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Three types of CuO with different micro–structures were applied to catalyze the conversion of glycerol to lactic acid. The structure–activity relationship between CuO and its catalytic performance was investigated by combining experiments and theoretical calculations. We demonstrated that two CuO samples (CuO–BCC and CuO–CA), as prepared by calcining copper salts, show larger lattice spacing than that of commercial CuO (CuO–COM). In the catalytic experiments, CuO–BCC, which had the largest lattice spacing (d = 0.2480 nm), exhibited the highest yield of 78.54% for lactic acid. The lattice strain caused by lattice expansion was considered more favorable for CuO–BCC in adsorbing glycerol molecules, thereby improving the conversion of glycerol to lactic acid. The DFT simulation calculation results further prove that CuO–BCC has a larger adsorption energy for glycerol and a smaller thermodynamic energy barrier for the dehydrogenation of glycerol to form the key intermediate products (glyceraldehyde and 1,3-dihydroxyacetone) than CuO–COM. This study demonstrates the role of lattice strain effects in the development of catalysts and provides ideas for catalytic glycerol-selective oxidation studies. [ABSTRACT FROM AUTHOR]

Cr, Fe, Ce and W doped MoVTeNbO M2 phase catalysts were synthesized and used in the selective oxidation of propylene to acrylic acid (AA). Results show that the introduction of Cr, Fe, Ce and W substantially affects the physicochemical properties and catalytic performance of MoVTeNbO-based catalysts. Un-doped catalyst consists of M2 phase and TeO2, while Cr, Fe, Ce and W-doped catalysts are mainly composed of M2 and MoO3. It is indicated that doping of Cr, Fe, Ce and W can restrain the formation of TeO2, but favour the formation of MoO3. Un-doped, Cr and W-doped catalysts display irregular-shaped particles morphology, while Fe and Ce-doped catalysts display nanosheets morphology. In addition, the valence of superficial elements of catalysts changed greatly with the doping elements. For catalytic performance, in addition to Cr, the propylene conversion of the catalyst decreases obviously with doping of other elements, probably due to the drastically reduced specific surface area with doping of Fe, Ce and W. The existence of Cr and Ce can increase the selectivity to AA at all test temperatures (360–440 ℃), while Fe and W-doped catalysts only show higher selectivity than the un-doped one at high temperature of 420 and 440 ℃. It is illustrated that the catalysts with redox ability at relatively low temperature is more favorable for the selectivity to AA. Among them, Cr-doped catalyst shows the highest selectivity (85.3%) and yield (63.5%) of AA at test temperature of 380 ℃, which are 15.3 and 7.5% higher than that of un-doped catalyst, respectively. The M2 phase MoVTeNbO catalysts doped with Cr, Fe, Ce and W have been synthesized. It is demonstrated that the addition of Cr improves the stability of Te4+, and Cr-doped M2 phase shows excellent catalytic performance in the selective oxidation of propylene to acrylic acid. [ABSTRACT FROM AUTHOR]

K-doped MoVTeNbOx were prepared rapidly and simply by spray drying method and applied to catalyze the selective oxidation of propane to acrylic acid. Results show that doping of K could affect the relative content of M1 and M2 phases in MoVTeNbOx. The as-prepared K-doped MoVTeNbOx exhibited a unique spherical structure agglomerated by needle particles. These needles shaped particles interlaced and stacked with each other to form a mesoporous structure with an average pore size range of 27.26 to 50.78 nm. Moreover, compared with undoped catalysts, doping of K increased the surface V5+ active sites content of the MoVTeNbOx from 60 to 75%. For the conversion of propane to acrylic acid, an appropriate amount of M2 increased the conversion of propane. The selectivity of K-doped MoVTeNbOx catalyst for acrylic acid was significantly improved, possibly due to the distinct reduction in the number of medium acid sites caused by the introduction of K. Furthermore, the special mesoporous structure formed boosted the adsorption and activation of the catalyst for propane and the diffusion of product, which is important to improve the catalytic performance of MoVTeNbOx. Under the optimal reaction condition, the maximum selectivity and yield of K-doped catalyst (K/Mo = 0.005) for acrylic acid reached 72.06% and 49.57%, respectively.Mesoporous K-doped MoVTeNbOx catalyze the direct oxidation of propane to acrylic acidGraphical Abstract: K-doped MoVTeNbOx were prepared rapidly and simply by spray drying method and applied to catalyze the selective oxidation of propane to acrylic acid. Results show that doping of K could affect the relative content of M1 and M2 phases in MoVTeNbOx. The as-prepared K-doped MoVTeNbOx exhibited a unique spherical structure agglomerated by needle particles. These needles shaped particles interlaced and stacked with each other to form a mesoporous structure with an average pore size range of 27.26 to 50.78 nm. Moreover, compared with undoped catalysts, doping of K increased the surface V5+ active sites content of the MoVTeNbOx from 60 to 75%. For the conversion of propane to acrylic acid, an appropriate amount of M2 increased the conversion of propane. The selectivity of K-doped MoVTeNbOx catalyst for acrylic acid was significantly improved, possibly due to the distinct reduction in the number of medium acid sites caused by the introduction of K. Furthermore, the special mesoporous structure formed boosted the adsorption and activation of the catalyst for propane and the diffusion of product, which is important to improve the catalytic performance of MoVTeNbOx. Under the optimal reaction condition, the maximum selectivity and yield of K-doped catalyst (K/Mo = 0.005) for acrylic acid reached 72.06% and 49.57%, respectively.Mesoporous K-doped MoVTeNbOx catalyze the direct oxidation of propane to acrylic acid [ABSTRACT FROM AUTHOR]

In this work, MoVTeNbOx catalysts was doped with Cr by using spray drying method. The effect of Cr doping on the crystalline phase, physicochemical properties, and catalytic performance of selective oxidation of propane to acrylic acid of MoVTeNbOx was investigated. The results showed that the samples as-prepared by spray drying method present unique spherical morphology stacked by rod particles. In addition, Cr doping induced a change in the mesopore structure formed by rod stacking, reducing the pore radius of the catalysts from 5-10 nm to 2-4 nm. Meanwhile, Cr doping dramatically reduced the average particle size of MoVTeNbOx catalysts, decreasing the rod cross-section diameter of catalysts from 234.21 to 134.96 nm and the rod length from 1.096 μm to 485.71 nm, which significantly increased the amount of (001) active crystalline plane. Moreover, an appropriate amount of Cr doping increased the number of reducible species in the catalyst and reduced its acidity. At the same time, the surface V5+ content of the catalyst was increased from 35.8% to 72.6%. Cr-doped MoVTeNbOx with mesoporous structure showed excellent performance in catalyzing selective oxidation of propane to acrylic acid reaction. Among them, S-3 sample (V: Cr = 1:0.015) increased the selectivity and yield to acrylic acid from 67.5% to 84.3% and from 26.4% to 43.2%, respectively, at reaction temperature of 380 °C. [ABSTRACT FROM AUTHOR]

