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We present a promising technique for transparent flexible conducting oxide heteroepitaxial films: the direct fabrication of epitaxial molybdenum-doped indium oxide (IMO) thin films on a transparent flexible muscovite substrate. An n-type epitaxial IMO film is demonstrated with a mobility of 109 cm2 V−1 s−1, a figure of merit of 0.0976 Ω−1, a resistivity of 4.5 × 10−5 Ω cm and an average optical transmittance of 81.8% in the visible regime. IMO heterostructure not only exhibits excellent performance but also shows excellent mechanical durability. This study demonstrated an extraordinary achievement for the evolution and expansion of next-generation smart devices.
Ferromagnetic semiconductors are promising candidates for high-performance multifunctional spintronic devices due to the peculiar magneto-electric and magneto-optical properties. However, the low spin ordering temperature limits their applications. By using high pressure to stabilize the crystal structure and oxygen content, an oxygen-deficient perovskite SrCr0.5Fe0.5O2.875 was synthesized. This compound displays ferromagnetic behavior with a spin ordering temperature as high as 600 K. Benefiting from the semiconducting direct bandgap (~2.28 eV), a field-tunable green fluorescent effect is observed. This work opens up a new avenue for research on room-temperature multifunctional materials with coupled magnetic, electrical, and optical performance.
The characteristics of I/Cl alloying structures in MAPbI3-xClx mixed-halide perovskites and their influences on the optoelectronic properties have been issues of long-standing controversy. In this work, by using on the time-dependent X-ray diffraction, 207Pb and 2H NMR, the authors investigated the I/Cl alloying structures and its long term stability in MAPbI3-xClx (x = 0.0 to 0.3) single crystals. It was found that Cl can substitute for I of the PbI3 inorganic lattice, leading to the tetragonal to cubic phase transition. Moreover, it revealed that the alloying structures of the MAPbI3-xClx crystals are metastable and may decompose over time.
An imprinted four-fold magnetic anisotropy was observed in the amorphous ferromagnetic layer of FeRh/CoFeB heterostructures. The easy magnetization axes of the CoFeB layer are along the FeRh〈110〉 and FeRh〈100〉 directions for the epitaxially grown FeRh layer in the antiferromagnetic and ferromagnetic states, respectively. The fourfold magnetic anisotropy of the amorphous CoFeB layer is imprinted due to the interfacial exchange coupling between the CoFeB and FeRh moments from the magnetocrystalline anisotropy of the epitaxial FeRh layer, which may be applied to probe the magnetic structures of antiferromagnetic materials without using synchrotron methods.
We first shaped the critical role of Ge vacancies in GeTe on the crystal structure-thermoelectric properties relationship by combining first-principle calculations, Boltzmann transport equation, and experimental properties studies, leading to the stabilization of the metastable cubic structure, unfavorable band structure modification, and stable N-type conduction.
All-carbon memristive synapse is built through photo-reduction of a nanocomposite comprised of graphene oxide and N-doped carbon quantum dots. The analog-type resistive switching was demonstrated, which enabled the emulation of synaptic learning and pattern recognition with high accuracy. The all-carbon devices possess excellent transferability, flexibility and resistance to high temperature, showing the potential for the development of wearable neuromorphic computing system.
A liquid-based neuromorphic device that can mimic the movement of ions in a nervous system is demonstrated by controlling Na+ movement in an aqueous solution. The liquid-based neuromorphic device consists of disodium terephthalate, Nafion, NaCl solution, and electrodes. The top and bottom electrodes work as pre- and post synaptic neurons, respectively, and the NaCl solution/Na2TP@Nafion works as a synapse. The device shows short-term and long-term plasticity such as EPSC, PPF, STDP, potentiation, and depression.
Water of aqueous PEDOT:PSS solution was successfully exchanged with ethylene glycol or ethanol solvents using ultrafiltration method. This novel solvent exchange process enables uniform and conformal nano-coating of PEDOT:PSS on hydrophobic substrates without the addition of surfactants. This process can be widely used in fabrication of various sensors or electronic devices using conducting polymers.
4D Printing Conduits: Electromagnitized carbon porous nanoccookies (NCs) under MF facilitate magneto-electrical conversion for growth factor release and cell simulation. Integrating four-dimensional (4D) printed technology, exposed NCs are able to enhances the cell adhesion and manifest directly electromagnetic stimulation to cells.
