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Grain boundary (GB) concentration of P in 12Cr1MoV steel after aging for 15 h under elastic stress of 30 MPa is found to be nearly equal to its initial thermal equilibrium level, which confirms that elastic stress affects thermal equilibrium segregation slightly. By the model and formulation between elastic stress and segregation Gibbs energy, the effect of elastic stress on GB segregation thermodynamics of P is calculated to be slight. The consistency between experiment and calculation gives direct evidence to the validity of the model and formulation. [ABSTRACT FROM AUTHOR]

Lithium ion conducting biodegradable gel polymer electrolytes based on a poly (ε-caprolactone):lithium tetrafluoroborate (PCL:LiBF) system doped with various concentrations of 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF) ionic liquid were prepared by solution cast technique. The gel polymer electrolyte was eco-friendly, flexible, transparent and free-standing. The conductivity and transference number measurements were carried out to investigate ionic conduction and charge transport in the gel polymer electrolytes. The frequency-dependent conductivity results revealed that the room-temperature electrical conductivity increased with increasing EMIMBF concentration. At room temperature, the gel polymer electrolyte with a composition of 85PCL:15LiBF + 40EMIMBF exhibited a high conductivity value of approximately 2.83 × 10 S cm, which was favored by the rich amorphous phase as confirmed with X-ray diffraction analysis. The lithium ion transport number and electrochemical stability of the 40 % EMIMBF gel polymer electrolyte were 0.43 and 3.7 V, respectively. These values are acceptable and quite enough for practical device applications. Consequently, the 40 wt% EMIMBF incorporated gel polymer electrolyte could be used to fabricate lithium ion batteries with a suitable selection of other components of the battery system. [ABSTRACT FROM AUTHOR]

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]

Hydroxyapatite/polyetheretherketone (HA/PEEK) composite materials were prepared via an in situ synthesis process in order to achieve strong bonding between PEEK matrix and hydroxyapatite fillers, and ultimately to improve the mechanical properties of the composites. In the study, the biocompatibility of the synthesized HA/PEEK materials was investigated by acute toxicity test, hemolytic test, sensitization test, pyrogen test, intradermal test, and toxicity assay test on animal tissue and cells for the purpose of examining the possible adverse effects of the residue organic chemicals from the in situ synthesis process. In vivo bioactivity of both lab-synthesized PEEK and HA/PEEK composites with various HA content was also studied. It is found that the in situ synthesized composite materials possess good biocompability without toxicity. Although the bioactivity of the material increases with HA content, the composite material with 5.6 vol % HA exhibits satisfactory bioactivity without compromising its excellent mechanical performance, which hints to a potential use as load-bearing orthopedic material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

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]

• Hot ductility of SA508-III reactor pressure vessel steel is considerably enhanced by minor rare earth Ce. • The grain boundary segregation of Ce occurs and it may play a dominant role in the enhancement of hot ductility. • A minor addition of rare earth element Ce is an effective way to improve the hot ductility of the steel. The hot ductility of the specimens for a reactor pressure vessel steel (SA508-III), undoped and doped with minor rare earth Ce, is studied through hot tensile tests by means of a Gleeble machine in conjunction with scanning electron microscopy, optical microscopy, and field emission gun scanning transmission electron microscopy. Both the undoped and Ce-doped specimens are heated at 1300 °C and then cooled down to different test temperatures between 650 and 1050 °C, followed by tensile deformation up to fracture. As demonstrated by the results, for the undoped steel, there is a wide and deep hot ductility trough and the bottom of the trough is flat and wide (700–850 °C), being only about 60% in reduction of area (RA). However, for the Ce-doped steel, the hot ductility trough becomes considerably narrower and shallower. In addition, the flat and wide bottom of the trough disappears. Overall, the Ce-doped specimens exhibit a much higher hot ductility than the undoped ones, being over 70%RA at temperatures above 800 °C. Therefore, the minor addition of rare earth Ce can considerably enhance the hot ductility of the steel. It may be expected that this Ce-doped steel will have a high performance in hot working. As shown by microanalysis, the segregation of Ce to austenite grain boundaries occurs, which could play an important role in the enhancement of ductility in the high-temperature single austenite range (above 700 °C). Moreover, the Ce-induced grain refinement may also contribute to the hot ductility improvement. [ABSTRACT FROM AUTHOR]

The creep properties of 2.25Cr-1Mo steel samples, undoped and doped with Sb (0.05 wt%), are examined under different applied engineering stresses (150–400 MPa) and temperatures (773–873 K). The creep behavior follows a unified Monkman-Grant relation ε ̇ m × t r 1.04 = 0.046 for both the undoped and Sb-doped steels, where ε ̇ m is the minimum creep rate in h−1 and t r is the rupture time in h. Under the same experimental conditions, the rupture time of the undoped steel is much longer than that of the Sb-doped steel, and meanwhile the minimum creep rate of the former is apparently smaller. Moreover, the threshold stress for creep is much lower for the Sb-doped steel than for the undoped one. This indicates that the impurity element Sb severely lowers the high temperature creep resistance of 2.25Cr-1Mo steel. As shown by boundary microanalysis, there is apparent grain or subgrain boundary segregation of Sb, which could promote the boundary sliding and the nucleation of cavities or microcracks, thereby leading to the creep property deterioration of the steel. [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]

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: 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]

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]

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]

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]