A high-pressure hydrothermal method was employed to introduce Ce element facilely into MoVTeNbO x catalysts in 0.5 h. It was indicated that Ce atoms were doped into the framework of MoVTeNbO x without changing the unique crystal structure of MoVTeNbO x. The introduction of Ce could facilitate the formation of oxygen vacancies and improve the redox ability of surfacial V. However, it was worth noting that the doping amount of Ce was negatively related to the content of M1 active phase. Within a certain range, the catalytic performance could be improved by sacrificing an appropriate amount of M1 phase. In the conversion of propylene to acrylic acid, the highest yield of 58.2% was obtained under catalyst MoVTeNbCeO x (V: Ce =1: 0.05) at 380 °C with the M1 phase content of 81.6%. The appropriate amount of Ce doping improved the propylene conversion by more than 20% compared to undoped. Moreover, the changes in Gibbs free energy of the rate-limiting step of direct oxidation of propylene before and after Ce doping were evaluated by Density functional theory (DFT). It is illustrated that the doping of Ce is thought to affect the main reason for the reduction of Gibbs free energy. [Display omitted] • Ce was successfully doped into MoVTeNbO x catalyst by high-pressure hydrothermal method in 0.5 h. • Doping of Ce promoted the lattice oxygen mobility and the redox ability of surfacial V. • The introduction of proper amount of Ce would sacrifice part of M1 phase, but can improve the activity of the catalyst. • DFT indicated that doping of Ce can reduce the activation energy barrier of V O at the adiabatic step. [ABSTRACT FROM AUTHOR]

Skutterudites based on CoSb 3 are considered potential candidates in thermoelectric applications in the field of mid-temperature power generation. The annealing process necessitates more than a week to complete the peritectic phase transition for traditional melting-quenching-annealing-sintering methods. Herein, a new strategy combining the temperature gradient zone melting process with hot pressing (TGZM-HP) was successfully employed to synthesize YbFe-doped p-type CoSb 3 in a shorter time. The resulting samples show enhanced thermoelectric properties compared to TGZM-grown ones, especially in the case of 1 at.% YbFe-doped CoSb 3. This compound exhibits a maximal Seebeck coefficient of 166.3 μVK−1 and a power factor of 1.8 mWm−1K−2 at 723 K, showing an increase in these values of 25% and 51%, respectively. Moreover, phonon scattering appears to be enhanced due to the significant reduction in the grain size of the TGZM-HP samples, resulting in a minimum thermal conductivity of 2.71 Wm−1K−1. A dimensionless figure of merit (ZT) of 0.48 was obtained for 1 at.% YbFe-doped CoSb 3. This value is 1.6 times larger than that measured for TGZM-grown CoSb 3. This work provides an alternative strategy to fabricate skutterudite materials and foster their development. [ABSTRACT FROM AUTHOR]

• CuO-NiO complex metal oxides catalyzed glycerol production of lactic acid. • Significant heterogeneous junctions were observed by HRTEM. • CuO1NiO2 has excellent catalytic activity (90.08 % lactic acid yield). • DFT calculations revealed that Cu-Ni composite metal oxides are more likely to adsorb glycerol. • The differential charge density verifies that the formation of heterojunctions promotes charge transport and enhances electronic synergies. One of the most essential techniques to achieve effective usage of the principal by-product (glycerol) in the manufacturing of biodiesel is catalytic conversion of glycerol to lactic acid. In this paper, CuO-NiO composite metal oxides with different Cu/Ni molar ratios were prepared by co-precipitation method to catalyze the conversion of glycerol to lactic acid in alkaline medium. By using XRD, SEM, TEM, BET, XPS, and H 2 -TPR characterisation, the catalysts' crystalline phase, shape, and performance were assessed. The results show that the electronic synergy of CuO-NiO composite metal oxides plays a positive role in catalyzing the conversion of glycerol to lactic acid. The production of lactic acid might reach 90.08 % when Cu/Ni molar ratio (CuO1NiO2) and reaction conditions are optimum. In conjunction with the analysis using Density Functional Theory: due to the formation of heterojunctions in CuO1NiO2 the formation of good contacts between the atoms at the CuO and NiO interfaces is conducive to promoting charge transfer and electron mobility, thus enhancing the synergistic effect of electron transfer. Meanwhile, DFT calculations revealed that the Cu-Ni composite metal oxides had stronger adsorption energy for glycerol, which favored the bonding of glycerol on their surfaces. The prepared CuO-NiO composite metal oxides were used to catalyze the conversion of glycerol to lactic acid. [Display omitted] [ABSTRACT FROM AUTHOR]

Three seaweed patterns, axial seaweed, titled seaweed, and degenerate seaweed were acquired from the various growth directions on the {111} planes of an Al-4.5% Cu single crystal. The inherently ordered crystal, with a seemingly disordered morphology, was investigated using back-reflection Laue (BRL) pattern and electron backscattered diffraction (EBSD). Microstructural characterization of the crystal indicated that the growth orientation of the seaweed could be linked to the crystallographic direction 〈011〉, having a favorable order. The formation of those three seaweed morphologies is sensitive to the anisotropy of the surface tension or interface stiffness caused by the six-fold symmetry of the crystal. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The fatigue deformation behavior of δ-Ni 3 Nb (D0 a intermetallic phase in nickel-based superalloy) was analyzed in detail to determine its fracture characteristics and possible slip systems. Strong arrangement-dependence (i.e. arrangement direction of plate length relative to loading direction) deformation characteristics were observed. When δ plates were arranged not paralleling to the loading direction, they exhibited certain degree of fatigue resistance. Slip traces were found in the non-parallel δ plates after some fatigue cycles. By analyzing the traces and habit plane of δ, the possible operative slip systems were confirmed to be (010) δ [100] δ and (010) δ [102] δ. Unlabelled Image [ABSTRACT FROM AUTHOR]

Cu3N microcrystals were synthesized by a supercritical MeOH-NH3 technique with copper oxide and NH3 as copper and nitrogen source, respectively. The influence of reaction temperature on the fabrication of Cu3N particles was studied. The microstructures of products were characterized by XRD, SEM, FTIR, TG-DTA and XPS. Results show that product compositions depend greatly on the reaction temperatures and highly pure phase of Cu3N can be obtained at 250 °C. The as-prepared Cu3N displays a unique pyramidal morphology and the average edge length is 3–5 μm. Furthermore, the synthetic mechanism of Cu3N is also proposed. [ABSTRACT FROM AUTHOR]

Twinned dendrites and regular dendrites have been respectively produced in A356 alloy by Bridgman solidification. The primary trunks of twinned dendrites grew along <110> direction and were split by a coherent (111) twin plane were characterized by electron backscattered diffraction (EBSD), which is different from the <100> regular dendrites. The growth of twinned dendrites was found to have a rotation relationship around a common <110> direction. With respect to the specimens with regular dendrites, the mean tensile strength, elongation and toughness of the specimens with twinned dendrites were increased from 230 MPa to 239 MPa, 16.69–18.99%, 34.45 J/m 3 to 40.88 J/m 3 , respectively. Meanwhile, the coefficient of thermal expansion (CTE) of the specimen with twinned dendrites increase monotonically up to 2.28 × 10 − 5 K − 1 at temperature of 473 K. This CTE was successfully lowered than that of specimen with regular dendrites at the temperature above 323 K, and reaches the maximum decrease around 4.2% at 473 K. The fractures of two types of specimens were both originated from the Si-rich regions where dimples formed. In addition, detailed analyses on coherent twin boundary (CTB) of twinned dendrites by transmission electron microscope (TEM) and high-resolution TEM (HRTEM) indicate that the mechanisms of twin and dislocation-CTB interactions can enhance the strength and ductility of the A356 alloy with twinned dendrites. [ABSTRACT FROM AUTHOR]

