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Two-dimensional materials have attracted great attentions due to their novel properties and promising applications in opto-electronic and spintronics devices, but the advance on engineering suitable band gap and ferromagnetic behaviour is still undergoing. Here, the electronic structures and magnetic properties of NM -doped (NM =Pd, Pt, Ag, Au, Cu) ZnO monolayer are investigated using first-principles calculations. The results show that the formation of NM -doped ZnO monolayer is easier under the O-rich condition than under the Zn-rich condition. Furthermore, the band gap of the ZnO monolayer becomes narrowed after NM doping. Moreover, all NM -dopants induce the polarization of the ZnO monolayer, and the total magnetic moments are within 0.8–2.0 μ B. The origin is attributed to the spin states of NM - d xy , NM - d x 2 -y 2 and p y , p x of their neighboring O atoms. In addition, we found that the Ag-, Au-, and Cu-doped ZnO monolayers are ferromagnetic half-metals, while Pd- and Pt-doping cases are ferromagnetic semiconductors. The present results demonstrate that NM -doping is a proper way to tailor the electronic and magnetic properties of the ZnO monolayer so as to expand its utilization in nanoelectronics and spintronics. Image 1 • Noble metal-doped 2D-ZnO is most likely to form in O-rich environments. • Noble metal-doped can result in the enhance magnetism and the narrowed band gap. • The magnetic moment comes from the noble metals and their neighboring O atoms. [ABSTRACT FROM AUTHOR]

Exploring the interactions between precipitates and grain boundaries (GBs) is of great important to tailor the high-temperature stability and mechanical property of precipitate hardened alloys. However, the influence of precipitate on GB stability in high entropy alloys (HEAs) is still uncovered at nanoscale. In this work, we investigate the effects of precipitate size and temperature on grain boundary migration (GBM) using molecular dynamic simulations. The results show that the GB stability is improved with the increase of the precipitate size, especially at low temperatures. Compared with the traditional dilute alloys, the strong atomic lattice distortion exits in HEAs, resulting in the localized high tensile/compressive stresses. Thus, GB bends towards the indeterminate direction due to the lattice distortion, different with the case bending towards precipitate in the dilute alloys. In addition, the lattice distortion makes dislocation nucleate at random GB region in HEA, which is different from that in dilute alloys. High temperature reduces lattice distortion and relieves the localized high stresses, thereby inhibits the nucleation rate of dislocations from GB. These results provide the fundamental messages for designing novel HEAs with excellent thermal stability. • Influence of precipitates on GB stability at nanoscale is still uncovered in high entropy alloys. • Complex atomic stress field around precipitate leads to irregularly non-localized deformation of GB. • GB roughness increases due to stress field induced by precipitate and lattice distortion. • High temperature reduces lattice distortion thus relives localized high stress, thereby inhibit dislocation nucleation. [ABSTRACT FROM AUTHOR]

Abstract: Nd3+-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursors were obtained from a mixed nitrate solution with precipitant of ammonium hydrogen carbonate. The precursors were sintered at different temperatures and the phase developments in heat treatments were investigated through methods of XRD and IR, showing the precursors transformed to pure-GSAG phase with no intermediate phases appeared at 900°C. The TEM observation revealed that the powders sintered at 900–1000°C were well-dispersed with average crystalline sizes of 30–80nm. Photoluminescence analysis of the Nd:GSAG nano-powders showed that the PL intensities changing significantly with the Nd3+ doping concentration, and the concentration quenching was observed as the Nd3+ concentration reached to 1.5at.%. [Copyright &y& Elsevier]

The species and morphology of the modified electrode material have an essential influence on its properties. Inspired by the morphology of the dendritic fossils, we obtained a porphyritic cobalt-nickel precursor material by a green preparation method without a template. Further studies showed that the precursor material was a composite of Ni&Co carbonates and hydroxides (NiCo 2 CO 3 (OH) 2), and the possible chemical component was M(CO 3) m ·[M(OH) n x ·yH 2 O (M = Co, Ni, m, n, x, y = 0～5). Moreover, this material exhibited electrochemical activity against ascorbic acid (AA), dopamine (DA), and uric acid (UA), enabling simultaneous detection of the three, with low detection limit, fast response and no interference between each other. It is foreseeable that such carbonate and hydroxide-rich precursor materials are also an essential source of modified electrode materials. Image 1 • Inspired by the morphology of the microporous fossil, a porous cobalt-nickel precursor material by a template-free method was prepared and analyzed. • The precursor is chemically rich in hydroxyl and carbonate functional groups, and the possible chemical formula is M(CO3)m·[M(OH)n]x·yH2O (M = Co, Ni, m, n, x, y = 0～5). • The precursors have good electrochemical activity for the neurotransmitter molecules UA, DA, and AA, and can simultaneously detect the three. [ABSTRACT FROM AUTHOR]

Refractory high entropy alloys (RHEAs) are promising high temperature structural materials because of their excellent high temperature strength and high melting point. With introducing secondary particles, the high temperature mechanical properties can be further improved. However, its poor ductility limits the industrial application. In the present work, a new ductile NbTaTiV RHEA-based composite reinforced with Ti-C-O particles were in-situ synthesized through spark plasma sintering (SPS). The composite exhibits excellent room temperature compressive properties with yield strength, ultimate strength and fracture strain of 1760 MPa, 2270 MPa and 11%, respectively. A model is presented to study the strengthening mechanism, and the theoretical calculation shows that the dramatically strength enhancement is mainly due to the in-situ formation of Ti-C-O particles. • A (NbTaTiV) BCC /Ti-C-O composite was in-situ synthesized through powder metallurgy method. • The composite exhibits desirable yield strength of 1.76 GPa and ultimate strength of 2.27 GPa with reasonable fracture strain of about 11% at room temperature. • The composite also maintains an outstanding yield strength of 685 MPa at 1000 °C. • A model was present to analyze the strengthening mechanism. [ABSTRACT FROM AUTHOR]

Different contents of carbon element (0-3 at.%) was added into CoCrFeMnNi high entropy alloys (HEAs) to prepare carbide-reinforced CoCrFeMnNi matrix composites. The effects of carbon on microstructures and mechanical properties were systematically studied. The CoCrFeMnNi HEA sheet without carbon showed fine recrystallized grains with a grain size of approximately 5 μm and contained Cr-rich sigma phase. The CoCrFeMnNiC x HEA sheets with 1.0 at.% and 3.0 at.% C presented fine recrystallized grains and a small fraction of elongated grains. A large number of nano-scaled carbides were observed in the carbon-containing HEA sheets. With the carbon content increasing from 0 at.% to 3.0 at.%, the strengthening of the α-fiber texture is more obvious, and tensile yield strength increased from 371 MPa to 792 MPa, however, the elongation decreased from 54% to 11%, respectively. The CoCrFeMnNiC 1 HEA sheet with a volume fraction of 2.9% nano carbides showed excellent balanced mechanical property, with tensile yield strength of 634 MPa and elongation of 38%. The increase of yield strength for the CoCrFeMnNiC 1 HEA was mainly ascribed to the combined effects of precipitation Orowan strengthening and dislocations strengthening. Precipitation Orowan strengthening is the primary strength contributor, with a value of approximate 157 MPa. • Cr-rich sigma phase was observed in C-free CoCrFeMnNi HEA sheet. • Nano-scaled M 23 C 6 carbides were found in C-containing CoCrFeMnNi HEA sheets. • The CoCrFeMnNiC 1 HEA sheet showed an excellent balance of strength and ductility. • Nano-scaled M 23 C 6 carbides provided the largest contribution to the increase of YS. [ABSTRACT FROM AUTHOR]

