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2D metal thiophosphate SnP2S6 was discovered as a new dielectric layer with a high dielectric constant (≈23), realizing a low subthreshold slope down to 69.4 mV dec−1 in the field effect transistor device geometry.

A novel complex [PtAg(dppm)2(CCC6H4COOCH3-4)2Cl] with two crystal morphologies as rod-like and prism was separately obtained by manipulating the recrystallization solvents. They exhibit glamorous morphology-dependent photoluminescence.

ZrB2 is widely used in refractory linings and electrodes as well as in a range of applications including microelectronics and cutting tools, owing to its excellent characteristics, such as high hardness, high melting point, high strength, high thermal conductivity, and good thermal shock resistance. However, ZrB2 readily oxidizes, especially at high temperatures, which is ascribed to the reaction between ZrB2 and O2 in air. This study shows that a structural self-deterioration phenomenon occurs in ZrB2, even in vacuum or inert atmosphere. ZrB2 exhibits a characteristic, irreversible increase in resistivity in a high vacuum–high temperature environment. During repeated variable temperature resistivity testing, the resistivity of ZrB2 increases by 3.28% in the first cycle and 0.61% in the second. To investigate further, in-situ TEM showed that ZrB2 experiences an unusual phase transition reaction at high temperatures, even under a high vacuum environment. Oxidation results in a large number of disordered, layered structures and holes inside the ZrB2 particles. This microstructure evolution mechanism decreases the electrical conductivity and affects the performance of ZrB2. The study demonstrates the need to thoroughly investigate the microstructure changes in ZrB2 at high temperatures, under an inert atmosphere or high vacuum, and to widen the investigations to other properties beyond electrical resistivity.

The hydrogen evolution reaction (HER) is an emerging renewable energy source to derive clean, efficient, and high-energy-density hydrogen fuel from electrochemical water splitting mostly by using t...

Traditional fluorinated carbon (CFx) batteries are greatly limited in their applications mostly because of inferior rate performances, initial voltage delay and low fluorine-to-carbon ratio below one. This work innovatively applies graphite nanosheets (NSs) as carbon source and optimizes the fluorination process at temperature range of 250–400 °C to prepare CFx NSs. Specifically, the edge defects and –CF2, –CF3 perfluorinated functional group active sites are introduced into NSs in the form of covalent/semi-covalent/semi-ionic bonds by adjusting the temperature which also breaks the limit of fluorocarbon ratio to achieve ultra-thin microstructure with high performances. In the battery assembly process, a series of discharge electrolytes are introduced to improve the quality and realize the ultrahigh specific capacity. The optimized CFx-400 °C NSs deliver an excellent specific capacity of 921 mAh·g−1 at a current density of 10 mA·g−1 with a high energy density value of 2210 Wh·kg−1. Moreover, the new electrolytes are selected which not only serve as electrolytes but also can be loaded on CFx surface for various discharge reactions without affecting the actual battery function. Thus, the lightweight tabs and current collectors are selected to control the loading of active material and injection coefficient. The presented battery design strategy provides a new strategy to achieve an ultrahigh specific energy density of 1116 Wh·kg−1.

The sensitivity of ethanol sensor is of paramount importance in a variety of areas, including chemical production with ethanol, alcohol testing for driving safety, etc. Herein, α-Fe2O3 nano-cylinders with atomic carbon layers are synthesized, for the first time, through in-situ catalytic chemical vapor deposition combined with hydrothermal techniques for the detection of ethanol. The reported α-Fe2O3@C nano-cylinders with double surficial strain effects deliver an ethanol detection sensitivity of ～8 times as compared with α-Fe2O3 nano-cylinders, ∼10 times higher as compared with its detection sensitivity to ammonia, para-xylene, methanol and benzene. The sensor also exhibits over-14-day operation stability and the minimum detection limit of 10 ppm. To our best knowledge, the performances surpass those of previously reported α-Fe2O3. Such attractive performances are attributed to the enhanced charge transfer in α-Fe2O3 owing to the double surficial strain effects of α-Fe2O3@C nano-cylinders and the efficient adsorption of ethanol with atomic carbon layers.

