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Sorbent-assisted AWH and moisture-enabled energy generation are reviewed in parallel to reveal the correlation between these two technologies.

Freestanding functional inorganic membranes have piqued immense interest, as they may extend the notion of a selective barrier beyond matter flow to encompass energy and even information flows, potentially unlocking new possibilities in advanced separation, catalysis, sensors, memories, optical filtering and ionic conductors. However, limited by the brittle nature of most inorganic materials along with their few surface unsaturated linkages, inorganic membranes are far less ubiquitous than their organic counterparts, which may be easily obtained from diverse top-down moldings and/or bottom-up syntheses. Up to now, only a few specific inorganic membranes were circuitously derived from the pre-deposited films by selective removal of the sacrificial substrates. Here, we demonstrate a facile strategy to switch the nucleation preference in the aqueous system, resulting in a versatile synthesis of various ultrathin inorganic membranes on solution surface. Through a comprehensive understanding of the kinematic evolution of floating building units for membrane construction, the phase diagram based on geometrical connectivity, as well as the principle of customizing membrane thickness and porosity, are established, providing access to unusual membrane topologies with complex architectures. This universal synthetic methodology, pivotal to both scientific and industrial communities, will hasten the exploitation of new functional membranes for a variety of novel applications.

To tackle the global restriction on the use of lead-based materials, a feasible strategy of developing a piezoelectric ceramic with a ferroelectric- and relaxor-coexisted hybrid state is proposed in order to reduce the energy barrier as well as to assist polarization rotation. A significantly enhanced piezoelectric coefficient, d33, of 173 pC/N along with a broadened high-temperature stability above 300 °C has been obtained. Further probing via piezoresponse force microscopy unveils the grain boundary-governed domain structures with complicated configurations, suggesting close correlations with the coexistence of ferroelectric and relaxor states. This work demonstrates a recipe for establishing a novel grain-based ferroelectric-relaxor hybrid state with improved piezoelectric performance, which can further be beneficial for realistic applications.

Mechanical properties of hydrogels are crucial to emerging devices and machines for wearables, robotics and energy harvesters. Various polymer network architectures and interactions have been explored for achieving specific mechanical characteristics, however, extreme mechanical property tuning of single-composition hydrogel material and deployment in integrated devices remain challenging. Here, we introduce a macromolecule conformational shaping strategy that enables mechanical programming of polymorphic hydrogel fiber based devices. Conformation of the single-composition polyelectrolyte macromolecule is controlled to evolve from coiling to extending states via a pH-dependent antisolvent phase separation process. The resulting structured hydrogel microfibers reveal extreme mechanical integrity, including modulus spanning four orders of magnitude, brittleness to ultrastretchability, and plasticity to anelasticity and elasticity. Our approach yields hydrogel microfibers of varied macromolecule conformations that can be built-in layered formats, enabling the translation of extraordinary, realistic hydrogel electronic applications, i.e., large strain (1000%) and ultrafast responsive (~30 ms) fiber sensors in a robotic bird, large deformations (6000%) and antifreezing helical electronic conductors, and large strain (700%) capable Janus springs energy harvesters in wearables.

Thermoelectric (TE) polymers have unique advantages in converting heat into electricity. But their Seebeck coefficient is lower than that of inorganic TE materials by about one order of magnitude. Here, surface energy filtering is proposed to significantly enhance the Seebeck coefficient of TE polymers. The as-prepared poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, the most popular TE polymer) films from aqueous solution have a low Seebeck coefficient of 15–18 μV K−1 and a power factor of ∼0.008 μW m−1 K−2. Depositing Rhodamine 101, a zwitterion, on PEDOT:PSS films can enhance the Seebeck coefficient to 47.2 μV K−1 and the power factor to 401.2 μW m−1 K−2. The Rhodamine 101 effect on the Seebeck coefficient is consistent with its effect on the work function of PEDOT:PSS. The enhancement in the Seebeck coefficient is ascribed to the dipole moment of Rhodamine 101 and the interfacial dipole moment formed at the surface of the PEDOT:PSS films. This is confirmed by theoretical simulations. We call this mechanism surface energy filtering. Surface energy filtering can increase the mean energy of the transporting carriers and thus the Seebeck coefficient of the PEDOT:PSS films while only slightly affecting the electrical conductivity. It can thus significantly enhance the Seebeck coefficient and the power factor simultaneously.