Abstract In this study, the effect of hot extrusion on the microstructure and anti-corrosion performance of LDHs (layered double hydroxides) conversion coating on AZ91D magnesium alloy was investigated by means of microscopic observation and electrochemical measurement. After hot extrusion, the refinement and rearrangement of the β-Mg 17 Al 12 phase promotes the microgalvanic effect in the formation process, and the increase of dislocation density, twin, grain boundary and texture accelerates the dissolution rate of the Mg matrix. Due to microstructural differences, the electrochemical activity of various specimens in the formation process can be ranked as the increasing series: as-cast < transverse < longitude. Therefore, a thicker and more compact LDH conversion coating is formed on the longitudinal section of the extruded alloy, indicating the highest anti-corrosion performance. Highlights • The CO 2 pressurization method is the most environmentally friendly method. • The microstructure of the alloy was combined with the formation mechanism. • The formation mechanism of effect for β-Mg 17 Al 12 phases was found. • The role of microgalvanic and electrochemical activity was confirmed. [ABSTRACT FROM AUTHOR]

Abstract A nanoscale petal-like α-Ni(OH) 2 /reduced graphene oxide (α-Ni(OH) 2 /RGO) composite was synthesized with the one-step microwave method. α-Ni(OH) 2 particles with sizes of approximately 200 nm are uniformly distributed on the reduced graphene oxide sheet in the sample. When used as an electrode for alkaline rechargeable batteries, the discharge capacity of the α-Ni(OH) 2 /RGO composite reaches 333.5 mAh/g at 0.2C and 247.1 mAh/g at 10 C, respectively, with an excellent rate capability. After 2000 cycles, the capacity of the electrode is insignificantly attenuated, indicating a high capacity retention and cycling stability. The outstanding electrochemical properties are attributed to the nanoscale petal-like structure α-Ni(OH) 2 anchoring on the RGO sheets, which facilitates ion diffusion and increases the active surface, which is effectively reacting with the electrolyte. The nanoscale petal-like electrode material fabricated in this study provides clues to address the problem of energy applications of high-performance alkaline rechargeable batteries. Highlights • Petal-like α-Ni(OH) 2 /RGO is prepared by one-step microwave method. • RGO plays an important role in determining the morphology of α-Ni(OH) 2 /RGO. • Compared to Ni(OH) 2 , petal-like α-Ni(OH) 2 /RGO has a superior electrochemical property. • Discharge capacity reaches 333.5 and 247.1 mAh/g at 0.2 C and 10 C, respectively. [ABSTRACT FROM AUTHOR]

Abstract Inconel 718 (IN718) superalloy has been fabricated by selective laser melting (SLM) technology, and the effects of the solution and double aging treatment on the microstructures and mechanical properties of the alloy have been studied. Under the same aging condition, the hardness of the IN718 superalloy first increased and then decreased with the increasing of the solution temperature. When the solution temperature was 980 °C, the average microhardness of the alloy was increased to 502 HV 0.2 , with 17.56% increase. With the solution temperature increasing, more short-rod δ phase (Ni 3 Nb) was precipitated at the grain boundaries and distributed homogeneously, and the γ′′ phase (Ni 3 Nb) and the γ′ phase (Ni 3 (Al, Ti)) were formed. The δ phase (Ni 3 Nb) can pin grain boundary, inhibit the grain growth and improve the mechanical properties. In addition, the corrosion resistance of the alloy decreased after heat treatment. After heat treatments, the formation of the second phase subsequently increased the number of corrosion microbatteries and reduced the anticorrosive ability of the alloy. Highlights • The anticorrosive ability of IN718 alloys decreased after heat treament. • The second phase improve the property, but decrease the anticorrosive ability. • Giving good comprehensive mechanical properties after heat treament. [ABSTRACT FROM AUTHOR]

In this paper, a hollow tubular Co 3 S 4 /NiS/FeS heterogeneous composite was prepared by an ordinary hydrothermal procedure. The inner Co 3 S 4 can act as the carrier of the outer NiS/FeS, and the outer NiS/FeS can effectively prevent the collapse of the inner Co 3 S 4 hollow structure, ensuring the durability of the structure and performance in the cyclic charge-discharge test. The strong electronic interaction between Co 3 S 4 and NiS/FeS significantly improves the catalytic activity. It shows a small 230 mV overpotential at 10 mA cm−2, which is superior to commercial RuO 2. The Zn-air battery assembled with Co 3 S 4 /NiS/FeS catalyst showed outstanding stability over 2700 cycles with a narrow voltage gap of 0.67 V at 3 mA cm−2. Flexible battery also combined based on this catalyst can generally be discharged/charged at each bending angle and the gap remained almost continuous. Furthermore, Co 3 S 4 /NiS/FeS also displays hydrogen evolution reactions activity, displaying a lower overpotential of 233 mV at 10 mA cm−2. In the overall water splitting, Co 3 S 4 /NiS/FeS is used as both anode and cathode electrocatalyst, which can reach 10 mA cm−2 at 1.52 V, and the performance remains steady for 50 h. In conclusion, Co 3 S 4 /NiS/FeS is a potential tri-functional catalyst for ZABs and overall water splitting. [Display omitted] • Hollow tubular Co 3 S 4 /NiS/FeS tri-functional catalyst was designed. • It exhibited high efficiency activity and long-term durability toward ORR/OER. • When used this catalyst in ZABs, it showed excellent high stability within 2700 cycles. • The assembled soft-packing flexible ZABs can maintain stable within 50 h. [ABSTRACT FROM AUTHOR]

With its unique structure and properties, Ti 3 C 2 T x MXene has shown great potential for application in anti-corrosion coatings in recent years. However, its good conductivity might accelerate the corrosion process if effective protective measures are not taken. Herein, we developed sulfonated polyaniline (SPANI)/imidazolium salts modified Ti 3 C 2 T x (I-Ti 3 C 2 T x) composites (SIT), which were synthesized by oxidative polymerization of o-aminobenzenesulfonic acid and aniline monomers in I-Ti 3 C 2 T x dispersion. The structure, chemical composition, and properties of epoxy (EP) coatings with different contents of SIT were evaluated by several techniques, such as SEM, TEM, XPS, XRD, FTIR, EIS, and SST (Salt Spray Test). The experimental results showed that SIT greatly enhanced the corrosion protection property of EP coating. Especially, the impedance of 0.5 wt% SIT/EP coating was maintained at 6.57 × 109 Ω cm2 after 180 days of immersion, which was much higher than that of other samples. Furthermore, LEIS test results evaluated the passivation behavior and protective effect of the coatings in the presence of artificial scratches. The excellent anti-corrosion performance of SIT/EP coatings was due to the synergistic effects of antioxidation stability, impermeability property, and self-passivation produced by the fabrication of such SIT 3D structure hybrid. • Sulfonated polyaniline (SPANI)/I-Ti 3 C 2 T x composites (SIT) were synthesized to develop a novel anti-corrosion additive. • SIT improved epoxy coatings exhibited outstanding corrosion protection ability. • The passivation effect by SPNAI could provide supplemental protection to the scratched position of the coatings. • The anti-corrosion mechanism produced by antioxidation stability, impermeability, and the passivation was proposed. [ABSTRACT FROM AUTHOR]