Chemical stability of phosphors is critical to the efficiency and lifetime of the white light-emitting diodes. Therefore, many strategies have been adopted to improve the stability of phosphors. However, it is still lack of report on the improvement of thermal stability and hydrolysis resistance of phosphors by a single layer coating. Due to the high transmittance and high chemical inertness of graphene, it was coated on the surface of Sr2Si5N8:Eu2+ phosphor by chemical vapor deposition, aiming to improve its thermal stability and hydrolysis resistance. The chemical composition and microstructure of the coating were characterized and analyzed. A nanoscale carbon layer was attached on the surface of Sr2Si5N8:Eu2+ phosphor particles in an amorphous state. In coated Sr2Si5N8:Eu2+ phosphor, the oxidation degree of Eu2+ to Eu3+ was significantly suppressed. At the same time, the surface of Sr2Si5N8:Eu2+ particle turned from hydrophilic to hydrophobic after carbon coating, and consequently the hydrolysis resistance of Sr2Si5N8:Eu2+ phosphor was greatly improved. After tests at 85 °C and 85% humidity for 200 h, the carbon coated Sr2Si5N8:Eu2+ phosphor still maintained about 95% of its initial luminous intensity as compared with 35% of the uncoated. By observing the in-situ microstructure evolution of coated phosphor in air-water vapor environment, remained presence of the carbon layer even at 500 °C explained the excellent chemical stability of carbon coated Sr2Si5N8:Eu2+ phosphor in complex environment. These results indicate that a nanoscale carbon layer can be used to provide superior thermal stability and hydrolysis resistance of (oxy) nitrides phosphors.

The helical structures possess unique physical and chemical properties, such as superelasticity, high specific strength, chirality, and electromagnetic cross-polarization characteristics. With the development of nanoscience and nanotechnology, helical structures with various scales have been discovered or synthesized artificially. Among them, the helical carbon materials receive much attention around the world. Herein, we present a brief review of the development of helical carbon materials in terms of structures, synthesis techniques and mechanisms, and applications. The controllable designing of catalysts, carbon sources and reaction parameters plays a key role to optimize the properties of the helical carbon materials. At the same time, the applications in microwave absorption devices, sensors, catalysts, energy conversions and storage devices, and solar cell are also presented. For the good chemical and physical properties, helical carbon materials have a good application prospect in many fields. The potential issues and future opportunities of the helical carbon materials are also proposed.

Low infrared emissivity in 3–5 μm or 8–14 μm band has been realized in different host materials. Realizing the low infrared emissivity in single material covering the entire band is rarely achieved. This research explores a binary system of ultra-high temperature ceramic ZrB2–CeO2 composites prepared by solid state sintering. their phase composition, microstructure evolution, reaction mechanism and infrared emissivity performance were discussed in detail. It was found that CeO2, ZrB2, ZrO2, and ZrnCe1-nO2 existed in the sample in addition to the coated glass phase of CeO2 on the surface of the sample. In-situ HRTEM results clearly revealed a series of reaction mechanism of CeO2 and ZrB2. With the increase of sintering temperature, the CeO2 particles gradually transformed into a glass phase, and were distributed on the surface of ZrB2 particles, and ZrO2 was formed on the surface of ZrB2, simultaneously. Consequently, ZrnCe1-nO2 is formed as the reaction of ZrO2 and CeO2. Compared with the infrared emissivity spectra of pure CeO2 and ZrB2, a low infrared emissivity less than 0.2 in a wider coverage band of 3–5 and 8–14 μm in ZrB2–CeO2 compounds was achieved as a result of synergistic interaction between CeO2 and ZrB2. The obtained information about the phase composition and microstructure evolution helps to realize low infrared emissivity in a wider coverage band in compounds via composition and microstructure modification.

