Search

Over the past few decades, telluride-based chalcogenide multilayers, such as PbSeTe/PbTe, Bi2Te3/Sb2Te3, and Bi2Te3/Bi2Se3, were shown to be promising high-performance thermoelectric films. However, the stability of performance in operating environments, in particular, influenced by intermixing of the sublayers, has been studied rarely. In the present work, the nanostructure, thermal stability, and thermoelectric power factor of Sb2Te3/Ge1+xTe multilayers prepared by pulsed laser deposition are investigated by transmission electron microscopy and Seebeck coefficient/electrical conductivity measurements performed during thermal cycling. Highly textured Sb2Te3 films show p-type semiconducting behavior with superior power factor, while Ge1+xTe films exhibit n-type semiconducting behavior. The elemental mappings indicate that the as-deposited multilayers have well-defined layered structures. Upon heating to 210 °C, these layer structures are unstable against intermixing of sublayers; nanostructural changes occur on initial heating, even though the highest temperature is close to the deposition temperature. Furthermore, the diffusion is more extensive at domain boundaries leading to locally inclined structures there. The Sb2Te3 sublayers gradually dissolve into Ge1+xTe. This dissolution depends markedly on the relative Ge1+xTe film thickness. Rather, full dissolution occurs rapidly at 210 °C when the Ge1+xTe sublayer is substantially thicker than that of Sb2Te3, whereas the dissolution is very limited when the Ge1+xTe sublayer is substantially thinner. The resulting variations of the nanostructure influence the Seebeck coefficient and electrical conductivity and thus the power factor in a systematic manner. Our results shed light on a previously unreported correlation of the power factor with the nanostructural evolution of unstable telluride multilayers.

Metal borides, a class of materials intensively used in industry as superconductors, magnetic materials, or hot cathodes, remain largely unexplored at the nanoscale mainly due to the difficulty in synthesizing single-phase nanocrystals. Recent works have shown that synthetic methods at lower temperatures (xB) could be a potential catalyst for a broad range of applications (hydrogenations, electrochemical hydrogen, and oxygen evolution reactions) under challenging conditions (such as high pH or high temperatures). Here, we report a novel solid-state method to synthesize NixB nanopowders (with a diameter of approximately 45 nm) and their conversion into colloidal suspensions (inks) through treatment of the nanocrystal surface. For the solid-state synthesis, we used commercially available salts and explored the reaction between the Ni and B sources while varying the synthetic parameters under mild and solvent-free reaction conditions. We show that pure phase Ni3B and Ni2B NCs can be obtained with high yield in the pure phase using as precursors NiCl2 and Ni, respectively. Through extensive mechanistic studies, we show that Ni nanoclusters (1-2 nm) are an intermediate in the boriding process, while the metal co-reactant lowers the decomposition temperature of NaBH4 (used as a reducing agent and B source). Size control can instead be exerted through reaction mediators, as seen from the differential nucleation and growth of Ni (clusters) or NixB NCs when employing L- (amine, phosphine) and X-type (carboxylate) mediators. Applying surface engineering methods to our NixB NCs, we stabilized them with inorganic (NOBF4) or organic (borane tert-butyl amine, oleylamine) ligands in the appropriate solvent (DMSO, hexane). With this method, we produce stable inks for further solution processing applications. Our results provide tools for further development of catalysts based on NixB NCs and pave the way for synthesizing other metal boride colloidal nanostructures.

The current lack of insight into nanoparticle-cell membrane interactions hampers smart design strategies and thereby the development of effective nanodrugs. Quantitative and methodical approaches utilizing cell membrane models offer an opportunity to unravel particle-membrane interactions in a detailed manner under well controlled conditions. Here we use total internal reflection microscopy for real-time studies of the non-specific interactions between nanoparticles and a model cell membrane at 50 ms temporal resolution over a time course of several minutes. Maintaining a simple lipid bilayer system across conditions, adsorption and desorption were quantified as a function of biomolecular corona, particle size and fluid flow. The presence of a biomolecular corona reduced both the particle adsorption rate onto the membrane and the duration of adhesion, compared to pristine particle conditions. Particle size, on the other hand, was only observed to affect the adsorption rate. The introduction of flow reduced the number of adsorption events, but increased the residence time. Lastly, altering the composition of the membrane itself resulted in a decreased number of adsorption events onto negatively charged bilayers compared to neutral bilayers. Overall, a model membrane system offers a facile platform for real-time imaging of individual adsorption-desorption processes, revealing complex adsorption kinetics, governed by particle surface energy, size dependent interaction forces, flow and membrane composition.

Finding simple, easily controlled, and flexible synthetic routes for the preparation of ternary and hybrid nanostructured semiconductors is always highly desirable, especially to fulfill the requirements for mass production to enable application to many fields such as optoelectronics, thermoelectricity, and catalysis. Moreover, understanding the underlying reaction mechanisms is equally important, offering a starting point for its extrapolation from one system to another. In this work, we developed a new and more straightforward colloidal synthetic way to form hybrid Au-Ag2X (X = S, Se) nanoparticles under mild conditions through the reaction of Au and Ag2X nanostructured precursors in solution. At the solid-solid interface between metallic domains and the binary chalcogenide domains, a small fraction of a ternary AuAg3X2phase was observed to have grown as a consequence of a solid-state electrochemical reaction, as confirmed by computational studies. Thus, the formation of stable ternary phases drives the selective hetero-attachment of Au and Ag2X nanoparticles in solution, consolidates the interface between their domains, and stabilizes the whole hybrid Au-Ag2X systems.

A non-equiatomic interstitial-strengthened high entropy alloy (iHEA), Fe49.5Mn30Co10Cr10C0.5 (at.%), is manufactured by laser powder-bed fusion (LPBF) with stripe and chessboard scanning strategies. The present study highlights the correlation between the laser scanning strategies with resulting microstructure, textures, and anisotropic mechanical properties in as-built iHEA. The results show that the LPBF processed iHEA exhibits an excellent strength-ductility synergy due to the combined deformation mechanisms of dislocation slip, martensite phase transformation- and nano twinning-induced plasticity. The samples printed by the stripe scanning strategy show more evident mechanical anisotropy than that of the chessboard-scanned samples. The difference in the degree of mechanical anisotropy is mainly attributed to the heterogeneous grain morphology and crystallographic texture resulted from different scanning strategies.