It is still a mystery whether disorders could be beneficial for the superconductivity or not. In this work, it is surprising to find out that the carbon disordered 2D β-Mo2C crystal sheet shows a much stronger superconductivity than the carbon ordered 2D α-Mo2C crystal sheet, and the in-situ order-disorder transition from α-Mo2C to β-Mo2C induced by e-beam irradiation results in an enhanced superconductivity. Especially, the Tc variation trends of α-Mo2C and β-Mo2C are different under hydrostatic pressures. These results highlight the important role of disorders in the superconducting properties owing to the carbon distributions in Mo2C.
Understanding the correlation between atomic-scale structural/elastic fluctuations and local plastic rearrangements (shear transformation zone (STZ)) is essential to the widespread use of metallic glasses (MGs). We report a strategy to control the local stress state and enhance the shear stability of MGs. The enhanced degree of structural/elastic heterogeneities relates to the increased nonaffine thermal strain of the short- and medium-range order. We demonstrate that variations in the stress field around STZ affect their dynamics and percolation process, the progressive formation of shear bands, and, consequently, the macroscopic deformability of MGs. This work paves a new way for designing ductile MGs.
Quantum dot LED (light-emitting diode) optimization through the control of charge carriers’ kinetics is presented using impedance spectroscopy. The mobility of charge carriers through each one of the layers provide a path to estimate the transition time of each one of the charge carriers toward the emitting layer. By focusing on thickness optimization of electron transferring layer we can control the transition time of charge carriers and maximize radiative recombination.
Our findings unearth the great importance of the size, core structure, and surface ligands in dictating the antibacterial activity of silver nanoclusters (AgNCs). Owing to the presence of amphiphilic ligands, AgNCs are more prone to adsorb the membrane and following endocytosis towards targeted bacterial cells, associated with membrane damage, as reflected by reinforced release of malondialdehyde (MDA). AgNCs bear strong peroxidase-like activity, coupled to massive production of reactive oxygen species (ROS). Altogether, these outstanding features of AgNCs resultantly elevated the bacteria-killing efficacy through impairing cell wall/membrane, promoting oxidative stress and attenuating pivotal cellular processes, e.g., ATP synthesis.
Speed-programmed melt electrospinning writing (sMEW) is used to create a hierarchically ordered biomimetic scaffold with long-range patterned and short-range porous architectures for cell growth in patterns with tunable cell density.
A sunlight management strategy in perovskite solar cells (PSCs) using silicon quantum dots (SiQDs) is proposed. Due to the reabsorption of visible light induced by SiQDs, the external quantum efficiency spectra of PSCs in a wide wavelength range of 360–760 nm is significantly improved, resulting in facilitated photocurrent collection and enhanced performance of SiQD-based PSCs.
Tailored hardening behavior of monolithic bulk metallic glass (BMG) is demonstrated experimentally. A 2D gradient rejuvenation is introduced into ZrCuAl BMG by a novel heat treatment method. The gradual change of free volume realizes sustainable hardening until fracture. The local free volume related to the rejuvenation state controls the shear band angle and the maximum effective shear stress. Hence, shear band propagation is prohibited and the formation of a complete shear plane transecting the whole specimen is blocked. The current approach offers a new paradigm for utilizing hardening capability of BMG as practical engineering materials.
Selective growth of ZnO nanorods/reduced graphene oxide composites via IR laser-induced reaction is developed for electrochemical devices. Optimized design of interdigitated supercapacitor electrodes can be achieved by programming of laser scanning lines. The integration of ZnO NRs on rGO improves supercapacitor performances due to synergistic effects of pseudo capacitance (ZnO) and electric double layer capacitance (graphene).
An effect of atomic-scale surface modulation on the magnetic properties and the interfacial Dzyaloshinskii-Moriya interaction (IDMI) is shown in Pt/CoFeSiB/X(MgO, Ta, Ru) ultrathin films sputtered on the epitaxial Pd layers of the different thickness and surface morphology. The correlated roughness of the bottom and top interfaces of CoFeSiB increases IDMI values by up to 2.5 times, with the maximum magnitude Deff = −0.88 erg/cm2. The main reasons for this significant enhancement are the intermixing at interfaces and the correlated interface-roughness variations, which both affect electronic transport across the interface and, as a result, the degree of the electron scattering.