Quantum conductance, known as Sharvin point contact, has been extensively investigated in many electronic devices, including diodes, transistors, and switches, especially in conductive filaments-based memristors. Quantum conductance with one or multiple atoms point connection can overcome the limitations of scaling and operating speed of nonvolatile multiple memory, logic device, and brain-inspired computing systems. However, because of the instability of the atomic arrangement in the one/multiple atoms connection in a conductive filaments-based memristor, it is a great challenge to maintain quantum conductance states for a long time. Here, we demonstrate that the stable long-time retention of multi-level quantum conductance states can be realized in Mott insulator vanadium dioxide with a highly oriented crystalline texture. According to in situ transmission electron microscope, conductive atomic force microscope, and detailed energy band analysis results, it is proposed that the grain boundaries act as reservoirs for oxygen vacancies and confine the oxygen vacancy diffusion in the narrow grain boundaries due to the higher bulk diffusion barrier. Our approach is extremely crucial for realizing quantum conductance-based electronic devices, such as multi-level and high-density storage and neuromorphic computing.

Catering to the general trend of artificial intelligence development, simulating humans' learning and thinking behavior has become the research focus. Second-order memristors, which are more analogous to biological synapses, are the most promising devices currently used in neuromorphic/brain-like computing. However, few second-order memristors based on two-dimensional (2D) materials have been reported, and the inherent bionic physics needs to be explored. In this work, a second-order memristor based on 2D SnSe films was fabricated by the pulsed laser deposition technique. The continuously adjustable conductance of Au/SnSe/NSTO structures was achieved by gradually switching the polarization of a ferroelectric SnSe layer. The experimental results show that the bio-synaptic functions, including spike-timing-dependent plasticity, short-term plasticity and long-term plasticity, can be simulated using this two-terminal devices. Moreover, stimulus pulses with nanosecond pulse duration were applied to the device to emulate rapid learning and long-term memory in the human brain. The observed memristive behavior is mainly attributed to the modulation of the width of the depletion layer and barrier height is affected, at the SnSe/NSTO interface, by the reversal of ferroelectric polarization of SnSe materials. The device energy consumption is as low as 66 fJ, being expected to be applied to miniaturized, high-density, low-power neuromorphic computing.

Piezoresponse force microscopy (PFM), as a powerful nanoscale characterization technique, has been extensively utilized to elucidate diverse underlying physics of ferroelectricity. However, intensive studies of conventional PFM have revealed a growing number of concerns and limitations which are largely challenging its validity and applications. In this study, an advanced PFM technique is reported, namely heterodyne megasonic piezoresponse force microscopy (HM‐PFM), which uses 106 to 108 Hz high‐frequency excitation and heterodyne method to measure the piezoelectric strain at nanoscale. It is found that HM‐PFM can unambiguously provide standard ferroelectric domain and hysteresis loop measurements, and an effective domain characterization with excitation frequency up to ≈110 MHz is demonstrated. Most importantly, owing to the high‐frequency and heterodyne scheme, the contributions from both electrostatic force and electrochemical strain can be significantly minimized in HM‐PFM. Furthermore, a special measurement of difference‐frequency piezoresponse frequency spectrum (DFPFS) is developed on HM‐PFM and a distinct DFPFS characteristic is observed on the materials with piezoelectricity. By performing DFPFS measurement, a truly existed but very weak electromechanical coupling in CH3NH3PbI3 perovskite is revealed. It is believed that HM‐PFM can be an excellent candidate for the ferroelectric or piezoelectric studies where conventional PFM results are highly controversial., A heterodyne megasonic piezoresponse force microscopy (HM‐PFM) is introduced for nanoscale ferro/piezoelectric characterization. HM‐PFM specially uses 106 to 108 Hz high‐frequency excitation and heterodyne method to measure piezoelectric strain, providing a substantial improvement for the signal source issue of conventional PFM. It is believed that HM‐PFM is an excellent candidate for ferro/piezoelectric studies where conventional PFM measurements are highly controversial.