Lignin is an attractive feedstock for low molecular weight biobased phenols using depolymerization strategies such as reductive catalytic fractionation or fast pyrolysis. Such strategies often yield a product mixture enriched in lignin-derived monomers with methoxy substituents. Selective catalytic hydrodeoxygenation (HDO) is an effective methodology to demethoxylate these monomers into valuable alkylated phenols. Here, we report the use of non-precious Cu based catalysts supported on SiO2, ZrO2, TiO2 (various forms), MoO3-ZrO2, and MoO3-TiO2 in a continuous fixed-bed reactor at elevated temperature and pressure (300–360 °C, 10 bar) for the selective demethoxylation of guaiacol. Among the various catalysts, Cu/TiO2-P25 was found to be an effective and highly stable catalyst (100 h on stream) with a selectivity of 87% to demethoxylated compounds like phenol and cresols at a guaiacol conversion of 98%. A correlation was found between the oxygen storage capacity of the support (TiO2-P25, TiO2-A HSA, TiO2-R, and MoO3-TiO2) and guaiacol conversion, indicating that this property plays a role in the catalytic cycle. Besides, the demethoxylation of 4-n-propylguaiacol and a realistic guaiacol-rich feed isolated from a representative pyrolysis oil was successfully demonstrated. 87% of the guaiacols present in the feed were converted to demethoxylated phenols with a selectivity of 81%.

3D superlattices made of colloidal quantum dots are a promising candidate for the next generation of optoelectronic devices as they are expected to exhibit a unique combination of tunable optical properties and coherent electrical transport through minibands. While most of the previous work was performed on 2D arrays, the control over the formation of these systems is lacking, where limited long-range order and energetical disorder have so far hindered the potential of these metamaterials, giving rise to disappointing transport properties. Here, it is reported that nanoscale-level controlled ordering of colloidal quantum dots in 3D and over large areas allows the achievement of outstanding transport properties. The measured electron mobilities are the highest ever reported for a self-assembled solid of fully quantum-confined objects. This ultimately demonstrates that optoelectronic metamaterials with highly tunable optical properties (in this case in the short-wavelength infrared spectral range) and charge mobilities approaching that of bulk semiconductor can be obtained. This finding paves the way toward a new generation of optoelectronic devices.

The areal footprint of memristors is a key consideration in material-based neuromorophic computing and large-scale architecture integration. Electronic transport in the most widely investigated memristive devices is mediated by filaments, posing a challenge to their scalability in architecture implementation. Here we present a compelling alternative memristive device and demonstrate that areal downscaling leads to enhancement in memristive memory window, while maintaining analogue behavior, contrary to expectations. Our device designs directly integrated on semiconducting Nb-SrTiO$_3$ allows leveraging electric field effects at edges, increasing the dynamic range in smaller devices. Our findings are substantiated by studying the microscopic nature of switching using scanning transmission electron microscopy, in different resistive states, revealing an interfacial layer whose physical extent is influenced by applied electric fields. The ability of Nb-SrTiO$_3$ memristors to satisfy hardware and software requirements with downscaling, while significantly enhancing memristive functionalities, makes them strong contenders for non-von Neumann computing, beyond CMOS., main text: 11 pages, 5 figures

Computing and fast data transfers propelled our technological progress in the past few decades with fundamental research on semiconductor materials. However, classical storage and computing technologies face scaling limitations and the Von Neumann architectural bottleneck. Phase-change materials (PCMs), with more than one stable phase and significant electrical and optical contrasts, are the primary contenders for fast, non-volatile, and large storage capacity devices for future optoelectronic applications. GeSbTe alloys, specifically Ge2Sb2Te5 (GST225), are the most studied and at the center of research in the field. However, major reliability issues hinder the full integration of the GeSbTe alloys into functioning devices. This thesis focuses on the growth, characterization, and functionality of various new-generation phase-change alloys. Thin films of phase-change alloys, with unique properties attractive for data storage and optoelectrical applications, have been produced by the pulsed laser deposition (PLD) technique. Growth optimization, characterization, and device designs and testing based on monatomic Sb, binary GaSb and Sb2Se3, and ternary Ge-rich GST thin films are detailed in this thesis. Superior properties, such as thickness-dependent crystallization dynamics, increased crystallization temperatures, and attractive optical contrasts, have been realized through state-of-the-art characterization tools. Moreover, optoelectrical devices utilizing the phase-change alloys and the realized properties have been designed, fabricated, and tested for applications in data storage, reflective-based display, and optical sensors.

Scanning transmission electron microscopy (STEM) is the most widespread adopted tool for atomic scale characterization of two-dimensional (2D) materials. However, damage free imaging of 2D materials with electrons has remained problematic even with powerful low-voltage 60 kV-microscopes. An additional challenge is the observation of light elements in combination with heavy elements, particularly when recording fast dynamical phenomena. Here, we demonstrate that 2D WS2 suffers from electron radiation damage during 30 kV-STEM imaging, and we capture beam-induced defect dynamics in real-time by atomic electrostatic potential imaging using integrated differential phase contrast (iDPC)-STEM. The fast imaging of atomic electrostatic potentials with iDPC-STEM reveals the presence and motion of single sulfur atoms near defects and edges in WS2 that are otherwise invisible at the same imaging dose at 30 kV with conventional annular dark-field STEM, and has a vast speed and data processing advantage over electron detector camera based STEM techniques like electron ptychography.

Two-dimensional transition-metal chalcogenides are one of the most interesting new classes of 2D materials. 2D cobalt selenide nanomaterials are being actively pursued and investigated as well, and recently, the first large-scale synthesis of half-unit-cell-thick Co9Se8 nanosheets has been reported. In the present study, using density functional theory calculations and employing the advanced hybrid HSE06 exchange-correlation functional, the electronic and magnetic structure of Co9Se8 nanosheets is investigated. To allow a comparison with bulk, the electronic and magnetic properties of Co9Se8 bulk are investigated as well. The bulk phase is found to be a ferrimagnetic semiconductor. Reducing the dimensions of Co9Se8 bulk to form a half-unit-cell-thick Co9Se8 nanosheet strongly alters the electronic and magnetic structure of the material. The nanosheet is predicted to have a different type of ferrimagnetic ordering and to be a metal with semimetallic features. Analysis of the X–M segment of the nanosheet's band structure, which mainly determines the electronic transport properties of the material, shows that within this segment, the main band below the Fermi level consists of only spin-up states (Se 4p), while the main band above the Fermi level consists of only spin-down states (Se 4p hybridized with Co 3d). This combination points to possibilities of selective conductivity of either spin-up or spin-down electrons and indicates that ultrathin Co9Se8 nanosheets are a most promising candidate for nanoelectronic and spintronic applications.

