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To improve the absorbing performance of the material, fully utilizing the interfacial polarization is an effective strategy for fabricate microwave absorbing materials. This study constructs flower-like ZnO modified by CuO nanoparticles/N-RGO composites through hydrothermal and subsequent heat treatment. Flower-like ZnO was fabricated by hydrothermal self-assembly of ZnO nanosheets. Due to the petals of ZnO provided a large surface area, the CuO nanoparticles uniformly modified on the flower-like ZnO petals. Meanwhile, the N-RGO was added to further improve the dielectric loss and polarization loss of the composites. The rich interface was rational designed by modifying CuO nanoparticles and adding N-RGO to regulate the microwave absorption properties. The flower-like ZnO modified by CuO nanoparticles/N-RGO composite showed considerable absorbing performance, with the bandwidth (≤−10 dB) was 2.8 GHz as the thickness was 2.8 mm. This work will provide a significant guidance for the design absorbing materials with special structure.

As a typical IV-VI compound, SnTe has aroused widely attentions in the thermoelectric community due its similar crystal and band structures with PbTe. However, both the large number of inherent Sn vacancies and high thermal conductivity result in inferior thermoelectric performance in intrinsic SnTe over a broad temperature. In this work, we successfully improved those disadvantages of SnTe via stepwisely Pb heavily alloying and then In doping. A significantly wide fraction of Pb into SnTe (0–50%) achieves multiple effects: (a) the carrier concentration of SnTe is reduced through decreasing Sn vacancies via alloying high solution Pb atoms in the matrix; (b) the band structure is optimized through promoting the convergence of the two valence bands, simultaneously enhancing the Seebeck coefficient; (c) HAADF-STEM coupled with EDS results illustrate that guest Pb atoms randomly and uniformly occupied Sn atomic sites in the matrix, concurrently strengthening the phonon scattering. Furthermore, we introduced indium into Sn0.6Pb0.4Te system to create resonant states further enlarging the power factors at low-medium temperature. The integration of bands convergence and DOS distortion achieves a considerably high ZTave of ∼0.67 over the wide temperature range of 300–823 K in (Sn0.6Pb0.4)0.995In0.005Te sample.

MXenes – In recent decades, great attention has been paid to the fast-growing two-dimensional (2D) transition metal carbides and nitrides, in terms of their prominent mechanical and electrical properties. The tribological essence of MXene has not yet been entirely investigated, although researches on MXene were conducted in all aspects of its applications. Hence, a newly compound 2D MXene (Ti3C2Tx) is exploited to reinforce the wear resistance of the chemically bonded silicate ceramic coatings, which are utilized to protect component surfaces under severe conditions. The structural features, hardness, and tribological behaviors of the targeted coatings are investigated and analyzed. Results show that the micro-hardness of the coatings increases to 156.9 HV0.5 when added 1.2 wt% MXene. The increment of microhardness extraordinarily reaches 33.3%, compared with the original. The coating with 1.2 wt% MXene also indicates a 31.6% decrement of the coefficient of friction (COF) and a 73% reduction of the wear rate respectively. Furthermore, fatigue is found to be the main reason of the wear mechanism, through exploring the surface morphologies of wear traces and counterpart balls.

In this study, ZnO/ZnO nanocrystal-modified reduced graphene oxide (rGO) foam composites having various morphologies and mass ratios were synthesized using the hydrothermal and freeze-drying processes. The free Zn2+ present in the composites controlled their morphology by regulating the pH value, and the Zn2+ ions adsorbed onto the rGO sheets to form ZnO nanocrystals. The rGO sheets were dispersed by growing ZnO and ZnO nanocrystals on them, effectively preventing their agglomeration. The effects of the ZnO morphology and ZnO:rGO mass ratio on the complex permittivity and microwave absorption properties of the composites were systematically studied. The results revealed that the composite with small hexagonal cylindrical ZnO and the ZnO:rGO mass ratio of 8:1 (pH = 8.5) showed considerable microwave absorption, and the bandwidths of the reflection loss (≤−10 dB) were 8.7–11.1 and 11.5–12.4 GHz when the thickness was 3.4 mm. The microwave absorption mechanism of the composites was investigated systematically. The results indicated the potential of the composites as an absorber material with high performance, broad bandwidth, and light weight.

Only 0.1% of the acoustic energy can transmit across the water-air interface because of the huge acoustic impedance mismatch. Enhancing acoustic transmission across the water-air interface is of great significance for sonar communications and sensing. However, due to the interface instability and subwavelength characteristics of acoustic metamaterials, wide-angle intermediate-frequency (10 kHz-100 kHz) water-air acoustic transmission remains a great challenge. Here, we demonstrate that the lotus leaf is a natural low-cost acoustic transmission metasurface, namely, the lotus acoustic metasurface (LAM). Experiments demonstrate the LAM can enhance the acoustic transmission across the water-air interface, with an energy transmission coefficient of about 40% at 28 kHz. Furthermore, by fabricating artificial LAMs, the operating frequencies can be flexibly adjusted. Also, the LAM allows a wide-angle water-to-air acoustic transmission. It will enable various promising applications, such as detecting and imaging underwater objects from the air, communicating between ocean and atmosphere, reducing ocean noises, etc.