Single crystal of iridium with two different orientations, [100] and [110] has been successfully prepared by electron-beam floating zone melting (EBFZM). The experimental results showed that the iridium single crystal with [100] orientation could be directly prepared without seeding at a low growth rate below 3 mm/min, and the single crystal with [110] orientation could be only obtained by seeding. The competitive growth of the bicrystal demonstrated that the [100] orientation of the iridium single crystal can overwhelm that of the [110] orientation at a growth rate of 2 mm/min. Moreover, the interface growth undercooling including curvature undercooling and kinetic undercooling has been calculated for iridium single crystal with these two orientations. The calculated data and analysis agree well with the experimental results. [ABSTRACT FROM AUTHOR]

Feathery crystals are an ensemble of twinned dendrites, and are characterized by a unique twin boundary (TB) structure in the solidification pattern of aluminum alloys. In this work, the high-density twinned dendrites of Al-4.5 wt% Cu alloys, produced during the Bridgman solidification, have been studied using electron backscattered diffraction (EBSD) and high-resolution transmission electron microscopy (HRTEM). The experimental results showed that, after systematically decreasing the growth rate from 3000 μm/s to 1 μm/s, the TBs remained stable, while the solute field around the TBs changed significantly. According to the HRTEM results, successive stacking faults were occurred near the TBs at 1 μm/s, while slight distortion was observed around the TBs at 3000 μm/s. The composition analysis revealed an obvious solute enrichment near the TBs. Furthermore, the solute gradient profile within the TBs became smoother with the decrease in the growth speed. This is due to the more sufficient solid-state back diffusion occurring perpendicular to the twin plane after the solidification. [ABSTRACT FROM AUTHOR]

Low temperature is one of the important limiting factors for growing season and geographical distribution of plants. Zoysiagrass (Zoysia Willd) is one of the widely used warm-season turfgrass that is distribute in many parts of the world. Zoysaigrass native to high latitude may have evolved higher cold tolerance than the ones native to low latitude. The objective of this study was to investigate the cold stress response in zoysiagrass native to diverse latitude at phenotypic, physiological and metabolic levels. Two zoysiagrass (Z. japonica) genotypes, Latitude-40 (higher latitude) and Latitude-22 (lower latitude) were subjected to four temperature treatments (optimum, 30/25°C, day/night; suboptimum, 18/12°C; chilling, 8/2°C; freezing, 2/-4°C) progressively in growth chambers. Low temperature (chilling and freezing) increased leaf electrolyte leakage (EL) and reduced plant growth, turf quality, chlorophyll (Chl) content, photochemical efficiency (Fv/Fm) and photosynthesis (Pn, net photosynthetic rate; gs, stomatal conductance; intercellular CO2; Tr, transpiration rate) in two genotypes, with more rapid changes in Latitude-22. Leaf carbohydrates content (glucose, fructose, sucrose, trehalose, fructan, starch) increased with the decreasing of temperature, to a great extend in Latitude-40. Leaf abscisic acid (ABA), salicylic acid (SA) and jasmonic acid (JA) content increased, while indole-3-acetic acid (IAA), gibberellic acid (GA3) and trans-zeatin ribside (t-ZR) content decreased with the reduction of temperature, with higher content in Latitude-40 than in Latitude-22. Chilling and freezing induced the up-regulation of C-repeat binding factor (ZjCBF), late embryogenesis abundant (ZjLEA3) and dehydration-responsive element binding (ZjDREB1) transcription factors in two genotypes, whereas those genes exhibited higher expression levels in Latitude-40, particularly under freezing temperature. These results suggested that zoysiagrass native to higher latitude exhibited higher freezing tolerance may attribute to the higher carbohydrates serving as energy reserves and stress protectants that stabilize cellular membranes. The phytohormones may serve signals in regulating plant growth, development and adaptation to low temperature as well as inducing the up-regulated ZjCBF, ZjLEA3 and ZjDREB1 expressions thus result in a higher cold tolerance. [ABSTRACT FROM AUTHOR]

By using the electron backscattered diffraction (EBSD) technique, pattern selection of twinned growth in Al-4.5 wt% Cu alloy has been studied in Bridgman solidification experiments. Based on the original twin planes formed at 3000 μm/s, the twinned growth was produced till the end of solidification after abruptly decreasing the growth rate to 100, 50, 20, 10, 5, 3, 1 and 0.3 μm/s. The stable twinned growth could be achieved during a wide range of solidification process. For the first time, the so-called twinned cell pattern was observed and prevailed in the solidified structure at 3 and less than 3 μm/s. The twinned growth in aluminum alloy was not limited to dendrite pattern as has previously been reported. The twinned pattern selection map was also revealed. Meanwhile, an interesting orientation rotation phenomenon was elucidated using EBSD technique on both sides of the coherent twin boundary during twinned cell growth. At a lower rate of 0.3 μm/s, the orientation rotation deflection concerning the original Σ3 60° twinning relation was confirmed. Some coincidence site lattice boundaries with higher Σ values served as the preferred states for this orientation deflection during growth. [ABSTRACT FROM AUTHOR]

A single crystal of Sb-doped Mg 2 Si 0.35 Sn 0.65 has been successfully prepared using high temperature-gradient directional solidification. The composition distribution of the crystal is uniform, and the preferred growth direction of the crystal is [111] orientation. The Seebeck coefficient ( S ) of the crystal is anisotropic in different orientations, and the electrical and thermal conductivity are isotropic properties. The S value in the [111] orientation can reach −265 μVK −1 , which is much larger than the reported results. Also, the power factor in the [111] orientation has a value of 5.56 mWm −1 K −2 , which leads to a maximum ZT of 1.3 at 730 K. Results of Hall testing and first principles calculations agree well with the experiment results. [ABSTRACT FROM AUTHOR]

The facile and fast synthesis of copper sulfide with controllable stoichiometric composition, crystal phase and shape, without using any additional surfactant and structure directing agent, is still highly attractive and remains a challenge. A supercritical methanol synthetic method was presented in this work, by which pure Cu 1.8 S and Cu 9 S 5 /CuS complexes with different particles size and phase composition could be synthesized by tuning the reaction temperature and time. It was demonstrated that higher temperature and longer time were beneficial to the formation of copper sulfides with higher Cu/S ratio and could cause obvious red shifts of band gap energies from 1.34 to 1.54 eV for copper sulfides. Furthermore, crystal phase evolution from Cu 9 S 5 to Cu 1.8 S was also observed in the preparation process. It was proposed that CuS was produced firstly by decomposing the complex Cu(CN 2 H 4 S) 2 (CH 3 COO) 2 , and then reduced to Cu 9 S 5 which was further evolved into Cu 1.8 S. [ABSTRACT FROM AUTHOR]