Scarce information is available on the thin film morphology of Dion-Jacobson halide perovskites. However, the microstructure can have a profound impact on a material's photophysics and its potential for optoelectronic applications. The microscopic mechanisms at play in the prototypical 1,4-phenylenedimethanammonium lead iodide (PDMAPbI4) Dion-Jacobson compound are here elucidated through a combination of hyperspectral photoluminescence and Raman spectro-microscopy supported by x-ray diffraction. In concert, these techniques allow for a detailed analysis of local composition and microstructure. PDMAPbI4 thin films are shown to be phase-pure and to form micron-sized crystallites with a dominant out-of-plane stacking and strong in-plane rotational disorder. Sample topography, localised defects, and a strong impact of temperature-variation create a complex and heterogeneous picture of the luminescence that cannot be captured by a simplified bulk-semiconductor picture. Our study highlights the power of optical microscopy techniques used in combination, and underlines the danger of conceptual oversimplification when analysing the photophysics of perovskite thin films.

Bi2Te3-based alloys are known to have outstanding thermoelectric properties. Although structure-property relations have been studied, still, detailed analysis of the atomic and nano-scale structure of Bi2Te3 thin film in relation to their thermoelectric properties remains poorly explored. Herein, highly-textured (HT) and single-crystal-like (SCL) Bi2Te3 films have been grown using pulsed laser deposition (PLD) on Si wafer covered with (native or thermal) SiOx and mica substrates. All films are highly textured with c-axis out-of-plane, but the in-plane orientation is random for the films grown on oxide and single-crystal-like for the ones grown on mica. The power factor of the film on thermal oxide is about four times higher (56.8 mu W.cm(-1).K-2) than that of the film on mica (12.8 mu W.cm(-1).K-2), which is comparable to the one of the polycrystalline ingot at room temperature (RT). Reduced electron scattering in the textured thin films results in high electrical conductivity, where the SCL film shows the highest conductivity. However, its Seebeck coefficient shows a low value. The measured properties are correlated with the atomic structure details unveiled by scanning transmission electron microscopy. For instance, the high concentration of stacking defects observed in the HT film is considered responsible for the increase of Seebeck coefficient compared to the SCL film. This study demonstrates the influence of nanoscale structural effects on thermoelectric properties, which sheds light on tailoring thermoelectric thin films towards high performance.

We have investigated the dynamical actuation of micro-electromechanical systems under the influence of attractive and repulsive Casimir forces between topological insulator plates as a function of their dielectric function and coating magnetization. The analysis of the Casimir force in the limit of strong and weak magnetization shows that the attractive force, which is produced for plate magnetizations in the same direction, is greater than the repulsive force that is produced for opposite magnetizations. However, both forces remain comparable for intermediate magnetizations. Moreover, for weak magnetization, the attractive force becomes stronger for an increasing dielectric function, while the opposite occurs for the repulsive force. On the other hand, increasing magnetization decreases the influence of the dielectric function on both the repulsive and attractive forces. Furthermore, for conservative systems, bifurcation and phase portrait analysis revealed that increasing magnetization decreases the regime of stable operation for devices with attractive forces, while their operation remains always stable under the presence of repulsive forces. Finally, for non-conservative periodically driven systems, the Melnikov function and Poincaré portrait analysis show that for magnetizations in the same direction leading to strong attractive Casimir forces, chaotic motion toward stiction is highly likely to occur preventing the long-term prediction of actuating dynamics. A remedy for this situation is obtained by the application of any magnetization in opposite directions between the interacting surfaces since the repulsive force makes it possible to prevent stiction.

New facile and controllable approaches to fabricating metal chalcogenide thin films with adjustable properties can significantly expand the scope of these materials in numerous optoelectronic and photovoltaic devices. Most traditional and especially wet-chemical synthetic pathways suffer from a sluggish ability to regulate the composition and have difficulty achieving the high-quality structural properties of the sought-after metal chalcogenides, especially at large 2D length scales. In this effort, and for the first time, we illustrated the fast and complete inversion of continuous SnSe thin-films to Sb2Se3 using a scalable top-down ion-exchange approach. Processing in dense solution systems yielded the formation of Sb2Se3 films with favorable structural characteristics, while oxide phases, which are typically present in most Sb2Se3 films regardless of the synthetic protocols used, were eliminated. Density functional theory (DFT) calculations performed on intermediate phases show strong relaxations of the atomic lattice due to the presence of substitutional and vacancy defects, which likely enhances the mobility of cationic species during cation exchange. Our concept can be applied to customize the properties of other metal chalcogenides or manufacture layered structures.

Lignin-derived monomers with methoxy substituents are abundantly present in bioliquids derived from lignocellulosic biomass. Examples are the products obtained from the reductive catalytic fractionation of lignin (RCF) and pyrolysis of lignocellulosic biomass and hydrotreated products thereof. An attractive valorization step for these liquids involves demethoxylation to obtain alkylated phenols through selective catalytic hydrodeoxygenation (HDO). Within the context of sustainable chemistry, there is a strong drive to use cheap, non-precious metal catalysts for this purpose. In this study, the HDO of guaiacol (5 wt% in toluene) was investigated in a continuous fixed-bed reactor at 380 °C, 20 bar over supported MoO3 catalysts. MoO3 (5 %) supported on TiO2 (P25) was shown to give superior performance compared with MoO3 supported on anatase TiO2, Al2O3, SiO2, Nb2O5, CeO2, and ZrO2. Additional studies involving variation of the Mo loading and process conditions were performed, and the highest selectivity to demethoxylated phenolics like phenol and methylated phenols was 82 % at 97 % conversion of guaiacol. Both 4-n-propylguaiacol and a realistic guaiacols-rich feed isolated from a representative pyrolysis oil were also successfully demethoxylated with the 5 % MoO3/TiO2 catalyst.

In this work we investigated the dynamical actuation of microsystems with non-identical material components in the presence of non-equilibrium Casimir forces between Au and highly doped SiC that show significant difference in conductivity. For autonomous systems, the bifurcation and phase space analysis revealed that when the less conductive material operates at higher temperature, then at short separations the non-equilibrium force causes instability. Furthermore, for periodically driven systems the Melnikov function and Poincare portrait analysis showed that the devices are more robust against chaotic motion when the less conductive component is at low temperature at short separations. At larger separations chaotic behavior is more likely to occur for systems with the more conductive component at higher temperature.

