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CuPbBi5S9 compounds have been investigated as gladite for years. However, there have been no significant studies on their physical and chemical properties. This work demonstrates that upon alloying with moderate Cu, Pb, Bi, and S using an appropriate preparation method, quaternary CuPbBi5S9 compounds can exhibit excellent figure of merit ZT within the temperature range 298–723 K. A low average velocity, low Young’s modulus and Debye temperature, and large Gruneisen parameter, determined experimentally, indicate strong lattice anharmonicity in CuPbBi5S9 crystals. Furthermore, density functional theory calculations (local vibration of low-frequency acoustic phonons) justify the low lattice thermal conductivity of CuPbBi5S9 compounds. Because of the low thermal conductivity (0.514 W m−1K−1) and a relatively high power factor (293 μW m−1K−2), a maximum ZT of 0.42 was achieved at 723 K for CuPbBi5S9 prepared by mechanical alloying combined with solid-state melting. Thus, CuPbBi5S9 materials are promising candidates for use as high-performance thermoelectric materials in the intermediate-temperature range.

The tropical tropopause layer (TTL) is the transition layer between the troposphere and the stratosphere. Tropical cyclones may impact the TTL by perturbing the vertical distributions of cloud, temperature, and water vapor. This study combines several A-Train instruments, including radar from CloudSat, lidar from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, and the Atmospheric Infrared Sounder (AIRS) on the Aqua satellite, to detect signatures of cyclone impacts on the distribution patterns of cloud, water vapor, temperature, and radiation by compositing these thermodynamic fields relative to the cyclone center location. Based on the CloudSat 2B-CLDCLASS-LIDAR product, this study finds that tropical cyclone events considerably increase the occurrence frequencies of TTL clouds, in the form of cirrus clouds above a clear troposphere. The amount of TTL cloud ice, however, is found to be mostly contributed by overshooting deep convection that penetrates the base of the TTL at 16 km. To overcome the lack of temperature and water vapor products in cloudy conditions, this study implements a synergistic method that retrieves temperature, water vapor, ice water content, and effective radius simultaneously by incorporating observations from AIRS, CloudSat, and CALIPSO. Using the synergistic method, we find a vertically oscillating pattern of temperature anomalies above tropical cyclones, with warming beneath the cloud top (around 16 km) and cooling above. Based on water vapor profiles retrieved by the synergistic method, we find that the layer integrated water vapor (LIWV) above 16 km is higher above tropical cyclones, especially above overshooting deep convective clouds, compared to climatological values. Moreover, we find that the longwave and net radiative cooling effect of clouds prevails within 1000 km of tropical cyclone centers. The radiative heating effects of clouds from the CloudSat 2B-FLXHR-LIDAR product are well differentiated by the collocated brightness temperature of an infrared window channel from the collocated AIRS L1B product. By performing instantaneous radiative heating rate calculations, we further find that TTL hydration is usually associated with radiative cooling of the TTL, which inhibits the diabatic ascent of moist air across isentropic surfaces to the stratosphere. Therefore, the radiative balance of the TTL under the impact of the cyclone does not favor the maintenance of moist anomalies in the TTL or transporting water vertically to the stratosphere.

Improving both surface and space utilization of active carbon is crucial for compact supercapacitors. Herein, two activated carbons are prepared through homogeneous activation (HAC) and traditional outside-in activation (OIAC). Compared with OIAC with deep and branched porous structure, HAC shows an interconnected porous structure, leading to higher density, better gravimetric and volumetric capacitances, and improved rate performance. The results demonstrate that interconnected porous structure by homogeneous activation promotes high surface and space utilization as well as robust ion transport kinetics of activated carbon for capacitive energy storage.

The management of thermal conductivity is of significant scientific interest, particularly for thermal barrier coatings (TBCs). Multifarious strategies have been used to regulate heat transportation, but it is hard to achieve limit thermal conductivity at elevated temperatures. A systematical investigation of weberite (La1-xGdx)3NbO7 was thus performed, and multiphonon scattering mechanisms were introduced to achieve limit thermal conductivity (0.92 W m−1 K−1). Phonon point defect scattering process accounted for thermal conductivity reduction at low temperatures. Additionally, lattice softening strongly contributed to the reduction of high-temperature thermal conductivity, and solid and stiff chemical bonds were beneficial for inhibiting thermal radiative conductivity. A novel strategy was presented to modify thermal transportation property of weberite RE3NbO7 ceramics. Also, the hardness, toughness, and modulus were improved to promote engineering applications of weberite RE3NbO7. This study also illuminates novel paths for thermal management and mechanical properties manipulation of TBCs, thermoelectric materials, and microelectronics.

Ferroelectric perovskite oxides exhibit the bulk photovoltaic effect, which enables an above-bandgap photovoltage, controllable photocurrent response, and higher efficiencies. Herein, the phase structure, ferroelectric, dielectric, light absorption, and photovoltaic properties in (Ba0.95Ca0.05)(Ti0.92Sn0.08-xZrx)O3 (BCTSZx) ceramics were investigated. All BCTSZx samples had good ferroelectric properties along with a narrow band gap (Eg = 2.53–2.60 eV). A large photovoltaic response under AM 1.5 G simulated sunlight was observed in the poled BCTSZ0.06 ceramics, in which the maximum short-circuit current (JSC = 3.66 nA cm−2) as well as the highest transient current (JTC = 32.56 nA cm−2) and photocurrent (JPC = 12.63 nA cm−2) were obtained in 500 μm-thick sample negatively poled at 30 kV cm−1. Our results deepen an understanding of the ferroelectric photovoltaic mechanism of perovskite materials and provide a new material for photovoltaic and multifunctional applications.