K2SiF6:Mn4+ phosphor is well known for its excellent red emission performance which is vital for improving the color rendering of white light-emitting diodes. However, the poor moisture resistance limits its application in optical devices. In this paper, K2SiF6:Mn4+ phosphor is coated with an inorganic hydrophobic protective layer to obtain good moisture resistance. Chemical vapor deposition method was used to decompose acetylene at high temperature, and the generated nanoscale carbon layer worked as a hydrophobic protective coating on the surface of the phosphor. Microstructure, compositions and properties of the synthesized K2SiF6:Mn4+@C phosphor were investigated in detail. It is found that most of the deposited carbon is coated on the surface of phosphor crystals in amorphous state. The carbon atoms are bonded with the fluorine element in K2SiF6:Mn4+ phosphor, forming carbon-fluorine (C–F) covalent bonds. The moisture resistance of K2SiF6:Mn4+@C phosphor is improved owing to the protection of the hydrophobic carbon. The relative emission intensity of K2SiF6:Mn4+@C phosphor could maintain 73% of the initial luminous intensity after immersing in the aqueous solution at room temperature for 8 h, whereas K2SiF6:Mn4+ phosphor without carbon coating was only 0.7% remaining of the initial value under the same conditions.

The interface characteristics of electrode materials are of tremendous value for supercapacitors, however, poor conductivity, instability in harsh reaction conditions and limited ion mobility in oxide materials are identified as immense challenges for generating high energy density without renouncing the power capability. Herein, a peculiar catalytic chemical vapour deposition (CCVD) approach is employed to decorate a very thin carbon capsules (CCs) on the surface of LiMn2O4 nanorods to synthesize a very active and uniformly distributed LiMn2O4/CCs nano-hybrid material with modified interface characteristics. The CCs not only provide the physicochemical protection as well as improve the electrical conductivity. As an electrode material, LiMn2O4/CCs possess the specific discharge capacitance of 451 F/g which is far superior to LiMn2O4 (304 F/g) at the current density of 0.5 A/g in 0.5 M Li2SO4 aqueous solution. In addition, the LiMn2O4/CCs exhibit an outstanding specific capacitance of 380 F/g even at a much higher current density of 8 A/g. Moreover, after 3000 charge and discharge cycles, LiMn2O4/CCs electrode retains nearly 95% of initial capacity, higher than that of spinel LiMn2O4 electrode which retains only 93%. This innovative technique can be adopted to construct a large variety of other nano-hybrid materials for consumer utilization in the field of supercapacitors.

In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, a novel glass mixture of K-Al-B-Si-O (KABS) and Zn-B-Si-O (ZBS) is introduced as a sintering aid of alumina to obtain ultralow-permittivity glass/Al2O3 composite. Meanwhile, the factors of glass mixture component on microstructure, phase structure and dielectric properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that pure crystalline phase of ZnAl2O4 spinel can be attained by tailoring the component of the glass mixture. In case of mass ratio of KABS: ZBS equal to 6:4, it favors to efficiently increase the sintering densification of composite, and significantly benefit the low dielectric loss, good mechanical and thermal performances. In detail, the optimal glass/ceramic composites sintered at 850 °C for 2 h exhibit the bulk density of 2.89 g/cm3, er of 4.92 at 14 GHz and Q × f of 6873 GHZ, flexural strength of 202 MPa, thermal expansion coefficient of 5.5 ppm/°C. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

Zirconium Boride is widely used as thermal protection materials. However, the characteristics of poor oxidation resistance of ZrB2 at high temperatures limits its applications. In order to improve the anti-oxidation performance of ZrB2, a novel method of doping LaF3 is adopted in present study. In the synthesis process of ZrB2 via carbothermal reduction method, LaF3 was introduced to the initial materials. Motivated by the slightly higher formation temperature of ZrB2 than the melting point of LaF3, a liquid glass phase composed of F and La was deposited on the surface of ZrB2, which naturally brought in oxygen starvation and contributed to improved oxidation resistance performance. The crystal lattice parameters and the anti-oxidation ability of ZrB2 are closely dependent on the added LaF3 content, which can ascribe to La3+/Zr2+ substitution and the amount of glass phase on the surface of ZrB2.

