The LiCoO2 films were directly deposited on stainless steel (SS) using medium-frequency magnetron sputtering, and the effects of annealing parameters, such as ambiences, temperatures, holding times, and heating rates, were systematically compared based on surface morphologies, crystal structures, and electrochemical properties. The results demonstrate that an aerobic atmosphere with 3.5 Pa is the most important parameter to maintain the performance of LiCoO2 films. The influence of the annealing temperature (>550 °C) ranks second because the formed (101) or (104) planes of LiCoO2 facilitate Li+ migration. A short holding time of 20 min and a moderate heating rate of 3 °C/min are selected to reduce the oxidation or inter-diffusion between the LiCoO2 films and the SS substrate. Finally, the optimal annealing process is confirmed and corresponds to the initial discharge capacity of 37.56 μA h/(cm2 μm) and the capacity retention of 83.81% at the 50th cycle.

Depth-sensing transmission electron microscopic (TEM) in situ mechanical testing has become widely utilized for understanding deformation in irradiated materials. Until now, compression pillars have primarily been used to study the elastic properties and yield of irradiated materials. In this study, we utilize TEM in situ compression pillars to investigate plastic deformation in two ion-irradiated alloys: Fe–9% Cr oxide dispersion strengthened (ODS) alloy and nanocrystalline Cu–24% Ta. We develop an algorithm to automate the extraction of instantaneous pillar dimensions from TEM videos, which we use to calculate true stress–strain curves and strain hardening exponents. True stress–strain curves reveal intermitted plastic flow in all specimen conditions. In the Fe–9% Cr ODS, intermitted plastic flow is linked to strain bursts observed in TEM videos. Low strain hardening or strain softening is observed in all specimen conditions. TEM videos link the strain softening in irradiated Fe–9% Cr ODS to dislocation cross-slip, and in Cu–24% Ta to grain boundary sliding.

Composites of 0–20 vol% Ti-coated cBN (cBN@Ti) particles dispersed in WC–Ni were densified by spark plasma sintering under 50 MPa at 1300 °C. The cBN particles were distributed homogeneously with a Ti-rich interfacial layer between the cBN particles and WC–Ni matrix. Increasing cBN@Ti to 20 vol% decreased the sample densification, but all the composites were still >97.5% dense. The Vickers hardness and flexural strength initially increased and then decreased, reaching the maximum values of 1820 HV10 with 15 vol% cBN@Ti and 1500 MPa with 5 vol% cBN@Ti, respectively, whereas the fracture toughness KIC gradually increased from 8 to 13 MPa m1/2. For cutting rocks, the wear significantly decreased with 5–15 vol% cBN@Ti but increased with 20 vol% cBN@Ti because of cBN particles pull-out.

Lithium was added to the hypereutectic Mg–Ni alloy to investigate the effect of volatilization of Li on the hydrogen storage characteristics of the eutectic Mg–Ni alloy at 300 °C. After fully activated at 300 °C, Li was almost completely volatilized and the structure of Li-containing Mg82Ni18 alloy was converted to the structure of Li-free Mg82Ni18 alloy, but hydrogen absorption capacity significantly decreased. This is because volatilization of Li weakened the bonding between eutectic Mg and Mg2Ni, lowering the catalytic effect of Mg2Ni on Mg. The decrease in hydrogen absorption capacity was more obvious with increasing Li content. In addition, experimental alloy in powder form could increase surface area, causing Li to volatilize at 300 °C.

Paper transistors are indispensable devices for paper-based electronic biosensing systems. Existing paper transistors mainly use paper as a mechanical support in a passive fashion. By taking advantage of the cellulose fibers in paper, here we report a transistor-in-paper where paper is employed as an essential part to allow for low-voltage operation, which addresses the long-standing challenge of high-voltage operation with existing paper transistors. Such a low-threshold voltage is because of the ion gel/cellulose fiber composite dielectric formed by modifying the paper with ion gels. We further developed paper-based inverters as examples of logic gates and an integrated tactile sensing mat based on a transistor array–enabled multiplexing device. The results collectively indicate that the ion gel–modified paper leads to a class of flexible, low-voltage transistors and integrated electronic devices, which hold promise in many applications.

In the three-phase (pure donor, pure acceptor, and mixed phases) morphologies of organic solar cells, the mixed phases produce an energy cascade that promotes the generation of free carriers. However, how to optimize the content of the mixed phases is a challenging problem. The authors proposed to control different content of mixed phases in DRTB-T and IDIC blends by additive and solvent vapor annealing (SVA). The authors first formed the largest extent amount of mixed phases by the additive cinene (2%) to inhibit the crystallization of DRTB-T and IDIC. And then, different amounts of mixed phases were achieved by further SVA for different times (from 0 to 50 s) to increase the content of pure DRTB-T and IDIC phases. The energetic offsets (ΔE) of pure and mixed phases gradually decrease from 0.529 to 0.477 eV for different content of mixed phases. When ΔE was 0.498 eV, the highest photocurrent density (Jsc) was obtained. The power conversion efficiency was increased from 3.23% (without any treatment) to 8.54%. Therefore, the authors demonstrated that the optimized content of the mixed phases is critical to device performance.

