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The paper uses X-ray diffraction (XRD) at different temperatures and both imaging and X-rays energy-dispersive spectroscopy (XEDS) in the SEM to examine changes that occur in this high-entropy oxide. The paper was handled by David Cann, one of our Editors whose own research emphasizes ceramics; it is entitled "Phase equilibria and metastability in the high-entropy A SB 6 sb B SB 2 sb O SB 17 sb oxide family with I A i = Zr, Hf and I B i = Nb, Ta." The paper is essentially a classical study of a ceramic material with the twist that these high-entropy ceramics had not been recognized as such until quite recently. [Extracted from the article]

Numerous catalysts have been studied and developed to catalyze the decomposition of methane and in this paper, an iron slab is selected as the catalyst to obtain stable Fe3C and C2 during the decomposition of methane. We combine ReaxFF MD simulations and laboratory work to investigate methane decomposition and carburization of carbon atoms. The analysis of XRD and TEM confirms the Fe3C formed after the reaction and demonstrates its microscopic morphology. Simulations reveal that the iron slab accelerates the primary decomposition of CH4 in the meantime promotes the synthesis of hydrogen molecules and the whole carburizing reaction mechanism has been characterized by the formation of Fe3C and diffusion of C atoms which has been described with carburizing depth. Finally, the influence of methane concentration is explored and the result shows that an appropriate enhancement accelerates the carburizing reaction while the excessive increase will inhibit it. [ABSTRACT FROM AUTHOR]

A facile, green method for fabrication of conductive ink composed of Ag flakes was developed for use in flexible printed electronics. The Ag flakes were prepared using AgNO3, nontoxic L-ascorbic acid (Vc) and polyvinylpyrrolidone (PVP) serving as a metal salt, reducing agent and capping agent, respectively. The prepared Ag flakes were characterized by XRD, SEM, and TGA. The combination of PVP and FeCl3 was found to be critical for the formation of the Ag flakes, and reaction activity was affected by temperature. Samples obtained at 140 °C were composed of Ag flakes with an average size of 0.94 ± 0.3 μm. A new fabrication method for producing conductive patterns was designed using a syringe with varying dispersion areas, allowing the ink (Ag flakes and organic solvent) to be applied directly onto a flexible photo paper. The conductivity and flexibility of the pattern were experimentally tested under varying reaction temperatures and bending cycles. Increasing contact area and packing density between Ag flakes resulted in an improved conductivity of the bending pattern. After more than 5000 bending cycles, the patterns were sintered at 160 °C and the resistivity increased from 4.6 ± 0.6 to 22.4 ± 0.8 μΩ cm, acceptable values for practical applications. Sample conductive lines drawn by the Ag flake ink exhibited excellent conductive performance and mechanical integrity, demonstrating a promising method for the formation of flexible microelectrodes or electronic devices. [ABSTRACT FROM AUTHOR]

The organic functionalization of polyoxometalate (POM) clusters has exhibited increasing superiority for the rational excavation and design of advanced POM-based materials. The architectures of such inorganic–organic hybrids are just like "molecular Lego" toys by virtue of the intermolecular and/or intramolecular interactions. Although numerous novel hybrids have been reported by pioneers, the relationship between organic segments and supramolecular architectures is still ambiguous. In this paper, we focus on the influence from organic bridging ligand to the structural orientation of POM hybrid materials by X-ray diffraction, molecular simulation, and energy calculation. The results indicate that rigid organic bridging ligand possesses a much stronger tendency to form intermolecular interactions than flexible ligand and can improve the electrochemical performance for hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Dual-phase high-carbon steels are of significant interest in mining industries particularly in comminution and rock handling applications where the strain rate varies from very low to very high. The effect of quasi-static strain rate on the deformation behaviour of austenite-martensite high-carbon low-alloy steel is investigated for compression loading in this paper. Experiments were conducted at different compressive strain rates (2.56 × 10−4 to 2.56 × 10−1 s−1), and the subsequent microstructural evolution was characterised by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy and electron backscatter diffraction (EBSD) techniques to establish the structure-property correlation. The experimental results indicated an increase in the yield strength (σy) with the increase in the strain rate due to the rate-dependent dislocation velocities. The strain hardening rate of the material exhibited a decreasing trend with an increase in the true strain values for all the applied strain rates. XRD results indicated the phenomenon of deformation-induced martensitic transformation (DIMT) to be rate dependent, whereas EBSD results showed an increase in the Kernel average misorientation values with increase in the strain rate. The volume fraction of retained austenite was observed to be decreasing with an increase in the engineering strain values irrespective of the applied strain rate. The microscopic features of the fracture surfaces showed the presence of transgranular cracking at low strain rates, whereas predominant intergranular cracks were found at higher strain rates. TEM results indicated the decrease in the lath martensites with increase in the strain rate. [ABSTRACT FROM AUTHOR]

Semiconductor materials keep occupying an excellent technological position for their importance in building integrated electronic systems. Semiconductor bridge (SCB) with N-type phosphorus-doped silicon material is a new generation of ignition device developed by semiconductor integrated circuit technology. A thermoelectrical model of the ignition device is established in this paper with the consideration of the external capacitor discharge circuit of SCB. The results reveal the thermal properties and electrical properties of the semiconductor device. The time evolution of electric field, current density and temperature distribution during the transient heating process are analyzed. In particular, the temperature distributions of the device show an obvious uneven melting phenomenon; ranging from room temperature to the melting point, the peak temperature points of the SCB transfer versus time, from the edges (0-1.78 ns) to the middle of the bridge (1.78-2.74 ns). The proposed model with specific heavily doped semiconductor material shows that the vaporization fronts tend to originate at the middle of the bridge, rather than the edges. An analysis on the relationship between thermal field and electrical field is conducted, demonstrating that the changes of temperature peak points in SCB are highly relevant to the “flow around” phenomenon in the uneven current density distribution. [ABSTRACT FROM AUTHOR]

In this paper, flower-like Ag nanocrystals and their fractal networks were successfully synthesized by gas-solution interface technique at the surface of AgNO3 water solution with the assistance of ammonium citrate and of gaseous N2H4 used as reductant. The synthesized flower-like silver structure consisted of a large number of petal-like silver nanoplates. They were characterized by scanning and transmission electron microscopy, absorption UV-Vis spectroscopy, and X-ray diffraction. In addition to the standard silver fcc modification, the nanostructures contained the hexagonal polymorph (4H-Ag) in the amount of about 5%. The effect of pH of the solution on the morphology of nanoparticles and on the silver crystal structure was examined. Depending on the time of treatment with gaseous hydrazine, it was possible to obtain either separate flower-like nanoparicles and their fractal networks, or continuous films formed by rather closely packed petal-like nanoparticles. The surface-enhanced Raman scattering effect was observed, and the most intense interaction of laser beam with the silver nanoparticles occurred when the solution side of the synthesized film was irradiated. [ABSTRACT FROM AUTHOR]