To achieve growth factor-free angiogenesis, a lipopolysaccharide-mimicking dodecyl group-modified gelatin microparticle (C12-MP) was fabricated. The water suspension of C12-MP formed a syringe-injectable hydrogel with shear-thinning properties. The C12-MP hydrogel induced localized and sustained angiogenesis in vivo for 22 days by stimulation of toll-like receptor 4 accompanied by endogenous growth factor secretion.
In this work, we report a strategy to build programmable atom equivalents (PAEs) with tailorable DNA bond length and bond energy using DNA encoders carrying consecutive adenines (polyA). We find that the bond length and bond energy can be tuned by programming the topologic configurations of the DNA encoders, which lead to differently leveled bonds and asymmetric PAEs allowing for directional, hierarchical assembly of multi-particle structures. This programmable bonding system may provide a new route for building complex plasmonic superstructures.
We report methacrylated silk fibroin sealant (Sil-MAS) with rapid crosslinkable, highly adhesive and biocompatible properties and demonstrate its versatility as medical glue. The excellence for physical properties of Sil-MAS is revealed via in vitro mechanical tests and ex vivo aorta pressure test. In in vivo biological tests on skin, liver, and blood vessels of rat, Sil-MAS showed a superb hemostatic and adhesive ability with high biocompatibility. Specifically, Sil-MAS strongly contributed to fast wound healing. Furthermore, we showed that Sil-MAS could be an ideal photocuring laparoscopic medical glue in laceration rabbit model of liver and stomach serosa using self-made endoscopic device.
A sequentially formed hybrid hydrogel system consisting of collagen and alginate was designed to control cell shape in 3D. The cell with different spreading state had significantly different responses to mechanical (i.e., matrix stiffness) and biochemical (i.e., transforming growth factor-β1 (TGF-β1)) cues.
Electric-field-driven ion migration is an effective way to control many physical properties such as electric and magnetic properties of materials. In this research, we demonstrated that remarkably small electric field as low as 105 V/m can effectively modulate resistance of a GdOx microwire due to the lateral motion of oxygen ions. This result enables mimicking a synaptic device with low power consumption like as a brain. Furthermore, huge MR modulation of the GdOx microwire with the electric field provides novel functionality as an electromagnetic device.
We show an efficient spin injection technique for a semiconductor using an atomically controlled ferromagnet/ferromagnet/semiconductor heterostructure with low-resistive Schottky-tunnel barriers. Even for semiconductor spintronic devices, the symmetry matching of electronic bands between the ferromagnet and the semiconductor should be considered. This approach provides a new solution for the simultaneous achievement of highly efficient spin injection and low electric power at the electrodes in semiconductor devices at room temperature.
Since the interfacial effect has been commonly understood to be generated entirely at the boundary between the two atomic layers, the strength of the interfacial effect has been considered independent of the thickness of each layer. In this study, contrary to the common concept, we show that the interfacial phenomenon requires threshold thickness for full emergence and is suppressed when it is too thin, by providing the result of the peculiar ferromagnet layer thickness dependence of the Dzyaloshinskii-Moriya interaction (DMI). Our result refines conventional perspectives on interfacial phenomena and provides the optimum thickness to maximize DMI for technological applications.
Very efficient, fast and scalable Fluidized Bed Reactor Atomic Layer Deposition (FBR-ALD) of highly dense and uniform Pt nanoparticles (NPs) on the functionalized carbon were successfully demonstrated for the proton exchange membrane fuel cell (PEMFC) application. The textural properties, functional groups and structural defects of the carbon supports significantly influenced Pt NPs deposition. A proper carbon supporter matching for FBR-ALD of Pt resulted in excellent electrochemical properties, long-term durability and fuel cell performance.
A germole-containing π-conjugated polymer is prepared from the corresponding tellurophene-containing polymer by its Te–Li exchange reaction using n-butyllithium followed by the reaction with dimethylgermanium dichloride. The low-lying LUMO energy level of the germole-containing π-conjugated polymer is also described.
The fiber membrane prepared from silk fibroin was modified by polydopamine and grafted the liposomes encapsulated leptin that endow the fiber with vascularization. The fiber membrane was covered with the defect of oral mucosa in rabbits, and leptin was released from the broken liposomes to promote early vascularization and accelerate the regeneration of mucous membrane.