Hot processing is extremely effective in optimizing the microstructure of γ-TiAl alloy, and hot deformation mechanism is the decisive factor in the microstructure evolution. In this paper, hot compression tests under different conditions were carried out to investigate the characteristics of hot deformation behavior and deformation mechanism of Ti-48Al-2 Nb-2Cr alloy with near-γ microstructure. The Arrhenius constitutive model was established, and the predicted flow stress agreed well with the experimental value. Hot processing maps at different strains were constructed. High power dissipation efficiency (η) region which was suitable for hot working appeared in the temperature range of 1180–1210 ℃ and the strain rate range of 0.001–0.01 s−1. At the strain rates from 0.001 to 0.1 s−1, dynamic recrystallization (DRX) served as the primary softening mechanism of the alloy, which was closely related to the disordered transformation of α 2 →α. At the temperature above T α 2 → α and the strain rate of 1 s−1, flow softening of the alloy was mainly controlled by dynamic recovery (DRV). The occurrence of DRX in the lamellar structure can be promoted by the elevated temperatures and reduced strain rates. Discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) appeared in the γ and α/α 2 phases of the alloy deformed at the conditions corresponding to high η region. With the decrease of η value, DRX nucleation of the alloy under the relevant conditions was chiefly dominated by DDRX. • Hot working window is optimized based on hot processing map and DRX mechanism. • Deformation mechanisms under different conditions are discussed. • Phase transformations of α 2 → α and γ → α play significant roles in the DRX behavior. • Relationship between DRX nucleation mechanism and η value is explored. [ABSTRACT FROM AUTHOR]

Sodium vanadium oxyfluorophosphate is a class of high-stability, high-capacity and high-voltage cathode materials for sodium ion batteries. But its practical performance is severely constrained by the low electric conductivity. In this paper, high-valence Zr4+ is designed and applied to improve the electrochemical performance of Na 3 V 2 (PO 4) 2 F 2 O (NVPFO). A series of Na 3 V 2−x Zr x (PO 4) 2 F 2 O (0 ≤x < 1) are prepared by a facile solid-state method. X-ray photoelectron spectroscopy and energy dispersive spectroscopy mapping demonstrate Zr4+ is successfully doped into NVPFO. X-ray diffraction with Rietveld refinement indicates the lattice parameters and cell volume are increased due to the large ionic radius of Zr4+. Scanning electron microscopy and transmission electron microscopy images verify the particle size is slightly decreased and more uniformly distributed after Zr4+ doping, and the carbon coating layer is also well reserved. The optimal doping is found 4 at% by generating Na 3 V 1.96 Zr 0.04 (PO 4) 2 F 2 O, which shows a specific capacity of 128, 106, 85 and 55 mA h g−1 at 0.1, 1, 8 and 60 C, respectively. After 350 cycles at 0.5 C, the specific capacity is gradually reduced from 115 to 87 mA h g−1 corresponding to a capacity retention of 75.7%. Its Na+ diffusion coefficient is calculated more than one magnitude higher than un-doped NVPFO. [Display omitted] • Zr4+ is successfully doped into Na 3 V 2 (PO 4) 2 F 2 O during a facile sintering process. • The influence of Zr4+ doping on structure and performance is investigated. • The optimal performance is obtained when the Zr4+ doping amount is 4 at%. • The underneath mechanism is studied combining a variety of characterizations. [ABSTRACT FROM AUTHOR]

A novel non-equiatomic Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 high entropy alloy (HEA) was fabricated via powder metallurgy (P/M) method. The Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 HEA exhibits dual-phase microstructure consisting of face-centered-cubic (FCC) and body-center cubic (BCC) phases. The Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 HEA has high compressive yield strength of 938 MPa and fracture strength of 3360 MPa, and still maintains moderate fracture strain higher than 40%. Also, the Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 HEA has high strength of 518 MPa at the temperature of 600 °C. Microstructural characterization shows that a large number of L1 2 and B2 nanoprecipitates are uniformly dispersed in the FCC and BCC phases, respectively, contributing to the enhancement of the strength of the two phases. The effective combination of FCC and BCC phases eventually leads to the high strength of the Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 HEA. This finding provides novel guidance for the development of high-performance structural materials with superior balance of strength and ductility for future industrial applications. • Novel Al 15.85 Fe 11.15 Co 32.11 Cr 10.76 Ni 30.13 HEA was prepared through powder metallurgy method. • The HEA exhibits dual-phase (FCC + BCC) microstructure. • Massive L1 2 and B 2 nanoprecipitates are embedded in the FCC and BCC phases, respectively. • The HEA exhibits high compressive yield strength of 938 MPa at room temperature. • The high strength is attributed to the hierarchically heterogeneous microstructure. [ABSTRACT FROM AUTHOR]

TiO 2 nanosheet based flowerlike architectures with a surface area as high as 171 m 2  g −1 were prepared through a solvothermal method. The sensing performance of TiO 2 nanosheet based flowerlike architectures is enhanced by increasing density of surface unsaturated Ti atoms with dangling bonds through hydrogenation. We proposed a concept of the unsaturated Ti atoms serving as the sensing reaction active sites, and described in detail the sensing mechanism at the atomic and molecular level. The unsaturated Ti atoms not only generate non-contributing (free) electrons and adsorb oxygen molecules, but also catalyze the sensing reaction. In principle, the hydrogenation strategy may be used to improve sensing performances and catalytic activities of other metal oxides. The concept of the unsaturated metal Ti atoms serving as active sites can deepen understanding of the sensing and other catalytic reaction mechanisms, and provides a new insight to the design and fabrication of advanced sensing materials, catalysts and electronic devices. [ABSTRACT FROM AUTHOR]

High temperature compressive deformation behaviors of a carbon-containing FeCoCrNiMn high entropy alloy (HEA) was investigated at temperatures ranging from 700 °C to 1000 °C, and strain rates from 0.001s −1 to 1s −1 . The microstructure mainly consists of fcc solid solution. The data obtained from the flow curves was employed to develop the constitutive equation, and the apparent activation energy (Q) was determined to be 385.43 kJ/mol. The size of the dynamically recrystallized grains decreased with the increasing value of Zener-Hollomon ( Z ) parameter. At high Z condition, dislocation cross slip can act as the main deformation mechanism. At intermediate Z condition, dislocation cross slip accompanied by discontinuous dynamic recrystallization (dDRX) becomes the main deformation mechanisms. At low Z condition, continuous dynamic recrystallization (cDRX) becomes the dominant softening mechanism. Nano carbides can be precipitated at intermediate Z and low Z condition, which prevent grain from growing up and promote the nucleation of DRX. [ABSTRACT FROM AUTHOR]

Pt-modified β -NiAl is an alloy of special interest for bond coatings in the hot sections of the engines. Nevertheless, the site occupancy of Pt is still an open issue. In this work, we have constructed a Ni-Al-Pt interatomic potential and carried out the molecular dynamics simulations to reveal the atomic structures and displacement behaviours of Pt in B 2-NiAl. The results of the simulations not only show that the Pt atoms have a strong preference for the Ni site in B 2-NiAl but also suggest that an increasing Pt concentration leads to a more pronounced displacement of the Al atoms. Moreover, the simulations predict the occurrence of phase separation in B 2-NiAl when the Pt concentration reaches 20%, which is confirmed in the subsequent experiments by the formation of a β -NiAl+Al 2 Pt dual-phase structure. The present findings promote the understanding of the atomic structures in B 2-NiAl, which in turn may provide useful guidance for the fabrication of high-quality β -NiAl bond coatings. [ABSTRACT FROM AUTHOR]

TiC reinforced titanium matrix composites are promising for advanced applications. Generally, the relative density of the composites and the interfacial bonding between the matrix and reinforced particles may have a great influence on the mechanical properties. This study presented the fabrication of the full-densified Ti-15Mo-xTiC (x = 1.5, 3.0, 4.5 wt%) composites through in-situ reactive sintering of Ti, Mo, and MoC powders and hot swaging process. Experimental results show the formation of TiC and the absence of MoC in the fabricated composites. After hot swaging, the TiC particles showed aligned distribution along the swaging direction, and exhibited well bonding with the β-Ti matrix. Increasing the TiC content leads to increase tensile strength and Young's modulus but decrease elongation. Ti-15Mo-4.5TiC offers and outstanding combination: ultimate tensile strength = 1290 MPa, yield strength = 1075 MPa, Young's modulus = 89 GPa, and tensile elongation = 3.1%. The strengthening effect is attributed to Mo solid solution in Ti matrix, β-Ti grain refinement, and TiC particle reinforcement. The specific contribution of each mechanism is quantitatively calculated, showing good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