Summary CeO2-based nanostructures have recently aroused interest for various applications because of their higher OSC and redox properties, allowing them to facilely switch between the oxidation states of Ce4+ and Ce3+. There are many studies that have been focused on the morphology-dependent catalysis and identification of the true active sites during catalysis reactions. Probing the intrinsic properties of CeO2 nanostructures, including the surface structure and reduction, oxygen vacancy, grain boundary, morphology, and dynamic structure under environmental conditions, is essential in clarifying their physical and chemical properties and expanding their potential applications. In this review, we summarize recent significant achievements in characterizing CeO2 nanostructures and related catalytic phenomena through advanced techniques. Several studies using model CeO2 catalysts have been selected to show the importance of strong metal-support interactions. A deep insight into the active sites in morphologically controllable CeO2 that exposes the highly active facets is expected to guide the design of nanocatalysts.

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.

Generalization of the concept of band topology from lower-dimensional to higher-dimensional (n > 3) physical systems is expected to introduce new bulk and boundary topological effects. However, theoretically predicted topological singularities in five-dimensional systems-Weyl surfaces and Yang monopoles-have either not been demonstrated in realistic physical systems or are limited to purely synthetic dimensions. We constructed a system possessing Yang monopoles and Weyl surfaces based on metamaterials with engineered electromagnetic properties, leading to the observation of several intriguing bulk and surface phenomena, such as linking of Weyl surfaces and surface Weyl arcs, via selected three-dimensional subspaces. The demonstrated photonic Weyl surfaces and Weyl arcs leverage the concept of higher-dimension topology to control the propagation of electromagnetic waves in artificially engineered photonic media.

Exceptional points (EPs) are the singularities of a non-Hermitian system where the eigenenergies and eigenstates simultaneously coalesce, a topological property that gives rise to a plethora of exotic phenomena. Probing the EPs and associated effects requires the system to go through the EPs. However, the ultrahigh sensitivity of an isolated EP to the external disturbances makes accessing the EPs difficult. To overcome this limit, many approaches have been presented to form the exceptional line/ring and surface. Here, we demonstrate that a quantum exceptional chamber, which is a three-dimensional collection of the EPs, can be constructed in the coupled plasmon-quantum dot (QD) systems by the nondipole effect of the QD. For an asymmetric QD adjacent to a plasmonic nanoparticle, it is found that the contributions of multipole transitions to the coupling strength can be larger than that of dipole transition. The orientation-dependent quantum interference between the dipole and multipole transitions can lead to controllable switch between the weak and strong coupling, and provides an extra degree of freedom to form a high-dimension EP space. Our approach provides a robust platform for accessing the quantum EPs and related applications.

Piezoelectrics exhibit mechanical strain in response to electrical stimuli and vice versa. A high level of electric-field-induced strain with minimal hysteresis is desired for piezoelectric materials when used as actuators. The past two decades have seen extensive research into lead-free piezoelectrics to replace Pb(Zr,Ti)O3 and compositional engineering has been demonstrated to be an effective method to tailor their functional properties. Doped (K,Na)NbO3 (KNN) compositions with elaborate compositional tuning can exhibit enhanced electromechanical properties. However, a balance between enhanced properties and non-toxicity of the dopants should be considered. In this work, we propose to use microstructural engineering to enhance the properties. Based on phase-field simulations, we propose to take advantage of depolarization energies generated by polar-nonpolar interfaces, to increase the contribution of domain wall motion to electric-field-induced strain. Heterogeneous ferroelectric-paraelectric microstructures were introduced into a KNN ceramic via a two-step sintering process. Their presence was characterized by high-resolution transmission electron microscopy. Enhanced reversible domain wall motion was verified by in situ high-energy X-ray diffraction. Electric-field-induced strain is enhanced by 62% and 200% at 25 °C and 150 °C, respectively. Considering lead-free piezoelectrics also represent an emerging class of biomaterials for medical technology, the non-toxicity and biocompatibility of the investigated compositions are examined by in vitro cell viability assays. Our results demonstrate that microstructural engineering is a promising alternative approach to enhance the electric-field-induced strain of lead-free piezoelectrics while maintaining biocompatibility

Optical imaging has played a vital role in development of biomedicine and image-guided theragnostic. Nevertheless, the clinical translation of optical molecular imaging for deep-tissue visualization is still limited by poor signal-to-background ratio and low penetration depth owing to light scattering and tissue autofluorescence. Hence, to facilitate precise diagnosis and accurate surgery excision in clinical practices, the responsive optical probes (ROPs) are broadly designed for specific reaction with biological analytes or disease biomarkers via chemical/physical interactions for photoacoustic and second near-infrared fluorescence (NIR-II, 900–1700 nm) fluorescence imaging. Herein, the recent advances in the development of ROPs including molecular design principles, activated mechanisms and treatment responses for photoacoustic and NIR-II fluorescence imaging are reviewed. Furthermore, the present challenges and future perspectives of ROPs for deep-tissue imaging are also discussed.

