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Hastelloy X (HX) is used in a wide range of aerospace applications due to its excellent high-temperature properties, Dynamic strain aging (DSA) and Dynamic recrystallization (DRX) are of great interest as they affect the mechanical behavior at high temperatures. In this study, the serrated flow behavior of highly textured Hastelloy X fabricated by laser powder bed fusion (LPBF) is investigated during uniaxial straining over a wide range of temperatures (20–800 °C) and strain rates (5×10−2 s−1 to 5×10−4 s−1). The alloy exhibits different types of tensile serrated flow in the temperature range of 200–600 °C. The alloy has been shown to have a very good tensile flow behavior. The presence of the Portevin-Le Chatelier effect (PLC) due to dynamic strain failure was observed at temperatures lower than 600 °C, respectively, with an average activation energy value of 45 kJ/mol calculated using the quasi-static aging (McCormick) model, and an average activation energy value calculated using the solute resistance (Cottrell) model of 41.8 kJ/mol, which is significantly lower than the 80–130 kJ/mol of conventionally fabricated HX. The effects of temperature and strain rate on fracture morphology and microstructure were analyzed by SEM, and the dynamic recrystallization behavior and nucleation mechanism were characterized by electron backscatter diffraction (EBSD). The changes in the content of recrystallized texture Cube and deformed texture Goss at different deformation temperatures are explained, and the dynamic recrystallization mode changes, from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX) as the deformation temperature increase. Verification of the different DRX mechanisms contributes to a comprehensive understanding of the microstructural evolution of the hot deformation of HX fabricated by LPBF. • The highly textured Hastelloy X was fabricated by laser powder bed fusion. • Influence of temperature and strain rate on serrated flow behavior of HX were investigated. • EBSD was utilized to determine the dynamic recrystallization mechanism and changes in texture content. [ABSTRACT FROM AUTHOR]

With an emphasis on the development of machine learning-based constitutive modeling approaches, the state of constitutive modeling techniques and applications for metals and alloys was examined. This study explored three distinct methods of constitutive modeling: phenomenological constitutive models, physical-based constitutive models, and machine learning-based constitutive models. There was discussion of the benefits and drawbacks of three constitutive models. Analyzed and reviewed were the corresponding uses of neural networks in phenomenological models and physics-based constitutive models. In-depth analysis was conducted on the development of machine learning-based constitutive modeling methods and their uses, particularly the application of machine learning in combination with finite elements (FE). The trends of constitutive modeling approaches are finally covered after going over and summarizing the advantages and current trends of employing machine learning modeling techniques in place of numerical constitutive modeling techniques. The review may offer a more comprehensive reference for the advancement of constitutive modeling techniques for metallic materials research. [ABSTRACT FROM AUTHOR]

A method for predicting fatigue life using damage variables coupled with multi-modal microstructure damage evolution was proposed after analyzing the weights of the multi-modal microstructure of directionally solidified Ni-based superalloys DZ125 in this paper. Mechanical property tests and metallographic observation tests were carried out, and the microstructure weights of the superalloys were quantified using principal component analysis (PCA) and entropy-based inter-criteria correlation (CRITIC) weight analysis. The relationship between mechanical properties and multi-modal microstructures of the superalloys was analyzed, and fatigue life was predicted using damage variables coupled with multi-modal microstructure damage evolution. The weights of multi-modal microstructures of Ni-based superalloys and the influence of multi-modal microstructural damage evolution on mechanical properties were quantified by taking into account the interactions among the microstructural factors and their combined effects, which were important references for the design and processing of the superalloy as well as the prediction of mechanical properties. [Display omitted] • Quantifying the weights of multi-modal microstructure morphology parameters. • Quantifying the weights of multi-modal microstructure. • Proposed damage variables coupled with multi-modal microstructure damage evolution. • A fatigue life prediction method coupled with multi-modal microstructure damage was proposed. [ABSTRACT FROM AUTHOR]

A low-cost and easily-accessible approach based on adsorption of small aromatic hydrocarbons (SAHs) was developed to synthesize graphene on Cu powders, which could supply raw material for powder metallurgy (PM) fabrication of graphene/Cu composites. Two common SAHs, naphthalene and α -naphthol, were chosen as the carbon precursors. Compared with naphthalene, it was found that the hydroxyl group in α -naphthol could be chemically adsorbed on Cu powders, which could not only be effective in preventing Cu powders from agglomerating together at high temperature but also promote the growth of high-quality graphene. Therefore, α -naphthol-derived graphene on Cu powders were chosen to fabricate graphene/Cu composites by spark plasma sintering and hot-rolling. The composites exhibited a microstructure with extremely homogeneous dispersion of graphene, exceptional high strength and simultaneously similar electrical conductivity compared with that of the matrix. Cu–O–C bond was found and could improve the interfacial bonding between graphene and matrix. Experimental and theoretical calculation results revealed that the load transfer, grain refinement and thermal mismatch mechanism provided by graphene were the main strengthening mechanism in the composite. This synthetic procedure is quite scalable for industrial use to fabricate graphene/Cu composites with high performance. Image 1 • A novel preparing method of graphene/Cu composite by in-situ growth was proposed. • Extremely homogeneous dispersion of graphene in the composite was obtained. • The mechanical properties of the composites were largely enhanced. • High electrical conductivity of the composites were obtained. • This is a very promising method for scalable production and application. [ABSTRACT FROM AUTHOR]

The effective characterization of the mechanical property degradation of turbine blades in service for an ultra-long-term had a significant impact on the service safety and maintenance decisions of turbine blades. In this study, the microstructure observation and mechanical property study of the K403 polycrystalline Ni-based superalloy turbine blade under four service times were carried out, using microstructure characterization methods to quantify the microstructure evolution of the superalloy at different parts of the turbine blade with increasing service time. The effects of the microstructure degradation of the superalloy under ultra-long-term service on the mechanical properties of the turbine blade were analyzed. The results show that the microstructural degradation characteristics of the superalloy turbine blades under ultra-long-term service were strongly correlated with the spatial structural characteristics of the turbine blades after service, and it was found that the carbon elements and other elements inside and at the boundary of the carbide showed regular migration behavior with the increase in service time. The regular influence of microstructural degradation of superalloy turbine blades under ultra-long-term service on their mechanical properties was demonstrated. These results can provide empirical support for the study of the predicted residual properties of nickel-based superalloy turbine blades under ultra-long-term service. [Display omitted] • Microstructure evolution of turbine blades under ultra-long-term service was studied. • Mechanical properties of turbine blades under ultra-long-term service were studied. • Influence of microstructure evolution on mechanical properties was studied. • Position-related microstructure evolution and mechanical properties was studied. • Quantitative study of carbide evolution with service time was performed. [ABSTRACT FROM AUTHOR]

For the first time, ZnTiO 3 applied as an innovative photoanode material in quantum-dot-sensitized solar cells (QDSSCs) has been systematically researched both theoretically and experimentally in this paper. The electron mobility (150–400 cm 2 /vs) of this material, achieved via the deformation potential theory, is much higher than that of most known photoanodes, including TiO 2 and ZnO which have been heavily researched. The preparation of QDSSCs with the structure of ZnTiO 3 /CdS/CdSe yielded a high energy conversion efficiency of 1.95% and a large short-circuit current density of 5.96 mA/cm 2 , which are also superior to the characteristics of other emerging photoanode materials, such as SnO 2 , Zn 2 SnO 4 , BaTiO 3 , and so on, indicating the good potential of this material for using in QDSSCs. [ABSTRACT FROM AUTHOR]