A novel layered (Ca 0.35 Sr 0.2 Ba 0.15 Na 0.2 Bi 0.1) 3 Co 4 O 9 high-entropy ceramic is prepared for the first time by the traditional solid-state reaction. The XRD, SEM-EDS and TEM data exhibit that the multi-component cations can be introduced into the Ca site to form a single-phase and homogeneous solid solution with highly preferential crystal orientation and multi-scale structural defects. The textured high-entropy ceramic, compared to the pristine Ca 3 Co 4 O 9 sample , shows a significantly increased electrical conductivity due to the higher carrier mobility derived from the c -axis selective orientation, and obtains an enhanced power factor of 0.27 mW·m−1·K−2. Besides, high entropy induced multi-dimensional lattice defects can act as the phonon scattering centers to effectively suppress the lattice thermal conductivity, and achieves an ultralow thermal conductivity of 0.87 W·m−1·K−1 as well as a peak figure-of-merit of 0.3 at 973 K, which is about 2.5 times larger than that of Ca 3 Co 4 O 9. Our work deeply reveals the impact of the microstructure on thermoelectric properties in a high-entropy ceramic, which may help to advance the understanding and design of high-entropy thermoelectric materials. • Single-phase (Ca 0.35 Sr 0.2 Ba 0.15 Na 0.2 Bi 0.1) 3 Co 4 O 9 high-entropy ceramic is prepared. • It shows c -axis preferential orientation and multi-dimensional structural defects. • Ultralow thermal conductivity (0.87 W·m−1·K−1) and enhanced ZT (0.3 at 973 K) are achieved. [ABSTRACT FROM AUTHOR]

Numerous theoretical and experimental studies suggest that the chemical ordering microstructure plays an important role for the strength and plastic deformation in the multi-principal-element alloy (MPEA). Despite the importance of this fact has been well confirmed, little is known about the influence of chemical ordering degree from the atomic scale to nano scale for the nanocrystal MPEA over a wide grain size range. In the present work, considering the abnormal local stacking fault energy originated from the heterogeneous chemical element concentration, the modified Hall-Petch relationship is elaborately established in MPEA, quite different from the traditional alloys. Additionally, the effects of the solid solution, local chemical ordering, and precipitation on the strengthening contribution and strain partition are evaluated. The increase of the chemical ordering degree improves the stacking fault energy and deformation gradient, as well as microrotation field. This trend leads to the yield strength owing to the formation of the slender shear bands. The geometry of the ordered structure is deformed and twisted to a certain extent, for the compatible plastic deformation. This work gives the atomic understanding of chemical-ordering-degree dominated strengthening mechanisms, to develop the strong and ductile MPEAs with desired properties. The data that support the findings of this study are available from the corresponding author upon reasonable request. • Influence of chemical ordering degree on strength is studied in MPEA over a wide grain size range. • Modified Hall-Petch relationship dependent upon stacking fault energy from heterogeneous chemical element is established. • Reasonable regulation of chemical ordering degree mediated deformation/strain partitioning could obtain high strength. [ABSTRACT FROM AUTHOR]

Exploring newly regulative strategies to design highly efficient electrode materials is of great importance for supercapacitors. Herein, we highlight an interfacial engineering strategy for fabricating NiMn-LDH/V 2 CT x /NF hybrids with heterogeneous structure via a simple hydrothermal reaction. Detailed analysis confirms that the interfacial effect between NiMn-LDH and V 2 CT x enables electron transfer from NiMn-LDH to V 2 CT x in the hybrid material, resulting in improved electrochemical reactivity. As expected, the optimal NiMn-LDH/V 2 CT x /NF-2 demonstrates much better specific capacity than that of its counterparts. Moreover, this strategy can be extended to NiFe-LDH/V 2 CT x /NF hybrids, further proving the coupling effect between MXene and LDH is beneficial for the electrochemical performance. This work presents a new pathway to design advanced materials for supercapacitors. [Display omitted] • Interface engineering of heterogeneous LDH/V 2 CT x MXene hybrids facilitates high reactivity and conductivity. • V 2 CT x nanosheets effectively prevent the agglomeration of LDH nanosheets, which ensure the full exposure of active centers. • LDH/V 2 CT x nanosheet arrays exhibit improved electrochemical performance for supercapacitors. [ABSTRACT FROM AUTHOR]

An increasing amount of nitric oxide (NO x) is being discharged into the atmosphere due to the development of industry and combustion of fossil fuels. Photocatalysis, as a green and renewable technology, has attracted increasing attention from global researchers to address environmental pollution caused by excessive NO x in air. g-C 3 N 4 is a metal-free organic polymer photocatalyst that has received widespread attention due to its unique physical and chemical properties. However, the photocatalytic activity of g-C 3 N 4 under visible light irradiation is limited by high photocarrier recombination, poor conductivity, and low visible light utilization. The construction of novel S-scheme heterojunction semiconductors based on g-C 3 N 4 is a promising strategy to enhance the photocatalytic activity. In this study, S-scheme CeO 2−x /g-C 3 N 4−x (Ce/CN) photocatalysts were synthesized by the thermal polymerization of melamine and Ce(NO 3) 4. The photocatalytic activity of the as-prepared photocatalysts was investigated for the removal of NO with visible-light irradiation. The photocatalytic efficiency of 4Ce/CN was about 1.7 times higher than that of g-C 3 N 4 with a low NO 2 yield. Material characterization and DFT analysis demonstrated that the enhanced photocatalytic activity was attributed to N and O dual defects, the excellent conductivity of CeO 2 , and the in-built field of the Ce/CN S-scheme heterojunction. [Display omitted] • S-scheme heterojunction CeO 2-x /g-C 3 N 4-x with dual defects were prepared by thermal polymerization. • The improved photocatalytic performance for removing NO is attributed to dual defective sites and the built-in electric field. • The synergistic effect of defects and heterojunction optimizes interfacial photogenerated charges dynamics and promotes the generation of reactive oxygen species. [ABSTRACT FROM AUTHOR]

The objective of this work is to investigate the plastic deformation induced nanocrack evolution in single-crystal and bicrystal copper using molecular dynamics simulations, focusing on the effect of loading condition on crack closure. The results show that the compressive stress induced by defects such as dislocation, 9R phases and deformation twinning drives the crack closure. The microstructural evolution of nanocrack closure zone can be divided into four stages which include crack surface contact, local closure with discontinuously, closure zone expanding, and global closure. In addition, the crack in a bicrystal heals more easily than that in a single-crystal, due to the formation of a 9R phase. After one cyclic shear loading in both single-crystal and bicrystal copper, there is no crack nucleation in the crack-closure zone. The MD results from this work may provide useful guidance for designing the optimal nanomaterial with high damage tolerance and long service life. [ABSTRACT FROM AUTHOR]

The films assembled from wurtzite CdS nanocrystals with average size of 8.0 nm and clean {0001} facets have been synthesized by heating Cd(NO 3 ) 2 -thiourea aqueous solution on Si substrate at 300 °C for 20 min. The CdS films show superior photoreactivity, in comparison with CdS dendrites and flowerlike architectures assembled from nanoflakes with exposed {0001} facets. The superior photocatalytic activity is attributed to the active {0001} facets. Structure of the wurtzite CdS {0001} facets was studied using periodic density functional theory. The exposed CdS {0001} facets were found to be polar surfaces, thus a charge separation model between polar Cd-CdS (0001) and S-CdS (000 1 ¯ ) surfaces was proposed. The internal electric field between the polar Cd-CdS (0001) and S-CdS (000 1 ¯ ) surfaces provides an effective driving force for the separation of photogenerated electrons and holes. The reduction and oxidation reactions selectively occur on the positive Cd-CdS (0001) and negative S-CdS (000 1 ¯ ) planes. The good charge separation results in high photocatalytic activity. The charge separation model may provide new insights into the understanding of charge transfer in the semiconductor nanomaterials with reactive facets and the design of advanced photocatalysts and photoelectronic devices. [ABSTRACT FROM AUTHOR]