ZrB2-based ceramics with different microstructures were prepared through different processes. Electrical resistivity of all samples was measured under vacuum environment by four-probe method over temperature range from 50 to 1000 °C. It was found that electrical resistivity and internal interface electrical resistivity of all samples increased linearly with environmental temperature. All samples showed nearly equal values of α, which was calculated using the formula: ρ(T1) = ρ(T0)+α·ρ(T0)·(T1-T0). This might be due to the fact that ZrB2 acted as electrical conductive phase in all samples. The relationship between electrical properties and microstructure of ZrB2-based ceramics was investigated. Increase in volume fraction of insulating phase and increase in internal interface electrical resistance can both cause effective electrical resistivity of ZrB2-based ceramics to increase. Internal interface electrical resistance was influenced by oxide impurities on the surface of ZrB2 particles and average particle size of ZrB2 particles.

Because of high color saturation and fewer layers, metal-dielectric thin film has been used for years in the field of special effect coatings such as security and decorative applications. In the application of red color, purple red and orange red metal-dielectric thin films have already been realized, however, pure red thin film has not been achieved. In this paper, color target optimization method is adopted to eliminate the blue second order reflect peak (460 nm–470 nm) and compress the red first order reflect peak (675 nm), consequently, a seven-layer metal-dielectric pure red thin film is designed and fabricated. The chromaticity coordinate is (x,y) = (0.635,0.32) at normal incidence, which is located in pure red region, and the gold color target coordinate is (x,y) = (0.52,0.45) at 45°. The final base structure is Air/1.5Cr/230SiO2/6.3Cr/225SiO2/8.9Cr/213SiO2/100Al/Glass, where the numbers refer to layer thicknesses in nanometers. As the observation angle is increased from 0° to 45°, the thin film varies from pure red to gold. Remote plasma sputtering technique is used to fabricate the multilayer thin film. Finally, pure red thin films are demonstrated for the automobile coatings and optically variable ink applications, and the practical color effects are presented.

Current study aimed at investigating oxidation behaviour of plasma-sprayed ZrB2-SiC coatings, which were deposited using different spray powers. Moreover, oxidation tests were carried out within temperature range of 400–1200 °C. Results from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) suggested that ZrB2-SiC coatings had been markedly oxidized at 600 °C. Besides, oxidation behaviour of ZrB2-SiC block ceramics, which had achieved different densities using spark plasma sintering (SPS) and pressureless sintering (PS), was also studied to explain oxidation behaviour of plasma-sprayed ZrB2-SiC coatings. Results revealed that high-density ZrB2-SiC block ceramics displayed better oxidation resistance than low-density counterparts, indicating that unfavorable oxidation resistance of ZrB2-SiC coatings could be ascribed to low density, since there were more pores in ZrB2-SiC coatings, which provided channels for oxygen diffusion.

The oxidative degradation of ZrB2 ceramics is the main challenge for its extensive application under high temperature condition. Here, we report an effective method for co-doping suitable compounds into ZrB2 in order to significantly improve its anti-oxidation performance. The incorporation of SiC and WC into ZrB2 matrix is achieved using spark plasma sintering (SPS) at 1800 °C. The oxidation behavior of ZrB2-based ceramics is investigated in the temperature range of 1000 °C–1600 °C. The oxidation resistance of single SiC-doped ZrB2 ceramics is improved due to the formation of silica layer on the surface of the ceramics. As for the WC-doped ZrB2, a dense ZrO2 layer is formed which enhances the oxidation resistance. Notably, the SiC and WC co-doped ZrB2 ceramics with relative density of almost 100% exhibit the lowest oxidation weight gain in the process of oxidation treatment. Consequently, the co-doped ZrB2 ceramics have the highest oxidation resistance among all the samples.

Rare-earth metal (Eu) doped aluminum nitride has potential application as luminescence materials due to its unusual mechanical and physical properties, as well as high chemical stability. Here we investigate the energetics, local structure and optical and electronic properties by means of a combination of experimental observations (XDR, SEM, HR-TEM and XANES) and first-principles simulations. Present study has revealed that Eu ions are likely to be co-doped with O in the form of Eu-O pairs. Eu ions or Eu-O pairs favor participation at the surfaces of the AlN crystallites. Our analyses show dependences of the Eu valence and electronic/optical properties on the local chemical composition and structure. The obtained information helps us to realize tuning of the optical properties of the luminescent materials via composition and site occupation modification. National Natural Science Foundation of China. Grant Number: 51302029; Fundamental Research Funds for the Central Universities. Grant Number: ZYGX2015J110.