The Magnetocaloric Effect (MCE) of directionally solidified Ni 50 Mn 18 Cu 7 Ga 25 alloy was improved based on texturation and introduction of extra phase transition in this paper. Magneto-structural transition is realized in directionally solidified Ni 50 Mn 18 Cu 7 Ga 25 alloy, with a value of Adiabatic Temperature Variation (Δ T ad) of − 1.35 K under magnetic field of 1.5 T. Through simple unidirectional compression, preferred orientation is formed and intermartensitic transformation is introduced in the present alloy. Preferred orientation strengthens the coupling of magnetic and structural transition, intermartensitic transformation makes transformation path more diverse, which both enhance Δ T ad of the directionally solidified alloy. A value of Δ T ad of − 2.34 K is obtained in the deformed alloy under magnetic field of 1.5 T, with a 73.3 % increase compared with the initial state. Moreover, the two incompletely overlapping structural transitions broadens the temperature range of MCE from 4.3 K to 7 K. The present work provides new insight on the MCE optimization of Ni-Mn-Ga alloy by simple and short-term unidirectional compression in view of merging different strengthening mechanisms. [Display omitted] • MCE optimized by different mechanisms: orientation and intermediate transition. • Simple compression to achieve equivalent effect with thermal-stress training. • Incomplete variant selection enriches transition path to increase transition scale. • Partly overlapped CMMT and CMIT improve Δ T ad and widen MCE temperature range. [ABSTRACT FROM AUTHOR]

Abstract: A series of LaFeAsO1−x F x (x =0–0.225) oxyarsenides have been synthesized by a solid-state reaction method in order to optimize electrical transport properties through appropriate F doping. Both electrical resistivity and Seebeck coefficient of undoped LaFeAsO show an anomaly at about 150K, which is related to a structural phase and/or spin-density-wave (SDW) transition. Seebeck coefficient seems to be determined by two competitive factors: it is enhanced by suppressing the structural phase and/or SDW transition, and reduced by increasing carrier concentration. Seebeck coefficient is significantly enhanced just after suppressing the anomaly, and the maximum Seebeck coefficient reached −142μV/K for the sample with F doping x =0.075 from −58μV/K for undoped LaFeAsO, and then decreased with further increasing carrier concentration through F doping. Meanwhile, the electrical resistivity is decreased with increasing F doping, resulting in a maximum power factor value of 1.2mW/mK2 at 80K for polycrystalline LaFeAsO0.85F0.15 sample, this value is the same order as that of the best low temperature thermoelectric Bi88Sb12 compounds, and could be significantly higher in single crystals. [ABSTRACT FROM AUTHOR]

Abstract: Microstructure and electronic characteristics of the 6H-type ABACAB LPSO structure in Mg97Zn1Y2 alloy are investigated by means of first-principles calculation within the generalized gradient approximation. The accurate positions of the solid solution atoms Y and Zn together with the arrangement rules are determined theoretically and the lattice distortion of the 6H-type ABACAB structure is also discussed in comparison with the 6H-type ABCBCB′ structure. The stability is also analyzed on the basis of the calculated cohesive energy, which reveals that Y element stabilizes the structure significantly. The electronic characteristics show that the Y element enhances the strength of alloy due to the presence of Mg–Y covalent bonding and the hybridization between Mg and Zn is relatively strong in entire region which contributes to improve the alloy''s ductility. [Copyright &y& Elsevier]

Abstract: Highly dense n-type Bi2Te3 dispersed with x vol% nano-SiC particles (x =0, 0.1, 0.5, 1.0) thermoelectric materials were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) method. The effects of nano-SiC addition on the thermoelectric and mechanical properties were studied. Compared with Bi2Te3 matrix, Bi2Te3 materials dispersed with nano-SiC show increased Seebeck coefficient, decreased electrical conductivity, and reduced thermal conductivity as well in the measured temperature range of 323–523K. The maximum dimensionless figure of merit (ZT max) was improved from 0.99 for Bi2Te3 sample to 1.04 for 0.1vol% SiC dispersed Bi2Te3 sample at 423K. The Vickers hardness increased linearly from 0.62 to 0.79GPa as 1.0vol% SiC was added. The highest fracture toughness of 1.34MPam1/2 was obtained for 0.1vol% SiC addition, and the highest Young''s modulus of 42.7GPa was obtained for 0.5vol% SiC added sample. [Copyright &y& Elsevier]

Abstract: Based on the successful applications of lattice inversion method in many fields, the crystal structure and phase stability of Cr23C6 and Mn23C6 are investigated using the interatomic potentials obtained by lattice inversion method in this research. The calculated atomic coordinates and crystal parameters are in good agreement with the experimental results and the phase stability of Cr23C6 and Mn23C6 are tested by random atom shifts and global deformations. The calculated energy also indicates that the Cr23C6 is more stable than Mn23C6. [Copyright &y& Elsevier]

• A novel cathode material prepared (Mn 5 O 8 /rGO) by the solution-phase method. • A H+/Zn2+ coinsertion mechanism of manganese oxide cathode was elucidated. • The addition of reduced graphene oxide enhances the cycling stability. • The Mn 5 O 8 /rGO cathode exhibits a high specific capacity with excellent rate and cyclic performance. Due to the higher requirements of energy storage equipment, aqueous rechargeable zinc ion batteries (ARZIBs) with the advantages of environmental friendliness, low cost and simple preparation have attracted wide attention. In this study, the composites of Mn 5 O 8 uniformly deposited on the surface of graphene used as cathode of ARZIBs are synthesized. Owing to the hierarchically porous morphology, the electrode delivers a high reversible capacity of 260 mA h g−1 at a current density of 100 mA g−1 and shows excellent long-term cycling stability of up to 1000 cycles with a capacity retention of 98.8%. In addition, the energy storage mechanism of H+ and Zn2+ coinsertion was tentatively studied as well. And this study provides some inspiration of designing high-performance ARZIBs for grid-scale energy storage. [ABSTRACT FROM AUTHOR]

Hot tearing susceptibility (HTS) refers to the casting defect that existed owing to the appreciable shrinkage at the final stage of solidification. Present research studied the effect of Y on the HTS of 3Y2O3/Al5Cu composite. After 0.3%, 1% and 2% Y (in wt.%) added, the HTS value of 3Y2O3/Al5Cu composite decreased by 2.1%, 39.5% and 61.9%, respectively. Mechanism analysis indicated that the refined grain size and reduced solidification temperature range contributed to the HTS improvement. The grain size of 3Y2O3/Al5Cu was 36.7 μm, while the grain size refined to 32.99 μm, 24.35 μm and 20.9 μm for the 0.3Y-3Y2O3/Al5Cu, 1Y-3Y2O3/Al5Cu and 2Y-3Y2O3/Al5Cu. The result indicated that the increase of grain growth restriction factor, which was caused by the Y element, improved the grain refinement efficiency. Furthermore, adding Y resulted in the novel Al8Cu4Y phase formation and solidification temperature range reduction. In addition, the Al8Cu4Y and Al2Cu phases promoted grain boundary bridges formation and prevented the cracks initiation and growth during solidification process. • The severe hot tearing susceptibility was significantly reduced by adding Y. • Y increased the grain growth restriction factor and refined the grain size. • The solidification temperature range reduced due to the Al-Cu-Y phase formation. • Hot tearing susceptibility and grain refinement mechanisms were carefully discussed. [ABSTRACT FROM AUTHOR]

The fracture mechanism of bimodal size lamellar O phase microstructure (BSLO microstructure) of Ti-22Al-25Nb alloy is studied. It is found that a BSLO microstructure fractures at room temperature via a quasi cleavage mechanism. The fracture is dominated by the cleavage of B2 phases. Micro cracks nucleate at O/O grain boundaries and O/B2 phase boundaries in the cleavage crack tip plastic zone. These micro cracks are blunted at B2 phase matrix. Fractured lamellar O phases form strip mini facets on cleavage planes and the blunted micro crack form tearing ridges. The mini facets and the tearing ridges comprise strip shallow dimples, which suggest the ductile fracture. It is determined that the crystal cleavage planes of B2 grains contain {100} and {110} via the SEM rotation operations and EBSD analyses. The cleavage cracks would be deflected at grain boundaries or at sub grain boundaries. The transformation of the crystal cleavage plane can lead to the deflection of a cleavage crack. The transformation of crystal planes can occur at either low angle boundaries or high angle boundaries. The newly defined cleavage factor f C is effective to present the cleavage favorability of a crystal plane. It is found that B2 grains cleavage generally along a plane with high f C but not always along the plane with the highest f C since the cleavage of a grain is also affected by its adjacent ones. • BSLO microstructures fracture at room temperature via quasi cleavage. • The fracture surfaces contain cleavage facets as well as shallow dimples. • The crystal cleavage planes of B2 phase is determined to be {100} and {110}. • Defined f C is effective to present the cleavage favorability of a plane. [ABSTRACT FROM AUTHOR]