The influence of nucleation layer (NL) morphology on the structural property of AlN films grown by metal organic chemical vapor deposition (MOCVD) has been investigated using atomic force microscopy (AFM). It is found that the initial Ⅴ/Ⅲ ratio of the NL effectively controls the polarity, size, density, and coalescence rate of the islands, which is one of the most critical parameters determining the crystalline polarity and surface morphology. Due to difference adatom diffusion on the growth surfaces, it is observed that AlN films grown under high initial Ⅴ/Ⅲ ratios exhibit N polarity with rough surface, while that grown under low initial Ⅴ/Ⅲ ratios show Al polarity with smooth surface. And high quality crack-free AlN film with thickness about 1.4 μm has been obtained by optimizing initial Ⅴ/Ⅲ ratios during the NL deposition stage. [ABSTRACT FROM AUTHOR]

Monoclinic vanadium dioxide is a thermochromic material for advanced applications to smart optoelectronic devices. However, the poor visible-light transmission and high phase transition temperature ( T c ) of VO 2 hinder its practical use. Our first-principles calculations show that group IV elements (Si, Ge, Sn, Pb) doping may be an efficient way to reduce the T c of VO 2 , which is coupled with the changes in the geometry and electronic structures, i.e., the decrease in T c is associated with the correlation between the volume and the β angle, and the variable band gaps between e g and t 2g are narrowed by 0.05–0.37 eV after doping. In addition, group IV elements (Si, Ge, Sn, Pb) doping can improve the absorption and transmittance of light in the low energy region, favoring the efficient utilization of sunlight in the infrared region. Our findings would provide a useful guidance for fabrication of high quality VO 2 based thermochromic materials. [ABSTRACT FROM AUTHOR]

A wide application of magnesium (Mg) alloys in electronic devices requires high thermal conductivity and mechanical properties simultaneously. Unfortunately, the strategies for increasing their strength, such as alloying, decrease their thermal conductivity. Aging treatment is an effective method to resolve the strength-thermal conductivity trade-off. In this study, the mechanical properties and thermal conductivity of previously designed as-cast Mg–Zn–La/Ce alloys were further improved by aging treatment. Mg–Zn–La/Ce alloys aged at 473 K for 20 h exhibit a good comprehensive property. The thermal conductivity, yield strength, and ultimate tensile strength of aged Mg 97.3 Zn 2.6 La 0.1 alloy and Mg 97.4 Zn 2.5 Ce 0.1 alloy reach 148.4 W/(m·K), 172.9 MPa, 218.7 MPa, and 155.3 W/(m·K), 172.1 MPa, 239.1 MPa, respectively. The effects of La/Ce addition and precipitation on thermal conductivity were analyzed from the aspects of intermetallic phases, precipitates, and solid solutions using transmission electron microscopy (TEM) observations and precipitation kinetic calculations. The addition of La or Ce has a positive effect on the thermal conductivity due to the formation of ternary τ 1 phase which reduces the supersaturation of the Mg matrix. The precipitation shows two opposite influences on thermal conductivity. The sharp reduction in supersaturation of the matrix enhances the thermal conductivity, but the dense precipitates hinder the free movement of electrons and phonons. ● The designed Mg-Zn-La/Ce alloys own good thermal and mechanical properties. ● The La/Ce can improve thermal conductivity due to the formation of τ 1 phase. ● The precipitation has both positive and negative effects on thermal conductivity. ● The predicted thermal conductivity of Mg-Zn alloy agrees with experimental data. [ABSTRACT FROM AUTHOR]

To improve the dynamic mechanical properties of the selective laser melting (SLM)-NiCrFeCoMo 0.2 high entropy alloy (HEA), dynamic impact experiments were carried out on this alloy with different characteristic molten pools. Melt pool structures of different special sizes can be obtained by adjusting the laser power and scanning speed during the SLM process. In this work, the split-Hopkinson pressure bar (SHPB) is used to conduct dynamic impact on the SLM-NiCrFeCoMo 0.2 HEA samples with different molten pool size. The X-ray diffractometer (XRD), the scanning electron microscope (SEM), the electron probes micro-analyzer (EPMA) and the transmission electron microscope (TEM) were used to characterize the microstructure and deformation characteristics of the of the molten pool. The SLM-NiCrFeCoMo 0.2 HEA shows high impact energy absorption density and compressive strength at high strain rate. Volume energy density (VED) refers to the power delivered by the laser per unit volume of material during a SLM process, which can affect the size of the molten pool formed. Mo-rich σ phase precipitations are distributed near the molten pool boundary. In the cooling stage of the SLM process, the center of the molten pool has a faster cooling rate than the molten pool boundary, so area near the boundary stays in the temperature range where the precipitation occurs for a longer time, which is the reason why the precipitates are concentrated near the boundary. The precipitation strengthening in the SLM-NiCrFeCoMo 0.2 HEA is considered by measuring the relationship between the molten pool structure and the precipitation distribution, considering the material as a composite of the precipitation dense region (PDR) and the precipitation free region (PFR), and the strength contribution of precipitation is estimated by mixing rules. [Display omitted] • Control the size of molten pool by adjusting the input volume energy density. • Mo-rich precipitates are concentrated near the molten pool boundary. • The uneven cooling rate causes the concentrated distribution of precipitates. • The precipitate around molten pool boundary improves the dynamic mechanical property. [ABSTRACT FROM AUTHOR]

Transition metal-based phosphides (TMPs) show great potential for hydrogen evolution reaction (HER). The fine regulation of the electronic structure of metal-rich phosphides is an effective and challenging strategy for better activity. Herein, a simple and effective molten salt treatment is designed to synthesize porous boron doped Ni 2 P rod nanoarrays (M-B-Ni 2 P) for alkaline HER. The molten salt treatment facilitates the formation of unique porous Ni 2 P rod nanoarrays with homogeneous boron doping. The synthesized porous M-B-Ni 2 P exhibit excellent catalytic performance in alkaline media, requiring only an overpotential of 217 mV to drive 100 mA cm−2, which is 79 mV lower than binary nickel phosphide (M-Ni 2 P). The boron doping not only optimizes the porous geometry to increase the number of active sites, but also regulates the electronic coordination to promote the dissociation of water and the adsorption and desorption of hydrogen atoms. In addition, the self-supported monolithic M-B-Ni 2 P electrode can operate at a larger current density of 100 mA cm−2 for at least 100 h. This study on realizing boron doping based on molten salt treatment provides a new strategy for constructing transition metal-based phosphides as electrocatalysts. [Display omitted] • The molten salt treatment facilitates the formation of unique porous Ni 2 P rod nanoarrays with homogeneous boron doping. • The boron doping optimizes geometry to increase active sites, and regulates the electronic coordination to improve reaction kinetics. • The porous M-B-Ni 2 P exhibit excellent catalytic HER performance in alkaline media. • The self-supported 3D electrode ensures the stability of the catalyst. [ABSTRACT FROM AUTHOR]

In this study, AlCrFeNiMn x high-entropy alloy coatings (x = 0, 0.5, and 1) were successfully prepared on a copper substrate by laser cladding. The influence of Mn addition was investigated on the phase constituent, microstructure, and mechanical properties of the HEA coatings. Due to the high-entropy effect, the AlCrFeNiMn x HEA coatings comprised only simple BCC and FCC structure phases. Moreover, the addition of Mn elements inhibited the formation of FCC phases due to the variation of ΔG mix , ΔH mix , δ, ∆x and VEC value. The addition of Mn leads to solute effect, so the grains were significantly refined with an increase in Mn content. When the Mn content was 0.5, good comprehensive mechanical properties were obtained with an average Vickers hardness of 625 HV, average friction coefficient value of 0.42, and a mass loss of 1.02 mg. • AlCrFeNiMn x HEA coatings are prepared on a copper substrate by laser cladding. • The addition of Mn inhibited the formation of FCC phase of the AlCrFeNiMn x HEAs. • The addition of Mn can significantly refine grains of the AlCrFeNiMn x HEAs. • The addition of Mn can improve the mechanical properties of the AlCrFeNiMn x HEAs. [ABSTRACT FROM AUTHOR]