Performing carbon coating on the surface of phosphors has been proven to be an effective strategy to enhance the oxidation resistance, which is an important factor to achieve stable luminescent devices. Therefore, a good understanding of the protection mechanism favors a continuous improvement of oxidation resistance of phosphors. In present paper, the evolution of the carbon layer, Eu valence (Eu 2+ /Eu 3+ ), and luminescent properties for the C coated BaMgAl 10 O 17 : Eu 2+ phosphor when annealed at high temperature is investigated carefully. Decrease of carbon layer promotes the appearance color transition from black to white as the annealing temperature rises to 1000 °C in air. As expected, the decrease of carbon layer will enhance the luminescence intensity, but risk the possible oxidation of Eu 2+ to Eu 3+ , which inhibits the blue emission ascribed to Eu 2+ . The results indicate that luminescence intensity of phosphor is dependent on the synergistic effect of carbon thickness and Eu 2+ /Eu 3+ ratio. Additionally, a reduction reaction of Eu 3+ to Eu 2+ is observed in C coated BaMgAl 10 O 17 : Eu 2+ phosphor when annealed at high temperature, which also contributes to the higher luminescence intensity.

A facile approach to fabricate nanoholes on the surface of a phosphor via a carbothermal reaction between C and BaMgAl10O17 was adopted. Drilling nanoholes greatly enhanced excitation light absorption and consequently increased the quantum efficiency, which provided new insight to help improve the luminescence efficiency of oxygen-containing phosphors.

The inevitable corrosion of magnetic microwave absorber (MA) remains a great challenge to adapt oxygen-containing environment. Herein we developed a plasma-induced approach for protecting the magnetic MA by anchoring robust SiO2 layers on their surface. Keeping the original flaky shape of FeSiAl (FSA) led to breaking the Snoek limit, which brought excellent ultra-low-frequency absorption. In detail, the ultrathin amorphous silica layer (5 nm) grew on FSA surface by the facile Stober method at low cost firstly. Plasma technology was introduced to make these SiO2 layers dense and attain the integrated P-FSA@SiO2. SiO2 layer protected FSA from the corrosive medium, which increased polarization resistance to 186.9 kΩ·cm2 of P-FSA@SiO2 (from 97.46 kΩ·cm2 of pure FSA) and decreased the corrosion current to 18.45 μA/cm2 (from 63.35 μA/cm2). The corrosion of the samples in acid solution also verified the electrochemical characterizations. Meanwhile, rich interface and sheet ordered structure enable P-FSA@SiO2 exhibit enhanced microwave absorption in ultra-low-frequency through multiple reflections, magnetic loss and the interface polarization between core and shell. The minimum reflection loss of P-FSA@SiO2 reduced from −8.0 dB (FSA) to −12.4 dB and the efficient absorption band (

Superior thermal quenching and degradation of phosphors are required for long lifetime lighting devices, such as light-emitting diodes, which can be realized through composition modification. Here, Al-N bonds in AlON: Eu 2+ phosphors are substituted by higher bond order of Si-C. Photoluminescence (PL) results show thermal quenching (at 150 °C) and thermal degradation (after 600 °C treatment in air) are improved by 5% and 8% with a small decrease of PL intensity in 5% SiC doped AlON: Eu 2+ phosphor. To explain these observations, first-principles computational study was performed to understand the Si and C configuration in AlON:Eu 2+ . The calculations reveal that Si and C elements are not randomly distributed in AlON lattice. It was found that Si prefers occupying tetrahedral sites (Td-Si) and the insertion of C in Td-Si is always energetically favorable, which results in the formation of SiC 4 and SiNC 3 clusters. Thus, the Al-N substitution by Si-C induces a stronger local structure, which accounts for the emission redshift and better thermal stability.