This paper describes the enhancement in stability and electrochromic properties of regioregular poly(3-hexylthiophene) (rrP3HT) polymer films in ambient conditions via ultrasonication of the polymer solution before deposition. The ultrasonicated polymer solution was spin coated onto an ITO substrate, and the electrochromic properties of the resulting rrP3HT films were characterized by UV-Vis spectroscopy, cyclic voltammetry and spectroelectrochemistry. The morphology and crystallinity of the polymer films were measured by atomic force microscopy and X-ray diffraction. Ultrasonication of the polymer solution controlled and increased the intra-chain interaction of the resulting polymer film on an ITO substrate. This method resulted in the polymer film changing colors at a voltage 0.2 V less than an untreated film with concurrent high stability and a fast response switching time of 1-2 s. This method was demonstrated to be a convenient way to lower the applied voltage and to increase the stability of the electrochromic rrP3HT film. [ABSTRACT FROM AUTHOR]

This paper presents results about the influence of the selective laser melting (SLM) process parameters on a FeCr4Mo1V1W8C1 (wt%) alloy regarding microstructure and mechanical behavior. Tailored parameter variation studies were performed to obtain crack-free and highly dense SLM parts. The microstructure was studied using scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy, and scanning transmission electron microscopy. Additionally, the mechanical properties were investigated by compression and tensile tests. The obtained microstructure is composed of complex nanoscale carbides, retained austenite, and martensite. Caused by the fast directional cooling during SLM, a completely dendritic solidification aligned in building direction occurs. Non-equilibrium segregation leads to an orderly phase arrangement of complex carbides at the boundary of the dendrites surrounded by retained austenite and martensite in the center of the dendrites. A strong work hardening behavior was observed, based on an austenite-to-martensite phase transformation (TRIP effect). This effect accounts for the outstanding mechanical properties such as compression strength of 6000 MPa, a 0.2% tensile yield strength of 560 MPa, and an ultimate tensile strength of over 1000 MPa. These findings reveal that SLM is advantageous for the processing of ultra-high-strength FeCrMoVWC tool steel. [ABSTRACT FROM AUTHOR]

In this paper, InAs/ZnS mixed nanocrystals were synthesized by dry high-energy milling approach in the first step. The obtained nanocrystals were characterized from structural point of view by X-ray diffraction analysis and Raman spectroscopy, and from the morphological point of view by scanning electron microscopy. In the next step, the nanocrystals were subjected to wet ultra-fine milling in order to obtain a nanosuspension of chitosan-coated InAs/ZnS nanocrystals with bio-imaging properties. The stability of the nanosuspension was examined by zeta potential and particle size distribution measurements. The prepared nanosuspension was stable with high values of zeta potential. Its optical properties were also studied using UV-Vis and PL spectroscopies. The determined fluorescent properties confirming the potential in bio-imaging applications were verified on cancer cell lines Caco-2, HCT116, HeLa, and MCF7. [ABSTRACT FROM AUTHOR]

This paper reports a new strategy for preparation of 2D molecularly imprinted materials (MIM) through the exploitation of thiol-ene click chemistry. 2D MIM for cholesterol was prepared using cholesterol as the template, acrolyl-modified β-cyclodextrin (acrolyl-β-CD) as the functional monomer, and thiol-modified SBA-15 (thiol-SBA-15) as the supporter. In this method, acrolyl-β-CD molecules were assembled around the templates by formation of template-monomer inclusion compounds. Then the acrolyl-β-CD molecules were anchored to the walls of the mesopores of SBA-15 via the thiol-ene click chemistry. After removal of the template molecules, the resulting recognition sites were formed in the mesopores of SBA-15. TEM, XRD, and N adsorption-desorption analysis results demonstrated that the synthesized MIM had a highly ordered mesoporous structure. Results from FT-IR revealed that acrolyl-β-CDs have been successfully conjugated to SBA-15. The density of β-CDs attached on the MIM is determined by EA and TGA. The equilibrium binding amounts of MIM and non-imprinted materials (NIM) for cholesterol are 53.50 and 25.24 μmol/g, respectively. The 2D MIM exhibited binding affinity and specificity for a group of analytes which have similar size and shape to those of template. The application of the prepared materials as stationary phases in thin layer chromatography was investigated preliminarily. The imprinted materials had higher retention ability for the template than the NIM. The retention factors ( R) of cholesterol on MIM and NIM are 0.62 and 0.81, respectively. The solid phase extraction of cholesterol using MIM as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction column for cholesterol were 77.1-94.7 % with relative standard deviations (RSD) of 2.25-6.78 %. [ABSTRACT FROM AUTHOR]

In this paper, we synthesized a new cathode material (CuBiS) by a solvothermal method for high-performance lithium-sulfur batteries. CuBiS with a unique flower structure was characterized using the X-ray diffraction, energy-dispersive X-ray spectrometer, and scanning electron microscopy. It is shown that the CuBiS/S flower exhibits a high initial capacity of 1343 mAh g at 0.2 C, and although a capacity fade in subsequent cycles occurs due to polysulfide dissolution and shuttle mechanism, 487 mAh g at 0.2 C can be retained after 100 cycles with the 90-95 % coulombic efficiency. [ABSTRACT FROM AUTHOR]

In this paper, BiS microflowers have been successfully synthesized via a facile one-pot hydrothermal method and characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy. Then the BiS microflowers were deposited on patterned ITO glass substrates by dip-coating to fabricate photodetectors. The photoresponse properties using BiS microflowers as a representative system show a significantly enhanced conductivity and the current-voltage characteristic exhibit ca. 1.7 orders of magnitude larger than the dark current. The response and decay times are estimated to be ~227 and 880 ms, respectively, indicating that flower-like BiS may be an excellent candidate for high-speed and high-sensitivity photoelectrical switches and light-sensitive devices. [ABSTRACT FROM AUTHOR]

Polymer processing generally plays a crucial role in determining the development of microstructure in the fabricated product. In this paper, isotactic polypropylene (iPP) containing 0.1 wt% β-nucleating agent was extruded via a slit die and immediately melt-stretched upon various stretching rates (SR) at the die exit. The microstructure of β-nucleated iPP samples was investigated using two-dimensional wide-angle X-ray diffraction and small-angle X-ray scatterings (2D-WAXD/SAXS) measurements. It is observed that, no matter what SR is, lamellar branching of β-form crystal is formed in melt-stretched samples, which is scarcely reported in open literatures. A method is proposed to calculate the crystallinity of daughter lamellae in β-crystal ( X). It is found that X decreases with increasing SR, indicating that lamellar branching of β-form crystal is restrained by higher SR. Such case should be attributed to the denser-oriented structures (e.g., shish) induced by higher SR, leaving a confined space between adjacent-oriented structures for the growth of daughter lamellae. [ABSTRACT FROM AUTHOR]