Effects of lattice distortion on the anisotropic magnetoresistance (AMR) of magnetron sputtered epitaxial La 0.67 Sr 0.33 MnO 3 (LSMO) thin films grown on (001)-oriented SrTiO 3 and MgO substrates were investigated. Lattice mismatch at the film/substrate interface gives rise to weak and strong lattice distortion of the LSMO/SrTiO 3 and LSMO/MgO films, respectively. The Jahn-Teller electron-phonon coupling in LSMO leads to significant localization of the e g electrons, causing smaller magnetization, lower transition temperatures ( T C , T MI ) and larger resistivity. Moreover, AMR of the LSMO films show strong correlations with the substrates. Only two-fold symmetric AMR can be observed in the LSMO/SrTiO 3 films. However, the AMR curves of the LSMO/MgO system show clear transitions between two- and four-fold symmetry. This behavior is ascribed to the lattice distortion in the LSMO films which enhances the magnetocrystalline anisotropy. [ABSTRACT FROM AUTHOR]

Bimodal size lamellar O phase microstructures containing coarse lamellar O phases and fine acicular O phases were obtained in Ti-22Al-25Nb orthorhombic alloy. The fracture toughness of such microstructure was studied. It is found that a higher volume fraction of B2 matrix and finer B2 grains are both favorable to increase the fracture toughness by inhibiting the propagation of the principal cracks. The microstructure with a higher volume fraction of B2 matrix has fewer lamellar O phases and fewer O/O boundaries. In front of the principal crack, O/O boundaries often provide initiation points of microcracks. The microcracks can promote crack growth by merging with the principal crack. Fewer O/O boundaries provide fewer initiation points of microcracks. In addition, more B2 matrix can blunt the crack more effectively. Thus more B2 matrix also helps prevent the principal crack merging with microcracks. As for the effect of the B2 grain size, finer B2 grains offer more B2 grain boundaries, which provide more obstacles to crack propagation. It is observed that the crack trended to cleavage along some crystal planes of B2 grains. B2 grain boundaries can deflect the cleavage crack and significantly increase the tortuosity of the crack path. Consequently, microstructure with a high volume fraction of B2 matrix and fine B2 grains possesses a high K IC value up to 35.9 MPa m . A model that can predict K IC using tensile properties is utilized. The predicted K IC shows a good agreement with the experimentally measured fracture toughness of the bimodal size lamellar O phase microstructures. [ABSTRACT FROM AUTHOR]

Abstract: We have performed a first-principles calculation within the generalized gradient approximation to investigate the β″ phase in Mg–Gd alloy system. The lattice parameters are determined theoretically by structural optimization of full relaxation and the β″ phase Mg3Gd is found to be energetically favorable from the calculated formation enthalpy. The nine independent elastic constants are calculated, indicating the proposed Mg3Gd structure is mechanically stable. Then the polycrystalline bulk modulus B, shear modulus G, Young''s modulus E and Poisson ratio ν are gained by the Voigt–Reuss–Hill (VRH) approximation. The elastic anisotropy is discussed in detail. The electronic density of states and charge density distribution are analyzed, indicating the existence of covalent bonding in Mg3Gd. The Debye temperature is also estimated for the investigation in the future. [Copyright &y& Elsevier]

Abstract: Amorphous coatings were fabricated by arc spraying and the effect of the post heat treatment on the microstructure, and the mechanical properties of arc sprayed coatings were studied. Post heat treatment was conducted in the atmospheric environment within the temperature ranged from 500°C to 800°C. The microstructure characteristics were analyzed by means of optical microscopy (OM), X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), scanning electron microscopy (SEM), differential thermal analysis (DTA) and transmission electron microscopy (TEM). It was found that with the increase of anneal temperature, the microstructure of the sprayed coatings had several changes as follows: the reduction of porosity, the decomposition and the crystallization of amorphous phase, and the formation of precipitates. The microhardness of the sprayed coatings increased after the heat treatment and it can reached to 1275 HV300g at the post treated at 600°C. All the coatings exhibited an excellent abrasive wear resistance, approximately 6 times higher than that of the arc-sprayed 3Cr13 coating. [Copyright &y& Elsevier]

To improve the electrochemical performance of supercapacitors, pseudocapacitive electrode materials must be synthesized with high surface activity, high electrical conductivity, and ultralong cycle life, which presents a significant challenge. In this study, we reported on the synthesis of sulfur-vacancy-enriched sheet-like Ni 3 S 2 @ZnS composites based on 3D network porous nickel foam (NF) using a two-step electrodeposition protocol. The Ni 3 S 2 @ZnS/NF exhibited a specific capacitance of 1141.9 C g−1 (241.0 mC cm−2) at a current density of 19 A g−1 (5 mA cm−2). The Ni 3 S 2 @ZnS/NF positive electrode was used to fabricate an all-solid asymmetric supercapacitor, which demonstrated an ultrahigh energy density of 12.0 μWh cm−2 at a power density of 7.2 mW cm−2, as well as an ultrahigh capacitance retention rate of 86.7% after 50,000 cycles. Experimental and theoretical results indicated that the introduction of sulfur vacancies could improve the surface activity of the electrode, as well as its hydroxide diffusion and adsorption ability by adjusting the surrounding local electron concentration of cations around them. This accelerated the interfacial redox reaction and resulted in remarkable electrochemical performance for the Ni 3 S 2 @ZnS/NF electrode. This research provides a pathway for the controlled synthesis of 2D nanosheets with vacancy-rich structures and their potential electrochemical applications. • The sulfur-vacancy-enriched sheet-like Ni 3 S 2 @ZnS composite has been conceived. • Abundant sulfur vacancies make the material have high capacitive properties. • The theoretical studies further deepen structure-activity relationship of sulfur vacancies. • An ultrahigh capacitance retention supercapacitor is fabricated. [ABSTRACT FROM AUTHOR]

Hastelloy X is widely used in aerospace because of its excellent high-temperature performance. Laser powder bed fusion (LPBF) can be used to manufacture Hastelloy X and its reinforced materials with more complex structures and better performance. In this study, Hastelloy X reinforced materials added Fe-based metallic glass powder was manufactured using LPBF, and four sequences of 0, 3, 5, and 7 wt%. The introduction of Fe-based metallic glass powder has exhibited notable improvements in the mechanical properties at room and high temperatures. At room temperature (RT), the 5 wt% reinforced material exhibited a larger increase in hardness, with a yield strength and ultimate tensile strength of 856Mpa and 1081 MPa, and the reduction in elongation was only 9.6%. At high temperatures, introducing Fe-based metallic glass enhanced the yield strength and ultimate tensile strength, and the elongation was greatly improved at 800 ℃. The enhancements are mainly due to the grain size refinement caused by the introduction of Fe-based metallic glass powder, which increases dislocation density and grain boundary strengthening. In addition, as the content of Fe-based metallic glass increased, the corrosion resistance of the samples was also improved due to increased Cr and W content and the refinement of grains. This study provides a new research direction for improving the properties of Hastelloy X. • The Hastelloy X and its reinforced materials added Fe-based metallic glass were fabricated via laser powder bed fusion. • The microstructure, corrosion resistance, and mechanical properties of HX, HX3, HX5, and HX7 were investigated. • The addition of Fe-based metallic glass refined the grain size and eliminated microcracks. • HX5 exhibited better comprehensive mechanical properties at both room and high temperatures. • The corrosion resistance improved with the increase in the content of Fe-based metallic glass. [ABSTRACT FROM AUTHOR]