This study reports on the ultralubricity of a high-temperature resilient nanocomposite WS2/a-C tribocoating. The coefficient of friction of this coating remains at around 0.02 independently of a thermal treatment up to ∼500 °C, as confirmed by high-temperature tribotests. Moreover, the coating annealed at 450 °C keeps exhibiting a similar ultralubricity when cooled back down to room temperature and tested there, implying a tribological self-adaptation over a broad temperature range. High-resolution TEM observations of the tribofilms on the wear track unveil that WS2 nanoplatelets form dynamically via atomic rearrangement and extend via unfaulting geometrical defects (bound by partial climb dislocations). The (002) basal planes of the WS2 nanoplatelets, reoriented parallel to the tribo-sliding direction, contribute to a sustainable ultralubricity. The declining triboperformance beyond 500 °C is associated with sulfur loss rather than the transformation of WS2 into inferior WO3 via oxidation as suggested earlier. This self-adaptive WS2/a-C tribocoating holds promise for a constant ultralubrication with excellent thermal performance.

Understanding the size-dependent electronic properties of germanium nanocrystals (Ge NCs) is of fundamental importance for improving the efficiency of optoelectronic devices based on such NCs. Here, Ge NCs with a tunable size were synthesized by magnetron-sputtering cluster-beam deposition, where the size of the as-deposited Ge NCs can be finely controlled between 6 and 36 nm by helium gas flow rates and variable magnetic field configurations above the target surface. Because the size of the as-deposited Ge NCs highly depends on the nucleation process inside the plasma region, a detailed comparison between these two process parameters on the size control was formulated from the perspective of the growth kinetic mechanism. Furthermore, the local surface potential of different-sized Ge NCs deposited on n-type silicon substrates was measured by Kelvin probe force microscopy. The surface potential fluctuation of n-type Si covered by Ge NCs shows a strong size-dependent relationship with the size of the Ge NCs, whereas the surface potential fluctuation increases when their size reduced. Because the surface potential fluctuation between the intrinsic Ge NCs and the n-type silicon substrate tends to get smaller as the NCs' size decreases due to the quantum confinement effect, the number of charges transferred between the electronic bands will reduce as the size of Ge NCs decreases. The latter exactly explains the observed experimental results. Therefore, this work offers a perspective to understand the behavior of charge transfer, which plays an important role in the performance of optoelectronic devices.

ACS sustainable chemistry & engineering 9(18), 6235-6249 (2021). doi:10.1021/acssuschemeng.0c08760, Published by ACS Publ., Washington, DC

PbS colloidal quantum dots (CQDs) are versatile building blocks for bottom-up fabrication of various optoelectronic devices. The transport properties of thin films of this class of materials depend on the size of the CQDs, their surface ligands, and stoichiometry. The most common synthetic methods yield PbS CQDs with an excess of Pb atoms, which induces n-type transport properties in CQD films. In this work, we developed a new synthesis, which offers S-rich PbS CQDs. Thanks to their sufficient colloidal stability in nonpolar solvents, we established a protocol for the integration of these CQDs into thin field-effect transistors and found strong hole-dominated transport with a hole mobility of about 1 × 10–2 cm2/Vs. Moreover, we were able to enhance the electron mobility for almost two orders of magnitude while keeping the hole mobility nearly the same. This approach allows us to obtain reliably p-doped PbS CQDs, which can be used for the fabrication of various electronic and optoelectronic devices., Chemistry of Materials, 33 (1), ISSN:0897-4756

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells., Germanane was synthesized by topotatic deintercalation of β‐CaGe2 in aqueous HF solution at room temperature under stirring for 2‐3 minutes. In order to remove the residual CaF2 the material was treated with a saturated aqueous solution of EDTA.

Intensive studies have been carried out over the past decade to identify nanostructured thermoelectric materials that allow the efficient conversion of waste heat to electrical power. However, less attention has been paid to the stability of such materials under operating temperatures, typically 400 degrees C or higher. Conventionally nanostructured ceramics tend to undergo grain growth at high temperature, lowering the density of interfaces and raising the thermal conductivity, which is detrimental to device performance. Therefore it is preferable to identify materials with stable nanostructures, for example systems that undergo spontaneous phase separation. Here we investigate PbTe-GeTe alloys, in which spinodal decomposition occurs on initial cooling from above 580 degrees C, forming complex nanostructures consisting of Ge-rich and Pb-rich domains on different size scales. The resulting dense arrangement of interfaces, combined with mass fluctuation associated with Pb-Ge mixing, enhances phonon scattering and strongly reduces the thermal conductivity. Here we focus on the nominal composition Pb0.49Ge0.51Te and show that by tuning the synthesis procedure, we are able to control the pattern of compositional domains and the density of interfaces between them. This allows low lattice thermal conductivities to be maintained even after thermal cycling over the operating temperature range.

China has implemented a series of measures to address air pollutants and carbon emissions from coal-fired power plants, which can mitigate toxic heavy metal emissions simultaneously. By integrating plant-level information and energy activity data, we investigated the co-benefits of clean air and low-carbon policies by compiling a detailed inventory of historical heavy mental emissions (i.e., Hg, Pb, Cd, Cr, Ni, Sb, Mn, Co, Cu, Zn, As, and Se) for China's coal-fired power plants during 2005–2020. Several scenarios were then designed to assess the evolution of heavy metal emissions for each coal-fired power plant with consideration given to the coal washing rate, air pollution control devices, operational hours and lifetime. The total emissions decreased from 12.9 thousand tons in 2005 to 8.8 thousand tons in 2020, which was mainly due to the widely installation of upgraded end-of-pipe devices and the decommissioning of small and emission-intensive plants, especially in Sichuan, Jiangsu and Zhejiang. Scenario analysis shows that reducing the operational lifetime to 20 years is the most effective measure to reduce national HM emissions, but the effects differ widely between regions. This study provides insights for the precise co-control of both heavy metals and carbon emissions, which is highly important for meeting the requirements of the Minamata Convention and carbon neutrality.