The structure of a high-temperature non-glass forming liquid Er2O3 was investigated by a combination of density measurements in the International Space Station and synchrotron X-ray diffraction measurements utilizing levitation techniques with the aid of computational and advanced mathematical analyses. These multidisciplinary approaches revealed that unusually sharp diffraction peak in the liquid is originated from the formation of distorted tetraclusters whose homology is similar to that of the crystalline phase.
Using a combination of angle-dependent spectroscopic ellipsometry and angle-resolved photoemission spectroscopy as a function of temperature and supported by first-principles calculations, we reveal a new pair of correlated plasmonic excitations at 1.04 and 1.52 eV and a significant Fermi level shift of 0.12 eV, accompanied by spectral weight transfer in the topological insulator, Bismuth Selenide (Bi2Se3). Interestingly, such a spectral weight transfer over a broad energy range causes a drastic change in the charge-carrier density whereby the contribution of charge-carriers in the bulk starts to rival those in the surface states and Bi2Se3 becomes more uniformly conducting.
An electrically tunable photonic band gap structure of monodomain blue phases shows the wide tunable band gap range of ~241 nm. A novel chiral monomer enables us to stabilize the blue phases and to induce electrostriction upon biased electric fields. This device also exhibits a color gamut 85% of NTSC with high color purity owing to narrow bandwidth of 31 nm.
Magnetic refrigeration, which is based on the magnetocaloric effect (MCE), is an emerging pathway for environment-friendly refrigeration. In this work, we performed a machine learning based approach to discover experimentally that HoB2 exhibits |ΔSM| = 40.1 J/kg K (0.35 J/cm−3 K) for μ0ΔΗ = 5 Τ at second order transition of TC ~ 15 K, having the largest |ΔSM| around this temperature region. Thus, HoB2 is a highly suitable material for hydrogen liquefaction and low-temperature magnetic cooling applications. Our study also sheds light on the machine learning approach as an effective method for searching functional materials characterized by complex physical properties.
Precise control of colloidal-semiconductor-quantum-dots (CQD) assembly morphologies and the related carrier transport characteristics are vital to advance their utilisations. Each application requires different assembly types to exploit either the quantum confinement effect or the large surface-to-volume ratio. On-demand control of CQD-solids‘ morphology are demonstrated using variety of assembly methods. Employment of the electric-double-layer gating on varieties of CQD solids reveals their intrinsic carrier transport and accumulation characteristics. Compact superlattice structure shows high conductivity, and the hierarchical porous assembly exhibits high carrier accumulations. These flexibilities in assembly controls and characteristic tunings signify CQD versatilities as building blocks for different modern electronics.
A low toxicity and high efficiency nucleic acid delivery system is the key to the successful implementation of gene therapy. In this study, a novel fluorinated polycationic carrier was used to effectively inhibit tumor growth by targeting VEGF genes with RNAi technology based on its unique fluorine effect, providing a feasible strategy for future clinical solid tumor treatment.
A data-driven approach, called materials informatics (MI) method, is developed to maximize the inference ability even using a small training dataset. The idea is to use a joint representation with the three descriptors to describe physical and chemical multifaceted perspectives of materials. This ensemble-based machine learning was trained with only 29 training data. Experiments confirmed that the virtual-screening process successfully discovered five oxygen-ion conductors, that have not been reported.
A submicron structure strategy was introduced in a selective laser melted (SLM) Ag-Cu-Ge alloy, showing semi-coherent precipitates distributed in a discontinuous but periodic fashion along the cellular boundaries. It leads to a remarkable strength of ~410 MPa with ~16% ductility, well surpassing the strength-ductility combination of their cast counterparts. The hierarchal SLM microstructure and high density of internal defects leading to a high strain hardening rate and strong strengthening. Premature failure occurred due to the external defects, such as pores and unmelted particles. This work paves a way for additively manufacturing materials towards high strength–ductility synergy.
The polyurethane–antimony tin oxide (PU–ATO) composite fibers makes infrared (IR) radiations emitted by an object to be as similar as possible to ambient background radiation such that an IR detection sensor fails to distinguish the target object. Hydrophobic surface of the PU–ATO composite fiber prevent the distortion of the IR and thermal radiation caused by the wetting of the PU–ATO composite fiber with water. The PU–ATO composite fiber-based textile can be applied in wearable IR- and thermal radiation-shielding technologies to shield IR signals generated by objects of diverse and complex shapes.