Highly efficient thermoelectric materials always have low thermal conductivities. Their phonon spectrum information is essential for understanding the procedure of thermal transport on thermoelectrics. Recently, palladium sulfide was found to be a potential thermoelectric material. However, the high thermal conductivity limits its thermoelectric performance and technological applications. Here, the phonon dispersion and phonon density of state in PdS are presented by using the first-principles theory. The phonon modes are assigned and compared with experiments. The evolution of optical modes with pressure is studied by using Raman spectroscopy. The low-energy and high-energy phonon bands are related to the vibrations of the heavy atom and the light atom, respectively. By combining Raman scattering and X-ray diffraction measurements, we obtain the mode-Grüneisen parameters for the detected phonon modes. The small mode-Grüneisen parameters indicate a weak anharmonicity in this material. This offers an explanation for its high thermal conductivity. The evolution of linewidths with pressure accounts for the decrease of the thermal conductivity upon compression. • The phonon dispersion and phonon density of state of PdS are given in terms of first-principles theory. • The observed optical phonon modes in Raman spectra have been assigned through theoretical calculations. • The structural evolution of PdS with pressure is given from high-pressure X-ray diffraction measurements. • The mode-Grüneisen parameters of the phonon modes of PdS are obtained from experiments. [ABSTRACT FROM AUTHOR]

Microstructures and mechanical properties of Ni matrix composites reinforced with amorphous SiO 2 particles by in-situ pyrolysis of polycarbosilane (PCS) coated on Ni powders were studied in this paper. The submicron spherical amorphous SiO 2 particles instead of traditional SiC uniformly distributing in the composites result from the generated silicon source by PCS pyrolysis combined with oxygen impurity in the preparation. The prepared composites achieve high yield strength, 172 MPa, and ultimate tensile strength, 494 MPa, as well as outstanding ductility, total elongation 28.4 %, which is improved 13.9 %, 50.6 % and 160.6 % compared with those for pure Ni samples, respectively. The effects of solid solution strengthening, grain refinement strengthening, reinforcement particle strengthening and dislocations behavior of at amorphous/crystalline interface on the combination of high strength and ductility of the composites were discussed. [Display omitted] • Amorphous SiO 2 reinforced Ni matrix composites were fabricated by in-situ pyrolysis of polycarbosilane coated on Ni powders. • Amorphous SiO 2 instead of crystalline SiC formed by the combination of silicon generated in the pyrolysis with oxygen. • The composites exhibit a combination of excellent tensile strength and ductility. [ABSTRACT FROM AUTHOR]

Herein, a nano-reticular structure cobalt diselenide (CoSe 2) film with high electroconductivity and electrocatalytic has been synthesized by one-step electrodeposition method and is applied as a counter electrode for dye sensitized solar cell (DSSC). Cyclic voltammetry (CV) measurements with different potential windows are carried out to reveal the deposition mechanism of cobalt selenide, illustrating that the formation of CoSe 2 occurred at −0.62 V via inductive effect reaction with selenide (Se2−). Tafel and CV characterizations demonstrate an excellent electrocatalytic activity of CoSe 2 counter electrode towards I−/I 3 − reduction reaction, which is attributed to the electronic effect between Co and Se and electrochemical active sites, provided by wrinkled layer structure, for adsorption and reduction of I 3 −. EIS measurements show a great electroconductivity ability of electrodeposition CoSe 2 film. The DSSC based on the CoSe 2 counter electrode yields a maximum power conversion efficiency of 3.96% (J sc = 10.84 mA cm−2, V oc = 0.65 V and FF = 55%) under the standard AM 1.5G illumination, which is 1.6 times higher than that of commercial Pt-based DSSC. Image 1 • A nano-reticular structure cobalt selenide film has been synthesized by a simple one-step electrodeposition method. • CV measurements illustrating that the formation of CoSe 2 occurred at -0.62 V via inductive effect reaction with Se2-. • The CoSe 2 film shown a great electroconductivity and electrocatalytic ability, resulting in a better PCE than Pt in DSSC. [ABSTRACT FROM AUTHOR]

Cu 5 Sn 2 Se 7 is a new family member of ternary Cu-based chalcogenides that consists of abundant and environmental friendly elements. It shows a great potential for thermoelectric application, but its metal-like electronic transport behavior leads to overall low thermoelectric performance. In this work, we successfully lower the intrinsically high hole concentration of Cu 5 Sn 2 Se 7 via an aliovalent doping approach, i.e. replacing the monovalent Cu by divalent Zn. It is shown that one single parabolic band model reasonably fits the room temperature carrier concentration dependent Seebeck coefficients of Cu 5−x Zn x Sn 2 Se 7 (x = 0–1) samples with a large effective mass of 2.5 m 0, and their power factors are significantly optimized by charge carrier concentration regulation. Moreover, these materials display ultralow lattice thermal conductivity close to the theoretical minimum (0.55 Wm−1K−1) at high temperatures because of its large Grüneisen parameter of ∼2 estimated by sound velocity data. Altogether, a maximum ZT of 0.51 is achieved at 750 K for Cu 4.1 Zn 0.9 Sn 2 Se 7 , which is 325% higher over the control sample Cu 5 Sn 2 Se 7 (ZT = 0.12 @ 750 K). • The thermoelectric properties of Cu 5−x Zn x Sn 2 Se 7 were systematically investigated. • Overcome the intrinsically high hole concentration of Cu 5 Sn 2 Se 7 and enhance its TE performance by using Zn as doping agent. • The electrical transport properties of Cu 5 Sn 2 Se 7 are explored through a SPB model. • A maximum ZT of 0.51 is achieved at 750 K for Cu 4.1 Zn 0.9 Sn 2 Se 7 , which is 325% higher than that of pristine Cu 5 Sn 2 Se 7. [ABSTRACT FROM AUTHOR]

Hot rolling is one of the most important thermoforming methods for metal matrix composites. However, to date, there are limited studies devoted to the research on the hot rolling behavior of graphene/metal composites. In this work, the influence of hot rolling on the evolution of microstructures, textures, and tensile properties of the graphene/Cu composites was systemically investigated. Firstly, this is done by comparing hot-rolled composites with different temperatures at 400 °C, 500 °C and 600 °C after 80% reduction. Interestingly, it was found that the graphene in the composite could be significantly exfoliated when rolling at 500 °C. Further texture analysis indicated that a strong component of shear deformation texture {001}<110> was formed. The exfoliation of the graphene can be explained by the presence of shear deformation and related mechanism was discussed. The composites with different rolling reductions (rolling at 500 °C) specifically revealed that the evolution of graphene gradually underwent three processes: 1. Aligned along rolling direction; 2. Broken into small pieces; 3. Exfoliated into thinned graphene. As a result, a high strength and good ductility composite can be realized. These findings provide new insights toward scalable and efficient fabricating of the graphene/metal composites with high performance. Image 1 • The hot rolling behavior of graphene/Cu composite was systematically investigated. • Graphene in the composite can be exfoliated when rolling at proper rolling process. • The exfoliation of graphene was considered to be caused by the shear deformation. [ABSTRACT FROM AUTHOR]