Based on the twin planes formed at 3000 μm/s, the growth stability of twinned dendrites in Al-4.5 wt% Cu alloy was studied in detail at a low growth rate during Bridgman solidification. Experimental results show that the twinned dendrite growth could still keep stable even after decreasing the rate to 20 μm/s. This is far below the usual rate threshold for the formation of twinned dendrites (∼1000 μm/s). The dominated twinned structures at 20 μm/s have their (1 1 1) twin plane and 〈1 1 0〉 dendritic trunk closest to thermal gradient direction. Importantly, distinct stacking fault (SF) structures directly connecting two adjacent twin boundaries provide a direct experimental evidence for the close correlation between the SFs and the twinned dendrite growth in aluminum alloys. [ABSTRACT FROM AUTHOR]

In this work, a Love wave biosensing platform is described for detecting cancer-related biomarker carcinoembryonic antigen (CEA). An ST 90°-X quartz Love wave device with a layer of SiO 2 waveguide was combined with gold nanoparticles (Au NPs) to amplify the mass loading effect of the acoustic wave sensor to achieve a limit of detection of 37 pg/mL. The strategy involves modifying the Au NPs with anti-CEA antibody conjugates to form nanoprobes in a sandwich immunoassay. The unamplified detection limit of the Love wave biosensor is 9.4 ng/mL. This 2–3 order of magnitude reduction in the limit of detection brings the SAW platform into the range useful for clinical diagnosis. Measurement electronics and microfluidics are easily constructed for acoustic wave biosensors, such as the Love wave device described here, allowing for robust platforms for point of care applications for cancer biomarkers in general. [ABSTRACT FROM AUTHOR]

Solid-state cooling based on elastocaloric effect possesses potential for refrigeration. The improvement of elastocaloric effect and thermal cycle stability is beneficial to enhance the refrigeration efficiency and service life of refrigeration equipment. Here, single-crystal Ni 50 Mn 31.6 Ti 18.4 shape-memory alloys were successfully prepared using directional solidification technique. The microstructure, martensitic transformation, isothermal stress-strain responses and elastocaloric effect of the single crystals with different solidification rates have been systematically studied. The single crystal solidified at 10 µm s−1 exhibits lower stress hysteresis Δ σ hy and much more superior adiabatic temperature |Δ T ad | than those of alloys solidified at 100 µm s−1 and 500 µm s−1, with the values of 34 MPa and 24.8 K. In addition, the single crystal at low solidification rate also performs excellent cyclic stability. All these results show that the single crystal with larger austenite primary dendrite arm spacing (PDAS) can effectively enhance the elastocaloric effect and thermal cycling stability in Ni 50 Mn 31.6 Ti 18.4 alloys. This work sheds a bright light on the relationship between the elastocaloric performance and microstructure for shape-memory alloys. • Single-crystal Ni 50 Mn 31.6 Ti 18.4 alloys were successfully prepared by directional solidification. • The alloy with large primary dendrite spacing has the excellent adiabatic temperature of 24.8 K. • Single-crystal prepared with larger primary dendrite spacing can effectively enhance the thermal cycling stability. [ABSTRACT FROM AUTHOR]

Copper sulfides were synthesized through a fast and simple subcritical and supercritical methanol technique by controlling the reaction temperature. CuS and Cu 9 S 5 microcrystals with different particle sizes and morphologies were prepared. The composition, morphology, and structure of the products were analyzed using XRD, SEM, TEM, DLS, XPS, and FTIR. UV–vis was used to investigate their optical behaviors. Results show that spherical CuS and polyhedral Cu 9 S 5 with an average size of 200–600 and 200–500 nm were obtained at 150 and 260 °C for 15 min in subcritical and supercritical methanol, respectively. The UV–vis absorption spectroscopy of the samples reveals that the band gap energies of CuS and Cu 9 S 5 were 1.77 and 1.55 eV, respectively. CuS exhibited excellent photocatalytic degradation of methylene blue (MB) without the use of hydrogen peroxides, showing 85.4% degradation rate of MB after 5 h irradiation. [ABSTRACT FROM AUTHOR]

Un-doped Mg 2 Sn single crystal has been revealed to be anisotropic in Seebeck coefficient at different orientations and possesses orientation-dependent conduction sign reversal (OCSR). At room temperature, the [111] orientation of the crystal shows the n-type conduction with a Seececk coefficient value of −265μVK −1 and the p-type conduction behavior in the [ 1 1 ¯ 0 ] and [ 11 2 ¯ ] orientations with 148μVK −1 and 115μVK −1 , respectively. First principle calculation on the anisotropic Seebeck coefficient of the crystal matches well with the experimental results, showing that the conducting effective mass plays an important role in determining the value of Seebeck coefficient. The single crystal Mg 2 Sn with the preferred [111] orientation is expected to have the best thermoelectric performance due to its large Seebeck coefficient value and the same electrical and thermal conductivities compared with other orientations of the crystal. [ABSTRACT FROM AUTHOR]

To improve the direct quantification of Carcinoembryonic Antigen (CEA) from body fluids by immunofluorescence, a surface acoustic wave (SAW) based biosensor was developed combined with an optimized silver nanostructure at the sensing region. Fluorescence signal amplification is achieved by patterning silver nanostructures using the rapid thermal annealing (RTA) method. In addition, the problem of background noise interference from nonspecific binding in human plasma is addressed by Rayleigh wave streaming at the immunoassay region, which shows a reduction in the limit of detection. The results show that the silver nanostructures significantly increase the sensor sensitivity by 49.99-fold and lower the limit of detection of CEA in phosphate buffered saline (PBS) solution to 101.94 pg/mL. The limit of detection of CEA biomarker in human plasma was successfully brought down to 11.81 ng/mL by reducing background noise using Rayleigh SAW streaming. This allows for a point-of-need sensor system to be realized in various clinical biosensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Phase selection under far-from-equilibrium condition has been investigated in three Cr 2 Nb-20/30/40Ti (at. %) alloys processed by laser surface melting (LSM) with scanning speeds of 50–200 mm/s. Phase identification was performed by micro-area XRD technique combined with SEM plus EDS methods. The results show that, at all scanning speeds of 50–200 mm/s, the microstructure of Cr 2 Nb-20Ti alloy consisted of single-phase Cr 2 Nb, whereas it evolved to monolithic β-Ti in the Cr 2 Nb-40Ti alloy. Meanwhile, the microstructure of Cr 2 Nb-30Ti alloy solidified with eutectic β-Ti/Cr 2 Nb at 50 mm/s, which transited to monolithic β-Ti as scanning speeds increased to 100–200 mm/s. Microstructures evolution was interpreted based on Trivedi-Magnin-Kurz (TMK) and Kurz-Giovanola-Trivedi (KGT) models incorporating the effect of non-equilibrium solidification. After the process of LSM, the micro-hardness of Cr 2 Nb-20Ti alloy was improved to a level of 9.0 GPa, and the fracture toughness was reduced to about 3.1 MPa m 1/2 ; while for the Cr 2 Nb-30/40Ti alloys, the micro-hardness decreased within a range of 5.5–6.6 GPa, but with a great increase of facture toughness of 21–23 MPa m 1/2 . [ABSTRACT FROM AUTHOR]