Fabrication of nanoparticle-dispersed composites is an effective strategy for enhancing the performance of thermoelectric materials, and in particular SiC nanoparticles have been often used to create composites with Bi2Te3-based applied thermoelectric materials. However, the effect of particle size on the thermoelectric performance is unclear. This work systematically investigated the electrical and thermal properties of a series of (Bi,Sb)2Te3-based nanocomposites containing dispersed SiC nanoparticles of different sizes. It was found that particle size has a significant impact on the electrical properties with smaller SiC nanoparticles giving rise to higher electrical conductivity. Even though the dispersed SiC nanoparticles enhanced the Seebeck coefficient, no apparent dependence of the enhancement on the particle size was observed. It was also found that smaller SiC nanoparticles scatter phonons to some extent while the larger nanoparticles contribute to increased thermal conductivity. Eventually, the highest ZT value of 1.12 was obtained in 30 nm-SiC dispersed sample, corresponding to an increase by 18% from 0.95 for the matrix made from commercial scraps, and then the ZT was further boosted to 1.33 by optimizing the matrix composition and expelling excess Te during the optimized spark plasma sintering process. This work proves that the dispersion of smaller SiC nanoparticles in p-type (Bi,Sb)2Te3 materials is more effective than the dispersion of larger nanoparticles. In addition, it is revealed that additional compositional and/or processing optimization is vital and effective for obtaining further performance enhancement for nanocomposites of SiC nanoparticles dispersed in (Bi,Sb)2Te3.

Extremely low lattice thermal conductivity is always the pursuit of thermoelectric materials research. In this work, we reported an exceptional effect of Ag2S addition in MnTe, an emerging promising mid-temperature thermoelectric material, to enable the realization of minimum lattice thermal conductivity, namely ∼0.4 Wm−1K−1. Such a low lattice thermal conductivity is guaranteed by the incorporation of in-situ formed Ag rich phase (Ag2Te) with ultralow lattice thermal conductivity and further scattering of phonons from the partial doping effects induced point defects and boundaries between various phases. Apart from the dramatically decreased lattice thermal conductivity, the partial doping of Ag and S simultaneously enhance the electrical conductivity, further contributing to enhanced thermoelectric performance. Meanwhile, an inverse sign of Seebeck and Hall coefficient was observed and rationalized by the influence of highly electron-conductive Ag2Te phase. Thanks to the synergetic modulation of electrical and thermal transport properties by in-situ formed composite, a high ZT value of 1.1 was achieved in MnTe based thermoelectric materials, which also demonstrates the importance of compositing approaches to design state-of-the-art thermoelectric materials.

This study investigates rare earth RE3TaO7 ceramics and shows that these materials may be optimal for thermal barrier coatings. ZrO2-Sm3TaO7 ceramics were prepared through a solid-state reaction. X-ray diffusion and structural refinement revealed a phase structure with an ordered orthorhombic phase for the Ccmm space group. The degree of structural disorder increased with increasing ZrO2 content. Gaussian function fitting of the oxygen 1s X-ray photoelectron spectra showed that the Sm3+ and Ta5+ ions were replaced by Zr4+ ions. At high temperatures, 8 mol% ZrO2-Sm3TaO7 has a high thermal expansion coefficient (10.9 × 10−6 K−1). The thermal conductivities of ZrO2-Sm3TaO7 (1.17 − 1.75 W·m−1 K−1) are lower than those of 7–8 wt.% yttria-stabilized zirconia, while those of 2% ZrO2-Sm3TaO7 are the lowest. The oxygen vacancies maintain the charge in equilibrium and enhance phonon scattering while decreasing the thermal conductivity. These results indicate that Sm3TaO7 can be used as a TBC.

We report a detailed analysis of the crystal structure, electronic structure, and thermoelectric (TE) properties of a stoichiometric Mn2CoAl inverse full-Heusler alloy, which has been predicted to ...

The year of 2021 is the 100th anniversary of the first publication of ferroelectric behaviour in Rochelle salt, focussing on its piezoelectric properties. Over the past many decades, people witnessed a great impact of ferroelectricity on our everyday life, where numerous ferroelectric materials have been designed and developed to enable the advancement of diverse applications. Now the driving forces for ferroelectric studies stem from regulations on environment, human health and sustainable society development. This leads to the resurgence of lead-free ferroelectric materials for the expectation of replacing the state-of-the-art lead-based counterparts. The next wave of explorations into ferroelectric materials maybe related to the Internet-of-Things, which requires millions of self-powered sensors and memories. This will promote research on ferroelectrics for sensing, energy harvesting and storage, communication and non-volatile memories, from centimetre scale to micro and nanoscale. This review gives a brief discussion from the materials viewpoint, on the challenges and current status of lead-free ferroelectrics based on prospective applications.

The powder samples of Ca9Sc(PO4)7:xDy3+ white emitting phosphors were prepared via a solid state reaction technique. The Ca9Sc(PO4)7:Dy3+ samples were researched by using the GSAS Rietveld refinement and X-ray diffraction (XRD) methods, and SEM images and elemental maps were recorded. Under 350 nm excitation, the emission spectra of Ca9Sc(PO4)7:xDy3+ samples have two obvious peaks and one weak peak at 484, 572 and 660 nm, corresponding to the characteristic electron transitions of (4F9/2 → 6H15/2, blue), (4F9/2 → 6H13/2, yellow) and (4F9/2 → 6H11/2, red), respectively. The concentration quenching effect, decay lifetime and thermal quenching of the as-synthesized Ca9Sc(PO4)7:Dy3+ samples were researched systematically. The Ca9Sc(PO4)7:0.02Dy3+ phosphor possesses a good thermal stability, of which the emission intensity at 423 K can maintain 79% of the initial value (273 K). In addition, through the study of the chromaticity coordinates of the Ca9Sc(PO4)7:0.02Dy3+ phosphor, it is found that it is located in the white region, and the Commission Internationalede L'Eclairage (CIE) chromaticity coordinates are (0.339, 0.389). The above results show that Ca9Sc(PO4)7:xDy3+ phosphors can be excellent candidate material for applications in NUV-excited white LEDs.