Achieving continuous dual-absorption peaks in ferromagnetic materials with micron-sized particles is quite challenging in designing the potential electromagnetic wave (EMW) absorbing materials. Here, we realize this effect in ball-milled Ni 2 MnGa microparticles and report their EMW absorbing properties for the first time. The as-milled Ni 2 MnGa/paraffin-bonded hybrids exhibit highly efficient EMW absorbing performance owing to the continuous dual-absorption peaks induced by enhanced dielectric loss and weakened magnetic loss associated with the permeability-to-permittivity energy transformation at the frequency of 2.0–18.0 GHz. The optimal EMW absorbing properties with the RL min value up to −65.2 dB can be obtained at a frequency of ∼14.4 GHz with a thickness of 2.90 mm. The effective absorption bandwidth with RL values less than −10 dB can reach 12.7 GHz through tuning the absorber thickness. It is demonstrated that Heusler-type NiMn-based alloys could be an attractive mono-component ferromagnetic absorber with highly efficient dual-absorption peaks. The continuous dual-absorption peaks are realized in ball-milled Ni 2 MnGa micro-sized particles for the first time, which substantially broaden the effective absorption bandwidth. The optimal EMW absorbing performance with the minimum reflection loss value up to −65.2 dB is achieved at a frequency of ∼14.4 GHz with a thickness of 2.90 mm in ball-milled microparticles. Image 1 • The continuous dual-absorption peaks are realized in ball-milled Ni 2 MnGa particles. • The permeability-to-permittivity transformation in Ni 2 MnGa microparticles are reported. • The dual-absorption peaks substantially broaden the effective absorption bandwidth. • The optimal RL min value up to −65.2 dB is achieved at the frequence of ∼14.4 GHz. [ABSTRACT FROM AUTHOR]

Tin sulfide (SnS), a typical IV–VI compound with low-cost, abundant-earth and eco-friendly elements, has aroused widespread attentions in the thermoelectric community due to its similar electron and phonon structures with SnSe. However, undoped SnS possesses the features of low carrier concentration and inferior band structures, which produces indecent thermoelectric performance. In this work, we successfully resolved these shortcomings of SnS through stepwise Na doping and Se alloying. Firstly, the carrier concentration of SnS was increased and optimized through Na doping, which leads to an enhancement both in electrical conductivity and Seebeck coefficients through activating multiple valance bands. Secondly, the electronic band structure of SnS was modified through Se alloying, both narrowing band gap and flatting valence band shape contribute excellent electrical transport properties, resulting in maximum power factor ∼6.0 μWcm−1K−2. After synergistically optimizing interdependent thermoelectric parameters through Na doping and Se alloying, a record high ZT of 0.70 at 873 K was obtained in polycrystalline SnS. Our work indicates that SnS is one of very promising earth-abundant thermoelectric materials for power generation in mediate-temperature range. • Power factor of p -type SnS was improved from 2.5 μWcm−1K−2 to 4.8 μWcm−1K−2 at 923 K through Na doping. • Power factor of p -type SnS was improved from 4.8 μWcm−1K−2 to 6.0 μWcm−1K−2 at 873 K through Se alloying. • ZT max of p -type SnS is distinctly enhanced from 0.25 to 0.70 at 873 K after Na doping and Se alloying. [ABSTRACT FROM AUTHOR]

Abstract In this work, we reported the thermoelectric performance of Sb doped n -type PbS can be improved through introducing different types of Cu inclusions (counter-doping, extra-adding and both of them). Firstly, Cu was selected to substitute Pb sites as counter-doping to tune the carrier density, resulting in maintaining power factor but a decreasing total thermal conductivity, thus in a maximum ZT (ZT max) ∼ 0.96 at 923 K in Pb 0.975 Sb 0.02 Cu 0.005 S. Then, we introduced extra Cu in n -type PbS to form interstitials to further reduce the lattice thermal conductivity to ∼0.77 W m − 1 K − 1 , and the ZT max was further enhanced to ∼1.06 at 923 K in Pb 0.98 Sb 0.02 S-0.02Cu. Finally, we combined both types of Cu (counter-doping and extra-adding) into n -type PbS, the power factor experiences slight reduction meanwhile the minimum lattice thermal conductivity can be reduced as low as ∼ 0.57 W m − 1 K − 1 at 923 K. Combining excellent power factor and dramatically reduced lattice thermal conductivity, we obtained a ZT max ∼1.23 at 923 K and the ZT ave ∼0.62 at 300–923 K in Pb 0.95 Sb 0.02 Cu 0.03 S-0.03Cu. This work provides a new idea to improve the thermoelectric performance in n -type PbS, indicating that PbS is one robust alternative of PbTe. Highlights • κ lat of n -type PbS is reduced from ∼ 1.33 Wm−1K−1 to ∼ 0.57 Wm−1K−1 at 923 K. • ZT max of n -type PbS is distinctly enhanced from 0.20 to 1.23 at 923 K. • ZT ave of n -type PbS is enhanced from 0.47 to 0.62 at 300–923 K. [ABSTRACT FROM AUTHOR]

Abstract In this work, we report that the high performance of SnTe could be realized by enhancing electrical transport properties (power factor) and reducing thermal conductivity through stepwisely introducing elements of Sb, In and Se. We found that Sb and In co-doping can enhance Seebeck coefficients in the broad temperature range via optimizing carrier density and introducing resonant state, respectively. Moreover, nanostructures could be formed when the Sb content beyond the solubility limit in SnTe matrix, which coupled with point defects from In and Se alloying result in a very low (lattice) thermal conductivity through the enhanced phonon scattering from defects and grain boundaries. A peak ZT ∼1.0 at 923 K can be achieved with the enhanced power factor and reduced thermal conductivity. Accordingly, the average ZT value increases from ∼0.20 for undoped SnTe to ∼ 0.60 for multiple-doped SnTe (Sn 0.823 Sb 0.17 In 0.007 Te 0.98 Se 0.02) over 300–923 K, generating a high calculated conversion efficiency ∼ 11%. Present results indicate the high performance of SnTe can be obtained through stepwisely optimizing strategy in both electrical and thermal transport properties. Highlights • A stepwisely enhancing in thermoelectric transport properties were achieved in p -type SnTe. • Power factor of p -type SnTe was enhanced from ∼3.4 μW cm−1 K−2 to ∼ 11.7 μW cm−1 K−2 at 300 K through Sb and In co-doping. • κ lat of p -type SnTe was reduced from ∼3.4 Wm−1K−1 to ∼ 1.4 Wm−1K−1 at 300 K through Sb, In co-doping, and Se alloying. • ZT ave of p -type SnTe is distinctly enhanced from ∼0.2 to ∼0.6 over 300–923 K. [ABSTRACT FROM AUTHOR]

The exploration of high-efficiency electrocatalysts for hydrogen evolution reaction (HER) still remains a tremendous challenge for energy conversion. Herein, a composite made from acetylene black (AB) and Cu-based metal-organic frameworks (Cu.BTC) via two different strategies shows distinctly electrocatalytic HER performance. The distinctive design of Cu.BTC incorporated AB exhibits high-efficiency HER activity with a smaller overpotential of 208 mV at −10 mA cm −2 , lower Tafel slope of 80 mV·dec −1 and long-term stability of at least 18 h. This work may provide a new strategy for the preparation of conductive MOFs-composite materials. [ABSTRACT FROM AUTHOR]

Te-free PbS has been regarded as a promising alternative candidate for PbTe thermoelectric materials due to its advances of low-cost, earth-abundant. In this work, we report an enhanced thermoelectric performance in n -type PbS system arising from synergistically optimized carrier and phonon transport properties. The electrical transport properties are optimized by tuning carrier concentrations via Sb doping, resulting in a maximum power factor of ∼16.7 μWcm −1 K −2  at 623 K, which is approximately tenfold higher than that of undoped PbS (∼1.8 μWcm −1 K −2 ). PbSe and PbTe co-alloying in PbS was carried out to reduce lattice thermal conductivity through introducing point defects scattering and second phase, resulting in a minimum lattice thermal conductivity ∼0.71 Wm −1 K −1  at 923 K. Combined the enhanced power factor with suppressed thermal conductivity, a maximum ZT value ∼1.0 was obtained in n -type (PbS) 0.53 (PbSe) 0.25 (PbTe) 0.2 Sb 0.02 at 923 K. [ABSTRACT FROM AUTHOR]