• Finding plate-like and hyperbranched seaweed in 3D conditions of metallic alloy. • Constructing a non-regular dendritic pattern selection map. • Well understanding effect of interface energy anisotropy on the dendritic pattern. Dendritic morphology and pattern selection are fundamentally important issues in solidification cycles. Here, a well-designed experiment was employed to investigate the solid–liquid interface energy anisotropy on the directionally solidified microstructures of Al-3 wt% Mg single crystals. Various dendritic morphologies, including regular dendrite, plate-like seaweed and hyperbranched seaweed, were found along the <100>, <110> and <111> orientations, respectively. The primary dendritic arm spacing (PDAS) of the seaweed pattern is closely related to the interface energy anisotropy and deviates from the current PDAS model. A non-regular dendritic pattern selection map is constructed to interpret the different dendrites occurring in alloy solidification. [ABSTRACT FROM AUTHOR]

Twinned dendrites were successfully produced with high reproducibility in Al–4.5 wt.% Cu alloys at various growth speeds ( V ) of 100, 200, 500, 1000, 1500 and 2000 μm s −1 during Bridgman solidification. Under a relatively high thermal gradient ( G , around 200 K cm −1 ), the growth speed condition necessary for the twinned dendrite growth has been broadened. Experimental results indicate that the increase in growth speed has substantially changed the twinned morphologies. Importantly, the isolated twinned dendrite growth was observed at the growth speeds less than 1 mm s −1 (100, 200, and 500 μm s −1 ). At higher growth speeds, the finer twinned dendrites developed the usual appearance of an ordered sequence of alternating twinned and untwinned lamellae. The G / V value is considered as the critical factor for the isolated or usual twinned dendrite growth. A detailed analysis of the melt flow confirms that the slight convection during Bridgman solidification is large enough for the twinned dendrite growth. Furthermore, a visualized way to evaluate the velocity of the in-plane twinned extension was provided and the extension velocity was typically one third of the growth speed (500 μm s −1 ). Based on frequent “penetration” growth phenomena among secondary arms, a possible lateral propagation mechanism of the twinned dendrites has been hypothesized. [ABSTRACT FROM AUTHOR]

In this work, silica‐based ceramic cores with alumina as a mineralizer were prepared via an injection molding method, and the effects of alumina on the microstructural evolution and properties at 1450°C (simulating the process of equiaxed castings) and 1550°C (simulating the process of columnar/single crystal castings) were investigated. It was found that alumina promoted the cristobalite crystallization of fused silica refractory during sintering but inhibited the devitrification rate in the subsequent heating. The flexural strength of silica‐based ceramic cores at an ambient temperature and 1450°C improved with an increasing alumina content, whereas the opposite trend appeared at 1550°C. The creep resistances of silica‐based cores were improved significantly and then slightly deteriorated with an increasing alumina content from 5% to 20%, depending on the competition effects of alumina hindering the viscous flow of liquid silica (favorable), but suppressing the devitrification rate (unfavorable). The results of this work show that silica‐based cores need to follow different compositional design principles for equiaxed and columnar/single‐crystal turbine blade castings. [ABSTRACT FROM AUTHOR]

A simple and potentially scalable sub- and super-critical methanol technique was applied to synthesize cuprous oxide. CuO microcrystals with two morphologies were obtained in methanol of subcritical domain by adjusting the feeding methods. The effects of the reaction time, temperature, pressure, and feeding method on the formation of CuO microcrystals were investigated. XRD, SEM, and XPS were applied to analyze the composition and morphology of products. Results showed that pure cuprous oxide could be obtained in subcritical methanol of 230 °C, 7.8 MPa for 15 min. The two as-obtained products displayed octahedral and cubic morphology with an average edge length of 4 and 2 μm by solution and solid feeding methods, respectively. The formation and crystal growth mechanism of CuO in subcritical methanol were also proposed on the basis of above results. Furthermore, the two microcrystals were employed as catalysts in the photodecomposition of negatively charged molecule methyl orange. Results showed that both microcrystals possessed excellent photocatalytic activities. However, the obvious difference between cubic and octahedral in photocatalytic performance was not found in the scale of micrometer (2-4 μm). [ABSTRACT FROM AUTHOR]

Columnar-to-Equiaxed Transition (CET) of binary Ti–Al alloys and multi-component Ti–48Al–2Cr–2Nb alloys is studied using Bridgman solidification technique. The effect of aluminum concentration and growth rate on CET is determined. It is found in Ti–46Al and Ti–50Al alloy ingots equiaxed grains develop ahead of the moving solid–liquid interface with a growth rate of 500 μm/s; microstructures in Ti–49Al alloy stay columnar dendrites with the same growth rate. CET in Ti–Al alloys are not only influenced by growth rate, but also by the solidification path that is related to alloying composition. CET in Ti–Al alloys is predicted using the dendritic growth model based on the criterion of growth at marginal stability. According to the calculated results and directionally solidified microstructures, values of the nucleation undercooling for α and β phases are given. The growth rates to avoid CET in Ti–48Al–2Cr–2Nb alloy are suggested. [ABSTRACT FROM AUTHOR]

The influence of electronic structure and doping level on the thermoelectric transport properties of BiSb 3 Te 6 compound was investigated using first-principle calculations and Boltzmann transport theory. The calculation results indicate that BiSb 3 Te 6 is a narrow gap semiconductor with an indirect band gap of 0.113 eV. The calculated band structures of the compound present nonparabolic curves with multi-valley band property. The density of states is enhanced below a few tenths of Fermi energy and the bands are flatted with heavy effective mass. The calculated thermoelectric coefficients of BiSb 3 Te 6 are anisotropic and mainly dependent on the doping concentrations. The dopant dependences of ZT values are given with the optimal carrier concentrations ∼10 19 cm −3 . This theoretical investigation gives a valuable insight into the relationship between the electronic structure and thermoelectric transport properties of BiSb 3 Te 6 material, and provides a quantificational doping level to improve the thermoelectric performance. [ABSTRACT FROM AUTHOR]

A series of MoVTeNbO x -mixed metal oxides were synthesized by high-pressure hydrothermal method. The effects of temperature and time during the preparation process on the structure and catalytic performance of MoVTeNbO x were investigated. It was demonstrated that high content of M1 phase (94.5%) MoVTeNbO x with typical needle-shape morphology and high surface abundance of V5+ (68.9%) could be fabricated by high-pressure hydrothermal method in a short time (30–60 min) without hydrogen peroxide post-treatment. The catalytic results of propane selective oxidation showed that the MoVTeNbO x sample synthesized at 200 °C for 30 min possessed the highest surface V5+ abundance and largest proportion of terminating (001) plane, displaying the highest selectivity (74.1%) for acrylic acid. Moreover, the prepared MoVTeNbO x showed excellent stability in high temperature continuous reaction. [Display omitted] • MoVTeNbO x was fabricated facilely by high-pressure hydrothermal technology. • This developed method could shorten preparation time dramatically. • High content M1 phase MoVTeNbO x could be obtained without H 2 O 2 post-treatment. • Synthesized MoVTeNbO x had high surface V5+ abundance of 68.9%. • As prepared MoVTeNbO x exhibited excellent catalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: Al–40% Cu hypereutectic alloy samples were successfully directionally solidified at a growth rate of 10μm/s in different sizes (4mm, 1.8mm, and 0.45mm thickness in transverse section). Using the serial sectioning technique, the three-dimensional (3D) microstructures of the primary intermetallic Al2Cu phase of the alloy can be observed with various growth patterns, L-shape, E-shape, and regular rectangular shape with respect to growth orientations of the (110) and (310) plane. The L-shape and regular rectangular shape of Al2Cu phase are bounded by {110} facets. When the sample size was reduced from 4mm to 0.45mm, the solidified microstructures changed from multi-layer dendrites to single-layer dendrite along the growth direction, and then the orientation texture was at the plane (310). The growth mechanism for the regular faceted intermetallic Al2Cu at different sample sizes was interpreted by the oriented attachment mechanism (OA). The experimental results showed that the directionally solidified Al–40% Cu alloy sample in a much smaller size can achieve a well-aligned morphology with a specific growth texture. [Copyright &y& Elsevier]

Copper powder with different sizewas synthesized using subcritical/supercriticalmild alcohols without additional reductant. The interaction influenceof the reducing atmosphere, including temperature, pressure, precursors,and alcohol types, was investigated. XRD and SEM were applied to analyzethe composition and morphology of products synthesized. Results showedthat the reducing atmosphere formed by critical conditions, precursors,and mild-alcohol types had a significant effect on the products. Thereducing atmosphere could be enhanced obviously with higher temperatureand pressure. CuO was easier to reduce than Cu(NO3)2and CuSO4under the same conditions. Comparedwith ethanol, methanol could form a stronger reducing atmosphere atthe same temperature and pressure. Supercritical methanol (250 °C,9 MPa) with CuO as a precursor could provide the optimal reducingatmosphere for the synthesis of copper powder. In addition, it wasproposed that mild alcohols should play an important role as cappingagents as well as reducing agents under subcritical/supercriticalconditions. [ABSTRACT FROM AUTHOR]

The microstructures and orientations of Al-40%Cu hypereutectic alloy prepared in a 0.45 mm high-purity alumina crucible at different directional solidification rates (5, 10 and 100 μm/s) were investigated. With solidification rate increasing, the primary phase Al2Cu of the alloy transits from complex dendrite morphologies to regular faceted square shapes. The surfaces of regular square morphology about Al2Cu phase are {110} facets. The orientation text results by XRD showed that at a growth rate of 5 μm/s, the phase displayed texture orientations at (310), (110), and (220). At 100 μm/s, the phase possessed a very strong preferred orientation at (310). The experimental results showed that growth in small-size samples at a higher growth rate can achieve a regular microstructure with preferred orientation. The growth morphologies are deduced from attachment energies descripted the microstructure evolution of the primary phase. [ABSTRACT FROM AUTHOR]

Abstract: The influence of temperature and pressure on the mechanical and thermodynamic properties of single crystal Bismuth Telluride material was investigated by the first-principle calculation and quasi-harmonic Debye model. The computation results indicated that the lattice constant in the c axis increases nonlinearly and the elastic constants Cij and bulk module B 0 increase linearly with increasing the pressure. The Young modulus of the Bi2Te3 crystal in the x and y axes are 28.6% larger than that in the z axis. The Poisson’s ratios along the three axes range from 0.2752 to 0.3853. When the temperature is less than 150K, the lattice specific heat capacity of Bi2Te3 depends on the temperature. The thermal expansion coefficients of Bi2Te3 vary remarkably with the temperature and pressure. The chemical balance bonding of Bi2Te3 is predicated to be based on the density functional theory, revealing the evident natural bonding interaction between Bi–Te and Te–Te. Those calculations are in good agreement with previous experimental data. [Copyright &y& Elsevier]

Al-4.5wt.%Cu alloy has been directionally solidified at constant and abruptly changing withdrawal rates, respectively. The effects of the withdrawal rate on solidification microstructure, primary dendrite arm spacing (PDAS) and liquid solute distribution in front of the solid-liquid interface were investigated. The experimental results for the PDAS at a constant withdrawal rate agree well with the values calculated by the Hunt, Trivedi and Hunt-Lu models. At an abrupt change in the withdrawal rate, the maximum to minimum ratio of the PDAS at a given solidification parameter, i.e. λ1 max/λ1 min, is more than 2, and the PDAS values are remarkably history-dependent. Further, the liquid-solute distribution curve based on theoretical calculation shows that the larger the initial withdrawal rate is, the smaller the minimum of liquid solute concentration in front of the solid-liquid interface is after the abrupt change in withdrawal rate. [ABSTRACT FROM AUTHOR]

• A two-step method was utilized to synthesize multi-element doped Ce 0.3 Ni 1.5 Co 2.5 Sb 12 film efficiently. • Well-crystallized CoSb 3 and CeSb coexisted, leading to a positive effect on electrical properties. • The maximum value of S and PF reach −250 μV/K and 5275 μW/(mK2) for Ce 0.3 Ni 1.5 Co 2.5 Sb 12 film at 673 K. The skutterudite CoSb 3 has been widely concerned, as one of the most studied candidate materials for thermoelectric applications. Here, n-type bulk skutterudite Ce 0.3 Ni 1.5 Co 2.5 Sb 12 was successfully prepared under TGZM effect and its thin film deposited by PLD on single crystal Si substrate, to further understand the effect of microstructure and the electrical transport mechanism on the thermoelectric properties from bulk to thin film. It is found that two phases of Sb and CoSb 3 coexist in bulk sample, while abundant nano-granular structures with well-crystallized CoSb 3 and little of CeSb generate in the film. As a result, the maximum value of S and PF reach −250 μV/K and 5275 μW/(mK2) for film sample at 673 K. The PF value of film is four times higher than that of the bulk sample. This provides a novel avenue to increase the thermoelectric properties of skutterudite. [ABSTRACT FROM AUTHOR]

Abstract: Microstructure and mechanical properties of a binary Cr2Nb-based alloy containing the Laves phase Cr2Nb and Cr phase have been studied in the arc-melted condition. Microstructure consisting of fully coupled eutectic was firstly observed in this hypereutectic alloy. The Cr2Nb primary phase experienced a faceted to nonfaceted transition as the solidification distance increased. Based on the maximum interface growth temperature criteria, the microstructure evolutions in this alloy were explained successfully by means of the competitive growth between the β-Cr2Nb phase and eutectic. Meanwhile, the yield strength and fracture toughness of the samples taken from the bottom of the ingot attained 1986MPa and 4.3MPa⋅m1/2 respectively, which were considerably enhanced over the monolithic Cr2Nb. The enhancements were explained in terms of the second Cr phase toughening and grain boundary toughening mechanisms. Furthermore, the variation of mechanical properties in different position of arc-melted ingot was proven to result in different eutectic fracture mechanisms. [Copyright &y& Elsevier]

Abstract: A method of high-performance liquid chromatography–tandem mass spectrometry (LC–MS-MS) has been developed for the trace analysis of paclitaxel and other six taxoids in three Taxus species including Taxus cuspidata, Taxus media and Taxus chinensis var. mairiei. Seven taxoids were separated using a gradient mode on an Eclipse XDB-C18 column (4.6×150mm; i.d., 5μm) at 20°C. The compound separations were detected by an API 3000 mass spectrometer equipped with a TurboIonSpray™ interface. The compounds were detected using electrospray ionization (ESI) in positive-ion mode and quantified by multiple-reaction monitoring (MRM) mode using the transition mass of m/z 567.4→445.4, 609.3→549.5, 944.9→286.4, 812.6→286.1, 832.8→264.1, 854.4→286.1, and 812.6→286.1 for 10-DAB III, baccatin III, 7-xyl-10-DAT, 10-DAT, cephalomannine, paclitaxel, and 7-epi-10-DAT, respectively. The ranges of limit of quantitation (LOQ) for taxoids were 32, 14, 26, 14, 20, 32, and 26ng/mL for 10-DAB III, baccatin III, 7-xyl-10-DAT, 10-DAT, cephalomannine, paclitaxel, and 7-epi-10-DAT, respectively. Linearity was confirmed over the whole calibration range (0.07–45, 0.058–37.5, 0.058–37.5, 0.056–36.3, 0.053–33.8, 0.057–37.5, and 0.06–38.8μg/mL for 10-DAB III, baccatin III, 7-xyl-10-DAT, 10-DAT, cephalomannine, paclitaxel, and 7-epi-10-DAT, respectively) with coefficients higher than 0.9903. The inter- and intra-day precision of taxoids ranged from 2.86% to 6.31% for retention time and ranged from 3.91% to 7.33% for peak area. The recovery rates of this method were higher than 94.32% for 10-DAB III, 94.68% for baccatin III, 93.65% for 7-xyl-10-DAT, 93.29% for 10-DAT, 92.91% for cephalomannine, 93.41% for paclitaxel, and 93.06% for 7-epi-10-DAT, respectively. [Copyright &y& Elsevier]

Abstract: Directional solidification experiments were performed on hyperperitectic Nd13.5Fe79.75B6.75 alloy using a Bridgman type furnace. The relationship between secondary dendrite arm spacing (λ 2) of primary γ-Fe phase as a function of growth velocity (V) was established. Experimental results show that λ 2 decreases with increasing V and give a constant value λ 2 V 0.33 of 5×10−7 m1.33 s−0.33. Using arm coarsening theory, secondary arm spacing of γ-Fe dendrites was calculated, during which temperature gradient changing with growth velocity in the experiment was taken into account. The calculation gives a constant value λ 2 V 0.31 of 8×10−7 m1.31 s−0.31. Theoretical predictions are in reasonable agreement with experimental results. In peritectic reaction, the dissolution rate of γ-Fe dendrite arms varied from 0.0061 to 9.1μm/s, as the growth velocity increased from 1 to 100μm/s. The dissolution rate of γ-Fe dendrites was extremely small in low-velocity specimens with plane front peritectic interfaces. [Copyright &y& Elsevier]

Based on the Boltzmann transport theory combined with first-principles calculations, we analyze the lattice anharmonicity of SnTe and the respective contributions of the lattice thermal conductivity (κ L) from six different phonon modes. The Grüneisen parameter (γ), three-phonon scattering phase space (SPS), phonon lifetime (τ), and phonon velocity (v) were obtained quantitatively. These calculations indicate that large τ with maximum value of 104 ps and high v of 4800 m/s for acoustic branches make the acoustic modes a major contributor to the high κ L of SnTe (～78% for acoustic branches and ～22% for Optical branches). Further, the dependence of κ L on phonon mean free path shows that designing nanostructures with characteristic length of less than 14.5 nm could be an effective way to decrease the κ L. In addition, we employed high-temperature gradient directional solidification technique to grow the SnTe single crystal and the measured κ L vaules of the single crystal match reasonably with the theoretical calculation results. • Lattice anharmonicity of SnTe was investigated based on first-principles calculations. • The respective contributions of κ L from six different phonon modes were computed quantitatively. • The theoretical calculation results of the κ L agree well with the experimental values of the single-crystal SnTe. • Designing nanostructures with characteristic length of less than 14.5 nm could be an effective way to decrease the κ L. [ABSTRACT FROM AUTHOR]

Abstract: Bridgman type directional solidification experiments were carried out in Nd14Fe79B7 alloy. Microstructure evolutions along with growth velocities were investigated. At low velocities from 1 to 200μm/s, the microstructures consisted of leading α-Fe dendrites and peritectic Nd2Fe14B phase in the interdendritic region. At medium velocities of 425 and 500μm/s, an incomplete banded structure formed, containing circles of α-Fe/Nd2Fe14B–Nd2Fe14B dendrites. At high velocities of 1, 3 and 5mm/s, a transition from γ-Fe dendrites to Nd2Fe14B dendrites occurred. Phase selection phenomena were theoretically studied using the extremum criterion which assumes growth-controlled phase selection. The theoretical results are in agreement with experimental results at low velocities of 1–200μm/s and high velocities of 3 and 5mm/s. The incomplete dendritic bands at 425 and 500μm/s were explained by nucleation of Nd2Fe14B phase at the γ-Fe dendritic interface, and growth competition between γ-Fe and the nucleated Nd2Fe14B phase. Phase transition from γ-Fe to Nd2Fe14B at 1mm/s was interpreted by abundant nucleation and quick growth of Nd2Fe14B phase at the γ-Fe dendritic interface. [Copyright &y& Elsevier]

Abstract: Microstructure evolution of Ni–24.19wt%Nb hypereutectic alloys was investigated to develop a method to increase the productivity of in situ composite in directional solidification. The results show that at the constant growth velocity of 10μm/s, coarse priamry β-Ni3Nb plate dendrites were firstly precipitated from the liquid. However, at the growth velocity changing abruptly from 1μm/s to 10μm/s, only coupled growth eutectics were observed in the solidification microstructure. The coupled eutectic growth stable at 10μm/s is possibly ascribed to the interface growth temperature of coupled eutecitc exceeding that of β-Ni3Nb single phase. Another probable factor to permit the coupled eutectic growth stable at 10μm/s is the difficult nucleation of β-Ni3Nb phase in front of the eutectic growth interface. By changing solidification process, the productivity for the formation of in situ composite of Ni–24.19wt%Nb hypereutectic alloy is improved by a factor of 5. [Copyright &y& Elsevier]

Abstract: A dual-frequency electromagnetic field is developed to smelt the solid metal and confine the molten metal into a final shape without any contamination. The process of the dual-frequency electromagnetic containerless confinement is controlled more easily than that of a single-frequency electromagnetic confinement. The dual-frequency electromagnetic pressure of 350 and 50kHz is analyzed and calculated as the sum of two single-frequency electromagnetic pressures by the superposition principle. By designing a suitable pattern of induction heating and electromagnetic confinement inductors, which produce electromagnetic pressure to balance static pressure of the height of the liquid metal, various cross-section shaped aluminum samples were successfully confined. [Copyright &y& Elsevier]

The concept of the dual-frequency electromagnetic (EM) shaping of liquid metal is first presented. The experiment of dual-frequency with 350 and 50 kHz EM shaping is successfully carried out. It is shown that the process of dual-frequency with 350 and 50 kHz EM shaping is implemented more easily than that of dual-high frequency with 350 and 200 kHz EM shaping, because the EM pressure with 350 and 50 kHz is large enough to balance the hydrostatic pressure of the liquid metal. By changing the shape of the solid metal and designing suitable heating and shaping coils, dual-frequency EM shaping experiments have been successfully realized to shape circular, elliptical and meniscus cross-sections, some new features in dual-frequency EM shaping are discussed. [Copyright &y& Elsevier]