Initiations of magnetic reversals can be described by microstructures of the hot-deformed permanent magnet. Strong dipole fields are applied at magnetic-nucleation sites. Inclinations of easy axes from a nominal easy axis are essential to generate the magnetic nucleation. The magnetization reversal tends to starts from regions in which the grains having tilted easy axis are concentrated. The results of this study show that the performance of the hot-deformed permanent magnet is enhanced by avoiding the concentration of the grains with the tilted easy axis.
In this work, we prepared laser-scribed graphene/LiNi1/3Mn1/3Co1/3O2 (LSG/NMC) without binder and conductive agent as a new breakthrough cathode through DVD burner. The obtained LSG/NMC delivers not only high capacitance but also rate capability and cyclability. This is because the NMC spacer maximizes the effective area of LSG. This work demonstrates that LSG/NMC cathode can be regarded as a candidate for high-performance hybrid supercapacitor.
Existing healing experiments on self-healing bulk materials typically rely on manual contact of fracture interfaces. Development of 3D-architected lattice structures that can autonomously heal fractures or damages is still an outstanding engineering challenge. This paper presents a class of additively manufactured lattice structures that can autonomously heal fractures by first aligning fracture interfaces through a shape-memory process and then repairing fracture interfaces through a fracture-healing process. Through harnessing the coupling of shape-memory and self-healing, this paper also demonstrates reversible configuration transformations of lattice structures among states of different stiffnesses, vibration transmittances, and acoustic absorptions.
In this paper, the authors present an ultrathin compound metamaterial coat that could make underwater objects simultaneously invisible from the detection of both magnetic field and acoustic wave. The robustness of the methodology to realize this dual functional coat has been verified experimentally in various electromagnetic and acoustic frequency bands.
In this study, we designed an injectable antibacterial hydrogel that was photopolymerized by visible light for the treatment of skin infections. The hydrogel consists of γ-poly(glutamic acid)-glycidyl methacrylate (γ-PGA-GMA) and ε-polylysine-glycidyl methacrylate (ε-PL-GMA). The hydrogels showed the characteristics of injectable and rapid gels, and were easy to use. Importantly, the hydrogels demonstrated high levels of antibacterial activity and biocompatibility. In in vivo infection models, the hydrogels reduced inflammation, promoted wound healing, and shortened the healing time. This highlights the hydrogels as promising candidates for anti-infection and wound healing.
Collective phenomena, such as charge/spin density waves and superconductivity, may change abruptly at the surface or in single layers of layered materials, whose observation may be affected by epitaxial strain. In Niobium diselenide, a stripe charge density wave, in place of a usual triangular one, has been observed at the surface, but not in single-layer. Phonon calculations and total energy calculations shed light on the intrinsic nature of the periodic lattice distortions, finding good agreement with experimental observations of phase separation between triangular and stripe phases, attributing to isotropic compressive strain the emergence of the latter.
Push-pull dye molecules self-assemble into two 2D Kagomé nanoarchitectures composed of a single or two chiral Baravelle spiral triangular trimer enantiomers. Only one of the two nanoarchitectures is able to trap coronene molecules.
ReRAM devices based on halide perovskites have recently emerged as a new class of data storage device, where the switching materials used in these devices have attracted huge attention in recent years. In this study, we compare the resistive switching characteristics of ReRAM devices based on a quasi-2D halide perovskite, (PEA)2Cs3Pb4I13, to those based on 3D CsPbI3. Astonishingly, the ON/OFF ratio of the (PEA)2Cs3Pb4I13-based memory devices was much higher than that of the CsPbI3 device. Also this device retained a high ON/OFF current ratio for two weeks under ambient conditions, whereas the CsPbI3 device degraded rapidly and showed unreliable memory properties after five days. We strongly believe that quasi-2D halide perovskites have potential in resistive switching memory based on their high ON/OFF ratio and long-term stability.
Quantum Dot: Shell cross-linking endows stability: Simple and facile cross-linking chemistry was employed to form the robust network shell on the quantum dot (QD) surface without altering the photoluminescence property of pristine QDs. The resulting shell cross-linked QDs exhibited exceptional tolerance against heat or chemical oxidations. And the exterior brush in QDs can be readily tunable and provide the miscibility with host polymer matrix, resulting in well-defined QD-nanocomposite films. This encapsulation strategy can be generally applicable to many other nanoparticles that are vulnerable to various external stimuli.