The Fe-16Cr-2.5Mo damping alloy was microalloyed with different amount of Zr element ranging from 0% to 0.5%. In this study, the effects of the different amount of Zr on the microstructure, mechanical properties and damping property of Fe-16Cr-2.5Mo alloys were investigated. The results suggested that the mean grain sizes of the Fe-16Cr-2.5Mo alloys with 0%, 0.1%, 0.3% and 0.5% Zr addition were 440 μm, 285 μm, 155 μm and 98 μm, respectively. The grain refinement strengthening was caused by Zener pinning and it leaded to improving the strength and elongation of the alloys. In addition, the Fe-16Cr-2.5Mo alloy with 0.1% Zr amount exhibited an impact toughness of 296J, which was much higher than those (<12J) of the alloys with more Zr element or without. On the other hand, Zr (Fe, Cr) 2 or Zr carbide precipitations (>0.5 μm) formed in the alloys notablely, based on the results of TEM and EDX. The large precipitations were apt to establish the cleavage initiation sites, thus damaging the impact toughness of the alloy. The maximum internal friction (Q −1 ) of the alloys fluctuated within 0.016–0.014 with the increase of Zr content at a low strain amplitude (9 × 10 −6 ∼3 × 10 −4 ). However, their damping properties are still marvelous. [ABSTRACT FROM AUTHOR]

We report n-type PbTe with a maximum ZT ∼1.2 at 673 K and an average ZT ave ∼0.84 at 300–823 K, which was achieved through a Sn and Se co-alloying approach. We find that the lattice thermal conductivity can be largely reduced through introducing Se in Te sites, and the power factor can be enhanced through introducing Sn in the Pb sites. Combining two strategies via Se and Sn co-alloying in PbTe, results show that the lattice thermal conductivity at 300 K can be reduced from ∼3.1 Wm −1 K −1 to ∼1.2 Wm −1 K −1 after alloying 15% Se, which is consistent with the Callaway model. Meanwhile, we find that both carrier concentration and mobility can be enhanced through alloying small amount of Sn, which are supported by DFT calculation with emphasis on the defect formation energies. The improvement on electrical conductivity elucidates an enhanced power factor at 300 K increasing from ∼6.4 μWcm −1 K −2 to ∼14.6 μWcm −1 K −2 . Through synergistically optimizing electrical and thermal transport properties of n-type PbTe via Sn and Se co-alloying, the ZT value is distinctly enhanced to 1.2 at 673 K, and the average ZT ave value is improved by ∼35%, from ∼0.62 in PbTe 0.997 I 0.003 to ∼0.84 in Pb 0.995 Sn 0.005 Te 0.847 Se 0.15 I 0.003 , ensuring a high maximum thermoelectric conversion efficiency ∼10.7%. [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]

SnTe, one lead-free analogue of PbTe, has been paid attention in thermoelectric community because it has the similar rock-salt crystal structure and electronic band structure. However, SnTe possesses a very high total thermal conductivity (∼10.0 W m −1 K −1 at room temperature) and a mediocre ZT (∼0.2 at 723 K). In this study, to reduce its thermal conductivity, we prepare SnTe samples by melting reaction followed by mechanical alloying and spark plasma sintering. We demonstrate that both total thermal conductivity and lattice thermal conductivity can be considerably reduced through reducing particle size from micro-scale to nano-scale via facially mechanical alloying method. Experimental results show that the total thermal conductivity at room temperature can be reduced from ∼10 W m −1 K −1 for SnTe ingot to ∼3Wm −1 K −1 for SnTe with mechanical alloying 25 h. Correspondingly, the lattice thermal conductivity at room temperature was reduced from ∼5Wm −1 K −1 to ∼2Wm −1 K −1 . Combination of reduced thermal conductivity and moderate power factor, average ZT ave can be increased by 33.3%, from 0.09 for SnTe ingot to 0.12 for SnTe with nano-grain size. [ABSTRACT FROM AUTHOR]

In 0.4 Yb 0.6 FeZnO 4 was confirmed to possess the lowest thermal conductivity in Yb-doped InFeZnO 4 . To further reduce the thermal conductivity, In 0.4 Yb 0.6 FeZn 1-x Mg x O 4 (x = 0, 0.1, 0.2,…, 0.8, 0.9, 1.0) ceramics were synthesized by solid state reaction at 1300 °C for 30 h. XRD results indicated that single phase In 0.4 Yb 0.6 FeZn 1-x Mg x O 4 ceramics were successfully synthesized with layered YbFe 2 O 4 -type crystal structure in the hexagonal R 3 ¯ m space group. It was found that the thermal conductivity of In 0.4 Yb 0.6 FeZn 0.5 Mg 0.5 O 4 (x = 0.5) reached a minimum value of 1.13 W m −1 K −1 at 1000 °C. The investigations on the thermal stability, thermal expansion coefficient, abradable property and erosion wear resistance indicate that In 0.4 Yb 0.6 FeZn 0.5 Mg 0.5 O 4 ceramics are promising thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Pd-based composite electrocatalysts made up of metallic oxide decorated Pd nanoparticles are gaining increasing interest due to their higher catalytic activity and superior stability. In this work, the WO 3 decorated Pd/C nanocomposite (Pd-WO 3 /C) was experimentally prepared using a simple microwave irradiation procedure to probe the electrocatalytic performance toward ethanol oxidation. The electrochemical tests reveal that the Pd-WO 3 /C composite outperforms the commercial Pd/C catalyst in terms of electrocatalytic efficiency. For instance, the mass activity can approach ∼2236 mA·mg−1 Pd , which is roughly twice that of the commercial Pd/C with the same Pd loading (10 wt%). Furthermore, the oxidation-peak current decays slowly over time and cycle, showing the exceptional durability. Based on first-principles calculations, the stronger electronic coupling interplay between Pd and WO 3 based on electron transfer, which provides more active sites by modifying the electron density on the Pd surface, could account for these emphasized advantages. • WO 3 decorated Pd/C composites were synthesized by a microwave irradiation approach. • The mass activity of ethanol oxidation for Pd-WO 3 /C composites is approximately twice that of the commercial Pd/C (10 wt%). • The stronger electronic coupling between Pd and WO 3 is responsible for the improved electrocatalytic activity and stability. [ABSTRACT FROM AUTHOR]

As an earth abundant material, PbS, has been paid extensive attention in the thermoelectric community. The high lattice thermal conductivity of PbS indicates there is room left to further improve thermoelectric performance of PbS. In this system we aimed to reduce the lattice thermal conductivity through nanostructuring grain sizes, which was processed by mechanical alloying followed by spark plasma sintering. We found that the lattice thermal conductivity can be reduced from ∼1.5 W m −1 K −1 at 723 K for PbS ingot to as low as ∼0.50 W m −1 K −1 for the PbS with nano-scale grain sizes, as a result, a ZT value of 0.80 at 723 K was achieved for 1.0% PbCl 2 doped PbS with the second phases of Bi 2 S 3 (Sb 2 S 3 , SrS, CaS). These results indicate that PbS is a robust alternative of PbTe and PbSe for medium temperature thermoelectric applications. [ABSTRACT FROM AUTHOR]

Abstract: We report on the effect of Mg doping on the thermoelectric properties of p-type BiCuSeO oxyselenide, with layer structure composed of conductive (Cu2Se2)2− layers alternately stacked with insulating (Bi2O2)2+ layers. The substitution of Bi3+ by Mg2+ leads to an enhancement of the electrical conductivity and a decrease of the thermal conductivity. Coupled to high Seebeck coefficients, ZT at 923K is increased from 0.45 for pristine BiCuSeO to 0.67 for Bi0.95Mg0.05CuSeO. However, the efficiency of Mg doping in the insulating (Bi2O2)2+ layer is low, and this doping only leads to a limited increase of the hole carriers concentration. Therefore Mg doped BiCuSeO has relatively low electrical conductivity which makes its thermoelectric figure of merit much lower than that of Ca, Sr and Ba doped BiCuSeO. [Copyright &y& Elsevier]

Abstract: The crystal structure of the 10H-type long-period stacking order structure in Mg–Y–Zn alloy was investigated by first-principle calculations. The calculated results show that the accurate positions and distinctive arrangement of Zn and Y atoms in the most stable 10H-type LPSO phase exhibit mirror symmetry with respect to the atomic layer C6, which agrees well with the experimental observations. Theoretical calculations still indicate that the mirror symmetry 10H-type ABACBCBCAB phase is not distorted, the lattice distortion of other LPSO phases may originate from the asymmetry of Zn element in the chemical order and stacking order. The obtained electronic density of states (DOS) reveals the underlying mechanism for mirror symmetry of 10H-LPSO phase. [ABSTRACT FROM AUTHOR]

Abstract: Porous Li2FeSiO4/C composite is synthesized using a facile one-step technique. The Li2FeSiO4/C composite is characterized by a large amount of particles with the size of ∼5μm. These particles are composed of a large number of smaller crystal grains with the size of ∼100nm, which are combined by many irregular pores. This structure can not only offer channels for infiltration of liquid electrolyte, but also avoid aggregation of nanoparticles during the synthesis itself and/or during electrochemical cycling. The electrochemical test result indicates that although the Li2FeSiO4/C cathode shows a lower initial discharge capacity of 134mAhg−1, it improves to 155mAhg−1 after 190 electrochemical cycles. [Copyright &y& Elsevier]

Solid-state electrolytes have become a promising approach for rechargeable lithium batteries with enhanced safety and high energy density. However, the rigid nature of ceramic electrolytes would result in the poor interfacial contact, and polymer electrolytes suffer from inferior electrochemical performance and unsatisfied mechanical strength to suppress Li dendrites. In this work, we report a flexible Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP)-reinforced polyvinylidene fluoride (PVDF)-based solid composite electrolyte with superior performances in terms of high ionic conductivity (1.64 × 10−3 S cm−1 at room temperature), high lithium transference number (0.45), wide electrochemical window (0–4.76 V) and enhanced tensile strength (14.2 MPa). The existence of LATP permits the utilization of high Li-salt content which increases the charge carrier concentration. Meanwhile, LATP facilitates the Li+ conduction process and enhances the mechanical strength, leading to a long-term electrochemical stability of symmetric Li cell for 600 h at 0.2 mA cm−2. Assembled with LiFePO 4 cathode, the all-solid-state Li battery delivers a high capacity of 153.7 mA h g−1 at 0.3 C with remarkable cycle stability. This work provides a bright future for composite polymer electrolytes in the application of all-solid-state lithium batteries. • A LATP-reinforced PVDF-based solid-state composite electrolyte was prepared. • The existence of LATP permits the utilization of high Li-salt content. • A long-term electrochemical stability of the Li symmetric cell was achieved. • LiFePO 4 | CPE |Li battery delivers excellent cycle stability at room temperature. [ABSTRACT FROM AUTHOR]

• Pt/g-C 3 N 4 composite photocatalysts synthesized by the low-temperature plasma treatment. • Ultrafine Pt nanoparticles were formed with appropriate ratio of Pt to PtO x and Pt‒N coordination bonds. • Ar plasma can modify the surface structure of g-C 3 N 4 to form oxygen-containing species. • Pt/g-C 3 N 4 -A150 composite exhibited the highest activity with a rate of 1150.8 μmol/h. Advanced photocatalytic systems are actively pursued to address a large number of pressing issues facing chemical engineering in applications. In the photocatalytic process, high-performance catalysts well beyond the current capacity and cost of platinum-carbon composites are required. In this work, Pt/g-C 3 N 4 composite photocatalysts were synthesized using a low-temperature inductively coupled plasma technique to substantially improve the photocatalytic performance for hydrogen production. After the plasma reduction of H 2 PtCl 6 , ultrafine Pt nanoparticles were uniformly deposited on g-C 3 N 4. By changing the plasma discharge power, the size of Pt nanoparticles, the composition and electronic structure of Pt and the interaction between Pt and g-C 3 N 4 can be effectively controlled. Moreover, Ar plasma modified the surface structure of g-C 3 N 4 to form new active oxygen-containing groups. The Ar-plasma-treated Pt/g-C 3 N 4 composites showed excellent activity for hydrogen evolution under visible light. When Pt/g-C 3 N 4 composite was plasma-treated at 150 W for 40 min, the achieved hydrogen production rate was 1150.8 μmol/h, which is about 63.2 and 4.6 times higher compared to the pristine g-C 3 N 4 and Pt/g-C 3 N 4 composite prepared by the photodeposition method, respectively. Our results indicate that the low-temperature inductively coupled plasma treatment is an effective and promising tool to fabricate high-performance catalytic materials. [ABSTRACT FROM AUTHOR]

Anti-correlated change between yielding strength (YS) and ultimate tensile strength (TS) was found in heat-treated lamella O microstructures of Ti–22Al–25Nb (at. %) alloy. The B2-phase-region-forged microstructure contained lamella O precipitates and residual B2 matrix. The initial forged lamella O microstructure was solution-treated in B2+O phase region and fine O precipitates transformed into B2 phase. The YS of the lamella O microstructure increased significantly while the TS decreased dramatically after the solution treatment. On the one hand, electron probe microanalyses indicate that the composition of the strong strengthener Al in the B2 matrix got enriched in the solution-treated microstructure and the composition of the weak strengthener Nb in the B2 matrix got diluted. Higher Al composition resulted in stronger solution strengthening effect (SSE) in the B2 matrix of the solution-treated microstructure. Since the B2 phase in such lamella O microstructures dominated the yielding behaviors, higher Al composition further resulted in the higher YS. On the other hand, transformation from O precipitates to B2 matrix during the solution treatment caused fewer O/B2 boundaries, which resulted in weaker precipitation strengthening effect (PSE) and led to the lower TS of the solution-treated microstructure. Inversely, the YS got decreased while the TS got increased when the solution-treated microstructure was subsequently aged at a lower temperature, where abundant acicular O re-precipitated from the B2 matrix. It is concluded that the anti-correlated change between YS and TS is attributed to the anti-correlation between SSE and PSE due to the appropriate composition of strong strengthener Al and weak strengthener Nb. Image 1 • Forged microstructure and aged microstructure have high TS and low YS. • Solution-treated microstructure has dramatically lower TS but higher YS. • The anti-correlated strength is due to anti-correlated SSE and PSE. • The anti-correlated SSE and PSE are due to appropriate Al and Nb composition. [ABSTRACT FROM AUTHOR]

BiSbSe 3 is a promising medium-temperature thermoelectric material on account of its intrinsically low thermal conductivity. To further enhance the thermoelectric performance in n -type BiSbSe 3 , we conduct Br doping at Se sites to optimize its carrier concentration and electrical conductivity, finally a maximum ZT of ∼0.8 in nanostructured BiSb(Se 0.94 Br 0.06) 3 is obtained at 700 K through mechanical alloying. Based on the optimal BiSb(Se 0.94 Br 0.06) 3 composition, we perform percolation effect with mixed grain sizes in nanoscale and microscale to enhance carrier mobility. It is found that carrier mobility is favorably improved by the addition of microscale grains (∼30 μm) in nanostructured BiSb(Se 0.94 Br 0.06) 3 matrix due to the reduced grain boundaries to carrier scattering, which benefits high electrical conductivity and power factor. Simultaneously, the BiSb(Se 0.94 Br 0.06) 3 matrix with mixed grain sizes still maintains very low thermal conductivity due to its intrinsically strong lattice anharmonicity. Owing to the optimized electrical properties and maintained low thermal conductivity, we obtain a maximum ZT value of ∼1.0 at 700 K in BiSb(Se 0.94 Br 0.06) 3 –4C matrix with 40% microscale grains. This work provides a feasible method to optimize thermoelectric performance by designing microstructure with percolation effect. • Carrier concentration was improved to ∼1.91 × 1020 cm−3 in n -type BiSbSe 3 by Br doping. • PF max of n -type BiSbSe 3 was significantly enhanced to ∼6.0 μW cm−1 K−2 at 700 K through improving carrier mobility via utilizing percolation. • ZT max of n -type BiSbSe 3 was enhanced from ∼0.1 to ∼1.0 at 700K. [ABSTRACT FROM AUTHOR]