Multifunctional materials with excellent biocompatibility and electron-transport properties are critical for the pursuit of point-of-care biosensing devices. The authors report the synthesis of zinc oxide–reduced graphene oxide (ZnO–rGO) nanocomposite for the fabrication of an electrochemical immunosensing test-bed for noninvasive onsite detection of oral cancer biomarker (interleukin-8, IL8). The immunosensor showed successful detection of IL8 at low concentration ranges, i.e., 100 fg/mL–5 ng/mL with a sensitivity of 12.46 ± 0.82 µA mL/ng and a detection limit of 51.53 ± 0.43 pg/mL. These results have been validated through in vitro investigations using real saliva samples spiked with IL8.

Constant strain rate nanoindentation is a popular technique for probing the local mechanical properties of materials but is usually restricted to strain rates ≤0.1 s−1. Faster indentation potentially results in an overestimation of the hardness because of the plasticity error associated with the continuous stiffness measurement (CSM) method. This can have significant consequences in some applications, such as the measurement of strain rate sensitivity. The experimental strain rate range can be extended by increasing the harmonic frequency of the CSM oscillation. However, with commercial instruments, this is achievable only by identifying higher CSM frequencies at which the testing system is dynamically well behaved. Using these principles, a commercial system operated at the unusually high harmonic frequency of 1570 Hz was successfully used to characterize of the strain rate sensitivity of a Zn22Al superplastic alloy at strain rates up to 1 s−1, i.e., an order of magnitude higher than with standard methods.

An analysis of indentation cyclic behavior of polymers is carried out with the aim to tackle time-dependent behavior of polymer at several time scales by one test. The method consists in cycling the load between a positive close-to-zero value and a maximum peak value (10 mN in this study) for long time with constant loading rate. The short time scale is characterized through the instantaneous elastic modulus determined from reloading curves at each cycle. The advantages of determination of instantaneous elastic modulus from reloading instead of commonly used unloading curves are discussed. The energy dissipation describes viscoelasticity and plasticity at the time scale of one cycle. The evolution of both parameters with cycles along with the cyclic creep describes the long-time viscoelasticity. The cyclic indentation behavior of poly(methyl methacrylate), PR520 epoxy, and high-density polyethylene (HDPE) polymers is analyzed, and a comparison with the macroscopic cyclic behavior of HDPE is presented.

Elastic modulus and residual stress in freestanding ultrathin films (<100 nm) are characterized using bilayer cantilevers. The cantilevers comprise a test film and a well-characterized reference material (SU-8). When released from the substrate, residual stresses in the bilayer cantilever cause it to deflect with measurable curvatures, allowing the determination of both stiffness and residual stress of the test film. The technique does not require sophisticated mechanical test equipment and serves as a useful metrology tool for characterizing coatings immediately after fabrication in a clean room assembly line. The measured biaxial modulus and residual strain of 75 nm copper films are 211 ± 19 GPa and (7.05 ± 0.22) × 10−3, respectively. Additional experiments on the freestanding structures yield a mean Young’s modulus of 115 GPa. These properties are in close agreement with those measured from additional residual stress–driven structures developed on the same coatings by the authors.

Polyhedral YVO4: Ln3+ (Ln = Eu, Sm, Yb/Er, Yb/Tm) microcrystals were fabricated via a facile sol–gel auto-combustion method using NH4VO3 as vanadium source in the presence of glycine. The X-ray diffraction patterns were well matched with pure YVO4, and the doped lanthanide ions did not change the host structure. The YVO4 microcrystals annealed from 500 to 1000 °C for 3 h were polyhedral and ranged in particle size from 0.1 to 2 μm. The luminescence properties of YVO4: Ln3+ (Ln = Eu, Sm, Yb/Er, Yb/Tm) samples indicated that all of the YVO4: Ln3+ samples exhibited typical emission spectra of Ln3+ cations, suggesting that the Ln3+ cations were well doped in YVO4 and could be excited efficiently through matrix absorption. In addition, the corresponding mechanisms of emission and energy transfer in the YVO4: Ln3+ are proposed.

The authors report the microwave-assisted hydrothermal synthesis of α-La(IO3)3 nanocrystals doped with Yb3+ and Er3+ ions, along with their structural and optical characterizations. 50-nm-sized α-La0.9−xYb0.1Erx(IO3)3 nanocrystals with x = 0.005, 0.01, and 0.02 were synthesized and dispersed in ethylene glycol. The as-obtained suspensions exhibit both second harmonic generation (SHG) signal and up-conversion photoluminescence (UC-PL) without interplay between the two signals under near-infrared resonant excitation. The relative intensity of SHG and UC-PL emission can be modulated according to the excitation wavelength. The most intense UC-PL signal is obtained from a 980-nm excitation, thanks to the sensitization of Er3+ by Yb3+.

The objective of the present work was to evaluate the behavior of osteogenesis of mesenchymal stem cells (MSCs) on a double-layer, protective, and bioactive hybrid coating sterilized by 3 different processes: steam autoclave, hydrogen peroxide plasma, and ethylene oxide. The hybrid coating was obtained from a sol consisting of the silane precursors tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES), applied on a Ti6Al4V substrate. To promote bioactivity, hydroxyapatite (HA) particles were dispersed in a second coating (bioactive layer: TEOS/MTES + HA) applied on the first (TEOS/MTES). The sterilized coatings were evaluated by scanning electron microscopy, wettability, and micrometer roughness. The behavior of hydrolytic degradation was evaluated by the mass variation of the samples and the release of silicon by the technique of high-resolution atomic absorption spectrometry. All coatings presented morphological and superficial alterations after sterilization. Sterilization by ethylene oxide and hydrogen peroxide plasma intensified the hydrolytic degradation of the bioactive coating causing a greater release of silicon. The sterilized hybrid coatings did not show cytotoxicity to MSCs. Adhesion, viability, and osteogenic differentiation were favored on the sterilized coating of hydrogen peroxide plasma, which is opposite to what was observed for the ethylene oxide-sterilized coating.

Flexible electrode is an indispensable component of emerging portable, flexible, and wearable electronic devices. Although various flexible electrodes with different dimensions and functions have been explored, developing a new electrode material with excellent mechanical reliability and superior electrical performance remains a challenge. Here, a graphene-covered Cu composite electrode film with a total thickness of ∼100 nm is successfully fabricated onto a flexible polyimide substrate by means of a series of assembly methods including physical vapor deposition, chemical vapor deposition, and transfer technique. The composite electrode film on the flexible substrate exhibits evidently enhanced tensile strength, monotonic bending, and repeatedly bending fatigue reliability as well as electrical performance compared with that of the bared Cu film electrode. Such excellent mechanical performances are attributed to the role of the graphene coating in suppressing fatigue damage formation and preventing crack advance. It is expected that the chemical vapor-deposited graphene-covered Cu composite electrode would extend the potential ultrathin metal film electrode as the innovative electrode material for the next-generation flexible electronic devices.

The design of high energy Li-ion batteries (LIBs) by coupling high voltage LiNi0.5Mn1.5O4 (LNMO) cathode and Li4Ti5O12 (LTO) anode ensures effective and safe energy-storage. LTO–LNMO full-cells (FCs) with difference in electrode grain sizes and presence of excess Mn3+ in cathode were studied using micron-sized commercial LTO, nanostructured LTO donuts (LTOd), P4332 LNMO nanopowders, and nanostructured Fd3m LNMO caterpillars (LNMOcplr). Among the studied FCs, LTOd–LNMOcplr was detected with a stable capacity of 69 mA h/g (1C rate), 99% coulombic efficiency, and 87% capacity retention under 200 cycles of continuous charge–discharge studies. The superior electrochemical performance observed in LTOd–LNMOcplr FC was due to the low charge transfer resistance, which is corroborated to the effect of grain sizes and the longer retention of Mn3+ in the electrodes. An effective and simple FC design incorporating both nanostructuring and in situ conductivity in electrode materials would aid in developing future high-performance LIBs.

Facilitating the application of machine learning (ML) to materials science problems requires enhancing the data ecosystem to enable discovery and collection of data from many sources, automated dissemination of new data across the ecosystem, and the connecting of data with materials-specific ML models. Here, we present two projects, the Materials Data Facility (MDF) and the Data and Learning Hub for Science (DLHub), that address these needs. We use examples to show how MDF and DLHub capabilities can be leveraged to link data with ML models and how users can access those capabilities through web and programmatic interfaces.

Polylactic acid (PLA) filament 3D parts printed by fused deposition modeling (FDM) have poor mechanical properties because of weak fusion interfaces. This article shows that SiC-coated PLA filaments are effective means to increase mechanical performance of PLA composites that are microwave heated. Numerical calculations on temperature-rising characteristics and temperature distribution of the interface in the microwave field are shown. 3D-printed specimens of PLA/SiC composites were printed by FDM and heated in a microwave. The experiments show the SiC/PLA composite filaments have better temperature-rising characteristics and temperature distribution at 185 °C for 60 s in the microwave field, and this enabled the 3D-printed specimens to achieve in situ remelting on the interface and increased interface bonding between PLA filaments. The SiC/PLA composite specimens heated using microwave increased by 51% in tensile strength, 42% in tensile modulus, and 18.7% in interlayer breaking stress relative to PLA. These results provided a new approach for the improvement of FDM workpiece strength.