In this study, Al-Cu alloy suitable for laser powder bed fusion (LPBF) is rapidly developed through casting and laser remelting. The microstructure of as-cast Al-Cu alloy is consisted of equiaxed grains, and it was significantly refined after remelting. The Vickers hardness in the remelted zone improved by approximately 33.7% compared with that of as-cast Al-Cu alloy. The effects of different element content on Al-Cu-Mg-Zr alloy were analyzed, and optimum alloy composition was obtained with Al-5Cu-2Mg-1Zr-0.3Mn-0.15Ti through comparing microstructure, the hardness and other properties after remelting. The nano-indentation hardness and Young's modulus of remelted Al-5Cu-2Mg-1Zr-0.3Mn-0.15Ti alloys were 1.86 and 86.7 GPa, respectively. The microstructure was dense without obvious crack after LPBF forming, and the tensile strength, yield strength and elongation values reach 483 MPa, 365 MPa and 13.4% after solution treatment. • The suitability of LPBF-fabricated alloys composition was judged by cast and laser remelting.. • The ultra-fine microstructure and Al2Cu dispersion distribution were observed in laser remelting alloy. • New composition Al-Cu alloy prepared by LPBF shows a dense structure and good mechanical behavior. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) are widely used to protect high temperature structure parts against oxidation and corrosion. The failure mechanism study of TBCs is very important and the stress evolution is core content of failure mechanism research. In this work, a 8YSZ:Eu coating was produced via atmospheric plasma spraying (APS) method. Thermal cycling tests was carried out at 1300 ℃. The residual stress evolution of the coating was detected by a Eu3+ photoluminescence piezo-spectroscopy based on the relationship between stress and the peak position of 5D 0 →7F 2 transition of Eu3+ ions. The failure mechanism of the 8YSZ:Eu coating was also studied. The as-sprayed 8YSZ:Eu coating contains metastable t ´ -ZrO 2 and amorphous structure. The stress distribution is inhomogeneous with both compressive stress and tensile stress. After 1000 thermal cycles, the initial compressive stress changed to tensile stress due to the thermal expansion coefficients (TEC) mismatch and irreversible plastic deformation during thermal cycling. With thermal cycling going on, the compressive stress appeared again and the averaged tensile stress decreased due to the volume expansion caused by phase transformation of the t ´ -ZrO 2 to m-ZrO 2 and the formation of cracks. Formation of the thermally grown oxide (TGO), phase transformation, thermal expansion mismatch are factors for the coating failure. • A Eu3+ photoluminescence piezo-spectroscopy was used to measure the residual stress. • The residual stress distribution and evolution of the 8YSZ:Eu layer during thermal cycling was studied. • A 8YSZ:Eu coating was prepared by atmospheric plasma spraying and thermal cycling behavior was studied. [ABSTRACT FROM AUTHOR]

In this study, we report a novel and facile synthesis approach of boron-rich transition metal borides such as LaB 6 and TiB 2 through reaction of lithium borohydride (LiBH 4 ) with corresponding metal hydroxide or oxide at temperatures below 600 °C. A fast endothermic reaction occurred at around 350 °C in the ball milled mixture of 6LiBH 4 + La(OH) 3 or 12LiBH 4 + La 2 O 3 , efficiently producing crystalline LaB 6 nanoparticles of a size smaller than 100 nm. In comparison, the reaction of LiBH 4 with TiO 2 proceeded within a wide temperature range from 120 °C to 500 °C, resulting in the formation of nanocrystalline TiB 2 of only a few nanometers. This synthesis method proved to be a facile and general route to fabricate nanosized transition metal borides. [ABSTRACT FROM AUTHOR]

• The noble-metal-free CuII/CuI was used as cocatalysts via transient CuII/CuI centers. • The non-traditional LLCMT pathway was formed as a novel charge transfer channel. • The Cu species transient center can enhance the charge carriers separation efficiency. The earth-abundant copper species anchored on the -NH 2 of NH 2 -MIL-101(Fe) as noble-metal-free cocatalysts via transient CuII/CuI centers were obtained via a convenient synthesis technique to achieve excellent photocatalytic hydrogen evolution performance in the dye sensitization system. The prepared sample 6Cu-NM-101 exhibited the best hydrogen evolution activity of 5770.96 μ mol·g−1·h−1, which was 4.06 times higher than the original NH 2 -MIL-101(Fe). A series of characterization tests, especially the CV and the Auger Cu LMM, demonstrated that the transient CuII/CuI center played a significant part in the novel ligand to linker metal charge transfer (LLMCT) process. In other words, the electrons could transfer from the lowest unoccupied molecular orbital (LUMO) energy level of the excited state Eosin Y (EY*) to the transient CuII/CuI center to further accelerate the carrier transfer and separation rate. Our work provided a more convenient and effective strategy to prepare various earth-abundant metal ions based on MOFs as low-cost cocatalysts via transient metal centers to boost the photocatalytic hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

• (PEA) 2 PbBr 4 with improved properties were obtained via CsBr additive; • Enhanced surface morphology and optical properties of modified (PEA) 2 PbBr 4 ; • Responsivity for 2D perovskite photodetector based on sol-gel method is 0.67 AW−1; • Rise time and decay time are about 0.28 s and 0.21 s; • Spectral wavelength selectivity of (PEA) 2 PbBr 4 based photodetector was accomplished. Wavelength-dependent responsivity and detectivity of cesium halides additive photodetectors based on two-dimensional perovskite: (C 8 H 9 NH 3) 2 PbBr 4 under 10 V bias. [Display omitted] Considering of cost-effective and simple assembly principle of organic-inorganic halide perovskite (OIHP), producing perovskites into polycrystalline thin films from precursor solution has proved to be appealing. In this paper, (C 8 H 9 NH 3) 2 PbBr 4 was fabricated based on C 8 H 9 NH 3 Br (PEABr) and PbBr 2 according to compositions in the vicinity of (PEA) 2 PbI 4 , and the two-dimensionally (2D) perovskite was obtained which entitled with superior photoelectric performance, excellent solution processability and flexible substrates compatibility. And hydrophobic nature of spacer cation of aromatic alkylammonium or a large aliphatic both with the highly consistent orientation of 2D perovskites are beneficial for reducing the grain boundaries density. Meanwhile, optimized (PEA) 2 PbBr 4 were obtained via CsBr additive. Systematic material characterizations manifested enhanced surface morphology, photoluminescence efficiency and carrier lifetime of the CsBr modified (PEA) 2 PbBr 4. Then related (PEA) 2 PbBr 4 based photodetectors exhibited a good responsivity of 0.67 AW−1 when detectivity approached 5.2 × 1011 Jones, and a large on/off ratio about 500 was obtained. Meanwhile, the devices possessed noticeable stability during the optical switch tests with the rise time and decay time about 0.28 s and 0.21 s for CsBr dopped devices illuminated by 385 nm under 10 V bias. More importantly, spectral wavelength selectivity of CsBr based photodetector indicated the potential utilization in ultraviolet detecting when a wide bandgap of 3.018 eV was obtained. [ABSTRACT FROM AUTHOR]