The Casimir forces induced by fluctuations of electromagnetic field have been measured with a high precision at distances above [Formula: see text] nm. Although at shorter separations the magnitude of the force increases, it is more complicated to measure the forces at distances below [Formula: see text] nm. We review the problems that appear in this range of distances and their possible solutions. The first problem is related to the pull-in instability that occurs when two surfaces get too close to each other. As a particular manifestation of this problem, the spontaneous formation of the capillary bridges at distances [Formula: see text] nm is discussed. As an alternative, we discuss the method of adhered cantilever, which does not suffer from the pull-in instability. The second problem is related to the roughness of interacting surfaces that gives a significant deviation of the force from the expected scaling with the distance. We explain how the deviation can be related to the contribution of high asperities to the force. Characterization of the deposited rough films is also covered with a special emphasis on the excessive number of high asperities for the films deposited under nonequilibrium conditions. The third problem is related to the poor precision in the determination of the absolute distance between the bodies that results in a large total error in the force. We discuss the methods to determine the distance upon contact and cover a proposition to improve this precision in the method of adhered cantilever.

Integration of the prototypical GeSbTe (GST) ternary alloys, especially on the GeTe-Sb2Te3 tie-line, into non-volatile memory and nanophotonic devices is a relatively mature field of study. Nevertheless, the search for the next best active material with outstanding properties is still ongoing. This search is relatively crucial for embedded memory applications where the crystallization temperature of the active material has to be higher to surpass the soldering threshold. Increasing the Ge content in the GST alloys seems promising due to the associated higher crystallization temperatures. However, homogeneous Ge-rich GST in the as-deposited condition is thermodynamically unstable, and phase separation upon annealing is unavoidable. This phase separation reduces endurance and is detrimental in fully integrating the alloys into active memory devices. This work investigated the phase separation of Ge-rich GST alloys, specifically Ge5Sb2Te3 or GST523, into multiple (meta)stable phases at different length scales in melt-quenched bulk and annealed thin film. Electron microscopy-based techniques were used in our work for chemical mapping and elemental composition analysis to show the formation of multiple phases. Our results show the formation of alloys such as GST213 and GST324 in all length scales. Furthermore, the alloy compositions and the observed phase separation pathways agree to a large extent with theoretical results from density functional theory calculations.

In this work, we investigated the influence of composition on the polycrystalline structure, elastic properties and fracture strength, of ZrxSi1-x, NbxSi1-x, and MoxSi1-x free-standing thin films that were deposited by magnetron sputtering and subsequently annealed at 500 °C. Despite deviations from the stoichiometric composition, the crystalline structure of all films, except for the most Zr-rich ZrxSi1-x, corresponded to their respective stoichiometric disilicide structures, without the formation of a second-phase. Off-stoichiometry was found to be accompanied by the presence of lattice defects and a decrease of the grain size, which bring about a lower tensile stress in the films. The dependence of the fracture strength on the composition was remarkably similar for the three silicides, with the lowest and highest strength values occurring for samples with 30% and 37–40% of metal content, respectively. The observed dependence of strength on composition was attributed to the combination of the Hall-Petch effect, changes in the morphology and strength of grain boundaries, and the enhancement of crystal plasticity due to lattice defects induced by off-stoichiometry.

Indium antimonide (InSb) nanowires are used as building blocks for quantum devices because of their unique properties, that is, strong spin-orbit interaction and large Landé g-factor. Integrating InSb nanowires with other materials could potentially unfold novel devices with distinctive functionality. A prominent example is the combination of InSb nanowires with superconductors for the emerging topological particles research. Here, the combination of the II–VI cadmium telluride (CdTe) with the III–V InSb in the form of core–shell (InSb–CdTe) nanowires is investigated and potential applications based on the electronic structure of the InSb–CdTe interface and the epitaxy of CdTe on the InSb nanowires are explored. The electronic structure of the InSb–CdTe interface using density functional theory is determined and a type-I band alignment is extracted with a small conduction band offset (⩽0.3 eV). These results indicate the potential application of these shells for surface passivation or as tunnel barriers in combination with superconductors. In terms of structural quality, it is demonstrated that the lattice-matched CdTe can be grown epitaxially on the InSb nanowires without interfacial strain or defects. These shells do not introduce disorder to the InSb nanowires as indicated by the comparable field-effect mobility measured for both uncapped and CdTe-capped nanowires.

Lead halide perovskite nanocrystals are highly attractive for next-generation optoelectronics because they are easy to synthesize and offer great compositional and morphological tunability. However, the replacement of lead by tin for sustainability reasons is hampered by the unstable nature of Sn2+ oxidation state and by an insufficient understanding of the chemical processes involved in the synthesis. Here we demonstrate an optimized synthetic route to obtain stable, tunable, and monodisperse CsSnI3 nanocrystals, exhibiting well defined excitonic peaks. Similar to lead halide perovskites, we prepare these nanocrystals by combining a precursor mixture of SnI2 , oleylamine and oleic acid, with a Cs-oleate precursor. Among the products, nanocrystals with 10 nm lateral size in the γ-orthorhombic phase prove to be the most stable. To achieve such stability, an excess of precursor SnI2 as well as sub-stoichiometric Sn:ligand ratios are key. Structural, compositional and optical investigations complemented by first-principle DFT calculations confirm that nanocrystal nucleation and growth follow the formation of (R-NH3 + )2 SnI4 nanosheets with R = C18 H35 . Under specific synthetic conditions, stable mixtures of 3D nanocrystals CsSnI3 and 2D nanosheets (Ruddlesden-Popper (R-NH3 + )2 Csn-1 Snn I3n+1 with n>1) are obtained. These results set a path to exploiting the high potential of Sn halide perovskite nanocrystals for opto-electronic applications. This article is protected by copyright. All rights reserved.

The present study is dedicated to explore the effect of grain refinement on cracking resistance of hot-dip galvanized Zn–Al–Mg coatings on steel substrate. In this work, we demonstrate the enhancement of plastic deformation and cracking resistance by refining the microstructure (primary zinc grains) of the Zn–Al–Mg coatings. For this purpose, two types of Zn–Al–Mg coatings namely, fine grained and coarse grained microstructures are investigated utilizing in-situ scanning electron microscopy tensile tests. Electron backscatter diffraction technique is used to illuminate the deformation behavior at the scale of grains (and/or within grains). The results reveal that the coating with fine grained microstructure possesses higher ductility and cracking resistance, whereas the coating with coarse grain microstructure induces more transgranular cracking during deformation. Moreover, primary zinc grain refinement has been shown to decrease the fraction of coarse deformation twins that serve as undesirable sites of micro-cracking. In particular, both deformation mechanisms and cracking behavior are found to be grain size-dependent in these coatings.