The phase relation of Li2O-FeO-P2O5 ternary system under the 95 %Ar + 5 %H2 atmosphere has been systematically investigated by X-ray diffraction (XRD), and there exist 8 binary compounds, 4 ternary compounds, 2 two-phase regions, and 17 three-phase regions. No other new lithium ferrous phosphates can be existed in the Li2O-FeO-P2O5 ternary system under the 95 %Ar + 5 %H2 atmosphere. In this system, the Li1+xFe1-xPO4 solid solution phase with the homogeneous range of −0.15 ≤ x ≤ 0.06 is determined. Their corresponding lattice parameters are obtained by the refinement results, and the results show that the lattice parameters ( a, b, c, V) vary linearly with the increasing amount of excess Li-ion ( x > 0) or with the increasing amount of excess Fe-ion ( x < 0). The phase diagram determined in this paper can provide more information about the phase relation of Li2O-FeO-P2O5 ternary system and serve as a guide for the future investigation of lithium iron phosphates in this system. [ABSTRACT FROM AUTHOR]

In the view of the advantages of using P, N, Si and graphene oxide (GO) for the development of flame retardants materials, a multi-structure synergistic composite was synthesized by grafting a novel nitrogen-containing polyhedral oligomeric silsesquioxane (HAK) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) on the surface of GO nanosheet. In the first step, 2-hydroxyethyl acrylate was selectively reacted, and then, HAK was synthetized by the condensation of the aza-Michael addition product with 3-(methacryloyloxy)propyltrimethoxysilane. Finally, the GO obtained by an innovative variant of Marcano-Tour improved exfoliation method was functionalized, first with DOPO, and then with HAK. The structural, morphological and surface properties of GO and GO-DOPO-HAK were investigated by means of XRD, TEM–EDX, FT-IR, Raman, zeta potential and XPS techniques, and it was evidenced the functionalization of GO with DOPO, and then with HAK. The performed microscale combustion calorimetry (MCC) and TG measurements indicated a great potential of the GO-DOPO-HAK as flame retardant material as the obtained residual weight for this sample was found to be the highest one compared to the other investigated samples. MCC analyses further revealed a major decrease in heat release capacity (HRC) and a significant increase in char yield, results that confirm the great potential of GO-DOPO-HAK as flame retardancy material. [ABSTRACT FROM AUTHOR]

The structural characteristics of silica aerogels prepared under different concentrations of Na+, Ca2+ and Al3+ were thoroughly evaluated by using XRD and FTIR, and then, their adsorption capacity for the oils and organic solvents was investigated through a combined technique of 1H-NMR, nitrogen adsorption and SEM observation. The results show that the different cations and their varied concentrations can significantly change the adsorption capacity of silica aerogels, which is closely related to the correspondingly modified pore structure and pore volume. Specifically, Na+ does not involve in the formed skeleton of the silica aerogel, but precipitates as sodium chloride crystals, which reduces the pore volume of silica aerogels and then decreases the adsorption capacity. The increased [Ca2+] can increase the pore volume and pore size of silica aerogels, but a first increase and then decrease in the adsorption capacity of the aerogels is observed, which could be related to the reduced capillary force due to the increased pore size. At last, the presence of Al3+ can greatly decrease the pore volume of the silica aerogels and their corresponding adsorption capacity, which could be caused by the participation of Al3+ in the formed skeleton of silica aerogels. [ABSTRACT FROM AUTHOR]

The present work details experimental phase stabilization studies for the disordered, multi-cation A6B2O17 (A = Zr, Hf; B = Nb, Ta) system. We leverage both high-temperature in situ and ex situ X-ray diffraction to assess phase equilibrium and metastability in A6B2O17 ceramics produced via reactive sintering of stoichiometric as-received powders. We observe that the A6B2O17 phase can be stabilized for any stoichiometric combination of Group 4B and 5B transition metal cations (Zr, Nb, Hf, Ta), including ternary and quinary systems. The observed minimum stabilization temperatures for these phases are generally in agreement with prior calculations for each disordered A6B2O17 ternary permutation, offering further support for the inferred cation-disordered structure and suggesting that chemical disorder in this system is thermodynamically preferable. We also note that the quinary (Zr3Hf3)(NbTa)O17 phase exhibits enhanced solubility of refractory cations which is characteristic of other high-entropy oxides. Furthermore, A6B2O17 phases experience kinetic metastability, with the orthorhombic structure remaining stable following anneals at intermediate temperatures. [ABSTRACT FROM AUTHOR]

For the simultaneous improvement of mechanical, corrosion, and tribo-corrosion properties of Zr–2.5Nb alloy, an adherent black coating was deposited on the Zr–2.5Nb substrate by thermal oxidation in air at different temperatures and times to use in biomedical applications such as knee joints and orthopedic/dental replacements. According to obtained results, the long-term corrosion and tribo-corrosion resistance, and frictional properties in the phosphate-buffered saline solution improved significantly by oxidization at 523 °C for 4 h compared to the bare substrate. XRD patterns and Raman spectra revealed the formation of monoclinic and tetragonal ZrO2, as well as Nb2O5 phases in the black coating. According to microstructural studies, high adherence between the compact oxide layer and substrate decreased due to the formation of micro-cracks in the coating at a high operating temperature of 700 °C. [ABSTRACT FROM AUTHOR]

Laser Powder Bed Fusion (PBF-LB/M) additive manufacturing (AM) induces high magnitude residual stress (RS) in structures due to the extremely heterogeneous cooling and heating rates. As the RS can be deleterious to the fatigue resistance of engineering components, great efforts are focused on understanding their generation and evolution after post-process heat treatments. In this study, one of the few of its kind, the RS relaxation induced in an as-built PBF-LB/M AlSi10Mg material by a low-temperature heat treatment (265 °C for 1 h) is studied by means of X-ray and neutron diffraction. Since the specimens are manufactured using a baseplate heated up to 200 °C, low RS are found in the as-built condition. After heat treatment a redistribution of the RS is observed, while their magnitude remains constant. It is proposed that the redistribution is induced by a repartition of stresses between the α-aluminium matrix and the silicon phase, as the morphology of the silicon phase is affected by the heat treatment. A considerable scatter is observed in the neutron diffraction RS profiles, which is principally correlated to the presence (or absence) of pockets of porosity developed at the borders of the chessboard pattern. [ABSTRACT FROM AUTHOR]