Polycrystalline Cr,Nd:GSAG powders were synthesized by co-precipitation method using NH 4 OH as the precipitant. XRD, TG/DTA, FT-IR and Raman spectroscopy were used to characterize the structural properties of the precursor and the powders sintered at different temperatures. It was found that pure GSAG polycrystalline phase was obtained by sintering the precursor at 900 °C. The structure of the Cr,Nd:GSAG powder sintered at 1000 °C was refined using the Rietveld method. The lattice parameters are a = b = c = 12.4370(4) Å, with α = β = γ = 90°. The highest photoluminescence intensity was achieved for the powder sintered at 1100 °C and optical properties of powders of different Cr 3+ ions concentration were characterized by using photoluminescence spectroscopy. [ABSTRACT FROM AUTHOR]

Highlights: [•] The wurtzite CdSe nanoflakes are enclosed by {001} top and down surfaces. [•] The CdSe nanoflakes results from the selective adsorption of oleylamine. [•] Size control of the CdSe nanoflakes from 3.3 to 18.6nm can be achieved. [•] The size-dependent absorption and photoluminescence properties are observed. [•] The CdSe nanoflakes show higher photocatalytic activity than CdSe powders. [ABSTRACT FROM AUTHOR]

• ZnO nanorod arrays were prepared using hydrothermal assisted with PEI. • The photodetectors based on PEI-ZnO show a quick response time (~4 s) and high responsivity (~56 A/W). • The flexible devices display reliable stability and robustness under bending tests. • Raman and XPS spectra reveal the defect mechanisms on improved performance. [Display omitted] Investigations on the high-performance flexible ultraviolet photodetectors have been becoming one of the interesting research focuses in recent years. ZnO is considered as suitable material for ultraviolet photodetection due to its wide bandgap (~3.37 eV). In this work, ZnO nanorod arrays were prepared using the hydrothermal method at the temperature of 70 ℃ on flexible substrates. Polyethyleneimine (PEI) was added into hydrothermal solution as the growth additive to achieve the performance improvement of the ZnO nanorod arrays ultraviolet photodetector. SEM, XRD, absorption spectroscopy, Raman spectroscopy and XPS were employed to characterize the morphology, crystallinity, optical properties and chemical composition. The introduction of PEI adjusts the growth process of ZnO nanorod arrays and affects the distribution of defect states, which brings out the improvement of the optoelectronic performance of ZnO nanorod arrays ultraviolet photodetectors. Compared with pure ZnO, the higher photo to dark current ratio and responsivity, and quicker time response speed are demonstrated in the PEI-assisted ZnO nanorod arrays photodetectors. And more photoresponse parameters are also discussed and compared. Furthermore, the photodetectors also display outstanding mechanical flexibility and robustness under multiple bending cycle tests. Our work presents a potential approach for improving the optoelectronic performance of simple-operated flexible ultraviolet photodetectors. [ABSTRACT FROM AUTHOR]

• The {001} faced PbTiO 3 nanosheets have higher sensitivity than PbTiO 3 powder. • The sensitivity of PbTiO 3 nanosheets is further enhanced by hydrogenation. • The exposed Pb-PbTiO 3 (001) plane was found to be gas sensing active surface. • The surface 8-coordinated Pb atom is evidenced to act as a sensing active site. • It adsorbs oxygen, generates free electrons and catalyzes the gas sensing reaction. PbTiO 3 (PT) nanosheets exposed with {001} crystal faces have prepared by using TiO 2 nanosheets having {001} facets as a Ti source. The PT nanosheets have higher response to acetone, formaldehyde, ethanol and triethylamine than the commercial PT particles. Their response can further be increased by increasing density of the unsaturated 8-coordinated Pb atoms at Pb-terminated PT (001) surface through hydrogenating. The unsaturated 8-coordinated Pb atoms on the (001) surface of PT are evidenced to act the sensing active sites, and an sensing mechanism at atomic level is presented. As an active atom, the 8-coordinated unsaturated Pb atom can adsorb oxygen from air, create electron and catalyze the gas sensing reaction. This mechanism can deepen comprehending of the gas sensing nature of metallic oxides. The surface unsaturated active metallic atom engineering may be a very effective general strategy to enhancing performances of metallic oxide sensing materials. [ABSTRACT FROM AUTHOR]

• Sensitivity of {111} faced MnO octahedron is signally increased by hydrogenation. • This results from an increase in the density of unsaturated Mn atoms on the surface. • The unsaturated Mn atoms are evidenced to serve as an active site for gas sensing. • They can absorb oxygen, generate free electrons and catalyze the sensing reaction. MnO octahedrons with exposed {111} crystal faces have been synthesized in a solvothermal system of Mn(Ac) 2 and C 2 H 5 OH at 200 °C for 48 h. Formation of the MnO octahedron results from the selective adsorption of -OCH 2 CH 3 and -OH groups on the (111) crystal plane. Responses of the MnO octahedrons towards acetone, triethylamine, ethanol and n-Butylamine are enhanced by increasing numbers of the unsaturated 2, 3 and 5-coordinated Mn atoms on the (111) surface by removing surface C 2 H 5 O- and -OH groups through hydrogenation. Thus, the exposed Mn-MnO (111) face is found to be a gas sensing active surface, the unsaturated 2, 3 and 5-coordinated Mn atoms on the (111) surface are evidenced to be the sensing reactive atoms and a detailed sensing mechanism is presented. The unsaturated active Mn atoms produce electrons, adsorb oxygen and catalyze the sensing reactions. The mechanism can deepen the understanding of the nature of oxide semiconductor gas sensing and is helpful to the design of high performance gas sensing materials. [ABSTRACT FROM AUTHOR]

• Seven AlSi10Mg alloys with different construction angles were prepared and researched. • The grains in vertical planes change from columnar grains to irregularly arranged grains, and then to equiaxed grains. • The AlSi10Mg exhibites mechanical property anisotropy that is a result of grain structure, dispersed Si, and residual stress. In this study, seven AlSi10Mg bulks with different construction angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) were fabricated by selective laser melting (SLM). The effects of different construction angles on the microstructure and mechanical properties of AlSi10Mg alloys were investigated. Increasing the construction angle changed the laser track segments from an ellipse to a semi-ellipse and then to fish-scale, specifically again from a semi-ellipse to an ellipse, due to the decrease of the laser radiation area. Meanwhile, the grains in the vertical planes changed from columnar grains to irregularly arranged grains, and then to equiaxed grains. The 45° sample exhibited the highest hardness of 154.44 HV 0.1. The 60° sample had a good combination of strength and plasticity with a tensile strength of 463.54 MPa, yield strength of 283.37 MPa, and elongation of 9.25%. The observed mechanical property anisotropy of the current AlSi10Mg alloy was a result of the pores, equiaxed grain structure, ultra-fine equiaxed sub-grains, and working hardening. In addition, the difference in the sample microstructures was attributed to the construction angles and deposited layer area. [ABSTRACT FROM AUTHOR]

Abstract: The production of titanium silicide, from elemental powder compacts was successfully synthesized by laser ignited self-propagating high-temperature synthesis (SHS) of Cu–Ti–Si system in this study. Effects of Ti/Si ratio on the combustion characteristics, combustion temperature, the composition and microstructure of final products were studied. The results showed that the combustion process was preceded by the fast propagation of a self-sustained combustion front, followed by vigorous bulk combustion, furthermore, the combustion temperature increased with the increasing of Ti/Si ratio. When Ti/Si ratio is 1:2, the polygon-like shape TiSi2 phase was the dominant phase, minor amounts of Ti5Si3 and Cu3Si were detected in the final product; when Ti/Si ratio is over 1:2, the amounts of TiSi2 and Ti5Si3 phases decreased and increased, respectively. Especially, the cobblestone-like shape Ti5Si3 as the dominant phase was identified in the final product when Ti/Si ratio is 5:3. [Copyright &y& Elsevier]

