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A unified model of grain-boundary segregation kinetics is established, which can simulate the equilibrium and non-equilibrium grain-boundary segregation kinetics during isothermal ageing. The results of model fittings/predictions are in a good consistence with those of the experiments. Values of several important parameters, such as vacancy formation energy, vacancy migration energy, and complex migration energy derived by model fittings, show a reasonably good agreement with those in the references. Relationship between the equilibrium and non-equilibrium grain-boundary segregation mechanisms is discussed in detail. The segregation peak/depletion trough observed in the non-equilibrium segregation kinetics may be ascribed to the vacancy flux. The equilibrium segregation kinetics is considered as a special case in non-equilibrium segregation kinetics with the zero vacancy flux. Both the equilibrium and non-equilibrium segregation kinetics are believed to be dominated by vacancy-solute complex flux. The proposed unified model can be a significant progress in grain-boundary segregation theory, with applications in guiding the design of materials. [ABSTRACT FROM AUTHOR]

The dependence of fracture appearance transition temperature (FATT) on phosphorus grain boundary segregation, yield strength, and grain size is experimentally evaluated for a 2.25Cr–1Mo low‐alloy steel. Both the phosphorus boundary segregation and yield strength are directly correlated to the FATT of the steel. However, the prior austenite grain size is not directly linked to the FATT although it influences phosphorus boundary segregation and yield strength. The FATT exhibits linear relations to phosphorus segregation concentration and yield strength, but there is no synergistic effect between these two entities. Based on the measurements, an embrittlement equation is established, which is expressed as FATT(°C) = 0.25σs + 2.64CP–270, where σs is the yield strength in MPa and CP is the phosphorus boundary concentration in at%. The calculated FATTs have a good agreement with the measured ones. [ABSTRACT FROM AUTHOR]

The fracture appearance transition temperatures (FATTs) are evaluated for the samples of a Nb-stabilized and P-strengthened interstitial free (IF) steel. Based on the measurements, the combined effect of hardening and phosphorus grain boundary segregation on the embrittlement of the steel is investigated. Both hardening and P boundary segregation can raise the FATT of the steel, causing hardening embrittlement and non-hardening embrittlement, respectively. Meanwhile, the grain size influences both kinds of embrittlement, i.e., there is a synergistic effect between grain size and hardening or P boundary segregation on the FATT of the steel. With the aid of the Taylor expansion along with the experimental data, a combined hardening and non-hardening embrittlement equation is established, being expressed as FATT  = 2.1 C p + 3.48 σ s − 22.36 d −1⁄2 + 0.64( C p − 14)( d −1⁄2 − 3.06) + 0.896( σ s − 14)( d −1⁄2 − 3.06) − 13.7, where FATT is the fracture appearance transition temperature in °C, C p is the phosphorus boundary concentration in at%, σ s is the yield strength in 10 MPa, and d is the grain size in mm. A comparison of the calculated and measured FATTs is made, demonstrating that the calculated FATTs are well consistent with the measured ones. [ABSTRACT FROM AUTHOR]

A biodegradable gel polymer electrolyte system based on chitosan/magnesium trifluoromethanesulfonate/1-ethyl-3-methylimidazolium trifluoromethanesulfonate (CA/Mg (Tf) 2 /EMITf) is developed. The structure, thermal performance, mechanical properties, ionic conductivity, relaxation time, electrochemical stability and ionic transport number of the membranes are analyzed by various techniques. The ion migration mainly depends on the complexation and decomplexation of Mg 2+ with amine band (NH 2 ) in chitosan. The 90CA-10Mg (Tf) 2 system plasticized with 10% EMITf (relative to the amount of 90CA-10Mg (Tf) 2 ) is identified as the optimum one and the temperature dependence of ionic conductivity obeys the Arrhenius rule. Moreover, the relaxation time of the electrolyte is very short, being just 1.25 × 10 −6 s, and its electrochemical stability window is quite wide, being up to 4.15 V. The anodic oxidation and cathodic reduction of Mg at the Mg-electrode/electrolyte interface is facile, and the ionic transference number of this electrolyte is 0.985, indicating that it could be a potential electrolyte candidate for Mg-ion devices. [ABSTRACT FROM AUTHOR]

The influence of ethylene carbonate (EC) addition on 85poly(ε - caprolactone):15Lithium thiocyanate (85PCL:15LiSCN) polymer electrolyte is investigated using X-ray diffraction, impedance spectroscopy, Wagner's polarization and electrochemical measurements. The results reveal that the amorphicity of the 85PCL:15LiSCN system increases with increase of EC content up to an optimal level of 40 wt.%. This is reflected in the electrical properties of the gel polymer electrolytes, i.e., the 40 wt.% EC-incorporated gel polymer electrolyte exhibits both high amorphicity and high electrical conductivity as compared to the other samples. The EC concentration dependences of dielectric constant and electrical conductivity show a similar trend, indicating that these properties are closely related to each other. The total ionic transference numbers of EC-incorporated gel polymer electrolytes are in the range 0.989–0.993, demonstrating that they are almost completely ionic conductors. The electrochemical stability window of the 40 wt.% EC-incorporated gel polymer electrolyte is ∼4.1 V along with the electrical conductivity of 2.2 × 10 −4 S cm −1 , which is significantly improved as compared to the 85PCL:15LiSCN system (3.0 V and 1.04 × 10 −6 S cm −1 ). Consequently, the addition of EC in the 85PCL:15LiSCN polymer electrolyte leads to a promising improvement in its various properties. [ABSTRACT FROM AUTHOR]

The samples of SA508-III reactor pressure vessel steel, undoped, doped with Sn, and doped with Sn + Ce, are heated at 1300 °C and then cooled down to different temperatures between 650 and 1050 °C, followed by tensile deformation until fracture using a Gleeble machine. The steel hot ductility evaluated by the reduction of area (RA) is determined at each test temperature. The tested samples are characterized using scanning electron microscopy, optical microscopy, and field emission gun scanning transmission electron microscopy. The steel exhibits a hot ductility trough and Sn substantially deteriorates the hot ductility of the steel by deepening and widening the ductility trough. However, Ce can well suppress this Sn-induced hot ductility deterioration. Grain boundary segregation of Sn or Sn + Ce occurs in the Sn-doped or Sn + Ce-doped samples. The segregation of Sn is primarily responsible for the hot ductility deterioration as it weakens grain boundary, thereby enhancing grain boundary sliding and deteriorating hot ductility. The segregation of Ce is mainly responsible for the suppression of the deterioration as it strengthens grain boundary, thereby restraining grain boundary sliding and suppressing Sn-induced hot ductility deterioration. [ABSTRACT FROM AUTHOR]

Lithium ion conducting polymer electrolyte films based on biodegradable poly(ɛ-caprolactone) (PCL) complexed with lithium thiocyanate (LiSCN) salt were prepared by solution cast technique. Thermal and electrical properties of the polymer electrolyte films were studied using differential scanning calorimetry (DSC) and ac impedance spectroscopy. In order to investigate the ion conduction mechanism and relaxation behavior of complex polymer electrolyte films, the conductivity, dielectric constant, loss tangent and electric modulus were analyzed as a function of frequency and temperature. The variation of conductivity with frequency obeyed the Johnscher's power law. The dielectric constant exhibited a higher value at a lower frequency and increased with rising temperature due to the polar nature of host polymer. The activation energies for both dc conductivity and relaxation had the same value (∼0.87 eV), implying that the charge carriers responsible for both conduction and relaxation were the same. [ABSTRACT FROM AUTHOR]

Abstract: High-density submicrometer-sized Ni0.5Zn0.5Fe2O4 ferrite ceramics were prepared by spark plasma sintering in conjunction with sufficient high energy ball milling. They were evaluated by different characterization techniques such as X-ray diffraction, scanning electron microscopy, and dielectric and magnetic measurements. All samples prepared at sintering temperatures ranging from 850 to 925°C exhibit a single spinel phase and their relative densities and grain sizes range from 90% to 99% and ~100nm to ~300nm, respectively. The dielectric constant increases with decreasing grain size until ~250nm, and then decreases dramatically with further decreasing grain size. The saturation magnetization increases continuously with increasing grain size/density but the magnetic coercivity decreases. The highest dielectric constant and saturation magnetization at room temperature are approximately 1.0×105 and 84.4emu/g, respectively, while the lowest magnetic coercivity is only around 15Oe. These outstanding properties may be associated with high density and uniform microstructure created by spark plasma sintering. Therefore, the spark plasma sintering is a promising technique for fabricating high-quality NiZn ferrites with high saturation magnetization and low coercivity. [Copyright &y& Elsevier]

Abstract: Nanosized Ba0.8Pb0.2TiO3 powders obtained by high energy ball milling were compacted and sintered into nanocrystalline ferroelectric ceramics using spark plasma sintering (SPS). The prepared ceramic samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and electrical property measurements. All the samples show a density over 97% of the theoretical value and an average grain size of ∼60–200nm depending on the ball milling time. The dielectric data exhibit a ferroelectric–paraelectric phase transition and a maximum relative permittivity of 19,000 at 225°C and 100kHz at the average grain size of ∼60nm. The values of the dielectric constants both at room temperature and at the phase transition temperature increase considerably as the average grain size decreases. The remanent polarization and coercive field strength decrease slightly as the average grain size decreases but remain at an acceptable level for ferroelectric applications. [Copyright &y& Elsevier]

Abstract: The barium lead titanate (Ba0.8Pb0.2TiO3, termed BPT) ferroelectric ceramics were prepared using microwave sintering and spark plasma sintering (SPS) techniques. The formation of single phase was confirmed by X-ray diffraction. The SPS-prepared BPT ceramics exhibited higher density and smaller grain sizes as compared with the microwave-sintered ones. Dielectric and ferroelectric properties were compared between the two-technique-prepared ceramics. It was found that the dielectric constant at room temperature was ∼500 higher for the SPS-prepared sample than for the microwave-sintered one, and ∼6000 higher at Curie transition temperature. The remnant and spontaneous polarization values were ∼2 times larger for the SPS-prepared sample as compared with the microwave-sintered one. On the whole, the promising SPS technique possessed distinguished characteristics of energy-saving, rapid processing and uniform temperature distribution throughout the sample. [Copyright &y& Elsevier]

Abstract: Coatings, which were made from pure epoxy and SiO2 nanoparticle modified epoxy composite, respectively, were applied onto the basalt fiber rovings. The SiO2 nanoparticles were synthesized using a sol–gel method and modified using coupling agent. Fourier transform infrared spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analyses indicated the formation of modified SiO2 nanoparticles. The SiO2 nanoparticle–epoxy composite coating gave rise to a significant increase in the tensile strength of the basalt fibers as compared with the pure epoxy coating, and also the coating endowed the basalt fiber with a promising interfacial property in the basalt fiber reinforced resin matrix composite. The coating modification was an effective way in improving the mechanical properties of basalt fibers and the properties of basalt fiber/epoxy resin composites. [Copyright &y& Elsevier]

Oxidation of air-plasma-sprayed (APS) thermal barrier coatings (TBCs) was carried out in air at 950 °C and was investigated using impedance spectroscopy coupled with scanning electron microscopy and X-ray diffraction. After oxidation for between 500 and 3000 h, a continuous alumina scale was formed at the bond coat/top coat interface in the TBCs, and was evaluated using impedance spectroscopy. The impedance spectra of the oxidised TBCs showed that there were four relaxation processes, which were attributed to the yttria-stabilised zirconia (YSZ) bulk of the TBCs, the thermally grown alumina scale, the YSZ grain boundary, and the metal electrode effect. Impedance analysis showed that the resistivity of the alumina scale increased with increasing oxidation time, demonstrating the thermally grown oxide (TGO) growth. The resistance of the YSZ grain boundaries also increased after oxidation for 2000 h, suggesting the composition change at grain boundaries after a long-term oxidation. [Copyright &y& Elsevier]

The electrical properties of the oxide film formed from the high-temperature oxidation of nickel have been evaluated using impedance spectroscopy. The impedance measurements were carried out on already oxidised films at temperatures ranging from 100 to 300°C. The conductivity of the oxide film, σ, was obtained as σ=0.19 exp[−0.39 eV/(kT)] Ω−1 m−1, with an activation energy of 0.39 eV close to that of the NiO published in literatures. The dielectric constant ϵ was found to be nearly independent of temperature with a value of 0.95, significantly lower than that of the bulk NiO. It was believed that some difficulty in achieving a full contact between the electrode and the oxide film during the measurements might have contributed some error in the measurements of both dielectric constant and electrical conductivity. However, the measured relaxation frequency of fR=2.99×109 exp[−0.43 eV/(kT)] Hz should be accurate because fR is independent of the specimen geometry and electrode/oxide contact area. [Copyright &y& Elsevier]

In this work, impedance spectroscopy (IS) has been used to evaluate the degradation of thermal barrier coatings (TBCs) due to oxidation at 1150 o C. The spallation of TBCs was found to be induced by the development of thermally grown oxides (TGO) produced from the oxidation of TBCs. The change in the electrical properties of the TGOs was found to be related to the change in the microstructure and microchemistry of the TGO. The resistivity of the TGO due to oxidation from 10 to 1000 h decreased rapidly, which corresponded to the increase in porosity in the TGO and the compositional change of the TGO from α-Al 2 O 3 to a mixture of α-Cr 2 O 3 and (Ni,Co)(Cr,Al) 2 O 4 spinel. The slow decrease in the resistivity of the TGO from oxidation for 1000–2000 h indicated that there was little change in the composition of the mixed oxides, although the growth rate of the TGOs was relatively fast during this oxidation period. The disappearance of α-Al 2 O 3 in the TGO caused a rapid oxide growth during oxidation and led to the spallation of TBCs. [ABSTRACT FROM AUTHOR]

A correction to the article "A unified model of grain-boundary segregation kinetics" that was published online on September 28, 2011 is presented.

Herein, an efficient, facile, scalable production of graphene dispersions via exfoliation of graphite in an environment-friendly PVA/H2O solvent system is reported. To warrant the impact of processing parameters on exfoliation efficiency, a systematic investigation is carried out using UV–visible spectroscopy. Under the optimal shearing parameters (1 h, 10 k rpm) with the PVA-to-fed graphite mass ratio of 10, a high concentration graphene dispersion (3.36 mg mL−1) is achieved. The estimated graphene yield is found to be 33% that further increases to 90% after sediment recycling. With the aim of detailed quality analysis, centrifugal cascading is adopted to predominately sort the graphene flakes from the upper end of the distribution. Through various characterization techniques, it is confirmed that the resulting dispersion comprises high-quality graphene flakes (1–5 layers) having thickness up to 1.48 nm, lateral dimension ranging from 0.3 to 4 µm, and quite a low level of defects (ID/IG = 0.1). The statistical distribution histogram reveals that most flakes are single-layer (41%), including some bi-layer (21%) and tri-layer (28%), while the remaining can be said five or multi-layer graphene. Meanwhile, the efficacy of the PVA/H2O solvent system is also demonstrated using ultrasonic exfoliation, providing a high concentration of graphene (1.1 mg mL−1) in a relatively short time (8 h). Furthermore, the applicability of the PVA-stabilized graphene dispersion is addressed by fabricating various graphene products such as graphene paper electrodes, graphene composites, and graphene thin films. Impressively, the graphene paper electrode imparts an exceptionally high specific capacitance of 199.63 F g−1 in a potential window range of 0 to 2 V, and hence could be a promising alternative to traditional electrodes in supercapacitors. Conclusively, the exfoliation of graphite in a green polymer–solvent system offers to produce highly concentrated graphene dispersions at a minimal cost that could be widely applicable in different research areas, thus holding the potential for commercial viability. [ABSTRACT FROM AUTHOR]

In this paper, in order to effectively utilize salt lake magnesium resources, we focused on a functional material containing magnesium, i.e. magnesium oxide, MgO, which is a type of antibacterial material. Through a first-principles study from the atomic level, the microstructure of MgO containing doped point defects of different elements was studied. The relationship between the microscopic structure of the material and its special antibacterial function was explored. The results are as following: the interstitial impurities in MgO are more helpful than substituted impurities for the improvement of the electronic structure. The analysis of the influence of different doping elements on the microstructure confirmed theoretically that Ag and Cu have the same highly active antimicrobial properties with the same change of microstructure, thereby confirming the relationship between microstructure and antimicrobial activity. The results of the simulations match the experimental results, thereby theoretically demonstrating the relationship between defects and antibacterial activities and providing further insight into the nature of the antibacterial mechanism. [ABSTRACT FROM AUTHOR]

Polymeric ionic liquid-based gel electrolyte films are a new generation of electrolyte materials for flexible energy storage device applications. In this work, Li-ion conducting gel electrolyte films are prepared with the polymeric ionic liquid poly(diallydimethylammonium) bis(trifluoromethane sulfonyl)imide (poly(DADMATFSI)) as the host polymer and the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt as the dopant. The crystalline nature, thermal stability, ionic conductivity and electrochemical stability window of the polymeric electrolyte films are analyzed by various characterization techniques. It is found that the polymeric electrolyte films exhibit high flexibility and excellent thermal stability. Their room-temperature electrical conductivity increases with increasing LiTFSI concentration and reaches a high value of 1.00 × 10 −3 S cm −1 at 20 wt% LiTFSI. The ionic transference numbers of the polymeric electrolyte films are in the range of 0.98–0.99, indicating that they are perfect ion conductors. Finally, the electrochemical stability window of the 20 wt% LiTFSI-doped polymeric electrolyte film is determined as approximately 6 V, which is a promising value for flexible energy storage device applications. [ABSTRACT FROM AUTHOR]

New polymer electrolyte films of lithium tetrafluoroborate (LiBF 4 )-complexed poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) embedded with different quantities of 1-ethyl-3methylimidazolium tetrafluoroborate (EMIMBF 4 ) ionic liquid were prepared by solution casting. The prepared films were characterized using various techniques: X-ray diffraction, scanning electron microscopy, impedance spectroscopy and electrochemical measurements. The pure PVdF-HFP possessed a semi-crystalline structure and its amorphicity increased with the addition of LiBF 4 salt and EMIMBF 4 ionic liquid. The size and interconnection of pores in the films were enhanced by EMIMBF 4 . Impedance measurements indicated that the room-temperature ionic conductivity of the films increased with increasing EMIMBF 4 concentration until 15 wt.%, being up to 0.202 × 10 −4 S cm −1 , and then decreased with further increasing EMIMBF 4 concentration. In addition, the temperature-dependent ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the 15 wt.% EMIMBF 4 -incorporated gel polymer electrolyte film exhibited a low activation energy for ionic conduction, being about 0.28 eV. Finally, the electrochemical stability window of the 85PVdF-HFP:15LiBF 4 +15 EMIMBF 4 gel polymer electrolyte films was evaluated as approximately 4.4 V, which is a promising value for ion battery applications. [ABSTRACT FROM AUTHOR]

Grain boundary (GB) segregation of P in 2.25Cr1Mo steel induced by elastic stress shows that the P equilibrium concentration, after reaching the non-equilibrium concentration maximum at critical time, returns to its initial thermal equilibrium level. This finding confirms the interesting phenomenon that the effect of elastic stress on GB segregation of P is significant in kinetics while slight in thermodynamics. Through extending the “pressure” in classical theory of chemical potential to the “elastic stress”, the thermodynamic effect of elastic stress on GB segregation is studied, and the relationship between elastic stress and segregation Gibbs energy is formulated. The formulas reveal that the difference in the segregation Gibbs energy between the elastically-stressed and non-stressed states depends on the excess molar volume of GB segregation and the magnitude of elastic stress. Model calculations in segregation Gibbs energy confirm that the effect of elastic stress on the thermodynamics of equilibrium GB segregation is slight, and the theoretical analyses considerably agree with the experimental results. The confirmation indicates that the nature of the thermodynamic effect is well captured. [ABSTRACT FROM AUTHOR]

Perovskite solid solution materials, namely, 0.67BiFeO 3 -0.33BaTiO 3 , were synthesized by spark plasma sintering method. The effects of the spark plasma sintering temperature on phase purity, microstructure, and electric properties of the as-prepared materials were investigated. The materials could be referred as pseudocubic phases based on the X-ray diffraction patterns. The bulk density first increased and then decreased. The 880 °C-sintered-ceramics had the maximal density and a compact microstructure with grain size of 0.77 ± 0.34 μm. The dielectric constant as a function of temperature exhibited a broad peak. At the optimal spark-plasma-sintering temperature, enhanced ferroelectric properties were observed with a value of P r ∼ 21 μC/cm2. This investigation on the spark plasma sintering process confirms it as an efficient approach to prepare outstanding performance BiFeO 3 –BaTiO 3 ceramics. [ABSTRACT FROM AUTHOR]

Abstract: Several shapes of Eu2+-doped barium silicate nanostructures have been simply obtained by a hydrothermal method. Hedgehog-like, spherical-shaped, porous irregular spherical, hollow worm-like, and cracked worm shell-like structures are synthesized with changing the molar ratios of Ba/Si in solution. The possible formation mechanisms of these barium silicate nanostructures are proposed. Under an excitation wavelength of 360nm, all the products show broad emission bands from about 400 to 625nm. The UV region excitation band from 300 to 400nm confirms the possibility that the nanostructures could be used as phosphors for white LEDs. [Copyright &y& Elsevier]

Abstract: In this paper, we investigated the structure, morphology and photoluminescence properties of hexagonal SrSiO3:Eu2+ micro-octahedrons and prism-like hollow microstructures prepared by the hydrothermal method at a relatively low temperature (180°C). Reactant concentration and reaction time showed strong effects on the phase formation and morphology of the products. The prepared samples were systematically characterized by X-ray diffraction, energy dispersive X-ray spectrometry, field emission scanning electron microscopy, excitation and emission photoluminescence (PL). The possible formation mechanisms of these SrSiO3:Eu2+ microcrystals were proposed. Finally, the PL properties of SrSiO3:Eu2+ microcrystals were also investigated. [Copyright &y& Elsevier]

Abstract: A model of non-equilibrium grain-boundary segregation of solute is expressed with graphs for the isothermal aging at various temperatures after quenching from a solution temperature. It is found from the graphical representations that when the samples are aged for a certain time at various temperatures there is a maximum value in the segregation concentration at a certain temperature. The aging time is equal or close to the critical time of non-equilibrium segregation corresponding to this temperature. This finding is experimentally confirmed with sulfur in an Ni-base superalloy with the aid of Auger electron spectroscopy. As an application of the new finding, a mechanism for intermediate temperature embrittlement of alloys is suggested and identified experimentally with tension tests of the superalloy. [Copyright &y& Elsevier]

Abstract: Polyetheretherketone–hydroxyapatite nanocomposite materials are investigated for the purpose of improving the bonding between polyetheretherketone (PEEK) matrix and hydroxyapatite (HA) fillers since their debonding deteriorates the otherwise superior antifatigue properties of PEEK materials. The nanocomposites are successfully produced by incorporating lab-prepared HA nanoparticles, up to 15.0vol%, to PEEK matrix via a compounding and injection molding process. The microstructures of the composite samples are observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallization and phase structure of the composites are examined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements. The mechanical properties of the composites are evaluated, and their tensile strength reaches 98MPa at 5.0vol% HA. Most importantly the study suggests that there is no debonding occurring between the well-dispersed HA nanoparticles and PEEK matrix, which provides a promising way to overcome the debonding issue of the PEEK–HA composites. [Copyright &y& Elsevier]

Abstract: Epoxy resins reinforced, respectively, by basalt fibres and glass fibres were treated with a seawater solution for different periods of time. Both the mass gain ratio and the strength maintenance ratio of the composites were examined after the treatment. The fracture surfaces were characterized using scanning electron microscopy. The tensile and bending strengths of the seawater treated samples showed a decreasing trend with treating time. In general, the anti-seawater corrosion property of the basalt fibre reinforced composites was almost the same as that of the glass fibre reinforced ones. Based on the experimental results, possible corrosion mechanisms were explored, indicating that an effective lowering of the Fe2+ content in the basalt fibre could lead to a higher stability for the basalt fibre reinforced composites in a seawater environment. [ABSTRACT FROM AUTHOR]

Abstract: For the first time the polyetheretherketone (PEEK)–hydroxyapatite (HA) nanocomposite materials were successfully prepared, and their microstructure and mechanical properties, such as tensile strength, load–displacement and Young''s modulus, were examined. The specimens laminated by the PEEK–HA composite layers with 5vol.% and 15vol.% HA were also successfully made, which gave a promising mechanical strength and a high HA content on the specimen surface. This novel approach should be of significance in manufacturing PEEK–HA biomaterials with both satisfactory mechanical properties and high bioactivity. [Copyright &y& Elsevier]

Abstract: Basalt and glass fibers were treated with sodium hydroxide and hydrochloric acid solutions respectively for different periods of time. Both the mass loss ratio and the strength maintenance ratio of the fibers were examined after the treatment. The morphologies of the fiber surfaces were characterized using scanning electron microscopy and their compositions were analyzed using energy dispersive X-ray spectroscopy. For the basalt fibers, the acid resistance was much better than the alkali resistance. Nevertheless, for the glass fibers, the acid resistance was nearly the same as the alkali resistance. Based on the experimental results, possible corrosion mechanisms are addressed. [Copyright &y& Elsevier]

Abstract: The treated basalt and glass fibers with sodium hydroxide and hydrochloric acid solutions for different times were analyzed, respectively. This paper summarized the mass loss ratio and the strength maintenance ratios of the fibers after treatment. The fibers’ surface corrosion morphologies were characterized using scanning electron microscopy and their compositions were detected using energy dispersive X-ray spectroscopy. The acid resistance was much better than the alkali resistance for the basalt fibers. Nevertheless, for the glass fibers the situation is different: the acid resistance was almost the same as the alkali resistance. Among the two types of aqueous environments evaluated, the alkali solution is the most aggressive to the fibers’ surface. The possible corrosion mechanisms are revealed. [Copyright &y& Elsevier]

Magnetoelectric particulate composites composed of (PZT) and CoFe2O4 (CFO) (molar ratio: =1:1) are prepared via an ethylenediaminetetraacetic acid (EDTA)–citrate gel process. In the composite sample sintered at 1080°C, crystalline CFO particles 1–2μm in size are uniformly distributed in the PZT matrix, which has a grain size of 0.3–0.5μm. This microstructure leads to a high electrical resistivity (∼, which is a significant improvement on previous studies. [Copyright &y& Elsevier]

Herein, an environmentally-benign, facile, efficient, low-cost, scalable fabrication process of achieving flexible graphene paper electrode at ambient conditions is reported. By means of high-shear exfoliation of graphite in aqueous polyvinyl alcohol (PVA), the graphene/PVA dispersion is prepared. Various characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, etc.) confirm that the resulting dispersion is with the presence of high-quality, single to few-layered graphene sheets with thickness up to 1.68 nm, lateral size of 0.5–2 μm, and low defect density (I D / I G = 0.09). Further, the applicability of the in-situ exfoliated graphene/PVA dispersion is demonstrated for the fabrication of flexible conductive paper electrodes through a simple intermittent soaking-drying approach. The graphene paper electrode possesses an electrical sheet resistance of 15 Ω sq−1, without any additional annealing treatment and conductive additives. Finally, the graphene paper electrode is integrated with ionic-liquid incorporated PVA polymer electrolyte to develop the all-solid-state supercapacitor. It imparts a considerable specific capacitance of 222.96 F g−1 along with ~60% capacitance retention and ~100% coulombic efficiency after 6000 charge–discharge cycles. Meanwhile, the polymer electrolyte exhibits a remarkable ionic conductivity (4.63 × 10−4 S cm−1) together with a wide electrochemical stability window (5.1 V), favorable for device applications. The unique interwoven nanoporous conductive network of PVA-stabilized exfoliated graphene provides fast diffusion pathways to electrolyte ions, thus significantly enhancing the charge-storage performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The effect of phosphorous on the hot-ductility of SA508Gr.4N reactor pressure vessel (RPV) steel has been studied. The investigation is done with the use of a Gleeble machine in conjunction with optical metallography, scanning electron microscopy, and transmission electron microscopy. It is observed that both the undoped and P-doped steels exhibit hot-ductility troughs between 750 and 900 °C. However, the trough for the P-doped steel is much shallower than that for the undoped steel. At around 850 °C, the reduction of area (RA) of the undoped steel is quite low (~50%), in comparison to the P-doped steel (~75%). Since there is no grain-boundary precipitation of ferrite and carbides in both undoped and P-doped samples over this temperature range, it can be inferred that the enhancement in hot-ductility for the P-doped steel is independent of these two factors. Grain-boundary microanalysis shows the presence of grain-boundary segregation of P in the tested P-doped samples, implying that the P-induced hot-ductility improvement of this RPV steel may arise from the suppression of grain-boundary sliding by P grain-boundary segregation. Undoubtedly, the present effect of P is unusual and the underlying mechanism for this effect has been briefly discussed. It needs to be underlined that a minor addition of P can play a positive role in the hot-ductility improvement of SA508Gr.4N RPV steel. [ABSTRACT FROM AUTHOR]

A sodium-ion conducting poly(vinyl alcohol)-based gel polymer electrolyte membrane is developed by plasticizing with an ionic liquid, for the fabrication of electric double-layer capacitors. Sodium triflate is selected as the sodium salt. 1-Ethyl-3 methylimidazoliumtrifluoromethanesulfonate is employed as the plasticizer. The properties of the electrolyte membranes are analyzed in terms of their crystallinity, morphology, thermal stability, electrochemical stability window, ionic transference number, and ionic conductivity. The composition with poly(vinyl alcohol) - 30% sodium triflate + 10% 1-ethyl-3 methylimidazoliumtrifluoromethanesulfonate shows the optimal performances such as good thermal stability up to 150 °C and wide electrochemical stability window of 4.70 V. It is thus employed in the fabrication of electric double-layer capacitors, serving as both ion-conducting electrolyte and separator. The capacitor shows almost 100% coulombic efficiency and stable charge-discharge cyclic property with almost 100% capacity retention after 1000 cycles, when charging up to 1.6 V and 2.0 V with a specific capacitance of 103.7 and 127.8 F g−1, respectively. It compares well with that made of a liquid electrolyte. This excellent performance is attributed to the sodium triflate with large-sized anions and thus high ionic conductivity (3.8 × 10−3 S cm−1) of the electrolyte membrane. [ABSTRACT FROM AUTHOR]

With 1-methyl-2-pyrrolidinone (NMP) as the solvent, the biodegradable gel polymer electrolyte films are prepared based on poly(vinyl alcohol) (PVA), lithium bis(trifluoromethane)sulfonimide (LiTFSI), and 1-ethyl-3 methylimidazoliumbis(trifluoromethylsulfonyl)imide (EMITFSI) by means of solution casting. The films are characterized to evaluate their structural and electrochemical performance. The 60PVA-40LiTFSI + 10 wt.% EMITFSI system exhibits excellent mechanical properties and a high ionic transference number (0.995), indicating primary ionic conduction in the film. In addition, because of the flexibility of polymer chain segments, its relaxation time is as low as 5.30 × 10−7 s. Accordingly, a high ionic conductivity (3.6 × 10−3 S cm−1) and a wide electrochemical stability window (~5 V) are obtained. The electric double-layer capacitor (EDLC) based on this electrolyte system shows a specific capacitance of 101 F g−1 and an energy density of 10.3 W h kg−1, even after 1000 charge-discharge cycles at a current density of 0.4 A g−1 under a charging voltage of 2 V. All these excellent properties imply that the NMP-soluble 60PVA-40LiTFSI + 10 wt.% EMITFSI gel polymer electrolyte could be a promising electrolyte candidate for electrochemical device applications. [ABSTRACT FROM AUTHOR]

The highly stretchable pure poly(vinyl alcohol) (PVA) membranes with high amorphicity and large ductility are prepared based on an N-methylpyrrolidone (NMP) solution. Meanwhile, the PVA based gel electrolyte membranes doped with magnesium trifluoromethanesulfonate (Mg(Tf) 2 ) and plasticized with 1-ethyl-3-methylimidazoliumtrifluoromethanesulfonate (EMITf) are fabricated with the NMP as the solvent. For the plasticized membranes, the 60PVA-40Mg(Tf) 2 + 10EMITf electrolyte system exhibits the highest room-temperature ionic conductivity (1.2 ×10 −3 S cm −1 ), excellent thermal performance and satisfying strength and flexibility. This system is applied for the fabrication of electric double-layer capacitors (EDLCs), acting as both separator and electrolyte. The EDLC shows a specific capacitance of 118 F g −1 with an excellent stability and almost 100% coulombic efficiency over 1000 charge-discharge cycles when charging at 0.85 V under a current density of 313 mA g −1 . When the charging voltage is increased to 2 V, the stability of the EDLC somewhat decreases but the coulombic efficiency is still near 100%. Additionally, the CV curves exhibit symmetrical and ideal rectangular shapes without the presence of redox peaks at low scan rates even for 1000 cycles. Consequently, this polymer electrolyte system should be an excellent candidate for ion device applications. [ABSTRACT FROM AUTHOR]

• Durable Zn anodes are achieved by negatively charged poly(zinc acrylate) coat. • Corrosion, passivation, and dendrite are suppressed by the 3D network coating. • The self-contained Zn2+ in poly(zinc acrylate) avoids the supply of sluggish ions. The application of low-cost and high-safety aqueous Zn metal batteries is seriously hindered by Zn anode stemming from its uncontrollable dendrite growth and detrimental water-induced side reactions. Herein, a zinc-enriched and negatively charged poly zinc acrylate (PZA) polyelectrolyte with hydrophobic 3D network is firstly constructed on Zn surface through facile UV light irradiation of ZA monomer. The as-obtained PZA coating exhibits a strong adhesion to Zn foil, persistently protecting Zn from water corrosion. Furthermore, the 3D interconnected network architecture favors the fast transport of Zn2+. Meanwhile, the anions can be shielded and desolvation of hydrated Zn2+ is accelerated. Notably, the self-contained Zn2+ in PZA can avoid the supply of sluggish ions. Accordingly, the Zn@PZA anode delivers a low energy barrier and high Zn2+ transference number. Moreover, it endows a superior Coulombic efficiency of 99.7 % and long-life dendrite-free plating/stripping (10 mA cm−2, 2 mAh cm−2). The MnO 2 ||Zn@PZA full cell displays a highly stable cycling behavior for over 700 cycles with a high capacity retention of 95.1 % at 1 A/g together with a satisfactory rate performance. This work delivers an affordable and facile strategy to realize the high reversibility and stability of Zn anodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrolyte membrane can efficiently restrain Zn dendrite growth and HER reaction. • The membrane demonstrates a good flame-retardant performance. • Zn-HS supercapacitor can be operated in a wide temperature range (RT-100 °C). • Supercapacitor exhibits an ultra-long cycling stability over 30,000 cycles at 80 °C. • Flexible supercapacitor offers a high flexible and thermotolerant performance. Hydrogel electrolytes often fail at high temperatures and thus common Zn-ion energy storage devices are rarely employed under high temperature conditions. Herein, a flexible heat-resistant nonflammable polymer electrolyte membrane has been prepared and employed in the fabrication of Zn-ion energy storage devices. The optimum electrolyte membrane exhibits a high room-temperature ionic-conductivity (∼1.52 × 10-3 S cm−1) along with a wide window of electrochemical stability (∼2.5 V). The membrane also shows a high tensile strength (4.3 MPa) and good flame-retardant performance. Moreover, it can effectively restrain the parasitic hydrogen evolution reaction as well as the Zn-dendrite formation. The Zn-ion hybrid supercapacitor (Zn-HS) fabricated with the membrane demonstrates good flexibility and thermotolerant performance. At a current density of 1 A/g, the device possesses a specific capacitance of 162.6 F/g at room temperature, 362.6 F/g at 80 °C, and 404.2 F/g at 100 °C. It also exhibits a long-term cycling capability (up to 30,000 cycles) even at 80 °C. Conclusively, the present work offers a promising way in designing heat-resistant nonflammable polymer electrolytes for flexible energy storage devices suitable for high-temperature applications. [ABSTRACT FROM AUTHOR]

Cu 2 ZnSnS 4 (CZTS) thin films are deposited by spin-coating deposition of sol–gel precursor followed by sulfurization under a sulfur-containing atmosphere. The impact of the sol–gel precursor treatment with preheating temperature on the properties of the CZTS thin films and its photovoltaic solar cell has been investigated. XRD analysis shows that all the deposited CZTS thin films exhibit kesterite crystal structure and own a best crystallinity when the sol–gel precursor is preheated at 300 °C. Raman analysis shows that ZnS as secondary phase has formed on surface of the deposited CZTS thin films and its contents decrease as the preheating temperature increases. Morphological analysis shows that the sol–gel precursor preheated at 300 °C can contribute to the improvement of grain size and crystallinity. Component analysis shows that the higher preheating temperature can contribute to the decrease of tin loss, ZnS content and carbon content but an increase of sodium content. Photoelectric properties analysis shows that the CZTS thin films as a function of preheating temperature at 300 °C have best values with a band gap of 1.45 eV, a resistivity of 8.42 Ω cm, a carrier concentration of 1.26 × 10 17 cm −3 and a mobility of 5.22 cm 2 V −1 s −1 , respectively. Finally, a solar cell device built with the best CZTS thin films exhibits a best efficiency of 1.45%. [ABSTRACT FROM AUTHOR]

This article has been retracted: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). This article has been retracted at the request of the Editors. The article duplicates significant parts of a paper that had already appeared in Mater. Des., 2010, 31 (9) 4244–4250, http://dx.doi.org/10.1016/j.matdes.2010.04.009 . One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process. [ABSTRACT FROM AUTHOR]

45 wt%-Hydroxyaptite/polyetheretherketone (HA/PEEK) coating materials modified by silane coupling agent (KH560) on PEEK substrate were successfully fabricated by solution casting method and characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) , scanning electron microscopy (SEM), and tensile testing. The modified HA fillers were obtained to be uniformly distributed in the HA/PEEK coating, which has better properties of tensile strength and fracture toughness than those of the unmodified specimen. A good bonding between the composite coating and the PEEK substrate was achieved by solution casting method, resulting in integral-fracture without falling apart or delaminating during tensile loading. The modified specimens dipped into simulated body fluid (SBF) were characterized by SEM, XRD and FTIR, indicating that the bioactivity of the dipped materials was demonstrated more apparent with extending the dipping time. Therefore, the coating materials may become the substitutes for the hard tissues of the human body in the future, which could realize the balance between the mechanical properties and the bioactivity by modifying the structural design of the coating. [ABSTRACT FROM AUTHOR]

Abstract: Cu/Ti films of various Cu/Ti ratios were prepared on a TiNi alloy via vacuum arc plasma deposition. The phase composition, structure, and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio and platelet adhesion of the different films were characterized to evaluate blood compatibility. The corrosion and ion release behavior were investigated via a typical immersion test and electrochemical method. The growth of endothelial cells (ECs) was investigated, and methylthiazolyte-trazolium method was employed to evaluate the effect of Cu2+. The sophisticated films showed good compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increased, and some platelets started to break slightly. The Cu2+ release was gradually stabilized. The open circuit potential of the Cu/Ti film-modified samples was lower than that of the TiNi substrate. The polarization test result indicates that the passivation stability performance of Cu/Ti film samples is less than the TiNi substrate, and is favorable to Cu2+ release. The adhesion and proliferation of ECs would be inhibited with 10wt.% Cu concentration of the film, and ECs would undergo apoptosis at >50wt.% concentration. A Cu/Ti film with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices. [Copyright &y& Elsevier]

Abstract: The deposition of coatings or films is an acceptable surface modification method for implanted cardiovascular devices. Cu/Ti coatings of various ratios of Cu and Ti atoms were prepared using the vacuum arc plasma deposition method. The phase composition and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum, respectively. The hemolysis ratio, lactate dehydrogenase (LDH), clotting time, and platelet adhesion of different coatings were characterized to evaluate blood compatibility. The growth of endothelial cells on various coatings was also investigated by observing the morphous and amount of human umbilical vein endothelial cells (HUVECs) under a scanning electron microscope. The Cu/Ti coatings present good blood compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increases, and some platelets begin to break slightly. The activated partial thromboplastin times (APTTs) of various coatings are similar to the TiNi substrate, the coatings can also inhibit platelet adhesion, and the amount of platelets of TiNi is more than the Cu/Ti coating from the LDH assay. The adhesion of HUVECs illustrates that endothelial cell adhesion and proliferation are significantly inhibited with >10wt.% Cu concentration. A Cu/Ti coating with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices. [Copyright &y& Elsevier]

Abstract: The mechanisms of Al speciation and hydrolysis in geopolymer systems are investigated based on the partial charge model together with preliminary experimental validation. Calculation of the partial charges of species discloses that the positive partial charge of the Al atom is always higher than that of Si atom under conditions of similar pH values, suggesting greater tendency of [Al(OH)4]− tetrahedra to attract negatively charged groups from other species. Given Al atom with four hydroxyl groups under alkaline conditions and the potential to expand its coordination number with greater ease, condensation reactions involving aluminate species appear to occur much more readily. Thus, the model essentially predicts that aluminate species promote condensations reaction owing to factors such as their partial charge and the number of hydroxyl groups, implying that the solubility of aluminate sources (i.e. metakaolin) and the distribution of [Al(OH)4]− ions have an important influence on the mechanical properties of inorganic polymers. Corresponding experimental data on aluminate dissolution obtained from progressive milling of metakaolin particles demonstrated that varying particle sizes and different degrees of aggregation of metakaolin can have an important influence on inorganic polymer properties such as setting time, microstructure and compressive strength. The results indicate that milled metakaolin powders with high specific surface area have faster setting characteristics, higher compressive strength, and possess a more homogeneous microstructure, attributable to Al availability as predicted by the partial charge model. [Copyright &y& Elsevier]

Gel electrolytes currently draw considerable interest for flexible supercapacitors. Conventional hydrogel electrolytes find limited suitability at low/high temperatures as they contain immense water. This hinders their application in supercapacitors under a harsh environment. Herein, a novel gel polymer electrolyte (GPE) membrane based on the PVdF-HFP/EMITf/Al(Tf) 3 system is prepared. The optimized GPE membrane exhibits a high ionic conductivity of ~1.6 × 10−3 S cm−1 at room-temperature with a high value of ~0.8 × 10−3 S cm−1 retained at a freezing temperature of −20 °C. The prepared GPE membrane also offers a wide electrochemical stability window (~5.6–4.2 V) in the temperature range of −20 to 60 °C. The supercapacitor cells designed with GPE membrane and graphene nano-platelet electrode display excellent capacitive performance (323.9 F g−1 at 2 V) and cycling stability (over 50000 cycles) at room-temperature. At −20 °C, the supercapacitor cells still maintain promising capacitive performance and outstanding cycling stability. Moreover, the designed flexible supercapacitors also offer remarkable performance under various bending conditions and maintain low-temperature tolerance. Consequently, it is believed that the low-temperature tolerance GPE membrane based on the PVdF-HFP/EMITf/Al(Tf) 3 system possesses potential applications in flexible supercapacitors under harsh environments. Image 1 • GPE membrane has a high ionic conductivity 0.8 × 10−3 S/cm at −20 °C. • Solid-state supercapacitors display a high specific capacitance 323.9 F/g at 2 V. • The supercapacitors exhibit an ultra-long cycling stability over 50000 cycles. • Flexible supercapacitors offer a high performance in various bending conditions. • Flexible supercapacitors display an excellent anti-freezing performance. [ABSTRACT FROM AUTHOR]

Abstract: Hydroxyapatite/polyetheretherketone (HA/PEEK) composite materials have potentials for use as load-bearing orthopedic materials due to PEEK outstanding properties, which could overcome the disadvantages of currently used metallic and ceramic materials. In the study HA/PEEK composite materials were successfully prepared via an in situ process, for the first time, in order to improve the mechanical performance of the existing HA/PEEK composites. The structure of the lab-synthesized materials was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the mechanical performance was investigated by a tensile strength test. The results exhibit the strong bonding between hydroxyapatite fillers and PEEK matrix and good mechanical properties of the composites, suggesting that the in situ synthesized HA/PEEK composite materials are promising for orthopedic applications. [Copyright &y& Elsevier]

In this study, novel ionic liquid-incorporated Zn-ion conducting polymer electrolyte membranes containing polymer matrix poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf), along with zinc trifluoromethanesulfonate Zn(Tf)2, are prepared and investigated. It is ascertained that the optimal membrane ILPE-Zn-4 (the mass ratio of EMITf:Zn(Tf)2:PVDF-HFP is 0.4:0.4:1), with abundant nanopores, exhibits a high amorphousness. At room temperature, the optimized electrolyte membrane offers a good value of ionic conductivity (~1.44 × 10−4 S cm−1), with a wide electrochemical stability window (~4.14 V). Moreover, the electrolyte membrane can sustain a high thermal decomposition temperature (~305 °C), and thus its mechanical performance is sufficient for practical applications. Accordingly, the ionic liquid-incorporated Zn-ion conducting polymer electrolyte could be a potential candidate for Zn-based energy storage applications. [ABSTRACT FROM AUTHOR]