Polymer-MOF hybrid enables simultaneous and uninterrupted sorption and release of atmospheric water., The atmosphere contains an abundance of fresh water, but this resource has yet to be harvested efficiently. To date, passive atmospheric water sorbents have required a desorption step that relies on steady solar irradiation. Since the availability and intensity of solar radiation vary, these limit on-demand desorption and hence the amount of harvestable water. Here, we report a polymer–metal-organic framework that provides simultaneous and uninterrupted sorption and release of atmospheric water. The adaptable nature of the hydro-active polymer, and its hybridization with a metal-organic framework, enables enhanced sorption kinetics, water uptake, and spontaneous water oozing. We demonstrate continuous water delivery for 1440 hours, producing 6 g of fresh water per gram of sorbent at 90% relative humidity (RH) per day without active condensation. This leads to a total liquid delivery efficiency of 95% and an autonomous liquid delivery efficiency of 71%, the record among reported atmospheric water harvesters.

Smart nanoparticle swarm allows dynamic multimaterials integration to access distinctive functions., Bioinspired nano/microswarm enables fascinating collective controllability beyond the abilities of the constituent individuals, yet almost invariably, the composed units are of single species. Advancing such swarm technologies poses a grand challenge in synchronous mass manipulation of multimaterials that hold different physiochemical identities. Here, we present a dynamic thermal trapping strategy using thermoresponsive-based magnetic smart nanoparticles as host species to reversibly trap and couple given nonmagnetic entities in aqueous surroundings, enabling cross-species smart nanoparticle swarms (SMARS). Such trapping process endows unaddressable nonmagnetic species with efficient thermo-switchable magnetic response, which determines SMARS’ cross-species synchronized maneuverability. Benefiting from collective merits of hybrid components, SMARS can be configured into specific smart modules spanning from chain, vesicle, droplet, to ionic module, which can implement localized or distributed functions that are single-species unachievable. Our methodology allows dynamic multimaterials integration despite the odds of their intrinsic identities to conceive distinctive structures and functions.

To tackle the global restriction on the use of lead-based materials, a feasible strategy of developing a piezoelectric ceramic with a ferroelectric- and relaxor-coexisted hybrid state is proposed in order to reduce the energy barrier as well as to assist polarization rotation. A significantly enhanced piezoelectric coefficient

A robust, superwetting and conductive amorphous NiFe (sulfur)oxyhydroxide porous nanoclusters/Ni foam composite electrode was fabricated using a facile one-step wet synthesis method. The S-incorporation strategy enhances the electron transfer and wetting performance of NiFe oxyhydroxide, and dramatically improves the oxygen evolution reaction (OER) performance. This catalytic electrode can drive a 1A cm−2 OER with the lowest reported overpotential of 260 mV and stably drive a 1 A cm−2, and a higher 3 A cm−2 OER process in 1 M KOH. 3 A cm−2 is the highest current density value recorded for a stably driven long-term OER process to the best of our knowledge. Inspired by the intrinsic OER equation, this study highlights that the conductive, large electrochemically active surface area (ECAS) and superwetting properties are important factors for designing large-current-density OER catalysts.

MXenes as 2D materials have attracted great attention due to their high electrical conductivity, high surface area, high transparency in the visible range and high hydrophilicity. They have been investigated in devices and systems including batteries, supercapacitors, and sensors as well as in catalysis but not in optoelectronic devices. In this work, we studied the application of Ti3C2Tx for electron and hole collection in organic solar cells (OSCs). The work function of Ti3C2Tx can be increased by a UV–ozone treatment and decreased through a treatment with N2H4. It can be thus tuned in a range from 4.08 to 4.95 eV. MXene films with different work functions are studied as electron and hole collection buffer materials for non-fullerene organic solar cells (OSCs) with poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC) as the active materials. The OSCs with MXenes for electron or hole collection layers can exhibit a power conversion efficiency of 9.06% or 9.02%. These efficiencies are comparable to those obtained using conventional charge-collection buffer materials.