● Pitting corrosion of AZ31 Mg alloy was in-situ monitored under nature corrosion state by combining EN and AE techniques. ● Three corrosion stages were identified according to EN and AE analysis results. ● Detailed relationship between EN and AE parameters and different corrosion mechanisms is discussed. Pitting corrosion of AZ31 magnesium (Mg) alloy was in-situ monitored by combining electrochemical noise (EN) and acoustic emission (AE) techniques. The EN signals were analyzed by transient shape observation, Hilbert spectrum and recurrence quantification analysis (RQA) based on recurrence plot (RP). AE characteristic parameters including rise time, amplitude, absolute energy and peak count were adopted to classify the AE signals. According to the mutual information obtained by EN and AE measurements, three corrosion stages including film-forming process, pit initiation and pit propagation can be identified. The detailed relationship between the AE and EN parameters and different corrosion mechanisms is discussed. The main contribution of present study is to provide a feasible method to effectively monitor the self-corrosion process of Mg alloy. [ABSTRACT FROM AUTHOR]

• The Au@mSiO 2 YSNs was synthesized by a facile one-pot method. • The synthesis of Au@mSiO 2 YSNs was a one-step synthesis of Au@mSiO 2 CSNs combined with organosilane-assisted etching process. • Au@mSiO 2 YSNs exhibited superior catalytic activity than that of Au@mSiO 2 CSNs in redox reaction of p-nitrophenol. • The evolution from Au@mSiO 2 CSNs to Au@mSiO 2 YSNs showed the enhanced SERS effect. The yolk-shell nanoparticles (YSNs) are promising functional nanomaterials for a variety of applications such as bio-medicine, catalysis, sensor, lithium battery and detection due to their unique structures and excellent properties. In the past few decades, the synthesis of YSNs generally requires multiple steps to complete, and the process is relatively tedious and complicated. Here, Au@mSiO 2 YSNs with good dispersibility were successfully synthesized by a facile one-pot process. The Au core with average diameter of 22 nm can move freely in the cavity and the silica shell with a thickness of 15 nm can effectively prevent Au particle aggregation. The method is a one-pot one-step synthesis of Au@mSiO 2 core-shell nanoparticles (CSNs) combined with an organosilicon-assisted etching process. Thanks to the unique properties of Au@mSiO 2 YSNs, such as low density and large surface area, we have conducted a series of studies on its properties. The redox reaction of p-nitrophenol (4-NP) was monitored by UV–vis absorption spectrum to investigate the catalytic performance of Au@mSiO 2 YSNs. The surface-enhanced Raman scattering (SERS) effect of Au@mSiO 2 YSNS was studied using p-aminophenol (PATP) as probe molecule. The results show that Au@mSiO 2 YSNs have higher catalytic activity and stronger SERS effect than that of Au@mSiO 2 CSNs. The Au@mSiO 2 YSNs will have great application prospects in catalysis, biosensing and detection, etc. [ABSTRACT FROM AUTHOR]

Abstract: Ti2SnC ternary compound was successfully synthesized utilizing laser ignited self-propagating high-temperature synthesis (SHS) of Sn–Ti–C system with the different C/Ti molar ratio. When C/Ti ratio is 0.7, Ti6Sn5 as the main phase appears, and a small amount of TiC is also found, most of the Ti6Sn5 phases synthesized exhibit the polygon-shaped coarse appearance with an obviously sintered morphology, and the distinct transgranular and intergranular microcracks can be observed. When C/Ti ratio increases over the range from 0.8 to 1.0, the relative content of Ti2SnC increase and the plate-like shape Ti2SnC appears. Furthermore, the sintered density increases firstly and then decreases with the increasing of C/Ti ratio. [Copyright &y& Elsevier]

• Metal-insulator alternates in VO 2 /TiO 2 superlattices with increasing VO 2 layers. • VO 2 /TiO 2 superlattices show insulating states in the 2/6, 4/6 and 6/6 systems. • VO 2 /TiO 2 superlattices present metallic states in the 1/6, 3/6 and 5/6 systems. • The 2/6, 4/6, 6/6 and 8/6 systems present oscillation of V-V distances. The interface between band insulator TiO 2 and correlated insulator VO 2 is a fertile ground for new behaviors. In the present paper, we conducted the first-principles calculations to study the interfaces of VO 2 (m)/TiO 2 (n) superlattices (referred as m / n for simplicity, where m and n denote the number of rutile VO 2 and TiO 2 layers, respectively). Interestingly, the VO 2 /TiO 2 superlattices show insulating states in the 2/6, 4/6 and 6/6 systems with the oscillation of V-V distances, while the superlattices present metallic states in the 1/6, 3/6 and 5/6 systems as the oscillation of V-V distances is broken. Accordingly, we reported an alternating metal-insulator behavior in VO 2 /TiO 2 superlattices with the increasing number of VO 2 layers. These findings may help to better understand the Peierls structural transition in correlated insulator, and may bring a light to the Schottky barrier homojunction composed of different VO 2 (m)/TiO 2 (n) superlattices. [ABSTRACT FROM AUTHOR]

Static recrystallization and texture evolution of the 80% cold-rolled (CR) powder metallurgy (PM) CoCrFeNiN 0.07 high-entropy alloy (HEA) during isothermal annealing were studied. The results show that the CR sheet exhibit a large number of shear bands, severe elongated grains and weak combination of α-fiber, γ-fiber and τ-fiber texture. The static recrystallization temperature of the CR sheet is 700 °C. The recrystallization activation energy is 232.7 kJ mol−1 following the Arrhenius-type relation. When the annealing temperature increase from 750 °C to 950 °C, the average recrystallization grain size increases from 635 nm to 2.7 µm, and the yield strength (YS) reduced from 712 MPa to 572 MPa, ultimate tensile strength (UTS) reduced from 981 MPa to 910 MPa, the elongation (EL) increased from 43% to 57%. Due to high dependence of recrystallization grain orientation on parent crystal, the {111}<112>F texture retained in recrystallized grains during annealing, but with the increase of recrystallization temperature, the recrystallization texture tends to be weak and scattered. • A FCC-type CoCrFeNiN 0.07 high-entropy alloys (HEAs) was fabricated by PM. • Preferred RX nucleation site is shear band, triple connection and grain boundary. • UFG with size of 635 nm were obtained by cold rolling and subsequent annealing. • {111}<112>F texture is retained a lot in RX grains during annealing process. [ABSTRACT FROM AUTHOR]

In this paper, an innovative designed TiO 2 nanosheets/CdSe/Polyaniline/Graphene (TCPG) quaternary composite was fabricated in order to improve the efficiency of photoelectron conversion and transmission. Then, by mixing TCPG with epoxy resin (ETCPG), in-situ coatings have been developed and prepared to realize photocathodic protection for 304 stainless steel(304SS). Compared to bare TiO 2 nanosheets and bare 304SS, the ETCPG coating exhibited remarkable photoelectrochemical properties, such as the photocurrent density increased 6.8 times to 340 μA/cm2 and the corrosion potential shifted from −408mV to −844mV respectively. Furthermore, the photocathodic protective performance of the coatings could last for at least 4 h in the dark condition, which showed excellent stability, energy storage and potential application. The synergistic effect between the extension absorption in the visible region and the efficient separation of electron-hole pairs improved the photoelectrochemical performance. The photocathodic protective mechanism was attributed to the shift of Fermi-level, which led the system achieved higher electric field strength in the semiconductor heterojunction interface, driving the electrons to flow directly to the substrate. Image 1 • Enhanced photoeletric performance was obtained by a novel designed TCPG composite. • An in-situ photocathodic protective coating was first developed by TCPG composite. • The corrosion potential of 304SS was shifted from −408mV to −844mV by this coating. • The synergistic mechanism promotes photoelectric conversion efficiency remarkably. • The controlled Fermi level shift drives the photoelectrons flow directly to 304SS. [ABSTRACT FROM AUTHOR]