Monitoring the cracks initiation and propagation of construction materials, as well as determining the fracture process zone, constitute two key factors to understand the damage mechanism of materials in order to control the risk of material degradation and failure. This paper demonstrates the results of a laboratory static test designed to investigate the in situ monitoring of crack tip growth in wood. LT-type single-edge notched specimens made of Chinese fir with the seam height ratio of 0.1, 0.2 and 0.3 were tested by three-point bending experiment. In this paper, acoustic emission (AE) method and digital image correlation (DIC) method were used to study the damage process of Chinese fir under monotonic loading techniques simultaneously. The results show that analyzing AE signals by considering the acoustic emission event number and the cumulative events yields interesting information on crack initiation and propagation. Based on the displacement field obtained from the DIC, the cracking displacement (COD) and crack extension length during crack propagation can be converted to provide information about the evolution of the fracture process zone at the interface. Moreover, an additional analysis of DIC and AE data indicates good correlation (involving the crack extension length and the cumulative events). It opens the possibility to characterize the crack initiation and propagation of wood materials without visible wood cracks.

Polyaniline nanofiber (PANI-f) was covalently linked with cetyltrimethyl ammonium bromide (CTAB) modified graphene oxide nanosheets (CTGO) to fabricate a smart composite coating for corrosion protection of carbon steel. In the copolymerization process, CTAB served both as a modifier for the modification of GO and a dispersant for the preparation of polyaniline nanofibers. The prepared PANI-f can avoid the accelerated corrosion of steel by a conventional synthesis method using hydrochloric acid as medium. The covalent binding between PANI-f and CTGO improved the compatibility of PANI-f-GO with the waterborne epoxy emulsion, which significantly enhanced the hydrophobicity and antipermeability of the coating. The PANI-f-GO waterborne epoxy coating exhibited excellent smart corrosion protection efficiency by catalyzing the formation of passivation film on the steel surface. Molecular adsorption energy on Fe(110) and radial distribution function confirmed the chemical adsorption of the PANI-f-GO composite on the steel surface. The superior smart protective performance can be ascribed to the synergistic effects of PANI-f and CTGO.

Using Martian resource to construct a site on Mars is a superior choice to instead of transporting all the construction materials from Earth to the Mas with incredibly high cost. This study proposes a developed Martian concrete composed of sulfur and magnetite, heated by microwave to meet the energy-poor environment on Mars. A lattice Boltzmann model is developed to determine the optimal microwave power and heating time for Martian concrete casting. The compressive strength and microstructure of Martian concrete casted by microwave are measured by test. Finally, a 3D printed device is conceived to prepare Martian concrete and the four-layered specimen is casted to simulate the 3D print process. The results indicate that the compressive strength of Martian concrete casted by microwave can reach 1.78 kgf/mm2 (17.44 MPa) on earth, which is corresponding to 4.62 kgf/mm2 on Mars. Since the heating rate of magnetite under microwave is very high, if possible, the low microwave power and long heating time should be chosen to reduce the temperature gradient in matrix and reduce the possibility of sulfur matrix boiling. In addition, the strength of four-layered (simulated 3D printed) Martian concrete can reach 1.21 kgf/mm2 (11.86 MPa) on earth, which is corresponding to 3.15 kgf/mm2 on Mars.

Chemical durability of lanthanide zirconates (A2Zr2O7) (A = La-Yb) under near-field environments is important for evaluating their application as potential nuclear waste forms. In this work, A2Zr2O7 (A = La-Yb) are synthesized by spark plasma sintering with controlled microstructure and their chemical durability are evaluated in a nitric acid solution (pH = 1). Scanning transmission electron microscopy analysis reveals an amorphous passivation film either enriched with Zr or lanthanide. The complex chemistry of the passivation films can be correlated with a transition in corrosion mechanisms from a preferential release of lanthanide in La2Zr2O7 to a preferential release of Zr in Er2Zr2O7 and Yb2Zr2O7. These results suggest a dominant mechanism of incongruent dissolution and surface reorganization for the formation of passivation films. Strong correlations are identified between the leaching rates and cation ionic size, ionic potential, electronegativity differences between A-site cation and Zr, and bonding valence sum of oxygen, suggesting important impacts of structural and bonding characteristics in controlling chemical durability of lanthanide zirconates.

The effect of high voltage electrostatic field and high voltage alternating current electric field on the heat exchanger surface fouling under the conditions of hard water was investigated. The Ca2+ concentration in two water conditions was 12 mmol/L. The Mg2+ concentration was 10 mmol/L and 12 mmol/L respectively. The concentration changed with the Mg2+ concentration. X-ray diffraction and scanning electron microscope results confirmed that the main crystal phases of the scale samples consisted of calcite and aragonite. The high voltage electrostatic treatment can promote scale growth under both water quality conditions. However, the high voltage alternating current electric field treatment shows a good scale inhibition effect under both water quality conditions, and the scale inhibition effect is best when both Ca2+ and Mg2+ concentrations are 12 mmol/L, and the average scale inhibition rate reaches 47.58%. When the calcite content of the scale sample is significantly higher than that of aragonite, Mg2+ affects the growth and solubility of crystals. Conversely, the high voltage alternating current electric field treatment can effectively extend the fouling induction period of the adherent scale on the heat exchanger surface, which is favorable for heat exchanger fouling. HIGHLIGHTS The scale inhibition experiments with different electric fields and Mg2+ concentrations were designed.; Different electric fields have different treatment effects.; The FIP can be used to evaluate the scale inhibition effect.; The HVAC electric field treatment can enhance the inhibition effect of Mg2+ on crystal growth.; After the HVAC electric field treatment, the calcite content in the scale sample increases.