Abstract: LaFe1-xZnxAsO0.85F0.15 composites were synthesized by solid state reaction in order to improve the mechanical properties while trying to keep the superconductivity. XRD results indicate that LaFe1-xZnxAsO0.85F0.15 are series of superconducting composites composed of LaFeAsO0.85F0.15 and LaZnAsO0.85F0.15. LaFe1-xZnxAsO0.85F0.15 still exhibits superconductivity up to Zn fraction as high as 80%. The critical temperature T c slightly decreases from 26.2K for LaFeAsO0.85F0.15 to 23.9K for LaFe0.2Zn0.8AsO0.85F0.15, which means that the superconductivity can be maintained if 20% of the superconducting phase exists in the composite. In addition, the mechanical properties of LaFe1-xZnxAsO0.85F0.15 including micro-hardness, Young’s modulus and fracture toughness have been significantly improved in the composite as compared to the Zn free sample. Therefore, we conclude the mechanical properties of the LaFeAsO system, and by extension of other systems, can be enhanced by introducing a second phase without deteriorating the superconductivity. [Copyright &y& Elsevier]

The n -type PbTe still maintains relatively low thermoelectric performance compared with its p -type counterpart. Thus, to promote its performance in n -type PbTe, we conduct successive strategies that firstly suppressing the lattice thermal conductivity (κ lat) through alloying with ternary compound AgSbSe 2 , and then optimizing carrier density with Sb, Bi or I doping. In AgSbSe 2 -alloyed PbTe samples, the κ lat can be evidently reduced, and the minimum κ lat decreases from ∼1.1 Wm−1K−1 in undoped PbTe to ∼0.8 Wm−1K−1 in PbTe–5%AgSbSe 2. Based on PbTe–5%AgSbSe 2 matrix, several dopants (Sb, Bi or I) are used to optimize its carrier density, and found that I element is verified to be the most effective dopant to enhance its electrical transport properties. In I-doped PbTe–5%AgSbSe 2 samples, the carrier density raises from ∼2.49 × 1016 cm−3 in PbTe–5%AgSbSe 2 to ∼1.15 × 1019 cm−3 in PbTe 0.992 I 0.008 -5%AgSbSe 2 , which contributes to the maximum power factor ∼14.8 μWcm−1K−2. Combining the reduced lattice thermal conductivity and improved power factor, the maximum ZT max and average ZT ave values in PbTe 0.992 I 0.008 -5%AgSbSe 2 are boosted to ∼1.0 at 723 K and ∼0.77 at 300–823 K, respectively. This work points out a valid avenue to improve thermoelectric transport property in n -type PbTe with separately successive strategies to adjust its thermal and electrical performance. • κ min ∼0.8 Wm−1K−1 was achieved in n -type PbTe through introducing AgSbSe 2. • PF max of n -type PbTe was significantly enhanced from ∼3.4 μWcm−1K−2 to ∼14.8 μWcm−1K−2 by I doping. • ZT max of n -type PbTe was enhanced from ∼0.45 to ∼1.00. [ABSTRACT FROM AUTHOR]

Chalcopyrite compounds are promising high efficient thermoelectric materials. However, the relatively high lattice thermal conductivity at modest temperatures limits their performance. Here, we investigate the lattice dynamics in a polycrystalline CuInTe 2 with a combined experimental and computational approach. The phonon dispersion and density of states are computed using the density functional theory. Raman scattering is performed to investigate the phonon dynamical properties. Together with the bulk modulus from X-ray diffraction, the mode-Grüneisen parameters are determined. The low energy B 1 1 and E2 modes characterize the weak anharmonicity, thus responsible for the high lattice thermal conductivity. Meanwhile, B 1 1 and E2 modes display energy redshift under pressure. The softening and enhanced anharmonicity of these modes naturally result in the reduction of the thermal conductivity. Our study suggests that pressure is a routine to reduce the phonon heat conduction at modest temperatures in chalcopyrites. • The phonon dispersion of CuInTe 2 is provided from the combined theoretical calculations and Raman scattering measurements. • The structural evolution of CuInTe 2 with pressure is given from high-pressure X-ray diffraction and Raman scattering measurements. • The mode-Grüneisen parameters of CuInTe 2 are obtained by combining the results from X-ray diffraction and Raman scattering measurements. [ABSTRACT FROM AUTHOR]

In this work, the thermoelectric performance of p -type PbS was boosted remarkably through Na doping and introducing Cu 2 S. Firstly, the electrical transport properties (power factor) of p -type PbS was optimized via Na doping, and the maximum ZT ∼ 0.67 was achieved in Pb 0.98 Na 0.02 S. Secondly, the total thermal conductivity of Pb 0.98 Na 0.02 S was suppressed through introducing Cu 2 S by means of significantly reducing the electronic thermal conductivity by 80% at 823 K through Cu counter-doping, meanwhile, the power factor of Pb 0.98 Na 0.02 S was further enhanced through optimizing carrier concentrations via introducing Cu. The combination of decreasing total thermal conductivities and the optimizing power factors leads to peak ZT ∼1.2 at 823 K in p -type Pb 0.98 Na 0.02 S–2%Cu 2 S. Present results illustrate that introducing Cu 2 S is an effective method to enhance the thermoelectric performance of p -type PbS through decreasing the electronic thermal conductivity which also has great potential in other thermoelectric materials system. • Thermoelectric performance of p -type PbS was remarkably boosted by reducing electronic thermal conductivity κ ele. • κ ele of p -type Pb 0.98 Na 0.02 S was reduced by 80% from ∼0.53 W m−1K−1 to ∼ 0.11 W m−1K−1 at 823 K with introducing Cu 2 S. • The maximum ZT ∼1.2 at 823 K was realized in p -type Pb 0.98 Na 0.02 S–2%Cu 2 S. [ABSTRACT FROM AUTHOR]

PbTe-based thermoelectric materials are considered to be a medium-temperature thermoelectric candidates and the high-performance n -type PbTe is urgently to be developed to match its p -type counterpart on account of practical application. Herein, we firstly optimized the carrier density of n -type PbTe through Sb doping, and obtained a maximum ZT value of ∼1.0. Then, based on the optimized carrier density, we introduced ternary compounds AgSb(Se, Te) 2 to suppress the lattice thermal conductivity. Minimum lattice thermal conductivity of n -type PbTe was reduced as low as ∼0.53 W m−1K−1 and ∼0.62 Wm−1K−1 through introducing AgSbSe 2 and AgSbTe 2 , respectively. Combining the maintained electrical properties with suppressed thermal conductivity, maximum ZT values ∼1.2 and ∼1.3 were obtained in PbTe+2%AgSbSe 2 and PbTe+2%AgSbTe 2 , respectively. This work provides an effective strategy of synergistically balancing charge and phonon transports in n -type PbTe with ternary AgSb(Se, Te) 2 compounds. • κ min of n -type PbTe was reduced to ∼ (0.53–0.62) Wm−1K−1 through introducing AgSb(Se, Te) 2. • Power factor ∼20.0 μWcm−1K−2 was realized in n -type PbTe through maintaining carrier mobility. • ZT max of n -type PbTe was enhanced from ∼1.0 to ∼ (1.17–1.25). [ABSTRACT FROM AUTHOR]