Berry curvature, the counterpart of the magnetic field in the momentum space, plays a vital role in the transport of electrons in condensed matter physics. It also lays the foundation for the emerging field of topological physics. In the three-dimensional systems, much attention has been paid to Weyl points, which serve as sources and drains of Berry curvature. Here, we demonstrate a toroidal moment of Berry curvature with flux approaching to π in judiciously engineered metamaterials. The Berry curvature exhibits a vortex-like configuration without any source and drain in the momentum space. Experimentally, the presence of Berry curvature toroid is confirmed by the observation of conical-frustum shaped domain-wall states at the interfaces formed by two metamaterials with opposite toroidal moments., The appearance of toroidal multipolar moments in electrodynamics interrogates the question for their existence in Berry curvature, which can be seen as the “magnetic field” in the momentum space. Here, the authors observe 3D vortex distributions in the Berry curvature within a photonic metamaterial.

BiFeO3-BaTiO3 is a promising high-temperature piezoelectric ceramic that possesses both good electromechanical properties and a Curie temperature (TC). Here, the piezoelectric charge constants (d33) and strain coefficients (d*33) of (1 - x)BiFeO3-xBaTiO3 (BF-xBT; 0.20 ≤ x ≤ 0.50) lead-free piezoelectrics were investigated at room temperature. The results showed a maximum d33 of 225 pC/N in the BF-0.30BT ceramic and a maximum d*33 of 405 pm/V in the BF-0.35BT ceramic, with TCs of 503 and 415 °C, respectively. To better understand the performance enhancement mechanisms, a phase diagram was established using the results of XRD, piezoresponse force microscopy, TEM, and electrical property measurements. The superb d33 of the BF-0.30BT ceramic arose because of its location in the optimum point in the morphotropic phase boundary, low oxygen vacancy (VO··) concentration, and domain heterogeneity. The superior d*33 of the BF-0.35BT ceramic was attributed to a weak relaxor behavior between coexisting macrodomains and polar nanoregions. The presented strategy provides guidelines for designing high-temperature BF-BT ceramics for different applications.

Transparent conductive electrodes (TCEs) have attracted considerable attentions as one of the essential components in optoelectronic devices. High conductivity, transmittance and flexibility are required for the practical applications of the TCEs in wearable and portable electronics. Here, a simple fabrication process of capillary force-induced printing has been developed to realize highly aligned silver nanowires (AgNWs) film with high flexibility, stretchability and conformability. Ultrathin and skin-attachable OLEDs have been realized based on the aligned AgNWs electrode. This work has proposed a low-cost and fast fabrication strategy to realize highly aligned AgNWs electrode for the flexible and stretchable optoelectronic devices.

Magnesium (Mg) alloys have received an increasing interest in the past two decades for their tremendous application potential. The strength and corrosion resistance levels of common Mg alloys are still relativity low, and especially they are to be improved simultaneously. The addition of rare earth (RE) to Mg alloys is believed to be beneficial for both the strength and corrosion resistance, and some RE-modified traditional Mg alloys have been studied and some new RE-containing Mg alloys have been developed by now. However, further simultaneous improvements in both strength and anti-corrosion require a better understanding of the behavior and mechanism of RE in Mg alloys. In this review, the common influence mechanisms of RE on mechanical and anti-corrosion properties of Mg alloys are summarized, and the latest research progress of RE-containing Mg alloys with simultaneously improved strength and corrosion resistance are introduced. It is demonstrated that the research on high-strength and high corrosion resistant RE-containing Mg alloys is still immature, and some opinions and suggestions are put forward for the synergetic improvement of the strength and corrosion resistance of Mg alloys, so as to contribute to the further development of Mg alloys with higher performance.

Depression is closely related to overactivation of N-methyl-d-aspartic acid (NMDA) receptors, and Zn2+ is a vital NMDA receptor modulator involved in the pathophysiological and physiological processes of depression. Therefore, quantitative and real-time detection of Zn2+ is very important for understanding the pathogenesis of depression. In this work, a near-infrared (NIR) fluorescent probe ISO-DPA was designed and synthesized for Zn2+ detection with a large Stokes shift (185 nm), high quantum yield (up to 44%), high sensitivity (LOD = 0.106 μM) and good pH stability. The probe showed rapid response within 10 s, accompanied by a distinct fluorescence change from faint to bright pink with the fluorescence intensity increasing 4.5-fold. Moreover, the sensing mechanism of ISO-DPA towards Zn2+ was supported by MALDI-TOF-MS and Job's plot. The probe ISO-DPA could detect instantaneous variation of exogenous and endogenous Zn2+ in PC12 cells. The bioimaging results reveal the increase of the endogenous Zn2+ concentration in PC12 cells under the oxidative stress induced by glutamate and confirm that overactivation of NMDA receptors results in an increase of the Zn2+ level. All the results proved that ISO-DPA is an excellent probe for detecting Zn2+ in solution and living cells and could help us better understand Zn2+ associated pathogenesis of depression.

Mg2Sn is a potential thermoelectric (TE) material that exhibits environmental compatibility. In this study, we fabricated Sb-doped Mg2Sn (Mg2Sn1-xSbx) single-crystal ingots and demonstrated the enhancement of TE performance via point defect engineering and Sb doping. The Mg2Sn1-xSbx single-crystal ingots exhibited considerably enhanced electrical conductivity because of the donor-doping effect in addition to high carrier mobility. Moreover, the Mg2Sn1-xSbx single-crystal ingots contained Mg vacancy (VMg) as a point defect. The introduced VMg and doped Sb atoms formed nanostructures, both acting as phonon-scattering centers. Consequently, lower lattice thermal conductivity was achieved for the Mg2Sn1-xSbx single-crystal ingots compared with polycrystalline counterparts. Owing to the significant enhancement in the electrical conductivity and the reduction in the lattice thermal conductivity, the maximum power factor of 5.1(4) × 10-3 W/(K2 m) and the maximum dimensionless figure of merit of 0.72(5) were achieved for the Mg2Sn0.99Sb0.01 single-crystal ingot, which are higher than those of single-phase Mg2Sn1-xSb polycrystals.

Monoclinic (m) and monoclinic-prime (m′) phases of Yb(TaxNb1−x)O4 ceramics were synthesized successfully, and the relationships between the crystal structures and the thermophysical properties were investigated by various methods. A ferroelastic domain existed in the m-Yb(TaxNb1-x)O4 ceramics, as observed by a scanning electron microscopy, which suggests that a ferroelastic phase transition occurred. The minimum thermal conductivity of the Yb(TaxNb1−x)O4 ceramics was 1.49 W m−1·K−1, whereas the maximum thermal expansion coefficient (TEC) was 10.6 × 10−6 K−1 (1200 °C). The m-phase had a lower Young's modulus (110–132 GPa) than the m′-phase (133–140 GPa). In view of the low thermal conductivity and high TEC, Yb(TaxNb1−x)O4 ceramics have the potential to be high-temperature structural ceramics.

8 wt% yttria-stabilized zirconia (8YSZ) powders are fabricated as high-temperature based materials via a solid-state reaction method and ground into spheres in this paper. Following that, 4 wt% Nickle (Ni), 4 wt% Hexagonal Boron Nitride (hBN) and 4 wt% PHB (Polyphenyl ester) are added to 8YSZ for getting 8YSZ ceramic-based abradable seal powders (8YSZ CASp). Then, the 8YSZ CASp are sprayed on the stainless steel substrate with a NiCoCrAlY transition layer by an atmospheric plasma spraying (APS) technology. The phase structure, surface morphology and the cross-section topography of the fabricated are analyzed, the indentation hardness and nano-indentation test are conducted. The experiments of 8YSZ ceramic-based abradable seal coatings (8YSZ CASc) show that the deposition efficiency and porosity are respectively 78.5% and 21.8%, the bond strength is 4.6 MPa, the cycle number of thermal shock resistance is 37 times, those parameters prove that the fabricated 8YSZ CASc are promising abradable seal coatings.

One of the key issues for composites is the formation mechanism and stability of the interface. Experimental technology and first-principles calculations with quasiharmonic approach considering the phonon and thermal electronic contribution are adopted to clarify the thermodynamics and thermal stress of the interface of tungsten carbide particle reinforced iron matrix (WCP/Fe) composites under finite temperature. The most favorable formation path of Fe3W3C at the interface is 3Fe+2WC + W2C→Fe3W3C+2C + W. For WCP/Fe and WCP/Co composites, the thermal stress of Co3W3C is smaller than Fe3W3C as the transition phase of the interface, and Fe is less suitable to be applied as the matrix of composites than Co. Our research provides significant guidance to improve the interfacial strength and stability of WCP/Fe composites.

Iridium (Ir) has an extremely high melting point (2443 °C), high chemical stability and is one of the most promising high-temperature materials. However, Ir is more difficult to process compared with other face-centered cubic metals, such as Ni and Al, which limits its applications. To solve this problem, we study the effect of 32 alloying elements (X) on stacking fault energy of dilute Ir-based alloys generated by shear deformation using the first-principles calculations. The investigation reveals that there are many alloying elements studied herein decrease the stacking fault energy of face-centered cubic (fcc) Ir, and the most effective element in reducing stacking fault energy of fcc Ir is Zn. The microscopic mechanism is caused by electron redistribution in the local stacking fault area. These results are expected to provide valuable guidance for the further design and application of Ir-based alloys.

Iron and oxygen co-doped graphite phase carbon nitride (Fe@O CN) is synthesized via a simple one-pot in-situ pyrolysis method. It is used in a favorable peroxymonosulfate (PMS) activation oxidation system to enhance Orange I (OI) degradation. The effects of dopant contents, different water conditions and the reusability are conducted to evaluate the removal efficacy of PMS catalytic over Fe@O CN in water. Moreover, OI degradation is almost stable under several typical anions (H2PO4−, Cl− and HCO3−) and humic acid existence. Theoretical calculation results reveal that effective-directional transfer of electrons is obtained by Fe@O CN, building the formation of high electron density areas around Fe and O. The quenching tests display that O2•− and 1O2 are responsible for OI removal, and SO4•− and •OH only donate a very small contribution. The electron transfer between electron-rich Fe, O element and HSO5− cycles facilitate HSO5− activation to generate reactive oxygen species. After co-doping, DFT calculations confirm the stronger binding energy, greater charge transferability and longer O O bond length for PMS activation in Fe@O CN/PMS system. Our findings provide a valuable insight for the development of efficient catalysts for PMS activation via metal and nonmetal co-doping, which display a promising application for polluted aquatic environment.

As candidate thermal/environmental barrier coatings (T/EBCs), the structure characteristics and comprehensive properties of monoclinic-prime (m') RETaO4 (RE = Yb, Lu, Sc) with excellent Al2O3/SiO2 chemical compatibility are studied. Excellent thermal insulation protection will be provided by m'RETaO4 due to their low thermal conductivity (∼1.6 W m−1 K−1, 900 °C) and prominent thermal radiation resistance, which is much better than those of YSZ (∼2.5 W m−1 K−1, 1000 °C) and La2Zr2O7 (∼2.0 W m−1 K−1, 900 °C). The thermal expansion coefficients (TECs) are 3.0–8.0 × 10-6 K−1 (200−1200 °C), which is suitable for T/EBCs applications. Furthermore, absence of phase transition and extraordinary chemical compatibility with Al2O3/SiO2 up to 1500 °C indicate the potential application prospect. The documented governing mechanisms of m'RETaO4 properties will enable researchers to promote their application in the future investigation.

To ensure the control of the precision of air-fuel ratio (AFR) of port fuel injection (PFI) spark ignition (SI) engines, a chaos radial basis function (RBF) neural network is used to predict the air intake flow of the engine. The data of air intake flow is proved to be multidimensionally nonlinear and chaotic. The RBF neural network is used to train the reconstructed phase space of the data. The chaos algorithm is employed to optimize the weights of output layer connection and the radial basis center of Gaussian function in hidden layer. The simulation results obtained from Matlab/Simulink illustrate that the model has higher accuracy compared to the conventional RBF model. The mean absolute error and the mean relative error of the chaos RBF model can reach 0.0017 and 0.48, respectively.

A cationic conjugated polyelectrolyte PPET3-N2 was used as a photosensitizer for photocatalytic oxidation of organic sulfides, including thioanisole, ethyl phenyl sulfide, 4-methylphenyl methyl sulfide, etc., to form sulfoxides with good yields and high selectivity. Oxidation reactions were performed in both batch and microfluidic reactors, where the microfluidic reactor can significantly promote the conversion of photocatalytic oxidation reaction to over 98% in about 8 min. Further studies of the photocatalytic oxidation of the antitumor drug ricobendazole in the microfluidic reactor demonstrate the potential application of the polymer material in organic reactions given its high selectivity, good efficiency, and operation convenience.

As a novel candidate of thermal barrier coatings materials proposed recently, rare earth tantalates (RETaO4) are attractive series because of its excellent attributes. With respect to RETaO4 compound, it exists at least three types of polymorphs and two phase-transformation mechanisms. In this paper, the monoclinic (Y1-xYbx)TaO4 compounds with diverse space groups are investigated systematically, and contents involve phase, microstructural and thermophysical properties’ evolution with the changes of composition and structure. The primary purpose of this paper is to optimize the thermophysical properties of (Y1-xYbx)TaO4 ceramics by adjusting the Y/Yb ratio, and further physical mechanisms of its heat transfer are also revealed.

Thermoelectric technology has been applied in the fields of industrial waste heat power generation, special spatial power supply, semiconductor chip cooling, advanced refrigeration, etc. Comparing to other thermoelectric material systems, bismuth telluride (Bi2Te3) based thermoelectric materials are widely used in industrial and commercial fields due to their stable zT values and relatively high conversion efficiencies at room temperature range. However, the low hardness and easy dissociation of Bi2Te3 materials lead to the waste of raw materials in industrial processing. Therefore, substantial efforts have been made to find a balance between the zT value and the hardness of bismuth telluride. In this study, the mechanical properties of commercial Bi2Te3 were significantly enhanced by dispersing the second phase of the SiC particles in the matrix via a combined process of mechanical alloying (MA) and spark plasma sintering (SPS). Although the zT value of the composite was slightly decreased, the average hardness was increased from ~1.2 to 1.7 GPa, and the modulus of the composite was also improved. The thermal expansion rate and thermal expansion coefficients were also measured. The mechanism of the enhanced mechanical properties of the Bi2Te3 was discussed in detail. This work offered a simple strategy for improving the machinability of commercial Bi2Te3, which is of high importance for the large scale industrial application of thermoelectric materials.

Three-phase meander-type dynamic wireless power transfer is ideal for the power supply or charging of rail vehicles. However, there is a lack of systematic analysis and design of the three-phase receiver. To achieve the compact design of the three-phase receiver in practical applications, this article studies the compact three-phase receiver with overlapped receiving coils and ferrite core. Based on the analysis of the fundamental coupling characteristic of three-phase meander-type dynamic wireless power transfer, two overlap modes of the receiving coils are concluded and compared. Meanwhile, by considering the influence of mutual inductance harmonic distortion, the accuracy of the receiving coil analysis and design is improved. Furthermore, a practical distributed strip core design is presented to enhance the coupling between transmitting coils and receiving coils. Additionally, the effect of the core on coupling imbalance is analyzed in detail and proves to have little effect on the power transfer. Afterward, a design flow of star-connected series-compensated receiver with the overlapped coils and the distributed strip core is proposed. Finally, for verification, a small prototype with an average output power of 154 W and average efficiency of 97% of the receiving coils is established.

Ultrathin metal films emerge as an innovative category of transparent electrodes in recent decades, holding great promises enabling the next-generation flexible organic light-emitting devices (OLEDs). Although metal thin films with polymer nucleation inducers have been extensively studied in OLEDs, satisfying the requirements of both superior optoelectrical and high optical outcoupling characteristics is still challenging. Here, we demonstrate a metal oxide/ultrathin Ag/polymer (MAP) composite electrode with low sheet resistance of 15.1 Ω/sq, high transmittance of 87.4% at 550 nm, and smooth morphology with surface roughness of 0.768 nm. Besides, the composite electrodes significantly enhance the outcoupling of the light trapped in OLEDs due to the relatively high-refractive index polymer. Flexible OLEDs with the MAP anodes exhibit over 2.3 times enhancement in efficiency to that of indium tin oxide (ITO)-based OLEDs. The flexible OLEDs can survive 1000 bending cycles at a bending radius of 8 mm with negligible decrease in electroluminescent performance.