In situ time/temperature-resolved synchrotron high-energy X-ray diffraction is applied to study heat-mediated structural changes and phase transformations in rolled sheets of AZ91 and AZ31 magnesium alloys. Azimuthal diffraction intensities along the Debye–Scherrer rings (AT-plots) are used to obtain information on grain recovery and recrystallization temperatures as well as temperature-assisted grain rotations. The azimuthally integrated diffraction intensities, plotted as functions of the scattering vector (QT-plots), provide vital data on the temperature-dependent lattice parameters of the Mg/Al matrix and intermetallic precipitates, as well as on the evolution of the precipitates' volume fraction. It was found that in AZ31, the main precipitates are of the AlMn type, which is rather stable in the investigated temperature range (up to 773 K). In contrast, in AZ91, the major intermetallic precipitates, Al12Mg17, undergo complete dissolution above 600 K. It is caused by the enhanced diffusion of Al into the Mg/Al matrix, which according to the Al–Mg phase diagram, can adopt more Al at elevated temperatures. This diffusion is revealed by the proportional diminishing of the matrix lattice parameter (chemical strain), allowing us to quantify the Al content in the matrix. Fast temperature-dependent manipulation with intermetallic content in the Mg/Al alloy can, in principle, be used for controlling its mechanical properties. [ABSTRACT FROM AUTHOR]

In situ thermal annealing (673-1273 K) during X-ray diffraction synchrotron measurements was performed to monitor the strain level as a proxy to follow the recovery of 300 keV Ar ion irradiated 4H-SiC single crystals. Results show that, when exposed to Ar ions at a fluence of 6.7 × 10 14 ions/cm 2 (0.7 dpa), the material suffers a maximum strain of 12 % that reduces to 2 % after the final anneal at 1273 K. In the same time, the disorder derived from the XRD data also demonstrates a thermal recovery of the crystalline structure. Hence, this work presents ion irradiation as a means to induce specific crystalline order and depth-controlled strain states within a few 100 s of nm window in 4H-SiC. [ABSTRACT FROM AUTHOR]

The phase composition, grain morphology and microwave dielectric performances of a novel BaZn2Ti4O11-based (BZT) composite ceramic were investigated through X-ray diffraction, scanning electron microscopy and vector network analyzer. BaCu(B2O5) (BCB) and Ba3Ti4Nb4O21 (BTN) were utilized as sintering aid and τf—tailoring material, respectively. Due to the large difference in crystal structure, BZT and BTN can coexist well during the sintering process. While EDS results show that ionic diffusion occurred between the two phases. The addition of BCB accelerates the densification process and promotes grain growth. The dielectric performances of composite ceramics are mainly affected by the sample density and the molar ratio of BZT and BTN. A temperature-stable composite ceramic of εr = 31.8, Q × f = 46,610 GHz (f = 6.102 GHz), τf = − 1.3 ppm/°C was acquired for the 0.9BZT-0.1BTN sample sintered at 1075 °C for 4 h, exhibiting a great development prospect in the application of microwave devices. [ABSTRACT FROM AUTHOR]

Additive manufacturing of bulk metallic glasses (BMGs) has opened this material class to an exciting new range of potential applications, as bulk-scale, net-shaped amorphous components can be fabricated in a single step. However, there exists a critical need to understand the structural details of additive manufactured BMGs and how the glassy structure is linked to the mechanical properties. Here, we present a study of structure and property variations along the build height for a laser powder bed fusion (LPBF) processed Zr-based BMG with composition Zr59.3Cu28.8Nb1.5Al10.4 commercially termed AMZ4, using hardness testing, calorimetry, positron annihilation spectroscopy, synchrotron X-ray diffraction, and transmission electron microscopy. A lower hardness, more rejuvenated glassy structure was found at the bottom of the build compared to the middle region of the build, with the structure and properties of the top region between the two. Such differences could not be attributed to variability in chemical composition or crystallisation; rather, the softer bottom region was found to have a larger medium range order cluster size, attributed to heat dissipation into the build plate during processing, which gave faster cooling rates and less reheating compared to the steady-state middle of the build. However, at the top of the build less reheating occurs compared to the middle, leading to a somewhat softer and less relaxed state. [ABSTRACT FROM AUTHOR]

The depth-dependent structural changes in oxidized graphite have not been precisely revealed because of its friable nature. Here, micro-focused X-ray diffraction is used to measure the structural changes of oxidized graphite. An improved polishing method is then applied to observe the friable microstructures via scanning electron microscope. The (002) peak intensity and peak width is found to be very sensitive to local weight loss. The peak width decreases with the increase of weight loss, indicating an oxidation-induced increase of the average coherent length. High-resolution depth profiles of oxidized graphite structures are obtained for the first time. A double-layer oxidation mechanism is revealed. In the inner oxidation layer, oxidation happened preferentially to the binder regions and defective filler particles and leaves complicated paths which greatly increased the active surface area. It is observed that the original pore structures maintained in the inner oxidation layer. The outer oxidation layer showed a depletion of the binder regions and was oxidized in a much slower rate. However, the graphite grains could fall off easily, which causes a rapid drop of (002) peak intensity at the very surface. [ABSTRACT FROM AUTHOR]

The α → β phase transformation upon heating in the Ti-5553 alloy with lamellar-nodular bimodal microstructure was tracked in situ with high energy X-ray diffraction. Rapid heating at 10, 50 and 100 °C s−1 from room temperature to 1050 °C was tested. Phase transformation on heating was studied by a combined analysis of the microstructural features that provides estimates of mass fractions, mean lattice parameters and full width at half maximum for the two phases. In comparison with equilibrium conditions, the experimental mass fractions reveal a shift of the transformation domain toward high temperatures when the heating rate increases. Also, the dissolution of the α phase is largely impacted by its morphology, the transformation being faster for α lamellae. The combined analysis of mean lattice parameters and full width at half maximum suggests that the α → β phase transformation on heating is diffusion controlled. The β phase therefore inherits the solute content of the adjacent parent α phase, leading to chemical heterogeneities in the β phase regardless of the heating rate. [ABSTRACT FROM AUTHOR]