• The nanostructured Te-SnTe composites were successfully prepared via a rapid fabrication process. • The eutectic Sn-90at%Te composite exhibits an enhanced thermoelectric performance. • An ultralow lattice thermal conductivity could be obtained for the Sb doped eutectics. • The improved thermoelectric properties for the eutectic system provide a new strategy to explore high-performance materials. The eutectic Te‒SnTe composites were successfully prepared via a melt spinning method combined with a spark plasma sintering technique. The differences in thermoelectric properties for alloys near the eutectic composition were investigated. These composites could benefit from both the higher electrical conductivity of the SnTe phase and the superior Seebeck coefficient of the Te phase. The eutectic Sn-90at%Te composite exhibits an enhanced thermoelectric performance. Its maximum ZT is 1.8–2.1 times higher than that of pristine SnTe and Te materials. Upon doping with the Sb element, the electrical transport behavior could be further improved. Large amounts of grain boundaries and phase interfaces can readily scatter phonons. Combined with the extra scattering from nanoprecipitates, dislocations, and strain fields, an ultralow lattice thermal conductivity of 0.49 W m−1 K−1 could be obtained for the Sn-90at%Te-2.0at%Sb alloy at 633 K. The improved thermoelectric properties for the Te‒SnTe eutectic system provide a new strategy to explore high-performance materials. [ABSTRACT FROM AUTHOR]

Skutterudite compounds, the structure of "phonon glass electron crystal" (PGEC), possess excellent thermoelectric properties. Here, temperature gradient zone melting combined with hot pressing technique (TGZM-HP) was employed to synthesize n-type skutterudite Ce x Ni 1.5 Co 2.5 Sb 12 thermoelectric material. By doping element Ce, the carrier concentration of the alloy was optimized efficiently and the total thermal conductivity declined. For the TGZM-HP Ce 0.6 Ni 1.5 Co 2.5 Sb 12 alloy, the power factor PF reaches to 1350 μW/(mK2), and the lattice thermal conductivity is dropped to 1.62 Wm−1K1 at 850 K, corresponding to an improved figure of merit ZT of 0.45. Importantly, compared with the traditional synthesis methods, this technique can precisely control the formation of thermometric phase and the preparation time is reduced remarkably. • A novel approach named TGZM-HP is proposed to synthesize single-phase CoSb 3 efficiently. • A low thermal conductivity of 2.76 Wm−1K-1 was obtained for the Ce 0.6 TGZM-HP alloy at 884 K. • It is convenient for further understanding "phonon glass electron crystal" (PGEC) structure. [ABSTRACT FROM AUTHOR]

SnTe based materials have attracted considerable attention owing to their eco-friendly nature. Here, we employed a melt spinning method combined with spark plasma sintering (MS-SPS) technique to optimize the electrical and thermal transport performance of SnTe based alloys. Doping with Sb optimizes carrier concentration efficiently, leading to an enhanced Seebeck coefficient and power factor. Unlike the original phonon dispersion relation, the introduction of Sb heightens the phonon-phonon interaction and flattens the phonon dispersion, resulting in a significant decline in the phonon group velocity. Combined with the enhanced scattering from lattice distortion, nanoprecipitates and large amounts of grain boundaries, an ultralow lattice thermal conductivity of 0.57 Wm−1K−1 was obtained for Sn 0.91 Sb 0.18 Te 1.18 MS-SPS alloy. An improved ZT value of 0.95 can be realized, which is 2.2 times higher than that of pure SnTe alloy. The enhanced phonon scattering and reinforced phonon-phonon interaction give valuable access to develop high-performance SnTe based thermoelectric materials. • Melt spinning followed by spark plasma sintering technique was employed to prepare nanostructured materials. • Introduction of element Sb changes the phonon dispersion relations of SnTe based materials. • An ultralow lattice thermal conductivity of 0.57 Wm−1K−1 was obtained for Sn 0.91 Sb 0.18 Te 1.18 alloy. • Nanostructuring is effective to enhance the thermoelectric performance. [ABSTRACT FROM AUTHOR]

Bulk NbCr 2 samples with ultra-fine grains have been fabricated by mechanical milling and subsequent spark plasma sintering. The room-temperature fracture toughness of these bulk samples achieves as high as 11.3 ± 0.5 MPa m1/2, which is remarkably improved compared to the as-cast monolithic NbCr 2 Laves phase (1.2 MPa m1/2). The microstructural analysis indicates the presence of abundant non-equilibrium Nb and Cr solid solutions among the grain boundaries. The formation of Nb and Cr solid solutions is attributed to the applied pulsed electric current during spark plasma sintering, which can decrease the critical nucleation undercooling, accelerate the atomic diffusion and enhance the nucleation rate. Based on the microstructural characterization, the enhancement in fracture toughness is ascribed to formation of non-equilibrium Nb and Cr solid solutions toughening and grain boundary toughening mechanisms. Furthermore, strong texture components have been detected in these bulk samples. For the sample sintered with the powder milled for 30 h, the <100> direction of NbCr 2 Laves phase is perpendicular to the compressive axis while the Nb and Cr solid solutions show random orientation. When sintered with the powder milled for 60 h and 90 h, the texture component in NbCr 2 Laves phase transforms into <110> fiber texture, and the Cr solid solution also show strong <100> and <110> texture components perpendicular to the compressive axis. The evolution of texture component is discussed by considering the crystallization behaviour of the milled powders. • Ultra-fine NbCr 2 bulks have been produced by mechanical alloying and spark plasma sintering. • The fracture toughness of the bulks attains 11.3 ± 0.5 MPa m1/2, which is 9.3 times of NbCr 2. • Non-equilibrium Nb and Cr solid solutions are detected among the NbCr 2 grain boundaries. • The NbCr 2 Laves phase and non-equilibrium Cr solid solutions show strong texture. • The texture in NbCr 2 Laves phase transformed from <100> to <110> with the increase of milling time. [ABSTRACT FROM AUTHOR]

A quinary Cr–12Nb–5Ti–5Mo–5Si (at.%) alloy was prepared by arc melting in this study to improve the strength and toughness of Laves phase Cr 2 Nb alloy. The quinary alloy was solidified with full eutectic Cr 2 Nb/Cr, in which the Cr 2 Nb phase exceeded 55 vol % and existed as matrix. The eutectic was developed with an orientation relationship of {001}Cr 2 Nb//{001}Cr, leading to a low lattice mismatch of 15.57% at the eutectic interface. The yield strength and fracture toughness of the quinary alloy reached 1950–1980 MPa and 14.0–14.8 MPa⋅m1/2, respectively, much higher than most reported Cr 2 Nb alloys. The reason for the superior properties is the synergistic effects of solid solution strengthening, alloying toughening, and eutectic strengthening-toughening. • The alloy Cr–12Nb–5Ti–5Mo–5Si was solidified with full eutectic Cr 2 Nb/Cr. • The orientation relationship of the full eutectic was {001}Cr 2 Nb//{001}Cr. • The improved strength and toughness was achieved in the quinary alloy. • Relevant strengthening and toughening mechanisms were discussed. [ABSTRACT FROM AUTHOR]