Objectives To develop a new Chinese medicine (CM)-based drug and to evaluate its safety and effect for suppressing acute respiratory distress syndrome (ARDS) in COVID-19 patients. Methods A putative ARDS-suppressing drug Keguan-1 was first developed and then evaluated by a randomized, controlled two-arm trial. The two arms of the trial consist of a control therapy (alpha interferon inhalation, 50 µg twice daily; and lopinavir/ritonavir, 400 and 100 mg twice daily, respectively) and a testing therapy (control therapy plus Keguan-1 19.4 g twice daily) by random number table at 1:1 ratio with 24 cases each group. After 2-week treatment, adverse events, time to fever resolution, ARDS development, and lung injury on newly diagnosed COVID-19 patients were assessed. Results An analysis of the data from the first 30 participants showed that the control arm and the testing arm did not exhibit any significant differences in terms of adverse events. Based on this result, the study was expanded to include a total of 48 participants (24 cases each arm). The results show that compared with the control arm, the testing arm exhibited a significant improvement in time to fever resolution (P=0.035), and a significant reduction in the development of ARDS (P=0.048). Conclusions Keguan-1-based integrative therapy was safe and superior to the standard therapy in suppressing the development of ARDS in COVID-19 patients. (Trial registration No. NCT 04251871 at www.clinicaltrials.gov) Electronic Supplementary Material Supplementary material is available in the online version of this article at 10.1007/s11655-020-3426-7.

Purpose Under the global climate change, carbon footprint has become a hot issue at home and abroad. However, there is no consensus on the concept, measurement and application of carbon footprint. Design/methodology/approach In this paper, first, the concept and connotation of carbon footprint are reviewed; then, different methods of carbon footprint measurement are compared, and it is found that “bottom-up” life cycle assessment and “top-down” input–output analysis are applicable to different research scales. Findings Finally, the problems in the process of carbon footprint assessment in textile industry are analyzed and further research directions are proposed. Originality/value Analyzed and further research directions are proposed.

CuWO4, as an n-type oxide semiconductor with a bandgap of 2.2 eV, has stimulated enormous interest as a potential broad-spectrum-active photocatalyst for environmental pollution remediations. However, rapid charge recombination greatly hinders its practical applications. Herein, we present a cascaded electron transition pathway in a ternary heterostructure consisting of CdS quantum dots, carbon dots (CDs) and CuWO4 hollow spheres, which proves to greatly facilitate the photogenerated electron-hole separation, and eventually boosts the degradation efficiency of phenol and congo red by 100% and 46% compared to bare CuWO4. The enhanced performance of the CuWO4/CdS/CDs heterostructure mainly originates from the unidirectional electron migration from CdS to CuWO4 and then to the organics through CDs. This work elucidates the electron transfer kinetics in multi-phase system and provides a new design paradigm for optimizing the properties of CuWO4 based photocatalysts.

In wireless power transfer systems, coil design has a great impact on coil–coil efficiency. This article analyzes the relationship between coil–coil efficiency and design parameters (three geometric parameters of coupling coils and working frequency) under typical constraints, and the function between optimal working frequency and geometric parameters is derived. Hence, the solution space of design parameters is reduced from four dimensions (geometric parameters of the coil and frequency) to three dimensions (geometric parameters), and particle swarm optimization (PSO) algorithm is applied to solve it. Moreover, a modified ac resistance evaluation method is proposed, in which conductive resistance is calculated with a frequency-dependent formula and proximity-effect resistance is calculated with a modified analytical method. Experimental results show that the modified method is precise for coils wound closely or sparsely. It is highlighted that extra finite element analysis software is not needed due to the modified calculation method of ac resistance, which makes the design process automatic and faster. Finally, a practical example is given, and two systems are designed with the PSO-based method and a conventional method, respectively. The coil–coil efficiency of the PSO-based method and the conventional method is 95.6% and 94.0%, respectively.

In this study, ceramic pebbles were prepared via a melt spraying method and their properties were systematically characterised. The average particle diameter, sphericity, grain size, specific surface area, and density of the ceramic pebbles prepared by melt spraying were 1.28 mm, 1.01, 2292.92 nm, 6.42 m2/g, and 95.1 %TD, respectively. The amount of Li loss was 3.7055%. A thermal cycle test was conducted, and it was found that the pebbles could withstand fifteen hot–cold cycles. The crush load of the pebbles after heat treatment was 21.6259 ± 5.6282 N. The performance of the ceramic pebbles prepared by melt spraying was compared to that of ceramic pebbles prepared by other methods, and the pebbles prepared via a melt spraying exhibited better properties. The results show that the ceramic pebbles prepared by melt spraying exhibited favourable properties.

Vanadium dioxide (VO2) is one of the most widely used thermally induced phase transition materials. However, the phase transition regulation mechanism and specific modulation relationship of VO2 materials are still not entirely clear. Here, we propose a comprehensive and precise phase transition material design criterion based on the cohesive energy and defect patterns. The results revealed that the associated regulation mechanism, including the size, strain, vacancy as well as crystal plane and shape, of these materials can be determined via design criteria and first principles calculations. Moreover, the specific modulation relationship of the thickness-induced phase transition can also be confirmed by means of experiments. These findings show that our design criterion provides an effective approach for the design of VO2 thermally induced phase transition materials.

A stable interface is vital for the long cycling stability of nickel-rich material LiNi0.8Co0.1Mn0.1O2 (NCM811). As such, the common remedy to improve the stability of nickel-rich layered oxide is ...