As a novel alternative biodegradable metal, magnesium possesses great potential and feasibility for bone fracture fixation due to its suitable mechanical properties, high degradability and biocompatibility. However, poor corrosion resistance in physiological fluids restricts their practical applications. In this study, HA contained coating on AZ31 Mg alloy substrate is prepared by MAO technique under various treatment times. The effect of treatment time on microstructure, composition, mechanical and corrosion properties is systematically investigated. The results indicate that MAO treatment is an effective route to improve the corrosion resistance. The enhanced corrosion is attributed to the barrier effect of the coatings. The failure mechanism of the MAO samples in Hank's solution is studied by long time immersion. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in Hank's solution is proposed.

Generally speaking, thermal stability is the key factor for microwave absorbers (MAs) at high temperature. In this paper, we first propose to apply a novel material called Cr2AlC (CAC) in the high temperature field. The self-made high purity CAC powder prepared by salt bath exhibits good microwave absorption performance and outstanding. Thermogravimetric (TG) analysis indicates the CAC begins to oxidize significantly above 800 °C. Moreover, the effective medium theory is adopted to calculate the microwave absorption performance for the CAC/paraffin composite material. We found that the sample with 70 wt% CAC (CAC70) has a minimum reflection loss of −25.09 dB at 11.08 GHz and its effective absorption bandwidth (below −10 dB) is 2.2 GHz (10.2–12.4 GHz) at the thickness of 2.00 mm, which indicates a thin layer of Al2O3 at room temperature will not affect the entry of electromagnetic waves and internal electrical losses. The high anti-oxidation layered structure CAC provides an opportunity to expand microwave absorption in high temperature applications.

As a promising material for electromagnetic microwave absorption, FeSiAl (FSA) alloy always suffers from inadequate corrosion resistance in the marine environment. Herein, the Raman and X-ray photoelectron spectroscopy (XPS) depth profiling techniques are adopted to investigate the basic corrosion behavior of FSA in salt spray environment. The Raman analysis contributes to the understanding of the composition change at various corrosive periods while the XPS depth profiling reveals the corrosion process of Fe0→Fe2+→Fe3+ in a sequence. The observed corrosion rates (CRs) of FSA immersed in 5 wt% NaCl solution for 1, 24 and 48 h are 2.99 × 10−12, 4.90 × 10−12 and 5.85 × 10−12 m/s, respectively. The increasing value of CRs as a function of time demonstrates the accelerated corrosion tendency. Moreover, to suppress the corrosive behavior of FSA alloy, carbon is decorated on its surface by catalytic chemical vapor deposition method using acetylene as the carbon source. The carbon coating restrains the corrosion process by impermeability and hydrophobicity of carbon materials in corrosive mediums. This study will help in the designing of microwave absorbers which can resist corrosion in harsh reaction conditions as well as available at commercial level to save the economy.

It is a challenge to recover copper from low grade ore in an environmentally sustainable way, especially from low-grade copper sulfide resources. This paper introduces Zijinshan Mine where an integrated process was developed and applied to recover copper from low-grade copper sulfide ore and acid mine drainage (AMD). The process includes the main operations of milling-flotation, heap bioleaching, solvent extraction-electrowinning (HBL-SX-EW) and copper precipitation. Ore with a grade higher than 0.25% Cu is fed to milling-flotation plant to produce copper concentrates, while the ore with grade lower than 0.25% Cu is sent to HBL-SX-EW to produce copper cathode via SX-EW. Because the copper resource consists mainly of secondary copper sulfides with high pyrite, and the mine is located in a region of high rainfall, a large volume of acid mine drainage is generated. In order to protect the environment, recover copper and make acid and iron balance, the acid mine drainage is respectively distributed to heap bioleaching, SX and sulfide precipitation, depending on the copper concentration of the wastewater. The paper also introduces the progress of tailings utilization, environmental protection and mine ecological restoration at Zijinshan mine.