The degradation of poly(ε -caprolactone)/poly(l-lactic acid) (PCL/PLLA) electrospun membrane was carried out in the phosphate buffer of esterase and water, respectively. A three-dimensional (3D) porous morphology was cultivated during esterase degradation, which was confirmed by scanning electronic microscope (SEM), while the structural evolution was analyzed by differential scanning calorimetry (DSC) combining with wide-angle X-ray diffraction (WAXD). Compared with hydrolysis, the degradation rate of enzymolysis was significantly faster. With the rapid decline in PCL crystallinity, the crystallinity of PLLA increased slightly after enzymolysis. The formation of porous morphology should be attributed to the relatively rapid degradation of PCL crystal and PLLA amorphous region attacked by esterase. Also, the number of micropores on the fiber surface increased with degradation time, which provides new ideas for preparing porous materials with higher porosity. [ABSTRACT FROM AUTHOR]

With the intent to comprehend the structure and hence the property changes in the PrAlO3 system, the substitution of Bi3+ for Pr3+ has been attempted. The samples were synthesized by solution combustion synthesis and characterized extensively. X-ray diffraction studies revealed that the rhombohedral perovskite structure was preserved up to 20 mol% substitution of bismuth, beyond which diffraction peaks of the secondary phase of α-Bi2O3emerged. The structural refinements indicated the increment of both a and c lattice dimensions with an increase in bismuth content. The samples had porous morphology, and a mean pore diameter of 22.4 nm, along with a surface area of 100 m2/g, was deduced from BET measurements for the 20 mol% bismuth-substituted sample. FTIR, Raman spectroscopic and electron microscopic analysis reinforced the perovskite structure adopted by the bismuth-substituted samples. Both Pr and Bi in Pr0.80Bi0.20AlO3 existed in the + 3 oxidation state as established from the XPS analysis. The inclusion of bismuth introduced intermediate energy levels within the bandgap, as suggested by the redshift of the absorption edge for the bismuth-substituted samples. As the optical bandgap values were in the semiconductor regime, the application of bismuth-replaced samples as a catalyst for the photodegradation of crystal violet dye solution was demonstrated. The amount of dye degraded increased with an increase in the amount of bismuth in the sample. Additionally, Pr0.80Bi0.20AlO3 catalyzed the reduction of nitroaromatics promoted possibly by the Bi3+/Bi(0) redox couple. [ABSTRACT FROM AUTHOR]

It has earlier been reported that that the gallium incorporation in wurtzite CuInS2 (CIS) results in structural distortion, non-homogeneous shape, and distribution of particles. However, a detailed study of the effect of Ga substitution on the structure and morphology has not been reported. Here, we report the synthesis of nanocrystalline CuInxGa1−xS2 (x = 1, 0.7, 0.5, 0.3, and 0) wurtzite particles by solution processing in a nitrogen atmosphere. Structural analyses by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the as-synthesized CuInS2 (CIS) and CuGaS2 (CGS) nanoparticle were single-phase wurtzite structures, whereas CuIn0.7Ga0.3S2, CuIn0.5Ga0.5S2, and CuIn0.3Ga0.7S2 had three wurtzite phases having In-rich, In–Ga, and Ga-rich compositions. The shape of the resulting nanoparticles was either elongated, polygonal, or tadpole depending on the phase composition. In-rich particles had elongated rod-like morphology, the In–Ga particles were irregular hexagonal/equiaxed, while the Ga-rich phase formed with a tadpole morphology. The bandgap of the wurtzite-CuInxGa1−xS2 increased with Ga substitution: from 1.49 eV for CIS to 2.0 eV for CGS. [ABSTRACT FROM AUTHOR]

In this work, a hot-rolled Ti–6Al–4V (Ti-64) sheet was annealed at 1050 °C (β field) and then subjected to different coolings (in water, air and furnace). Electron backscatter diffraction, electron channeling contrast imaging, energy-dispersive spectroscopy and X-ray diffraction techniques were jointly utilized to comprehensively reveal microstructural and textural characteristics of the specimens following various β-cooling rates. Hardness measurements were also performed to probe the hardness variation associated with the β-cooling rates and were further rationalized based on the revealed microstructures. Results show that the β-cooled specimens in water, air and furnace exhibited twinned martensite, basket-weave and parallel-plate Widmanstätten structures, respectively. The Burgers orientation relationship is always obeyed during the β → α transformation at all cooling rates. After phase transformation, major α texture components ((0°, 60°, 0°), (90°, 30°, 30°) and (90°, 90°, 30°)) are completely different from those of the as-received material ((0°, 90°, 0°) and (90°, 30°, 0°)). Slow cooling facilitates preferable nucleation of α phases at prior β boundaries and strengthens α-variant selection, leading to greatly intensified transformation texture (the maximum density from 9.5 to 31.1 times of random). Hardness values of the β-cooled specimens drop from 416.8 ± 4.3 HV for water cooling to 329.2 ± 23.6 HV for furnace cooling. Quantitative calculations suggest such hardness variation can be more related to differences in grain size between them, as compared to specific contributions from other microstructural and textural characteristics. [ABSTRACT FROM AUTHOR]

For the sake of excellent strain performance for actuator application, Sn-modified Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3 (BNT–BKT) ceramics were designed and prepared by solid-state reaction method. The crystal structures and microstructures of Bi0.5(Na0.75K0.25)0.5(Ti1−xSnx)O3 (abbreviated as BNKT–xSn, x = 0, 0.02, 0.05, 0.08) were systematically investigated together with their strain performance. It is found that all the compositions possessed a single perovskite structure phase by X-ray diffraction patterns. With increasing Sn content, the ferroelectric phase with mainly tetragonal structure gradually transformed into the ergodic relaxor phase in pseudocubic structure with nanodomains further confirmed by high-resolution transmission electron microscope images. Both the P–E and I–E loops confirmed this structural change and the coexistence of ferroelectric phase and ergodic relaxor phase at x = 0.02, where a large strain of 0.37% was achieved with low hysteresis (21.8%). By analyzing the bipolar and unipolar strain curves and the origin of strain, we believe that the large strain is contributed to the phase transition from ferroelectric phase into ergodic relaxor phase, and the low hysteresis is beneficial from the existence of ergodic relaxor phase, which should pave a way for future developing high-performance actuators. [ABSTRACT FROM AUTHOR]

The research on the cement hydration with graphene oxide (GO) can provide a guidance for designing GO-modified cement-based materials. Ye'elimite is the dominant mineralogical phase in calcium sulfoaluminate cement. However, an in-depth understanding of GO on the hydration behavior of ye'elimite is still lacking. Here, we demonstrate the influences of GO on the hydration process and products of ye'elimite. Firstly, GO was successfully coated on the surface of ye'elimite and then the hydration development of ye'elimite was investigated by iso-thermal calorimetry and X-ray diffraction. The results revealed that the hydration time of ye'elimite moved up at first and delayed later with the increasing amounts of GO. The addition of GO could enhance the hydration degree of ye'elimite and promote the formation of monosulfate. The complexation effect of Ca2+ and –COOH group played a negative role in the formation of ettringite. This study provides a promising way for employing GO to regulate the hydration of ye'elimite. [ABSTRACT FROM AUTHOR]