The nitrogen-decorated CeO2/reduced graphene oxide nanocomposite (CeO2/N-rGO) was one-step synthesized by a facile hydrothermal technique and applied as counter electrode materials for dye-sensitized solar cells (DSSCs). For comparison, CeO2/rGO and rGO were also synthesized by adjusting corresponding reactants. It was found that the as-synthesized CeO2/N-rGO shows better electrocatalytic activity for triiodide/iodide reduction than that of pure rGO and CeO2/rGO, and a synergistic effect of nitrogen and CeO2 on the rGO sheets was observed. The photoelectric conversion efficiency of DSSCs based on CeO2/N-rGO counter electrode was 3.20%, which is higher than that of CeO2/rGO (2.45%) and rGO counter electrode (1.37%). Furthermore, the synergistic effect of nitrogen and CeO2 on the rGO sheets was also discussed in detail with different CeO2 amount levels. It is believed that this one-step synthetic method is a potential way to synthesize low-cost and efficient rGO-based multiple composited counter electrode materials to replace more expensive Pt.

A simple and rapid pipette-tip solid-phase extraction (PT-SPE) procedure with derivatization prior to gas chromatography triple quadrupole mass spectrometry analysis is developed for the simultaneous determination of amphetamine (AMP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA) in urine samples. The PT-SPE procedure using self-made sorbent could extract drugs within 6 min from 100-μL urine samples, requiring low solvent-consumption (

Solution-processing thin-film solar techniques, such as organic solar cells (OSCs) and perovskite solar cells (PeSCs), hold great promise as cost-effective renewable energy sources with feasible large-scale manufacturing. However, these devices are suffering from the incomplete photon absorption and thereby cannot unlock the full potential of device efficiency despite their rapid development in recent decades. Incorporation of plasmonic metal nanoparticles (NPs) into the thin active layers has been considered as a breakthrough strategy to solve this inherent limit and represent an imperative milestone toward the highly efficient OSCs and PeSCs, arising from the significantly enhanced light absorption and electrical characteristics in fundamental. Herein, the recent advances in fabrication and incorporation strategies of plasmonic NPs are reviewed. The in-depth efficiency and stability enhancement mechanisms are investigated and highlighted. Meanwhile, potential strategies and perspectives for their further development of NP-based solution-processing OSCs and PeSCs are presented.

A numerical method for the transmission loss prediction of the water muffler has been provided according to the measuring process of the two-load method. The commonly used acoustic loads can be applied in the proposed method. The accuracy of the proposed method has been proved by comparing the calculated transmission loss with that from the traditional direct predicting method. And then the proposed method is used to discuss effects of test bench on transmission loss measurement. The predicted transmission loss curves are consistent reasonably based on different test models. The location of monitors relative to the muffler inlet and outlet has little influence on the result. But the distance between the two monitors upstream or downstream should be controlled within a certain range based on the concerning frequency band and the main pipe diameter. It is found that modes of the coupled system consisting of the test pipes and the water cause extra peaks on the transmission loss curve. The influence can be reduced by arranging appropriate fixed points. The proposed method can be used to to explain the reasonability and validity of the test bench design.

Halide perovskite semiconductors exhibit ultralow thermal conductivities, making them potentially suitable for thermoelectric applications. Nevertheless, the thermoelectric properties of the protot...

As a carbon-neutral alternative to the Haber-Bosch process, electrochemical N2 reduction enables environment-friendly NH3 synthesis at ambient conditions but needs active electrocatalysts for the N2 reduction reaction. Here, we report that conductive metal—organic framework Co3(hexahydroxytriphenylene)2 (Co3HHTP2) nanoparticles act as an efficient catalyst for ambient electrochemical N2-to-NH3 fixation. When tested in 0.5 M LiClO4, such Co3HHTP2 achieves a large NH3 yield of 22.14 µg·h−1mg−1cat. with a faradaic efficiency of 3.34% at −0.40 V versus the reversible hydrogen electrode. This catalyst also shows high electrochemical stability and excellent selectivity toward NH3 synthesis.

Polarization switching in lead-free (K0.40Na0.60)NbO3 (KNN) single crystals was studied by switching spectroscopy piezoresponse force microscopy (SS-PFM). Acquisition of multiple hysteresis loops on a closely spaced square grid enables polarization switching parameters to be mapped in real space. Piezoresponse amplitude and phase hysteresis loops show collective symmetric/asymmetric characteristics, affording information regarding the switching behavior of different domains. As such, the out-of-plane polarization states of the domains, including amplitudes and phases can be determined. Our results could contribute to a further understanding of the relationships between polarization switching and polarization vectors at the nanoscale, and provide a feasible method to correlate the polarization hysteresis loops in a domain under an electric field with the polarization vector states.

Bi2Te3-based compounds are the most mature and widely used thermoelectric materials. However, industrial device fabrication will inevitably produce a lot of Bi2Te3 scraps, which results in wastes of expensive material resources. In this work, we recycled p-type (Bi,Sb)2Te3 scraps and reprocessed them by making nanocomposites with nano-SiC. The thermoelectric performance was enhanced, and a high ZT value of 1.07 was achieved, which is a significant improvement compared with commercial p-type (Bi,Sb)2Te3 ingots. Also, the hardness showed a notable increase, which is beneficial for device fabrication. In addition, we adjusted the proportion of Bi/Te of the commercial p-type (Bi,Sb)2Te3 scraps, thereby improving the thermoelectric performance and obtaining a higher ZT value of 1.2.