Designing of materials which can resist aging and corrosion in harsh reaction conditions is required to mitigate the omnipresent issue of electromagnetic interference pollution. Particularly, FeSiAl alloy is a relevant composite material, however, it always suffers aging and corrosion when exposed to crude saline environment. Herein, Carbon-encapsulated FeSiAl (FeSiAl@C) hybrid flakes are developed by catalytic chemical vapor deposition (CCVD) technique through the reaction of FeSiAl precursor with acetylene (C2H2) gas at 300 °C for 5 min. The carbon coating efficiently improves the impedance matching characteristics of FeSiAl powder leading to enhance microwave absorption. Not only that, the carbon capsule also plays an effective shielding function to prevent the alloy from corroding. Specifically, the FeSiAl@C-300 °C delivers increased complex permeability and permittivity in the frequency range of 7–14 GHz, as well as improved impedance matching. In addition, the corrosion resistance is measured using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 5 wt% NaCl solution. The results indicate that the synthesized hybrid exhibits excellent corrosion resistance capability. So, the composite synthesis is a worthy approach to design hybrid materials for effective microwave absorption and corrosion resistance properties for practical applications.

Aerospace vehicles are subjected to high temperatures because of surrounding aerodynamic drag and the formation of large temperature gradients across the external structural parts of their airframe. To protect the vehicles, high-infrared emissivity coatings that can radiate a large amount of heat into outer space are in demand. In this work, we describe the development and characterization of high emissivity ceramic coatings formed on a TC4 alloy surface by micro-arc oxidation. We evaluate, in particular, the influence of NiSO4 concentration on current-time response, the thickness, surface roughness, morphologies, bonding strength, and emissivity of these coatings. The results indicate that by increasing the NiSO4 concentration in electrolytes, the thickness and surface roughness of the coatings increase. The bonding strength becomes smaller with increasing concentration of NiSO4, but is still maintains a value higher 30 MPa. The coatings possess good thermal shock resistance after being subjected to severe thermal shocks for 50 cycles, and no peeling of the coating is observed. A higher concentration of NiSO4 in electrolytes also leads to an increasing percentage of the nickel components in the coating to form a NiO phase, which enhances the emissivity of the coatings in the wavelength range of 3-8 μm.

A method is designed to improve the luminescence of AlN-based phosphors by tuning the band structure and crystal structure due to alloying with GaN. The pure (Al,Ga)N:Eu phosphors were initially prepared by gas-phase reaction in an NH3 atmosphere. GaN alloying was used to expand the crystal lattice of AlN due to Ga3+ substituting for smaller Al3+ ions, making dissolution of Eu2+ easier. The dissolution of Ga in the AlN lattice was proven by the result of the Rietveld refinement and the increase in lattice parameters with increasing Ga content. To introduce other energy states mixing with the 5d states of Eu2+, Ga doping was also used to tune the band structure of AlN by acting on Eu2+ ions. The theoretical result was analyzed using the Cambridge Sequential Total Energy Package (CASTEP). According to the calculated total and atom resolved partial density of states, it was observed that the Ga 5p states contribute a large portion to the corresponding Eu2+ absorption band in (Al,Ga)N:Eu phosphors. As a consequence, an enhanced emission intensity at 470 nm and a high quantum efficiency for excitation at 330 nm was obtained despite of stronger thermal quenching of the (Al,Ga)N:Eu phosphors compared with AlN:Eu.

Polypyrrole (PPY) was prepared by the method of chemical oxidation polymerization in ice bath, and a series of products with different morphology or particle size were obtained through changing volume ratio of acetonitrile to water (VRAW) in the mixed reaction solvents. The structures, morphologies, yield, and conductivities of the as-prepared PPY were characterized by FTIR, SEM, electronic balance, and Four-probe conductivity meter. Furthermore, the effect of VRAW on the morphology of the obtained PPY was investigated in detail. As shown from the corresponding results, PPY's average diameter decreased with the increase of VRAW in the range of 1:9 to 4:6, with particle morphology; the film-shaped PPY was obtained when VRAW was in the scope of 5:5 to 7:3. According to the analysis on the polymerization mechanism of pyrrole in the reaction mixture, the change of PPY's morphology was attributed to the structure change of acetonitrile micelle from spherical structure to double layered structure. As the further study shown, the PPY synthesized at a VRAW of 1:9 shows higher yield and conductivity than which prepared in pure water without acetonitrile; however, the further increase of VRAW results in the decrease of the yield and conductivity. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers