film thickness increases with rpm (for {\textstyle \alpha _{o}} = 47 {\displaystyle ^{0}} and for {\textstyle \alpha _{o}} = 58 {\displaystyle ^{0}} ).

© The Author(s) 2019. Published by ECS. In this work, we demonstrate electrochemical methods for determination of porosity and surface area of thin films of interconnected nickel nanowires. While the standard porosimetry and gas adsorption methods lack sensitivity for characterization of thin metallic films, the electrochemical methods employing coulometry, cyclic voltammetry and electrochemical impedance spectroscopy can be applied to accurately determine textural properties of micron- and sub-micron thick nanostructured materials. Additionally, in this work we evaluated accuracy and precision of five electrochemical signals recorded during cyclic voltammetry and electrochemical impedance spectroscopy, which are commonly used for determination of electrochemical surface area (AECSA) of various nickel electrodes. By verifying the data with two independent surface characterization techniques, we found that the analysis based on surface-limited oxidation of nickel and on capacitive charging of nickel surface during hydrogen evolution reaction give the best accuracy and smallest errors. We also show that experimental conditions play a crucial role in the accurate determination of AECSA of nickel nanomaterials. If the influence of experimental conditions is not corrected for, the electrochemical surface area can differ by over 250% compared to the surface area determined with other methods. ispartof: JOURNAL OF THE ELECTROCHEMICAL SOCIETY vol:166 issue:6 pages:D227-D235 ispartof: location:LA, New Orleans status: published

Fast charging of batteries is currently limited, particularly at low temperatures, due to difficulties in understanding lithium plating. Accurate, online quantification of lithium plating increases safety, enables charging at speeds closer to the electrochemical limit and accelerates charge profile development. This work uses different cell cooling strategies to expose how voltage plateaus arising from cell self-heating and concentration gradients during fast charging can falsely indicate plating, contrary to prevalent current assumptions. A solution is provided using Differential Voltage (DV) analysis, which confirms that lithium stripping is observable. However, scanning electron microscopy and energy-dispersive X-ray analysis are used to demonstrate the inability of the plateau technique to detect plating under certain conditions. The work highlights error in conventional plating quantification that leads to the dangerous underestimation of plated amounts. A novel method of using voltage plateau end-point gradients is proposed to extend the sensitivity of the technique, enabling measurement of lower levels of lithium stripping and plating. The results are especially relevant to automotive OEMs and engineers wishing to expand their online and offline tools for fast charging algorithm development, charge management and state-of-health diagnostics.

Sr0.7R0.3CoO3-δ (R = Tb and Er) tetragonal perovskites have been prepared and evaluated as mixed ionic-electronic cathodes for SOFC. Neutron powder diffraction (NPD) measurements evidenced that both compounds are oxygen hypo-stoichiometric with long-range order of oxygen vacancies that leads to a tetragonal perovskite-type superstructure (s.g. I4/mmm) stable within the whole temperature range under study. The oxygen vacancies located mainly in the equatorial oxygen positions exhibit large displacement factors. The high oxygen mobility in Sr0.7Tb0.3CoO3-δ was confirmed by 18O oxygen labeling followed by Secondary Ion Mass Spectrometry (SIMS) with values of oxygen self-diffusion of 1.29 × 10−10 cm2/s at 525°C. Polarization resistances with LSGM as electrolyte gave values as low as 0.011 Ω⋅cm2 and maximum output powers of 570 mW/cm2 at 850°C were obtained in test cells set in electrolyte-supported configuration. Electrical conductivity, thermal and chemical expansion and stability measurements confirm the potential of these materials as cathodes for SOFC.

Despite the potential of solid electrolytes in replacing liquid electrolytes, solid-state lithium-metal batteries have not been commercialised for large-scale applications due to manufacturing constraints. In this study, we demonstrate that the desired energy and power output for large-format solid-state lithium-metal batteries can be achieved by scaling and stacking unit cells. Two stack configurations, a bipolar and a parallel stack are modelled and compared. With 63 cells stacked in series, we show that a bipolar stack could reach a stack voltage up to 265 V. In contrast, a parallel stack with 32 double-coated cells could achieve a nominal capacity of 4 Ah. We also demonstrate that the choice of current collectors is critical in determining the gravimetric power and energy density of both stacks. By coupling the electrochemical stack model thermally, we show that the Joule heating effects are negligible for bipolar stacks but become dominant for parallel stacks. Bipolar stacks are better due to their higher power and energy densities and lower heat generation, but a lower Coulombic stack capacity limits their performance. In contrast, parallel stacks generate more heat and require more advanced thermal management. These thermally-coupled stack models can be used as prototypes to aid the future development of large-format solid-state batteries.

Amino-rich thin coatings, known to show superior cell adhesion, proliferation and viability, are prepared in this study by means of plasma polymerisation. The Yasuda parameter (W/FM) is used as a scaling factor for the deposition of cyclopropylamine based plasma polymer films (CPA-PPFs) making use of a dielectric barrier discharge (DBD) operated at sub-atmospheric pressure. In this paper, the experimental research is focussed on the stability of the CPA-PPFs in water, a property of PPFs which is often overlooked in literature. More specifically, after their plasma-assisted fabrication, the polymerised samples are immersed in water for 24 h after which the coatings are chemically evaluated using Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy. The obtained results reveal that for all W/FM values under study water immersion results in a significant loss in C N/C N groups and a shift of primary to secondary/tertiary amines combined with the incorporation of oxygen at the surface as amides and alcohols/ethers. Moreover, FTIR, XPS chemical depth profiling (by means of C60 sputtering) and scanning electron microscopy (SEM) results also reveal that at W/FM values ≤ 288 MJ/kg, the PPFs are gradually dissolving during water immersion, while at W/FM values > 288 MJ/kg, the PPFs are delaminating from the substrate due to their high crosslinking degree. Nevertheless, cell-coating interaction studies reveal no signs of cytotoxicity 1 day after cell seeding and show that the thin coatings remaining on the substrate still strongly increase the adhesion of fibroblasts. In the near future, efforts will be undertaken to avoid the delamination from the substrate of the PPFs prepared at high W/FM values.

In2O3 is one of the most important semiconducting metal oxides primarily because of its wide band gap, high electron mobility and processing versatility. To this end, high-quality thin films of In2O3 can be prepared using scalable and inexpensive solution-based deposition methods, hence making it attractive for application in a number of emerging electronic applications. However, traditional solution processing often requires high temperature and lengthy annealing steps, making it impossible to use in combination with temperature-sensitive plastic substrates, which would be desired for numerous emerging flexible device applications. Here, rapid photonic curing of In2O3 layers is explored as an alternative to thermal annealing. Oxide thin films are successfully prepared on a range of substrates, including glass, polyimide, and polyethylene naphthalate. The effect of substrate and post-processing treatment on the morphology, surface chemistry, and electronic properties is investigated by atomic force microscopy and X-ray photoelectron spectroscopy. Systematic trends are identified, particularly in the degree of conversion of the precursor and its influence on the electronic structure.

The safety, performance and lifetime of lithium-ion cells are critical for the acceptance of electric vehicles (EVs) but the detection of cell quality issues non-destructively is difficult. In this work, we demonstrate the use of a multi-dimensional laser scanning method to detect local inhomogeneities. Commercially available cells with Nickel Cobalt Manganese (NMC) cathode are cycled at various charge and discharge rates, while 2D battery displacement measurements are taken using the laser scanning system. Significant local swelling points are found on the cell during the discharge phase, the magnitude of swelling can be up to 2% of the cell thickness. The results show that the swelling can be aggravated by a combination of slow charge rate and fast discharge rate. Disassembly of the cells shows that the swelling points are matched with the location of ‘adhesive-like’ material found on the electrode surfaces. Scanning Electron Microscope (SEM) images show that the material is potentially blocking the electrodes and separators at these locations. We therefore present laser-scanning displacement as a valuable tool for defect/inhomogeneity detection.

We have studied the crystallization reaction of polycrystalline Cu2ZnGeSe4 solar cell absorbers fabricated by H2Se selenization of sequentially deposited metal layer stacks. We have executed a stop experiment, stopping the crystallization reaction at different times during the process, then analyzing the subsequent X-ray diffraction patterns. We have found that mainly Cu3Ge and ZnSe phases form very rapidly at temperatures below 350 °C. Depending on the order of the sequentially deposited metal layer stack, the formation reaction proceeds at different speeds. Putting the Ge layer in the bottom and the Cu layer on top leads to a very fast nucleation reaction of Cu2ZnGeSe4, leading to small grains that have obtained their final size already after 3 min of selenization at 460 °C. The inverse stack with Ge on top and Cu in the bottom delays the nucleation of Cu2ZnGeSe4, leading to a somewhat slower formation reaction and larger Cu2ZnGeSe4 grains, which obtain their final grain size only after 15 min of selenization at 460 °C. This research is partially funded by the Flemish government, Department Economy, Science and Innovation. This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 640868. B. Vermang acknowledges the financial support of the Flemish Research Foundation FWO (mandate 12O4215N).

WOS: 000464099100001, In this study, the labyrinth resonator based chemical liquid and transformer oil condition sensor are presented in a microwave frequency range both numerically and experimentally. The transmission coefficient is observed by the magnetic coupling between the transmission line and resonator which also contain a sensing layer. The sensor structure is tested with the ethanol-water mixtures, methanol-water mixtures and different kind of pure chemical fluidics. In addition, the proposed sensor is used for distinguishing the waste and clean transformer oil sensitively. In the chemical liquids sensing study, linear response characteristics of the sensor have been investigated by the resonance frequency shifts for ethanol-water and methanol-water mixtures. The frequency shifts for each 10% steps of ethanol and methanol content have been monitored as about 25 MHz and 15 MHz, respectively. In the transformer oil condition sensing study, non-destructive methods have been used for providing the long term stability of the sensor structure. In addition, the measured response time between the signal applied from the input port and observation of the transmitted signal from the output port is around 5ns. This value is consistent with the period of the applied signal and the length of the receiver/transmitter cables and the sensor circuit. (c) 2019 The Electrochemical Society., Scientific Project Unit of Cukurova University [FDK-2018-10488], The authors acknowledge the Scientific Project Unit of Cukurova University (FDK-2018-10488)

A hydrogen-vanadium electrochemical system was characterized using extensive experimental tests at different current densities and flow rates of vanadium electrolyte. The maximum peak power density achieved was 2840 W m− 2 along with a limiting current density of over 4200 A m− 2. The cycling performance presented a stable coulombic efficiency over 51 cycles with a mean value of 99.8%, while the voltage efficiency decreased slowly over time from a value of 90.3% to 87.0%. The capacity loss was of 5.6 A s per cycle, which could be related to crossover of ionic species and liquid water. A unit cell model, previously proposed by the authors, was modified to include the effect of species crossover and used to predict the cell potential. Reasonable agreement between the model simulations and the experimental charge-discharge data was observed, with Normalized Root-Mean-Square Errors (NRMSEs) within the range of 0.8–5.3% and 2.9–19.0% for charge and discharge, respectively. Also, a good degree of accuracy was observed in the simulated trend of the polarization and power density, with NRMSEs of 3.1% and 1.0%, and 1.1% and 1.9%, for the operation at a flow rate of vanadium electrolyte of 100 and 50 mL min− 1, respectively, while the voltage efficiency during the cycling test were estimated within a Root-Mean-Square Error (RMSE) of 1.9%. A study of the effect of the component properties on the cell potential was carried out by means of a model sensitivity analysis. The cell potential was sensitive to the cathodic transfer coefficient and the cathode porosity, which are directly related to the cathodic overpotential through the Butler-Volmer equation and the cathodic ohmic overpotential. It was recognized that a kinetic study for the cathodic reaction is needed to obtain more reliable kinetic parameters at practical vanadium concentrations, as well as reliable microstructural parameters of carbon electrodes.

Battery performance is strongly correlated with electrode microstructural properties. Of the relevant properties, the tortuosity factor of the electrolyte transport paths through microstructure pores is important as it limits battery maximum charge/discharge rate, particularly for energy-dense thick electrodes. Tortuosity factor however, is difficult to precisely measure, and thus its estimation has been debated frequently in the literature. Herein, three independent approaches have been applied to quantify the tortuosity factor of lithium-ion battery electrodes. The first approach is a microstructure model based on three-dimensional geometries from X-ray computed tomography (CT) and stochastic reconstructions enhanced with computationally generated carbon/binder domain (CBD), as CT is often unable to resolve the CBD. The second approach uses a macro-homogeneous model to fit electrochemical data at several rates, providing a separate estimation of the tortuosity factor. The third approach experimentally measures tortuosity factor via symmetric cells employing a blocking electrolyte. Comparisons have been made across the three approaches for 14 graphite and nickel-manganese-cobalt oxide electrodes. Analysis suggests that if the tortuosity factor were characterized based on the active material skeleton only, the actual tortuosities would be 1.35–1.81 times higher for calendered electrodes. Correlations are provided for varying porosity, CBD phase interfacial arrangement and solid particle morphology.