Microscopy and diffraction measurements are presented of ultrathin binary alloy films of ruthenium and molybdenum that are obtained by standard sputter deposition. For compositions close to Ru50Mo50, we find the films to be amorphous. The amorphicity of the films is accompanied by a significant reduction of the roughness with respect to the roughness of equally thick films of either ruthenium or molybdenum. We ascribe this to the absence of the grain structure that is characteristic of the polycrystalline films of the separate elements.

Free-standing layers of nanoscale thickness are essential in numerous applications but challenging to fabricate for all but a small selection of materials. We report a versatile, chemical-free pathway of exfoliating centimeter-sized free-standing nanolayers from Si(100) with native oxide based on the spontaneous delamination of thin Ru and Ru-based films upon annealing at temperatures as low as 400 °C. Combining results from X-ray photoelectron spectroscopy (XPS), and transmission and scanning electron microscopy (TEM, SEM), we identify that the element Ru, a thin SiO2 layer, and the Si(100) substrate are essential ingredients for the delamination and propose a stress-based mechanism to explain the effect. The diffusion of Si into the layer upon annealing leads to the formation of a Ru-Si compound at the thin-film side of the Ru/Si(100) interface and pyramidal cavities in the Si(100) substrate. Moreover, the uptake of Si results in an increase in layer thickness and the buildup of in-plane compressive stress, which is reduced by local buckling and finally by the separation of the full layer from the substrate at the SiO2-Si(100) interface. The use of a thin Ru-buffer layer allows us to apply this delamination process to produce free-standing nanolayers of Mo and HfMoNbTiZr in this simple, chemical-free, and vacuum-compatible manner. These results indicate the potential of the reported effect for the fabrication of free-standing layers using a wide range of compositions, deposition techniques, and growth conditions below the onset temperature of delamination.

High quality Van der Waals chalcogenides are important for phase change data storage, thermoelectrics, and spintronics. Using a combination of statistical design of experiments and density functional theory, we clarify how the out-of-equilibrium van der Waals epitaxial deposition methods can improve the crystal quality of Sb2Te3 films. We compare films grown by radio frequency sputtering and pulsed laser deposition (PLD). The growth factors that influence the crystal quality for each method are different. For PLD grown films a thin amorphous Sb2Te3 seed layer most significantly influences the crystal quality. In contrast, the crystalline quality of films grown by sputtering is rather sensitive to the deposition temperature and less affected by the presence of a seed layer. This difference is somewhat surprising as both methods are out-of-thermal-equilibrium plasma-based methods. Non-adiabatic quantum molecular dynamics simulations show that this difference originates from the density of excited atoms in the plasma. The PLD plasma is more intense and with higher energy than that used in sputtering, and this increases the electronic temperature of the deposited atoms, which concomitantly increases the adatom diffusion lengths in PLD. In contrast, the adatom diffusivity is dominated by the thermal temperature for sputter grown films. These results explain the wide range of Sb2Te3 and superlattice crystal qualities observed in the literature. These results indicate that, contrary to popular belief, plasma-based deposition methods are suitable for growing high quality crystalline chalcogenides., Comment: 24 pages, 8 figs

A series of monometallic and bimetallic metal catalysts (Pd, Cu, Fe, PdCu, PdFe) supported on ZrO2 (6-8 nm) were synthesized and tested for the hydrogenation of bio-oil model compounds (furfural, vanillin, glucose) under 50 bar H2 at 100 °C. The catalysts were fully characterized and their properties related to their catalytic activity. The bimetallic PdFe and PdCu displayed enhanced catalytic performance compared to the monometallic catalysts for aldehyde hydrogenation (furfural, vanillin, glucose). For the best catalyst, 98% vanillin alcohol (VA) and 65.5% furfuryl alcohol (FA) conversion was obtained for 80 min batch-time. PdFe showed high selectivity toward sorbitol (74%) from glucose, though at low conversion (20%). Overall, we have demonstrated that bimetallic Fe- A nd Cu-based catalysts promoted by Pd show significantly better performance for the partial hydrogenation of bio-oil model compounds than the corresponding monometallic ones. The better performance of the Pd-doped Fe/Cu catalysts is linked to the presence of smaller and better dispersed Pd nanoparticles (STEM) and their lower acidity (∼90 μmol/g cat) than corresponding monometallic ones (∼167 μmol/g cat).

Size-dependent optical properties of germanium (Ge) nanocrystals (NCs) make them a desirable material for optoelectronic applications. So far, the synthesis of ligand-free and tunable-size Ge NCs by inert gas condensation has been scarcely reported. In this work, we introduce a gas-phase approach to synthesize quantum-confined Ge NCs by inert gas condensation, where the size of the Ge NCs can be readily tuned by controlling the thickness of a Cu plate supporting the Ge target. As explained by simulations using the finite element method, the magnetic field configuration above the target can be manipulated by varying the thickness of the Cu backing plate. In-depth analysis based on transmission electron microscopy (TEM) results reveals the morphology and crystalline structure of Ge NCs. X-ray photoelectron spectroscopy has proven the formation of a substoichiometric Ge oxide shell for the as-deposited Ge NCs. In addition, Raman spectroscopy indicated peak shifts according to the phonon confinement model that yielded nanoparticle sizes in a good agreement with the TEM results. Furthermore, the quantum confinement effect for Ge NCs was demonstrated by analysis of the absorption (UV-vis-NIR) spectrum, which indicated that the band gap of the Ge NCs was increased from ∼0.8 to 1.1 eV with decreasing size of Ge NCs. Comparison with theory shows that the quantum confinement effect on the band gap energy for different-sized Ge NCs follows the tight-binding model rather well.

Phase change materials, with more than one reflectance and resistance states, have been a subject of interest in the fields of phase change memories and nanophotonics. Although most current research focuses on rather complex phase change alloys, e.g., Ge2Sb2Te5, recently, monatomic antimony thin films have aroused a lot of interest. One prominent attractive feature is its simplicity, giving fewer reliability issues like segregation and phase separation. However, phase transformation and crystallization properties of ultrathin Sb thin films must be understood to fully incorporate them into future memory and nanophotonics devices. Here, we studied the thickness-dependent crystallization behavior of pulsed laser-deposited ultrathin Sb thin films by employing dynamic ellipsometry. We show that the crystallization temperature and phase transformation speed of as-deposited amorphous Sb thin films are thickness-dependent and can be precisely tuned by controlling the film thickness. Thus, crystallization temperature tuning by thickness can be applied to future memory and nanophotonic devices. As a proof of principle, we designed a heterostructure device with three Sb layers of varying thicknesses with distinct crystallization temperatures. Measurements and simulation results show that it is possible to address these layers individually and produce distinct and multiple reflectance profiles in a single device. In addition, we show that the immiscible nature of Sb and GaSb could open up possible heterostructure device designs with high stability after melt-quench and increased crystallization temperature. Our results demonstrate that the thickness-dependent phase transformation and crystallization dynamics of ultrathin Sb thin films have attractive features for future memory and nanophotonic devices.