Noticeable pseudo-capacitance behavior out of charge storage mechanism (CSM) has attracted intensive studies because it can provide both high energy density and large output power. Although cyclic voltammetry is recognized as the feasible electrochemical technique to determine it quantitatively in the previous works, the results are inferior due to uncertainty in the definitions and application conditions. Herein, three successive treatments, including de-polarization, de-residual and de-background, as well as a non-linear fitting algorithm are employed for the first time to calibrate the different CSM contribution of three typical cathode materials, LiFePO4 , LiMn2 O4 and Na4 Fe3 (PO4 )2 P2 O7 , and achieve well-separated physical capacitance, pseudo-capacitance and diffusive contributions to the total capacity. This work can eliminate misunderstanding concepts and correct ambiguous results of the pseudo-capacitance contribution and recognize the essence of CSM in electrode materials.

Thermoelectric materials transfer heat and electrical energy, being useful for power generation or cooling applications. Many of these materials have narrow bandgaps, especially for cooling applications where this property has been seen as particularly important for enhancing the thermoelectric properties. We developed SnSe crystals with a wide bandgap Eg ~ 33 kBT with attractive thermoelectric properties through Pb alloying. The momentum and energy multiband alignment promoted by Pb alloying resulted in an ultra-high power factor ~75 μWcm–1K–2 at 300 K, and a ZTave ~ 1.90. We show that a 31-pair thermoelectric device can produce a power generation efficiency ~4.4% and a cooling ΔTmax ~ 45.7 K. These results demonstrate that wide bandgap compounds can be used for thermoelectric cooling applications.

Heat transport has various applications in solid materials. In particular, the thermoelectric technology provides an alternative approach to traditional methods for waste heat recovery and solid‐state refrigeration by enabling direct and reversible conversion between heat and electricity. For enhancing the thermoelectric performance of the materials, attempts must be made to slow down the heat transport by minimizing their thermal conductivity (κ). In this study, a continuously developing heat transport model is reviewed first. Theoretical models for predicting the lattice thermal conductivity (κlat) of materials are summarized, which are significant for the rapid screening of thermoelectric materials with low κlat. Moreover, typical strategies, including the introduction of extrinsic phonon scattering centers with multidimensions and internal physical mechanisms of materials with intrinsically low κlat, for slowing down the heat transport are outlined. Extrinsic defect centers with multidimensions substantially scatter various‐frequency phonons; the intrinsically low κlat in materials with various crystal structures can be attributed to the strong anharmonicity resulting from weak chemical bonding, resonant bonding, low‐lying optical modes, liquid‐like sublattices, off‐center atoms, and complex crystal structures. This review provides an overall understanding of heat transport in thermoelectric materials and proposes effective approaches for slowing down the heat transport to depress κlat for the enhancement of thermoelectric performance.

An advanced method called internal electromagnetic stirring (I-EMS) was investigated to resolve the engineering problems like coarse-grain, inhomogeneous structure and macrosegregation. The electromagnetic stirrer functioned with internal-cooling was inserted in the melt during DC casting. In this study, a round billet of 2219 alloy DC cast with a diameter of 880mm under I-EMS process condition was produced, and its structure and composition distribution were comparatively characterized. The results show that the mean grain size decreased from the range of 872, 1023, 332 μm to the range of 317, 438, 271 μm at different billet positions with I-EMS. I-EMS consequently produce superior grain refinement and homogeneity. The effect of I-EMS on the grain-refinement and macrosegregation was also discussed.

Graphene nanosheets (GNSs)/ZnO/Al2O3 composite coatings with different GNSs content were prepared by air plasma spraying technique. The scanning electron microscope results show that the GNSs were homogeneously dispersed in the powders and coatings. The influence of different GNSs content on complex permittivity and microwave absorption properties have been systematically investigated at the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the coating was improved with the increase in GNS content, due to the high conductivity and polarization loss of GNS. The GNSs/ZnO/Al2O3 coating with 15 wt.% GNSs in the thickness of 1.82 mm presented the most prominent microwave absorption properties, which exhibited strong absorption (minimum reflection loss of −45 dB) and the reflection loss ≤ −10 dB bandwidth at the frequency range of 11.2-12.0 GHz. Meanwhile, the hardness of the coating increased from 914.2 HV0.2 to 1057.3 HV0.2 with the introduced 15 wt.% GNSs. These results suggest that GNS can be a promising nanofiller to simultaneously improve the microwave absorption properties and mechanical properties of absorbing coatings.

As a simple binary compound, p-type SnS shows great competitiveness in thermoelectrics due to the certain appealing carrier and phonon transport behaviors, coupled with its cost-effectiveness, earth-abundance and environmental compatibility. To promote the application of low-cost thermoelectric devices, we synthesized n-type SnS crystals through bromine doping. Herein, we report a high in-plane power factor of ∼28 µW cm−1 K−2, and attribute it to an outstanding in-plane carrier mobility in the crystal form and the large Seebeck coefficient benefitting from the low carrier concentration. The calculations of elastic properties show that the low lattice thermal conductivity in SnS is closely related to its strong anharmonicity. Combining the excellent electrical transport properties with low thermal conductivity, a final ZT of ∼0.4 is attained at 300 K, projecting a conversion efficiency of ∼5% at 873 K along the in-plane direction.

Mortise-and-tenon joints have been widely used for thousands of years in wooden architectures in virtue of their artistic and functional performance. However, imitation of similar structural and mechanical design philosophy to construct mechanically adaptive materials at the molecular level is a challenge. Herein, we report a mortise-and-tenon joint inspired mechanically interlocked network (MIN), in which the [2]rotaxane crosslink not only mimics the joint in structure, but also reproduces its function in modifying mechanical properties of the MIN. Benefiting from the hierarchical energy dissipative ability along with the controllable intramolecular movement of the mechanically interlocked crosslink, the resultant MIN simultaneously exhibits notable mechanical adaptivity and structural stability in a single system, as manifested by decent stiffness, strength, toughness, and deformation recovery capacity.

SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports. But the polycrystalline SnSe possesses much lower performance especially for the low carrier mobility and electrical conductivity. We firstly attempted to explain and verify the difference in the electrical conductivity as a function of temperature between p-type crystalline and polycrystalline SnSe by considering the grain boundary effects in the polycrystalline samples. On the basis of 2% Na doping to optimize the carrier concentration, the carrier mobility is improved by further introducing In, leading to enhanced carrier mobility from 3 to 9 cm2·V−1·s−1 in polycrystalline SnSe. Moreover, In doping introduces extra resonant levels in SnSe, which increases the density of states near Fermi level and leads to an enhanced band effective mass. Large Seebeck coefficient of ~ 205 μV·K−1 at 300 K and maximum power factor of ~ 7.5 μW·cm−1·K−2 at 773 K can be obtained in the Sn0.975Na0.02In0.005Se sample, leading to a competitively high dimensionless figure of merit (ZT) value exceeding 1.1 at 773 K. 晶体 SnSe 由于出色的电声传输性能, 不断表现出优异的热电特性。但是, 相对于晶体, 多晶 SnSe 的电导率和载流子迁移率呈现数量级的降低。首先, 我们试图通过考虑多晶样品中晶界的影响来解释 p 型晶体 SnSe 和多晶 SnSe 的电导率随温度变化的差异。通过掺杂 2% 的 Na 来优化多晶 SnSe 的载流子浓度, 在此基础上引入 In 提高了基体的载流子迁移率, 样品的室温迁移率由 3 cm2·V-1·s-1增加到 9 cm2·V-1·s-1。此外, 通过在多晶 SnSe 中掺杂 In 引入了额外的共振能级, 增加了费米能级附近的态密度, 提高了能带有效质量 。引入 In 之后, Sn0.975Na0.02In0.005Se样品在 300 K 时的塞贝克系数从 ~ 137提高到 ~ 205 μ V·K-1, 在 773 K 时的最大功率因子从 ~ 3.9提 高到 ~ 7.5 μ W·cm-1·K-2, 使热电优值 (ZT) 在 773 K 时超过了 1.1

Advanced materials and processes are required to separate halides and fission products from complex salt waste streams associated with the chemical reprocessing of used nuclear fuels and molten salt reactor technologies for immobilization into chemically durable waste forms. In this work, we explore an innovative concept using metal halide perovskites as advanced host phases to incorporate Cs and Cl with very high waste loadings. Wet chemistry-synthesized Cs2SnCl6 powders from CsCl salt solutions are successfully encapsulated into a silica matrix to form a composite using low-temperature spark plasma sintering with tunable Cs and Cl loadings up to 31 and 26 wt %, respectively. Chemical durability testing of the composite waste forms by semi-dynamic leaching experiments demonstrates that an incongruent leaching mechanism dominates the release of Cs and Cl. The metal halide perovskite-silica composite waste forms display exceptional chemical durability with the long-term release rates of Cs and Cl comparable to or outperforming the state-of-the-art waste form materials but with significantly higher waste loadings. The scalable synthesis of the metal halide perovskite from wet chemistry processes opens up new opportunities in designing advanced waste forms for salt wastes with very high waste loadings and exceptional chemical durability for the sustainable development of advanced fuel cycles and next-generation reactor technologies.

Super-fine L10-FePt nanoparticles (NPs) with high ordering degree were successfully prepared by a modified two-step sintering method, which includes low-temperature pre-sintering, and the high magnetic field (HMF) assisted post-sintering processes. The particle size of the L10-FePt NPs was obviously refined by lowering the sintering temperature. By applying the HMF during the post-sintering process, the fine size characteristics of L10-FePt NPs were retained, and the ordering degree was significantly improved. The L10-FePt NPs with sizes of about 4.5 nm, ordering degree of 0.940, and coercivity of 22.01 kOe were obtained by this two-step sintering under a magnetic field of 12 T. The mechanism investigation of HMF enhancing the ordering degree indicates that the HMF enhances lattice distortion and magnetization energy (Zeeman energy). The enhanced lattice distortions cause high stress existing in the lattice, which can effectively promote the disordered-order transition. When the magnetic field reaches to 3 T, the Zeeman energy of the NPs is higher than the thermal disturbing energy of the NPs, and the magnetization effect is stronger. Therefore, the HMF (higher than 3 T) can obviously improve the disorder-order transition by lowering the energy barrier and accelerating the orderly diffusions of atoms. The HMF is a promising assistant to synthesize the L10-phase NPs with both of high ordering degree and super-fine size.