Phase equilibria in Al–Ni–Sc ternary system have been measured through alloy sampling. According to the results from electron probe microanalysis and X-ray diffraction techniques, isothermal sections of Al–Ni–Sc ternary system at 1173 K and 1273 K were constructed, where four new ternary phases, τ7 (Ni2Al5Sc), τ8 (Ni2Al4Sc), τ9 (NiAl2Sc3) and τ10 (NiAlSc5), were detected along with the formerly reported ternary compounds, τ1 (NiAlSc), τ2 (Ni2AlSc) and τ5 (NiAl2Sc). The existence of τ3 (Ni7Al16Sc6), τ4 (NiAl4Sc) and τ6 (Ni3Al9Sc) reported previously in the literature was not confirmed in this work. And τ1 shows large composition range at 1173 K and 1273 K. [ABSTRACT FROM AUTHOR]

The NdCrO3 perovskite nanoparticles have been successfully synthesized using sol-gel auto-combustion process. Structural and morphological characterizations of the material have been performed at room temperature using XRD and SEM, respectively. Frequency- and temperature-dependent dielectric measurements have been performed in the range of 1 Hz-10 MHz and RT − 300 °C, respectively. The dielectric constant is found to be in the order of ε′ > 103 at room temperature, indicating the colossal dielectric constant behaviour. Ferroelectric phase transition temperature has increased with an increase in frequency, suggesting that the material is a relaxor ferroelectric nature. Temperature- and field-dependent magnetization measurements have been carried out in the temperature range (5-400 K) and field up to 5 T. M-T curve exhibited a diamagnetic-like behaviour in low temperature and low fields. Two magnetic transitions were found at TN1 (223 K) and TN2 (33 K) which correspond to para to weak ferromagnetic transition and Nd3+ spin ordering, respectively. Hysteresis loop noticed weak ferromagnetism. [ABSTRACT FROM AUTHOR]

The effect of heating rate (in the range of 0.083-3.333 K s−1) on the parameters of thermal stability and crystallization kinetics of the Fe40Ni40P14B6 metallic glass has been investigated by differential scanning calorimetry and X-ray diffraction. An analytical model of glass crystallization describing the homogeneous nucleation rate, the velocity of interface-limited growth, the number of crystal volume density in crystallized samples as well as the crystallization kinetics at constant rate heating is presented. A modified procedure of estimation of thermodynamic and kinetic parameters governing the rate of crystal nucleation and growth based on the use of the measured heating rate-dependent variations of the volume fraction crystallized and the average grain size is proposed. The values of the effective diffusivity have been estimated by the Kissinger-like isoconversional method accounting the contribution of both the free energy difference and the specific interfacial nucleus-melt energy changes estimated from the structural data. It has been shown for the first time that the shapes of the non-isothermal experimental kinetic crystallization curves measured at the heating rates ≤ 1.333 K s−1 are well described by the approximate analytical equation and the values of the Avrami exponent lowering from 5.5 to 2.3 with the heating rates increasing have been estimated. The evaluated ranges of the nucleation rate (1.4 × 1016-2.5 × 1017 m−3 s−1) and growth velocity of crystals (2.05 × 10−9-3.0 × 10−7 m s−1) in Fe40Ni40P14B6 glass at temperatures from 653 to 714 K are in reasonable agreement with the experimental data. Possible variations of the established eutectic crystallization mechanism revealed by changes of the Avrami exponent with the heating rate increasing are discussed. [ABSTRACT FROM AUTHOR]

Zinc oxide is densified to 97% by the cold sintering process using an aqueous zinc acetate solution as the secondary transport phase. The mechanical response of the cold-sintered zinc oxide ceramics is investigated through the ball-on-three-balls biaxial bending technique. The analysis demonstrates that ZnO cold-sintered samples follow a Weibull distribution with a characteristic strength (σ0 ~ 65 MPa) and Weibull modulus (m ~ 8). Phase purity and residual secondary phases were analyzed via X-ray diffraction and Raman spectroscopy. This report provides an initial demonstration of the mechanical properties of cold-sintered parts in the as-pressed and unmodified state and serves for comparison with conventionally prepared ceramics. [ABSTRACT FROM AUTHOR]

Scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray diffraction were successfully used to observe the location and morphology of the silica phytoliths in biomass-derived carbons and their transformation into SiC and SiO2 particles at high heat treatment temperatures (HTT). The analyses were conducted in chars derived from the endocarp of babassu coconut (EBC), which naturally contains 1.6 wt% of silica in its mineral matter. It was observed that EBC chars with 500-1200 °C HTT present globular echinate SiO2 phytoliths with sizes of 12-16 μm; these phytoliths are mostly concentrated around the surface of the submillimeter char fibers and also in the carbonaceous char matrix. No phytoliths are found in the interior of the char fibers. At 1200 °C HTT, the phytoliths begin to be rounded, and above 1300 °C HTT, most phytoliths decompose and silicon reacts with carbon-forming nanocrystalline β-SiC particles (~ 35 nm crystallite size). Numerous (tens to hundreds) micro- and sub-micro-amorphous or nanostructured SiO2 particles (with sizes predominantly below 2 µm) are then observed at the sites previously occupied by the phytoliths. Few rounded phytoliths survive at 1400 °C HTT, but disappear at higher HTTs (1600-2000 °C). It is likely that the ensembles of micro- and sub-micro-SiO2 particles observed in many sites correspond to the inner remaining part of the original phytoliths, whose most external SiO2 structures (at and near the surface) decompose and take part in the carbothermal reaction for the formation of SiC. [ABSTRACT FROM AUTHOR]

Tungsten borides, such as tungsten tetraboride (WB4) exhibit a wide range of appealing physical properties, including superhardness, chemical inertness and electronic conductivity. Among the various tungsten borides, the most puzzling remains WB4, with its crystal structure to linger in question for over half a century (Lech et al. in Proc Natl Acad Sci USA 112:3223-3228, 2015). In the present investigation, polycrystalline WB4 samples have been synthesized with two different methods and characterized at the atomic level by combining X-ray diffraction, scanning electron microscopy and nuclear magnetic resonance spectroscopy. The 11B multiple quantum MAS experiment revealed a range of boron sites that were not resolved within the experiment. This result is in contrast to the 11B MAS spectrum of WB2 with four resolved, discernible boron resonances. However, despite the structural complexity and boron-site variety in WB4, the detection of a single exponential of 11B spin-lattice relaxation recovery suggested that all of the boron sites relaxed with a single time constant. The Knight shift (K) was found to be independent of temperature while the T1-1 was governed by the Korringa law with a Korringa product T1T = 350 sK across the entire temperature range (168-437 K) of this study. The measured Korringa product was small, indicating substantial spin-lattice relaxation resulting from coupling with the conduction carriers. The abovementioned experimental results not only clearly rule out structures, such as the “MoB4-type phase” of WB4, with the resulting Fermi level in the pseudo-gap as has previously been predicted theoretically; but they also provide a comprehensible and valuable insight into the structural and electronic properties of WB4 at the atomic level. [ABSTRACT FROM AUTHOR]