Utilizing a superlattice structure is an advantage in enhancing the thermoelectric performance. For instance, the Bi2Te3/Sb2Te3 superlattice is famous for its exceptionally high figure of merit. 3D/3D films systems have been studied most intensely and have been successfully applied in industry. However, introduction of 2D materials makes the strain behaviour in hetero-structures elusive. It is well known that the electronic properties of materials can be extremely sensitive to the strain, and doping can easily affect the Seebeck coefficient of materials. However, the strain state and the thermal stability of these multilayers are still not studied in-depth, which may be the possible reasons why different researchers generated such a wide spread in (thermoelectric) data. In this thesis, we use telluride films i.e., Bi2Te3, Sb2Te3, Ge1+xTe, and GeTe, as examples to address the strain evolution in these materials and how the nanostructure and intermixing affect the thermoelectric properties.

The research in this thesis describes a physical way to produce nanosized particles (NPs). The inert gas condensation method with magnetron sputtering produces NPs from various single and multi-element compositions. The proper manufacturing of a monodispersed NPs beam with real size control in the nanometer range (10-9 m) combined with motif and composition control opens up many new, previously impossible opportunities (e.g., new catalyst, QDots, etc.). The different surfaces coated with these distinct NPs show wetting behavior different than the bulk solids of the same material. These nanoscale rough surfaces serve as model systems for some intriguing wetting behavior found in nature. Surfaces covered with various degrees of NPs show behavior that contradict the well-known models of wetting founded in 1805 by T. Young and later adapted for real surfaces by Wenzel and Cassie Baxter. The Hydrophobic yet high adhesion wetting behavior (known as the rose petal effect) of intrinsic hydrophilic material is explained by the pinning of the water triple line by the many small apexes from these NPs. In the wetting of surfaces, surface chemistry plays a crucial role. Clean surfaces are necessary to understand the intrinsic behavior of a (clean) surface and the subsequent role of (airborne hydrocarbon) surface contamination. This surface contamination can be removed by a UV-Ozone treatment. Moreover, the aging of Ag NPs was investigated. The aging of NPs leads to an increase in the size of the NPs, affecting it’s wetting properties. This aging is also associated with the presence of (initially invisible) Ag adatoms, remnants from the sputtering process. These adatoms were made visible due to the UV-Ozone treatment, and the imaging was (only) possible with the current state-of-the-art STEM.

Zn-Al-Mg coatings are important materials for the corrosion protection of steel sheets. However, susceptibility towards cracking limits the formability performance of these coatings. In this study, we focus on the effect of the underlying steel substrate on cracking behavior in these coatings. In order to elucidate this, a high-strength low-alloy (HSLA) steel substrate and an interstitial-free (IF) steel substrate are coated with two different ZnAlMg coatings with and without binary eutectic microstructures. Meticulous in-situ tensile and bending tests are conducted in a scanning electron microscope. To quantify the strain distribution and damage incidents, micro and macro digital image correlation techniques are utilized in order to illuminate the associated cracking causes across length scales. Furthermore, electron backscatter diffraction method is applied to study the role of crystallographic orientation on the cracking tendency. Crack opening and crack area fractions are correlated with the applied strain and bending angles. The findings denote that the discontinuous yielding (Luders banding) of the HSLA steel substrate generates substantial surface roughening and heterogeneous deformation in the coatings that facilitates cracking. In contrast, the IF steel induces a more uniform deformation within the coatings leading to much reduced crack size and crack area fraction. This study has resulted in a key element of a guideline towards crack-resistant and formable Mg-alloyed zinc coatings.

The wetting state of surfaces can be rendered to a highly hydrophobic state by the deposition of hydrophilic gas phase synthesized Ag nanoparticles (NPs). The aging of Ag NPs leads to an increase in their size, which is also associated with the presence of Ag adatoms on the surface between the NPs that have a strong effect on the wetting processes. Furthermore, surface airborne hydrocarbons were removed by UV-ozone treatment, providing deeper insight into the apparent mobility of the NPs on different surfaces and their subsequent ripening and aging. In addition, the UV-ozone treatment revealed the presence of adatoms during the magnetron sputtering process. This surface treatment lowers the initial contact angle of the substrates and facilitates the mobility of Ag NPs and adatoms on the surface of substrates. Adatoms co-deposited on clean high surface energy substrates will nucleate on Ag NPs that will remain closely spherical and preserve the pinning effect due to the water nanomeniscus. If the adatoms are co-deposited on a UV-ozone cleaned low surface energy substrate, their mobility is restricted, and they will nucleate in two-dimensional islands and/or nanoclusters on the surface instead of connecting to existing Ag NPs. This growth results in a rough surface without overhangs, where the wetting state is reversed from hydrophobic to hydrophilic. Finally, different material surfaces of transmission electron microscopy grids revealed strong differences in the sticking coefficient for the Ag NPs, suggesting another factor that can strongly affect their wetting properties.

OBJECTIVES The liquid–solid interactions have attracted broad interest since solid surfaces can either repel or attract fluids, configuring a wide spectrum of wetting states (from superhydrophilicity to superhydrophobicity). Since the blood–artificial surface interaction of bileaflet mechanical heart valves essentially represents a liquid–solid interaction, we analysed the thrombogenicity of mechanical heart valve prostheses from innovative perspectives. The aim of the present study was to modify the surface wettability of standard St. Jude Medical Regent™ occluders. METHODS Four pyrolytic carbon occluders were irradiated by means of ultra-short pulse laser, to create 4 different nanotextures (A–D), the essential prerequisite to achieve superhydrophobicity. The static surface wettability of the occluders was qualified by the contact angle (θ) of 2 µl of purified water, using the sessile drop technique. The angle formed between the liquid–solid and the liquid–vapour interface was the contact angle and was obtained by analysing the droplet images captured by a camera. The morphology of the occluders was characterized and analysed by a scanning electron microscope at different magnifications. RESULTS The scanning electron microscope analysis of the textures revealed 2 different configurations of the pillars since A and B showed well-rounded shaped tops and C and D flat tops. The measured highest contact angles were comprised between 108.1° and 112.7°, reflecting an improved hydrophobicity of the occluders. All the textures exhibited, to different extents, an orientation (horizontal or vertical), which was strictly related to the observed anisotropy. CONCLUSIONS In this very early phase of our research, we were able to demonstrate that the intrinsic wettability of pyrolytic carbon occluders can be permanently modified, increasing the water repellency.