Possessing inherently low thermal conductivity, BiSbSe3 is a promising thermoelectric material for medium temperature. Therefore, to substantially optimize the thermoelectric performance of BiSbSe3, researchers mainly focus on the strategies to improve its electrical transport properties. Among these strongly coupled thermoelectric parameters, carrier concentration and effective mass are two intrinsic variables to decisively affect the electrical transport properties. In this work, Cl as a donor dopant is effective to provide extra electrons in n-type BiSbSe3, and the carrier concentration and effective mass can be well optimized simultaneously with increasing Cl content owing to the multiple conduction bands in BiSbSe3. What’s more, maximum weighted mobility ∼53 cm2 V−1 s−1 is obtained in Cl-doped BiSbSe3, which contributes to a largely enhanced power factor ∼4.8 μW cm−1 K-2 at room temperature and outperforms other halogen-doped BiSbSe3 samples. Finally, combining the significantly enhanced power factor and maintained low thermal conductivity, a maximum ZT ∼1.0 is achieved in Cl-doped BiSbSe3 at 800 K.

Multicomponent pyrochlore solid solutions with and without uranium incorporation were fabricated and their thermal-mechanical properties were characterized. Multicomponent pyrochlore solid solutions without uranium exhibit comparable thermal conductivity and higher mechanical strength compared to baseline single component rare-earth titanate pyrochlore (A2Ti2O7). Uranium incorporation reduces hardness as compared with single component compositions. High entropy pyrochlore with uranium displays the highest thermal conductivity within multicomponent pyrochlore solid solutions with significantly better mechanical properties than UO2. The measured thermal conductivity correlates well with A-site cation mixing entropy and a modified size disorder parameter, and thus the size disorder and mixing entropy could be good indicators for predicting thermal conductivity of multicomponent pyrochlore solid solutions. This work opens up the possibility of designing multicomponent oxide solid solutions by controlling their chemical disorder/mixing entropy to achieve acceptable thermal-mechanical properties, desired radiation and corrosion performance for potential nuclear waste form and inert matrix fuel applications.

Uniformly aligned silicon nanowire (SiNW) arrays are promising building blocks for a range of photoelectrical and sensing devices attributable to their unique optical, electrical, structural, mecha...

The unique microstructure of biomaterials provides inspiration in materials structure design and performance breakthroughs. Here we prepared a MoAlB reinforced Al matrix composites with laminated structure and strong interfacial bonding. This work mainly focuses on the relationship between tribological properties of the MoAlB/Al laminated composites and the MoAlB layer orientation. The results show that the tribological properties of the composites deeply depend on the relation of sliding direction VS. the MoAlB layer orientation, while the dependency gradually decreases with the MoAlB content increasing. The friction coefficient and wear rate of the composites can be decreased by 55.5% and 95.1%, lower than those of pure Al, when 15 vol% MoAlB reinforcement is added. The friction and wear mechanisms of the MoAlB/Al laminated composites are proposed, and the outstanding tribological properties are ascribed to the formation of tribochemical worn film and different stress states caused by the laminated structure.

Single walled carbon nanotubes have special chemical and physical properties, at the same time, they have the advantage of macro maneuverability in maneuverability, so they have the potential of multi-functional applications. At present, composite materials, super capacitors and corresponding personal care products based on carbon nanotubes are widely used in all aspects of people’s lives, and these products have obvious functional advantages. In this paper, based on the application of single-walled carbon nanotubes technology in personal care products, the separation and purification of ginsenoside pods, the raw material of high-end washing and care products, was studied. In order to enhance the conductivity and tensile strength of SWNTs, this paper innovatively introduces the purification method of current acid treatment to enhance the performance of SWNTs. Based on the improved single-walled carbon nanotubes technology, the extraction efficiency of the optimized single-walled carbon nanotubes was analyzed. In the end of this paper, the optimized extraction method of ginsenoside pods from SWNTs is compared with the traditional extraction method. The experimental results show that SWNTs has obvious time efficiency advantage.

Among the intricately coupled thermoelectric parameters, carrier effective mass (m*) and carrier density (n) are two key parameters to determine the electrical transport properties. To enhance the broad-temperature thermoelectric performance in n-type PbSe, this work elaborately optimizes its power factor with the intrinsically proportional relationship between carrier effective mass and carrier density, n ∼ (m*)3/2. Herein, the carrier effective mass in n-type PbSe is first optimized with Sn alloying and undergoes a decrease from ∼0.34me in PbSe to ∼0.25me in Pb0.77Sn0.23Se because of band sharpening. This reduced carrier effective mass contributes to an obvious enhancement of carrier mobility, thereby boosting the maximum power factor from ∼16.8 μW cm−1 K−2 in PbSe to ∼20.5 μW cm−1 K−2 in Pb0.85Sn0.15Se. Moreover, to match the reduced carrier effective mass in n-type Pb0.85Sn0.15Se, its carrier density is well tuned with Ag counter doping, which further facilitates a high average power factor in the whole working temperature range. The average power factor in Pb0.85Sn0.15Se systems increases from ∼15.6 μW cm−1 K−2 with a carrier density of ∼6.21 × 1019 cm−3 to ∼17.6 μW cm−1 K−2 with a carrier density of ∼2.12 × 1019 cm−3 at 300–873 K. Finally, an average ZT (ZTave) of ∼0.95 is achieved in the n-type Pb0.85Sn0.15Se sample at 300–873 K, and the sample outperforms most other n-type PbSe-based thermoelectric materials.

It is well known that the thermoelectric performance of GeTe is difficult to manipulate due to its intrinsic overhigh carrier concentration and phase transition. Herein, we demonstrate that the electrical and thermal transport properties of GeTe can be synergistically promoted by lowering the phase transition temperature via doping Sb. A maximum ZT of ∼1.8 at 773 K and a ZTave of ∼1.1 at 300–773 K are acquired in a Ge0.9Sb0.1Te sample. The prominently increased performance originates from three functions of the Sb dopant: (1) being an effective counter-dopant to tune the carrier concentration to an optimum range; (2) promoting the crystal symmetry of GeTe to enlarge the band degeneracy while flattening the valence band, thus elevating the density-of-state effective mass from ∼1.34m0 to ∼2.34m0; (3) introducing mass fluctuation and point defects to intensify phonon scattering, which decreases the lattice thermal conductivity. This work gains deep insights into the influence of Sb doping on electron–phonon transfer in GeTe-based materials, providing a valid strategy for achieving exceptional performance in other thermoelectric materials.

Ternary compound CuSbSe2-alloyed PbTe, CumPb100SbmTe100Se2m (CLAST), presents outstanding n-type thermoelectric transport behavior and features hierarchical Cu-based precipitates and interstitials that can balance phonon and carrier transport. Results show that a small amount of CuSbSe2 (∼3%) alloying in CLAST can realize a room-temperature carrier concentration of ∼1.7 × 1018 cm−3 and then optimize the power factor, and simultaneously precipitate out embedded Cu-based nanostructures in the matrix to lower the lattice thermal conductivity. Additionally, extra Cu atoms adding in CLAST can form interstitials and further improve both the carrier concentration to ∼3.0 × 1018 cm−3 and carrier mobility to ∼1227.8 cm2 V−1 s−1 at room temperature, which benefits a maximum power factor of ∼20.0 μW cm−1 K−2 in Cu3.3Pb100Sb3Te100Se6. Moreover, the Cu interstitials together with massive Cu-based nanoprecipitates can strongly scatter a wide set of phonons, and largely lower the lattice thermal conductivity to ∼0.44 W m−1 K−1 in Cu3.4Pb100Sb3Te100Se6 at 623 K. Finally, these Cu-based hierarchical structures in CLAST samples can synergistically optimize the phonon and carrier transport properties and contribute to a high ZT of ∼0.5 at 300 K and a peak ZT of ∼1.4 at 723 K. A remarkably high ZTave of ∼0.94 at 300–723 K is achieved in Cu3.3Pb100Sb3Te100Se6 due to high ZT values in the low temperature range, outperforming other high-performance n-type PbTe-based thermoelectric materials.

Herein, we develop a novel hydrogel-based microfluidic chip, which can serve as a multifunctional analytical platform. The chip was fabricated through a newly developed hydrogel material, which shows satisfactory properties such as fast forming speed and good hydrophilicity. The chip mainly consists of two independent functional parts: a chromogenic layer and a microfluidic layer. The specially-designed toothed structure in the microfluidic layer can promote surface interactions and realize efficient enrichment of the target. The chromogenic layer contains chromogenic media, which can achieve rapid target identification through a simple visual readout. As a proof of concept, the proposed chip is employed for pathogen analysis. It shows satisfactory performance for efficient enrichment of Escherichia coli (E. coli) O157:H7. On the other hand, the visual detection limit of the chip for E. coli O157:H7 can reach 10 cfu mL−1. It is believed that this work could provide a valuable reference for chip material exploitation and application.

NdFeB magnetic nanoparticles with a main phase of Nd2Fe14B have successfully been synthesized. The preparation includes the following processes. First, the NdFeB intermediate was synthesized by a wet-chemical method. The NdFeB intermediate was annealed at 800 °C, which resulted in the formation of an NdFeB oxide. Then, the NdFeB oxide was reduced into NdFeB nanoparticles by a second-step reduction annealing with a CaH2 reductant. The second-step reduction annealing temperature was a key factor in preparing the NdFeB nanoparticles. A lower reduction temperature of 900 °C could not completely reduce the NdFeB oxide into Nd2Fe14B. There were some residual unreduced nonmagnetic phases in the prepared materials, which resulted in obvious decreases of coercivity. A sufficiently high second-stage reduction temperature resulted in an increased reduction, and more of the Nd2Fe14B phase could be obtained. In this work, nanoparticles with a uniform morphology and an increased Nd2Fe14B phase could be obtained at an optimum reduction temperature of 940 °C, achieving a high coercivity of 5.4 kOe.

The metallic engineering structures were commonly covered and protected by the anti-corrosion coatings. The early corrosion under the coatings and at the defects was concealed. Once the corrosion was visible to the naked eye, it indicated that the corrosion has developed seriously. Therefore, it was practical significant to detect the early corrosion of the metal under the coatings and at the defects. The formation of iron ions and anodic acidification were the characteristics of local corrosion process. Based on this fact, iron ions and protons responsive fluorescent on-off probes Rhodamine B Acylhydrazone (RBA) were prepared for the detection of corrosion. In the prepared supramolecules of RBA/LDHs, RBA intercalated and was loaded between layered double hydroxide (LDHs) to protect RBA from premature exposure to corrosive environment and fluorescence quenching. When corrosive Cl− was presented, the RBA loaded by LDHs exchanged with Cl− in corrosive environment, and RBA was released, and Cl− intercalated and was loaded between layers of LDHs. Therefore, the response to corrosion factors and release of RBA were realized, and was accompanied by the capture of Cl− and treatment of corrosion region. In the epoxy coatings, RBA/LDHs indicated the occurrence of corrosion and accurately locate the corrosion site and coating defects in form of fluorescence. Simultaneously, the sheet morphology and dispersion distribution of RBA/LDHs enhanced the shielding performance of the coatings.

The Hf(OTf)4-catalyzed three-component reaction (3CR) was employed as a powerful tool for facile access to a library of 23 pyrimido[2,1-b][1,3]benzothiazole (PBT)-based AIEgens with full-color tunability, solid-state fluorescence quantum yields of up to 86.8%, and high crystallizability. As atypical propeller-shaped molecules, PBT AIEgens were experimentally determined to dissipate the energy of the excited state via the rotation of the exocyclic carbonyl (ester/ketone) rather than the commonly known phenyl group. Theoretical calculations and crystallographic analysis of PBT AIEgens provide insights into their unique structure–property relationships and AIE mechanism from orbital and molecular aspects, respectively.

Recently, low-cost and environmentally friendly materials have attracted increasing attention in the thermoelectric community. SnS2 as a sister compound of SnS with abundant and nontoxic elements e...

All-dielectric nanostructures have attracted attention for highly efficient light manipulation. Higher Q-factor Fano resonance can be excited due to the rich phenomenology of optical modes supported by high-index dielectric materials with low intrinsic material loss, including both electric and magnetic multipolar Mie resonances. So far, there have been few studies done on the sensing with Fano-resonant all-dielectric resonator nanostructures. Here, an all-dielectric self-referenced optical sensor is numerically demonstrated based on Si quadrumers and mirror-symmetric 1-D photonic crystals (1DPCs) hybridstructure, operating at the infrared wavelength range with higher sensing performance and much more stable reference signal. Magnetic Fano resonance and Fabry-Perot resonance were combined into such a hybridstructure for the first time. The influences of the gap distance, including Δx and Δy , on the coupling effects between the Si nanodimers along the polarization direction and the 1DPCs are systematically discussed. The sensing performance has been numerically investigated in different analytes with the sensitivity and figure of merit (FOM) of 760 nm/RIU and 1515 RIU−1 respectively, which paves the way to be a much more sensitive detection of small refractive index changes in an unstable environment and suggests potential applications in biological and chemical sensing.

Low temperature selective catalytic reduction (SCR) catalysts were prepared by using acetic acid modified fly ash (ACFA) and TiO2 with the loading of Mn-Ce. The powder catalysts were characterized by BET, XRD and SEM. The effects of Mn-Ce molar ratio on the NO conversion of SCR catalyst were investigated under different atmospheres of N 2 and CO2, respectively. The 8% Mn-Ce/ACFA-TiO2 catalyst with Mn-Ce molar ratio of 1:1 showed good performance of NO conversion at 300 °C, 84.28% in N 2 atmosphere and 74.29% in CO2 atmosphere. N 2 O was observed in the experiments of 8% Mn/ACFA-TiO2, 95.3 ppm in N 2 atmosphere and 103.6 ppm in CO 2 atmosphere, respectively.

Direct arylation methods have been used to polymerize thienylmethylene oxindoles (TEIs) and 3,3-bis[[(2-ethylhexyl)oxy]methyl]-3,4-dihydro-2H-thieno-[3,4-b][1,4]dioxepin (ProDOT) for new donor-acceptor conjugated polymers. The polymers exhibited blue hues in neutral-state with distinct color-to-transmissive reversible electrochromic switching under applied potentials from 0 V to +1.5 V, and showed high coloration efficiencies (436–438 cm2·C−1) in near-infrared regions with high switching speeds around 1–2 s under ambient conditions.

Owing to their low density, high porosity and unique micro-nanostructures, aerogels are attractive for application in various fields; however, they suffer from shrinkage and/or cracking during preparation, mechanical brittleness, low production efficiency and non-degradation. Herein, we introduce the concept of dynamic covalent polymer chemistry to produce a new class of aerogels—referred to as DCPAs. The resulting lightweight DCPAs have the potential to be prepared on a large scale and feature high porosity (90.7%–91.3%), large degrees of compression (80% strain) and bending (diametral deflection of 30 mm) without any cracks, as well as considerable tensile properties (an elongation with a break at 32.7%). In addition, the DCPAs showcase the emergent characteristics of weldability, repairability, degradability and closed-loop recyclability that are highly desirable for providing versatile material platforms, though hardly achieved by traditional aerogels. Taking advantage of their robust porous structures, we demonstrate the potential of DCPAs for applications in thermal insulation and emulsion separation. These findings reveal that the dynamic covalent bond strategy would be generalized for the production of a new generation of aerogels with customized features for functioning in the field of intelligent and sustainable materials.

Author(s): Pham, AT; Vu, TH; Cheng, C; Trinh, TL; Lee, JE; Ryu, H; Hwang, C; Mo, SK; Kim, J; Zhao, LD; Duong, AT; Cho, S | Abstract: High-quality SnSe2 single crystals were successfully synthesized using a temperature gradient method. N-type characteristics and strong anisotropic transport properties of SnSe2 single crystals were exhibited between the ab plane and the c-axis. At 673 K, the power factor (PF) value along the ab plane is 3.43 μW cm-1 K-2, while it is 0.92 μW cm-1 K-2 along the c-axis. The ratio between thermal conductivities along the ab plane (κab) and c-axis (κc) is on the order of 7.6 at 300 K, while this value is about 5.6 at 673 K. The thermoelectric figure of merit (ZT) in the c-axis (0.15) is higher than that (0.1) along the ab plane, according to the ultralow out-of-plane thermal conductivity. The electronic band structure results, which were examined by angle-resolved photoemission spectroscopy (ARPES) predicted the potential of improving the thermoelectric performance of SnSe2 single crystals by electron doping.

A novel epoxy composite with flame retardance and fire resistance was prepared by adding silicate glass frit (SGF) and ammonium polyphosphate (APP) into the epoxy resin. In the combustion test, epoxy composites displayed obvious flame retardance feature, showing much lower heat release rate, total heat release and total smoke production than epoxy resin. The composite residue formed at 900 °C had a flexural strength of 19.05 MPa. In addition, possible mechanisms for the phase separation and crystallization reactions at high temperatures were also investigated in detail through thermogravimetric analyzer, X-ray diffraction, X-ray photoelectron spectrometer, and scanning electron microscopy. It was suggested that phosphorus element tends to migrate to the surface of the composite residue during firing process, and sodium element from SGF is selectively combined with the phosphorus element to obtain crystalline phases. With this unique phase separation and crystallization reactions, the fire resistance of the epoxy composite was significantly improved.

Room-temperature self-healing and self-growing of the exoskeleton with aligned structures in insects has few analogs in synthetic materials. Insect cuticle, such as elytra in beetles, with a typical lightweight lamellar structure, has shown this capability, which is attributed to the accumulation of phenol oxidase with polyphenol and amine-rich compounds in the hard cuticle. In this study, laminar-structure-based intelligence is imitated by incorporating adaptable and growable pyrogallol (PG)-borax dynamic-covalent bonds into a poly(acrylamide)-clay network. The events that lead to crack formation and water accumulation quickly trigger the deprotection of PG. Subsequently, atmospheric O2, as a regeneration source, activates PG oxidative self-polymerization. Multiple permanent and dynamic cross-links, with the involvement of the sacrificed borax, and initiation of a series of intelligent responses occur. The fabricated composites with an aligned lamellar structure exhibit outstanding characteristics, such as air/water-triggered superstrong adhesion, self-repairing, self-sealing and resealing, and reprocessing. Moreover, the strategy endows the composites with a self-growing capability, which leads to a 4- to 10-fold increase in its strength in an outdoor climate (up to 51 MPa). This study could lead to advances in the development of air/water-responsive composite materials for applications such as adaptive barriers.

In this work we investigated the thermoelectric transport behaviors of p-type PbS and n-type PbS with an emphasis on its contrasting electronic band structures. We found that the Seebeck coefficients of p-type PbS increased faster with rising temperature than that of n-type PbS with the same carrier concentration. The Density functional theory (DFT) calculation of the energy band structure of PbS as a function of temperature illustrates a significant contribution from multiple valence bands in K-doped p-type PbS. This work revealed one important information that manipulating electronic bands is also suitable in developing high-performance PbS thermoelectric systems.

A Mach-Zehnder interferometer (MZI) based on two spherical structures is proposed and temperature and humidity are measured simultaneously. The device is fabricated by inserting two spherical structures into a single mode optical fiber (SMF). The results of the experiment indicate that the temperature sensitivities are 0.079 nm/°C and 0.090 nm/°C from 10 °C to 60 °C, respectively. When the humidity changes from 30% to 70%, the humidity sensitivities are 0.148 nm/%RH and 0.06 nm/%RH, respectively. Therefore, temperature and humidity are measured simultaneously by the sensitive matrix. The new structure is demonstrated to be a particularly useful approach to detect temperature and humidity.

In this paper, Ge0.94Bi0.06Te was firstly fabricated by mechanical alloying. Compared with the Ge0.94Bi0.06Te sample prepared by the melting process, the maximum ZT achieved an improvement from 1.4 to 1.8. The thermoelectric performance of Ge0.94Bi0.06Te can be improved through suppressing Ge vacancies and refining grains via mechanical alloying. Further introducing nano-SiC into the matrix of Ge0.94Bi0.06Te improves thermoelectric performance by increasing Seebeck coefficient and reducing thermal conductivity. Meanwhile, the mechanical properties including the microhardness and Young's modulus are also enhanced by dispersing nano-SiC. Consequently, a maximum ZT ~ 2.1 at 723 K was achieved in GeTe-based materials.