Vanadium dioxide (VO2) undergoes an insulator to metal transition (MIT) and an accompanied phase transition from a monoclinic (M) structure to rutile (R) structure near room temperature, forming the basis for many VO2-based functional devices. The MIT transition of VO2 and the functionality of VO2-based devices can be controlled by a variety of chemical and physical stimuli. With these external stimuli, defects, such as oxygen vacancies, are often inevitably introduced. However, due to the VO system-induced challenge to synthesize stable VO2 with different oxygen vacancy concentrations, the impact of oxygen vacancies on the resistance and transition of the VO2 is not fully understood. Oxygen vacancy, as one of the typical defects in VO2, is expected to concentrate at grain boundaries, and hence a concentration gradient of oxygen vacancies may exist between the grains interior and the boundaries, and this suggests a possibility to study the effects of oxygen vacancies on the transition of VO2 by probing local phenomena at the grain boundaries. For investigating local phenomena at the grain boundaries, Scanning Probe Microscopy (SPM) techniques are effective, which allows probing the structure and various properties at the nanoscale. In this work, a series of SPM techniques, including Atomic Force Microscopy (AFM), conductive-AFM (c-AFM), Electrochemical Strain Microscopy (ESM), and Kelvin Probe Force Microscopy (KPFM), are employed to measure variations of the surface structure, the resistance, the oxygen vacancy concentration, and the work function between the grain interior and the grain boundary. It has been demonstrated that, for most cases, both the resistance and the work function are lower at the grain boundaries as a result of the accumulation of oxygen vacancies at those positions. In addition, the resistance change induced by the electric field has been observed in the deposited VO2 thin films, which may be associated with the generation/annihilation of the oxygen vacancies, rather than charge injection. This work has demonstrated the effects of oxygen vacancies in the transition of VO2 by probing the local phenomena at grain boundaries, also provided a new insight into the resistance change of VO2 under an electric field. Keywords: Fermi level, VO2 thin film, c-AFM, KPFM, ESM

Current-voltage (I-V) characteristics well reveal the resistive switching performance of materials promising for the next-generation memory-resistance random access memory (ReRAM). It has been observed that the atmospheric environment can affect the resistive switching performance, but the origin of this effect is still under debate. Conductive Atomic Force Microscopy (c-AFM) is widely used to study the resistive switching performance because of its capability to realize the resistive switching at the nanoscale that is becoming attractive as the miniaturization of memory devices. This study therefore aims to understand the effects of oxygen and moisture on the I-V characteristics of the TiO2 thin film by performing c-AFM measurements in ambient air, synthetic air, and argon gas. It is found that the oxygen in the environment can reduce the set and the reset voltages for the resistive switching, and it can also reduce the resistance at the low resistance state (LRS). Where the moisture in the environment can increase the set and reset voltages, and increase the resistance at LRS. These effects of oxygen and moisture in the environment can be attributed to the modification of the effective electric field during the resistive switching processes, which have been further confirmed by Kelvin Probe Force Microscopy (KPFM) measurements. In addition, it is found that the local ionic dynamics of TiO2 during the resistive switching are strongly dependent of the environments by performing the FORC-IV (First Order Reversal Curve-Current-Voltage) measurements in the three gas environments. Results in this work can provide a new perspective on the effect of environments on the resistive switching of materials, that is, the modulation of the effective electric field due to the adsorption of oxygen and moisture under the c-AFM tip. Keywords: Resistive switching, Environmental control, c-AFM, KPFM, FORC-IV

Metal matrix composites (MMC) find their uses as high performance materials. The selective laser melting (SLM) of a 316L stainless steel and Al2O3 MMC is presented in this paper. Agglomerate Al2O3 particles had shown to be an adequate powder choice with uniform dispersions in the resultant prints. Relative density, phase, microstructure and mechanical properties of all 1-, 2-, 3-wt% doped products were carefully analyzed. Finite element modeling model was developed to study the associated multi-physics phenomena with high efficiency for process parameter optimization. It is found that the change in SLM temperature profile with Al2O3 addition is mainly due to the change in optical properties rather than thermal. Hence, both simulation and experimentation revealed that higher laser energy input is needed for optimized melting. In addition, cellular dendrites were found to coarsen with increasing Al2O3 addition due to the decreased cooling rate. With hard particle strengthening effects, all samples showed improved hardness with 3-wt% up to 298 HV and 1-wt% samples showing much improved yielding and tensile stresses of 579 and 662 MPa from 316L. Corresponding microlattice built this way demonstrated a 30 and 23% increase in specific strength and energy absorption from that of 316L too. Keywords: Selective laser melting, Stainless steel, Alumina, Finite element modeling, Metal matrix composite, Microlattice

In this study, ilmenite-type NaNbO3 microplates were prepared by a facile surfactant-free method, using NaAc and KOH as a sodium resource and as a mineralizer, respectively. The effects of each reactant were identified, and the formation process and crystallization pathway of ilmenite-type NaNbO3 microplates were explored based on the phase constitution, microstructure and chemical compositional analysis. The indispensable roles of K ions, which participated in the formation of layered KNN-hydrate intermediates, were revealed. Ilmenite-type NaNbO3 microplates were formed by the dissolution of these intermediates and subsequent recrystallization into K-containing NaNbO3, followed by the ion-exchange between K and Na ions. Meanwhile excess K ions would hinder the release of K ions associated with the dissolution of intermediates, thus preventing the formation of ilmenite-type NaNbO3. Moreover, the morphological evolution of ilmenite-type NaNbO3 microplates from platelets to octahedra was interpreted in terms of their intrinsic structure and KOH concentration.

Resistive switching on the nanoscale is an emerging research field and Scanning Probe Microscopy (SPM) is a powerful tool for studies in this area. Under the SPM tip, the electrical field is very high due to the small tip radius on the order of tens of nanometers, and this can enable a range of ionic/electrochemical phenomena during the resistive switching of the materials under the SPM tip. Although the ionic/electrochemical phenomena have long been considered vital for the resistive switching of materials, a few pieces of experimental evidence, as well as the decoupling of the effects of the electrochemical processes at different stages, are still needed. In this work, we applied SPM based techniques to study resistive switching as well as the electrochemical phenomena during the resistive switching of the TiO2 thin films prepared using Pulse Laser Deposition (PLD). It was found that the reversible or irreversible electrochemical processes initiated at different voltages can promote or degrade the resistive switching behavior of TiO2. Combined with an electrical cell with environmental control, these electrochemical processes have been shown to require the involvement of moisture; the accumulation of oxygen vacancies, protons, and hydroxyls at the tip/TiO2 junction may contribute to the promoting effect of the reversible electrochemical process on resistive switching, while the oxygen vacancy ordering and the injection of protons and hydroxyls into the lattice may lead to the irreversible electrochemical process. This work provides a detailed insight into the characteristics, origins, and the effects of the electrochemical phenomena on resistive switching performance, and will provide a further understanding of the electrochemical phenomena in various functional materials.

Unlike traditional water splitting in an aqueous medium, direct decomposition of atmospheric water is a promising way to simultaneously dehumidify the living space and generate power. Here, a tailored superhygroscopic hydrogel, a catalyst, and a solar cell are integrated into a humidity digester that can break down ambient moisture into hydrogen and oxygen, creating an efficient electrochemical cell. The function of the hydrogel is to harvest moisture from ambient humidity and transfer the collected water to the catalyst. Barium titanate and vertical 2D MoS2 nanosheets are integrated as the catalyst: the negatively polarized cathode can enhance the electron transport and attract H+ to the MoS2 surface for water reduction, while water oxidation takes place at the positively polarized anode. By employing this mechanism, it is possible to maintain the relative humidity in a medium-sized room at

The fundamental understanding of the influence of molecular structure on the carrier transport properties in the field of organic thermoelectrics (OTEs) is a big challenge since the carrier transport behavior in conducting polymers reveals average properties contributed from all carrier transport channels, including those through intra-chain, inter-chain, inter-grain, and hopping between disordered localized sites. Here, combining molecular dynamics simulations and experiments, we investigated the carrier transport properties of doped highly oriented poly(3-hexylthiophene) (P3HT) films with different side-chain regioregularity. It is demonstrated that the substitution of side chains can not only take effect on the carrier transport edge, but also on the dimensionality of the transport paths and as a result, on the carrier mobility. Conductive atomic force microscopy (C-AFM) study as well as temperature-dependent measurements of the electrical conductivity clearly showed ordered local current paths in the regular side chain P3HT films, while random paths prevailed in the irregular sample. Regular side chain substitution can be activated more easily and favors one-dimensional transport along the backbone chain direction, while the irregular sample presents the three-dimensional electron hopping behavior. As a consequence, the regular side chain P3HT samples demonstrated high carrier mobility of 2.9 &plusmn, 0.3 cm2/V&middot, s, which is more than one order of magnitude higher than that in irregular side chain P3HT films, resulting in a maximum thermoelectric (TE) power factor of 39.1 &plusmn, 2.5 &mu, W/mK2 at room temperature. These findings would formulate design rules for organic semiconductors based on these complex systems, and especially assist in the design of high performance OTE polymers.

Ionic transport and electrochemical reactions underpin the functionality of the memory devices. NiO, as a promising transition metal oxide for developing resistive switching random access memory, has been extensively explored in the terms of the resistive switching. However, there is limited experimental evidence to visualize the ionic processes of the NiO under the external electrical field. In addition, the correlation between the ionic processes and the resistive switching has not been established. To close this gap and also to determine the role of the ionic processes in resistive switching of the NiO, in this study, a series of scanning probe microscopy techniques, including electrochemical strain microscopy (ESM), conductive atomic force microscopy, Kelvin probe force microscopy, and a newly developed first-order reversal curve-IV, are employed to measure the ESM response, the resistive switching performance, the work function, and the ionic dynamics of NiO, respectively. The results in this work have clearly visualized the ionic transport and electrochemical reactions of NiO when subjected to the electrical field. It has been found that the ionic processes and the resistive switching accompanied each other. Furthermore, it is found that the electrochemical reactions play a determinative role in the resistive switching of the NiO, and this electrochemically induced resistive switching performance can be explained by an integrated mechanism that has combined the filamentary and the interfacial effects underlying resistive switching. In addition to providing a better understanding of the resistive switching of NiO, this work also provides effective methods to probe the ionic processes and to correlate these ionic processes to the performance of functional materials.

Resistive switching on the nanoscale is an emerging research field and Scanning Probe Microscopy (SPM) is a powerful tool for studies in this area. Under the SPM tip, the electrical field is very high due to the small tip radius on the order of tens of nanometers, and this can enable a range of ionic/electrochemical phenomena during the resistive switching of the materials under the SPM tip. Although the ionic/electrochemical phenomena have long been considered vital for the resistive switching of materials, a few pieces of experimental evidence, as well as the decoupling of the effects of the electrochemical processes at different stages, are still needed. In this work, we applied SPM based techniques to study resistive switching as well as the electrochemical phenomena during the resistive switching of the TiO

In the current study, Al2O3–TiN composites were successfully fabricated with various particle sizes (10, 20, 30, and 50 μm) and concentrations (5, 10, 15, and 20 vol %) via a novel ball milling + Ti reactive sintering process. By applying the reactive sintering, Ti powders will transform into TiN particles, which act as mechanical reinforcements and electrical conductors in the Al2O3 matrix. The ball milling process alters the Ti powder morphology from a low-aspect-ratio sphere into a high-aspect-ratio disc, which reduces the electrical percolation threshold value from 29% to 15% in the current setup. However, such a threshold value is insensitive to the particle size. Meanwhile, the Ti particle size has a significant influence on the material’s mechanical properties. A small particle size results in less porosity and hence higher flexural strength of the composite.

The CoNi alloy nanoparticles with different molar ratios of Co:Ni were prepared by the liquid-phase reduction, and the morphology, chemical composition and structure of the particles were investigated by field-emission scanning electron microscopy and X-ray powder diffraction. The complex permittivity and permeability of the nanoparticles were investigated by network analyzer in the frequency range of 1–18 GHz. The reflection loss was calculated based on the determined complex permittivity and permeability. The field-emission scanning electron microscopy results showed that all samples with different Co:Ni molar ratios were spherical and evenly distributed with the diameter ranging from 60 to 200 nm. Compared with other samples with different Co:Ni molar ratios, the sample with Co:Ni molar ratio of 1:2 displayed higher microwave-absorbing properties due to the higher imaginary parts of the complex permittivity and permeability.

CoNi alloy nanoparticles were obtained using liquid phase reduction method. The size of particles was selected as the research index, and the impacts of experimental conditions on the particle size were investigated. These experimental conditions included reaction temperature, solvent, initial concentration, and the amount of reducing agent and surface active agent. Through the orthogonal test, the optimized process parameters of preparing CoNi alloy nanoparticles by liquid-phase reduction were determined. The size of the particles prepared on the basis of the optimum technology was 60 nm. The particle size would impact the magnetic properties of CoNi nanoparticles measured by the test of hysteresis loops. The test result showed that the Hc of the CoNi alloy nanoparticles decreased and the Ms increased, with the increase of the particle size.

The structure-function relationship at the nanoscale is of great importance for many functional materials, such as metal oxides. To explore this relationship, Scanning Probe Microscopy (SPM)-based techniques are used as powerful and effective methods owing to their capability to investigate the local surface structures and multiple properties of the materials with a high spatial resolution. This paper gives an overview of SPM-based techniques for characterizing the electric properties of metal oxides with potential in the applications of electronics devices. Three types of SPM techniques, including conductive AFM ([Formula: see text]-AFM), Kelvin Probe Force Microscopy (KPFM), and Electrostatic Force Microscopy (EFM), are summarized with focus on their principles and advances in measuring the electronic transport, ionic dynamics, the work functions and the surface charges of oxides.

In order to develop an environmental friendly passive films on galvanized steel sheet, a chromium-free passive solution based on waterborne polyurethane (WPU) and Manganate was studied. The results show that the optimized compositions in passive solution are KMnO4 6g/L, (NH2)2CS 5g/L and WPU 150g/L. The passive films were prepared by dipping steel substrates into the passive solution for 10 seconds and drying at 120 °C for 30 seconds. SEM observation shows that the film’s thickness is about 1.5 µm. XRD patterns indicates that the chromate-free passive films mainly consisted of MnO2 and K2MnO4. Anticorrosion tests indicate that the chromate-free passive films can provide an excellent barrier to corrosive agents.

In this study, environmental friendly hybrid passive films on galvanized steel sheet were prepared from waterborne polyurethane and Titanate. The experimental results show that the optimized composition in passive solution was 30 g/L TiOSO 4 , 5 g/L (NH 2 ) 2 CS, 10 g/L NH 4 F and 150 g/L WPU. The samples were dipped into passive solution for 10 s, dried at 120 °C for 15 s. Though the film's thickness is just 0.5 μm, the white rust resistance is excellent.

The structural changes in HgBa 2 CuO 4+ δ (Hg-1201) induced by the extra oxygen atoms in the Hg plane and by high pressure were investigated using computer simulation techniques. Without partial replacement of Hg by Cu, the most favorable oxygen interstitial position is the O3 site (0.5,0.5,0), while with partial replacement of Hg by Cu, the extra oxygen atom can be located at the O4 site (0.5,0,0.087). These results agree excellently with experimental results. Under high pressure, the Cu–O2 bond is compressed much more and the Hg–O2 bond is compressed much less compared with the unit cell in the c direction. The Ba–O2 interlayer distance is found to have the largest compressibility, four times as much as that of the lattice parameter c . The Ba–O2 interlayer distance becomes zero at 87 GPa, implying occurrence of structural transition. Our simulation found the structural changes induced by O3 oxygen and by high pressure are similar: the Cu–O2 bond and Ba–O2 interlayer distance are shortened while the Hg–O2 bond is relatively elongated. This result agrees with the experimental result.

We have developed a set of interatomic potentials for the simulation of structural changes in HgBa 2 Ca 2 Cu 3 O 8+ δ at δ =0 under pressure up to 20 GPa. Our calculated compressibilities of lattice parameters agree well with experimental values. We predicted that the Cu-O3 bond is more compressible than the Hg-O3 bond. We also predicted the unusual compression of the Ba-O2 and Ba-O3 bonds under pressure, and the buckling of the Cu2-O2-Cu2 plane under pressure. Further, we found that structural changes in HgBa 2 Ca 2 Cu 3 O 8+ δ are similar to those in HgBa 2 CaCu 2 O 6+ δ .