Polymers are an increasingly used class of materials in semiconductors, photovoltaics and energy storage. Polymers bearing triphenylamine (TPA) or its derivatives in their structures have shown promise for application in electrochemical energy storage devices. The aim of this work is to systematically synthesize polymers bearing TPA units either as pendant groups or directly along the backbone of the polymer and evaluate their performance as electrochemical energy storage electrode materials. The first was obtained via radical polymerization of an acrylate monomer bearing TPA as a side group, resulting in a non-conjugated polymer with individual redox active sites (rP). The latter was obtained by oxidative polymerization of a substituted TPA, resulting in a conjugated polymer with TPA units along its backbone (cP). These polymers were then developed into electrodes by separately blending them with multi-wall carbon nanotubes (rC and cC). The electrodes were characterized and their charge storage stability and mechanical properties were investigated for up to 1000 cycles by cyclic voltammetry, galvanostatic charge–discharge measurements and nanoindentation. The results show that cC offers a higher initial charge capacity than rC as well as improved carbon nanotube dispersion due to its conjugated structure. Although the improved dispersion results in a higher elastic modulus for cC (compared to rC), the stiffer nature of cP made it more vulnerable to degrade upon repetitive volumetric change, while with rP, the decoupled acrylate monomer remained more protected when its redox active units of TPA underwent charge–discharge cycling.

We investigated here the influence of the lateral and normal Casimir force on the actuation dynamics between sinusoidal corrugated surfaces undergoing both normal and lateral displacements. The calculations were performed for topological insulators and phase change materials that are of high interest for device applications. The results show that the lateral Casimir force becomes stronger by increasing the material conductivity and the corrugations toward similar sizes producing wider normal separation changes during lateral motion. In a conservative system, bifurcation and Poincaré portrait analysis shows that larger but similar in size corrugations and/or higher material conductivity favor stable motion along the lateral direction. However, in the normal direction, the system shows higher sensitivity on the optical properties for similar in size corrugations leading to reduced stable operation for higher material conductivity. Furthermore, in non-conservative systems, the Melnikov function with the Poincaré portrait analysis was combined to probe the possible occurrence of chaotic motion. During lateral actuation, systems with more conductive materials and/or the same but high corrugations exhibit lower possibility for chaotic motion. By contrast, during normal motion, chaotic behavior leading to stiction of the moving components is more likely to occur for systems with more conductive materials and similar in magnitude corrugations.

The thesis reports a gas-phase method for synthesizing semiconductor nanoparticles, such as germanium (Ge) and antimony(Sb), with readily size control. Based on the size distribution analysis by transmission electron microscopy (TEM), precise deposition parameters are determined to regulate the size of as-deposited nanoparticles. Because additional chemical agents can be avoided throughout the synthesis process, the as-deposited semiconductor nanoparticles can be considered as the three-dimensional model, allowing us to investigate the novel characteristics of nanoparticles due to the size effect. Specifically, by studying the optical and electrostatic properties of varied size (7 – 14 nm) Ge nanoparticles, the quantum confinement effect for semiconductor nanocrystals has been proven, such that the band gap of Ge nanocrystals can be widen by reducing the size of nanocrystals. Furthermore, due to spatial confinement in three dimensions, the amorphous phase of Sb nanoparticles can be stabilized at room temperature, as demonstrated by electron micrscope.

Although the contact theory between rough surfaces is designed for adhesion energies ≳100mJ/m2, microsystems are controlled by much weaker adhesion ≲100μJ/m2, which is critical for their operation. The weakest adhesion is related to the omnipresent fluctuation-induced dispersion forces. We develop a theory for such a weak adhesion emphasizing that the adhesion energy as a function of the average distance separating the bodies is almost entirely defined by the dispersion interaction. This dependence can be evaluated using the Lifshitz theory, but the effects of contact interaction or plastic deformations give only small contribution to the adhesion. Such a behavior is explained by a specific roughness of the deposited thin films used in microtechnologies. The films deposited on cold substrates have a much larger number of high asperities than is predicted by the Gaussian distribution and the contact occurs over a few asperities with heights much larger than the root-mean-square roughness. Finally, we discuss application of the effect for more precise determination of the distance upon contact, which is crucial for precise measurements of the dispersion forces especially at short separations in the range 5

Mg-alloyed zinc coatings suffer from early cracking during deformation due to the combined influences of detrimental constituents (e.g., Zn/MgZn2 binary eutectic), unfavorable crystal orientations and incompatible local plastic deformation. This study addresses the crack resistance and deformation mechanisms of a ZnAlMg coating, in the absence of binary eutectic, by using correlative in-situ scanning electron microscopy tensile tests, electron backscatter diffraction, scanning transmission electron microscopy and micro digital image correlation methods. The plasticity and strengthening mechanisms of the binary eutectic-free ZnAlMg coating are thoroughly unravelled via theoretical and experimental approaches including dislocation slip trace analysis, Taylor factor calculations, quantitative dislocation density determination and slip/strain transfer across the grain boundaries. It has been found that the microstructure of the coating, comprising of primary zinc and ternary eutectic, effectively accommodates the applied strain without cracking till fracture of steel substrate. The absence of binary eutectic and the activation of abundant deformation mechanisms in the coating microstructure, promote local compatible plastic deformation and inhibit early damage. Effective slip transfer is unveiled by activation of pyramidal slip in addition to primary dislocation slip systems. The present findings deliver significant insights and solution for improvement in the formability of Mg-alloyed zinc coatings on steel sheets by tailoring the microstructure.

The roughness of solids is crucial for interactions between bodies at short separations due to capillary or van der Waals-Casimir forces and for contact mechanics. Specifically, it is critical for the fabrication and operation of microelectromechanical systems, for which functional materials are deposited using thin film coating technologies. Here, it is demonstrated that the materials deposited by magnetron sputtering or thermally evaporated on a cold Si substrate reveal a significantly larger number of high asperities than that predicted by the normal distribution. Such asperities define the distance between the solids in contact that is the key parameter for many problems. The effect is related to the nonequilibrium deposition conditions and is suppressed if the material is deposited on a hot substrate or annealed. The high asperity tails can be described by the extreme value distribution or in some cases by the exponential distribution.