Hybrid supercapacitors are successfully introduced to reduce the gap between high-capacity battery electrodes and high-power capacitor electrodes in case of electrochemical energy storage devices. Niobium pentoxide (Nb2O5) has attracted great interest for hybrid supercapacitors because of its moderate capacity and excellent cycle performance. However, its low electronic conductivity is still a major problem. Carbon is usually incorporated to address this limitation. Here, we report the Nb2O5 nanoparticle networks to facilitate electronic transport via continuous connection of materials. Additionally, the high surface area of the nanoparticles is maintained. The Nb2O5 nanoparticle network was synthesized using a simple solvothermal reaction in organic media. The materials characterization was performed using X-ray diffraction analysis, and scanning and transmission electron microscopies. The charge storage mechanism of the synthesized Nb2O5 material was investigated by cyclic voltammetry. In galvanostatic charge-discharge tests, the synthesized Nb2O5 nanoparticle network electrode exhibited stable cycle performance and remarkable rate capability without carbon incorporation. [ABSTRACT FROM AUTHOR]

Two novel porous metal-organic frameworks (MOFs) Cu(TCPBDA) and Cd(TCPBDA) based on a new ligand, namely N,N,N′,N′-tetrakis(4-carboxyphenyl)biphenyl-4,4′-diamine (H4TCPBDA), were synthesized by solvent thermal method and characterized with scanning electron microscopy, powder X-ray diffraction, BET analysis and spectrofluorometry. The static adsorption of the two MOFs for lead ions (Pb2+) was investigated. Cu(TCPBDA) showed a higher adsorption capacity for Pb2+ compared with Cd(TCPBDA), and its maximum adsorption capacity was 300 mg/g. The adsorption performance of Cu(TCPBDA) was then further studied. It was found that the adsorption of Cu(TCPBDA) for Pb2+ fitted the Freundlich model and pseudo-second-order equation very well. The adsorption ability of Cu(TCPBDA) was applied to fast and efficient adsorption for Pb2+ in toner. The results indicates that Cu(TCPBDA) is a promising material in adsorption and removal of heavy metal ions. [ABSTRACT FROM AUTHOR]

Crystallographic structural changes in a commercial 5 Ah prismatic graphite-NMC battery were investigated during its operation using energy-dispersive X-ray diffraction. The characteristic diffraction peaks for the anode and cathode were identified, and their peak positions were linked to the charge-discharge cycle of the battery. The edge of the negative terminal of battery was shown to undergo irregular cycling behavior. Stresses developed at the battery layer interfaces were proposed to be the source for this deterioration, which limits the lifetime of the battery. The effect of pulse discharge on strain in cathode has also been studied. [ABSTRACT FROM AUTHOR]

Bacillus anthracis marker (dipicolinic acid, DPA) is a biological warfare agent. The excessive amounts of the compound would lead to serious problems in human health. It is essential to develop a straightforward and rapid detection technology of DPA. For this reason, an optical sensing platform was established on a robust alginate film. Firstly, green emission CQDs were synthesized via a one-step microwave carbonization method based on citric acid and urea. In the next step, europium ions were employed to chelate the carboxyl groups of CQDs and sodium alginate was selected to assemble the green fluorescent film (CQDs-Eu film). In the presence of DPA, the emission peaks evolved from green to red region. The ratio of I615/I554 linearly increased with the addition of DPA in the range of 1-45 µM with a detection limit as low as 0.17 µM. This CQDs-Eu film-based sensing nanostructure showed its potential applications in the fields of biology and food analysis. [ABSTRACT FROM AUTHOR]

This study proposes a type of trabecular-honeycomb biomimetic structures with high-efficiency energy-absorbing abilities inspired by beetle elytra. Because the trabecular structure is distributed at the ends of the honeycomb walls, the proposed structure is named an end-trabecular beetle elytron plate crash box, or EBEP crash box for simplification. A comparison between the EBEP crash box and conventional crash box (a buffering structure generally used in modern devices and vehicles) is conducted using compression experiments and finite element method. We present the following results. (1) In contrast to the fluctuation stage with a low force in a conventional crash box, the force-displacement curve of the EBEP crash box possesses a rising stage and an approximate plateau with a higher force; as a result, the absorbing energy ability and compression force efficiency are 5 and 2.6 times greater than those of a conventional crash box, respectively. (2) Experimental and numerical comparisons reveal that there is cracking failure in the conventional crash box; however, the coordinated and uniform S-typed laminated compression deformation is developed in the EBEP crash box. (3) The influences of the amplitude (A) of the sine wave deformation line on the peak force and the compression force efficiency of the EBEP crash box are investigated, thereby providing a feasible method for adjusting the peak force according to different engineering requirements. These results provide new inspiration for applying EBEP crash boxes and exploiting new buffering structures and materials in the energy-absorbing field. [ABSTRACT FROM AUTHOR]

The aim of this study is to obtain novel selenium and strontium co-doped functional hydroxyapatite (Se-Sr-HA) material, which may play a potential role in inducing new bone formation and inhibiting the recurrence of cancer for osteocarcinoma patients. Se-Sr-HA was successfully synthesized by chemical precipitation method. The physicochemical and structural properties of the co-doped samples were well characterized by X-ray fluorescence spectroscopy, X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and so on. The XRD studies revealed that the characteristic peaks were consistent with hydroxyapatite, and no other phases or impurities were detected. The SEM observations suggested that the doping component reduced the crystallization of the samples and reduced the particle size. Rietveld refinements were performed to show the change of crystal structure after co-doping. It’s found that co-doping increased the lattice parameter a and c. The thermal stability of the co-doped samples related to the actual amount of incorporated ions. In addition, the biocompatibility of Se-Sr-HA samples and their inhibitory effect on osteosarcoma cells also make them have potential applications in biomedical materials. [ABSTRACT FROM AUTHOR]

A new solid freeform process, 3D gel printing (3DGP), was proposed for designing and manufacturing graded composites. As an example, TiC-high manganese steel cermet with a gradient distribution of TiC was successfully designed and fabricated by 3DGP. The rheological behavior and polymerization of slurries with different TiC content have been researched. The complex-shaped green bodies were printed accurately by depositing slurries layer by layer. The scanning electron microscopy and X-ray diffraction revealed the gradient distribution and morphology of the TiC particles within a sintered sample. The density, hardness, abrasion wear resistance, transverse rupture strength and impact toughness of the 3D gel-printed TiC-high manganese steel cermet appeared graded distribution corresponding to its gradient structure. Gradient distribution of the composition, microstructure and mechanical properties of the 3D gel-printed part are consistent with the design concept. Results indicated that 3DGP is a promising approach for high-throughput design and fabrication of complex-shaped graded composites. [ABSTRACT FROM AUTHOR]

Thanks to aqueous sol-gel chemistry, it is now possible to prepare several phase pure TiO2 brookite colloidal systems that significantly differ on nanoparticles size and shape. This TiO2 polymorph is more difficult to be obtained as phase pure material than anatase or rutile. Here we have prepared a set of four different sol-gel brookite syntheses with particles size ranging from 10 to 500 nm and significantly different morphologies as demonstrated by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. We have studied their photocatalytic activities in aqueous solution on phenol and formic acid. The brookite sample with higher specific surface displays better activity for both pollutants abatement than anatase and rutile reference samples and very close to the TiO2 P25 commercial reference. Additional experimental characterization of photogenerated charge carriers and their lifetime is performed using time-resolved microwave conductivity. We could then explain why another efficient brookite material is able to compensate a significantly lower specific surface with a higher photon conversion rate. This study involving a broad set of pure phase brookite samples brings back that phase into the TiO2 polymorphs race for light-enhanced applications. It confirms that size/shape-activity correlation already observed for the anatase polymorph is also valid for the brookite phase. [ABSTRACT FROM AUTHOR]

The lithium-ion batteries with high energy density, large power density and long cycle life have attracted much attention. Among various anodes, the CuO anode possesses a high specific capacity of 670 mAh g−1. However, the CuO anode suffers from capacity fading after the first cycle, and the reason is not clear up enough to now. To investigate the nature of CuO anode lithiation-delithiation conversion in lithium-ion batteries, we investigated the phase conversion of CuO anode by in situ X-ray diffraction. We discovered that the specific discharge capacity of CuO during the first discharge cycle is usually more than 670 mAh g−1, but this value decreases to approximately 400-450 mAh g−1 after the second cycle and is stable for the subsequent cycles. The in situ X-ray diffraction observations reveal that in the discharge process of the first cycle, the CuO crystalline phase changes gradually to Cu. However, during the charge process of the first cycle, the delithiation product phase is Cu2O. The same phenomenon occurs again in the second charging-discharging cycle. The obtained scientific understanding reveals that the nature of CuO anode lithiation-delithiation phase conversion in Li-ion battery is between Cu2O and Cu, not CuO and Cu, which is responsible for capacity fading of CuO anode. The present research provides a certain scientific basis for the application of CuO in lithium-ion batteries. The in situ XRD method is helpful to understand the mechanism of electrochemical behaviour of other transition metal oxygen (sulphur, and fluorine) and can make an in-depth study of the searching for commercial anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Ultra-sensitive H2S sensors operated at room temperature were fabricated using Ag-In2O3 nanorod composites synthesized using sol-hydrothermal method followed by NaBH4 reduction process. TEM proved that the In2O3 was nanorod structures of ~ 110 nm in length and ~ 35 nm in diameter. Ag nanoparticles with diameters from 10 to 15 nm homogeneously decorated on the surfaces of the In2O3 naonorods. XRD and XPS analysis proved that the Ag elements existed as zero-valent metallic silver on the surface of the In2O3 nanorods. Ag nanoparticles could enhance the formation of chemisorbed oxygen species and interactions between H2S molecules and oxygen species due to spillover effect, and the electron transfer between Ag and In2O3 nanorods also enhanced the sensing properties. Therefore, the H2S sensors based on the Ag-In2O3 nanorod composites showed significantly improved sensing performance than those based on the pure In2O3 nanorods. The optimized content of Ag nanoparticles is 13.6 wt%. Operated at room temperature, the H2S sensors made of 13.6 wt% Ag-In2O3 nanorod composites exhibited an ultra-high response of 93719 to 20 ppm H2S and a superior detection limit of 0.005 ppm. The sensor also showed good reversibility, good selectivity, excellent reproducibility and stability for detection of H2S gas. [ABSTRACT FROM AUTHOR]

Interface interactions are the important problems in improving the mechanical properties of graphene and polymer composites. In this work, a simple method is proposed to prepare epoxy composites with admirable properties through constructing dendrimers with cyanuric chloride (TCT) and diethylenetriamine (DETA) onto graphene oxide (GO) surface. The FTIR, XRD, XPS, Raman spectroscopy, SEM and TEM were used to confirm the successful grafting of TCT and DETA molecules onto the surface of GO. The interfacial adhesion between GO-TCT-DETA and epoxy resin is enhanced due to the formation of a strong chemical bond between the amino group on the GO surface and the epoxy resins. The tensile and flexural strength of GO-TCT-DETA/epoxy composites have considerable improvement (40.79 and 48.56%) compared with that of epoxy resin due to stronger interfacial interaction. In addition, the strengthening mechanism and dispersion of GO-TCT-DETA in epoxy matrix were also demonstrated. [ABSTRACT FROM AUTHOR]

We prepared graphite-infused aluminum composites by electron-beam vacuum melting and electromagnetic stirring with 0% and 4 wt% graphite addition. Bulk density of 2.69 g/cm3 was measured for samples with 0% graphite addition (AlCv0) and 2.66 g/cm3 for samples with 4 wt% graphite addition (AlCv4). Both are > 99% of their theoretical values. X-ray diffraction indicated that AlCv0 is phase pure, while the AlCv4 sample is a composite consisting of aluminum, Al4C3, and graphite. Electron microscopy and energy-dispersive X-ray spectroscopy revealed pockets of carbon-rich phase of 10-50 μm in sizes dispersed in the Al matrix in AlCv4. Scanning transmission electron microscopy showed that Al4C3 crystallites of 1-2 μm sizes are mostly located near the outer shell of the pockets of carbon-rich phase and with undissolved graphite at the center. Thermal conductivity of 107.8 W/m K was measured for the AlCv4 and 226.7 W/m K for the AlCv0. Our work demonstrated the feasibility of producing pore-free high-density graphite-infused aluminum composite materials by electron-beam melting and electromagnetic stirring in vacuum. [ABSTRACT FROM AUTHOR]