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Due to the suitable bandgap structure, efficient conversion rates of photon to electron, adjustable optical bandgap, high electron mobility/aspect ratio, low defects, and outstanding optical and electrical properties for device design, III–V semiconductors have shown excellent properties for optoelectronic applications, including photodiodes, photodetectors, solar cells, photocatalysis, etc. In particular, III–V nanostructures have attracted considerable interest as a promising photodetector platform, where high-performance photodetectors can be achieved based on the geometry-related light absorption and carrier transport properties of III–V materials. However, the detection ranges from Ultraviolet to Terahertz including broadband photodetectors of III–V semiconductors still have not been more broadly development despite significant efforts to obtain the high performance of III–V semiconductors. Therefore, the recent development of III–V photodetectors in a broad detection range from Ultraviolet to Terahertz, and future requirements are highly desired. In this review, the recent development of photodetectors based on III–V semiconductor with different detection range is discussed. First, the bandgap of III–V materials and synthesis methods of III–V nanostructures are explored, subsequently, the detection mechanism and key figures-of-merit for the photodetectors are introduced, and then the device performance and emerging applications of photodetectors are provided. Lastly, the challenges and future research directions of III–V materials for photodetectors are presented. [ABSTRACT FROM AUTHOR]

In this research the combination of neutralization activation and acid activation processes was employed to improve the physicochemical characters of red mud. In order to better understand the phosphate adsorption behaviors and further improve the phosphate adsorption performance of acid-activated neutralized red mud (AaN-RM), for the first time the impact of operational parameters on phosphate adsorption onto AaN-RM was systematically investigated, and back propagation artificial neural network (ANN) modeling was conducted. The results demonstrated that phosphate adsorption capacity of AaN-RM decreased with the enhancement of adsorbent dosage and the concentration of the competing ion (carbonate), while it increased with the increase of initial phosphate concentration and contact time. The optimal adsorption temperature and initial solution pH for phosphate adsorption onto AaN-RM were 50 °C and 4.0, respectively. Moreover, a 6-10-1 feed forward ANN structure with trainlm algorithm was successfully constructed for predicting the phosphate removal by AaN-RM. The RMSE and R 2 values for two subsets (training and validation subset, and testing subset) were 3.06 and 2.61, and 0.9932 and 0.9969, respectively. Furthermore, the importance analysis showed that contact time and initial phosphate concentration were the most influential parameters on phosphate removal by AaN-RM, the importance of which reached 24.64% and 22.16%, respectively. [ABSTRACT FROM AUTHOR]

Acid-activated Bauxsol was applied to treat wastewater with high phosphate concentration in a batch adsorption system in this paper. The effect of acid activation on the change of Bauxsol structure was systematically investigated. The mineralogical inhomogeneity and intensity of Bauxsol decreased after acid activation, and FeCl 3 ·2H 2 O and Al(OH) 3 became the dominant phases of acid-activated Bauxsol adsorption. Moreover, the BET surface area and total pore volume of Bauxsol increased after acid activation. Interaction of initial solution pH and adsorption temperature on phosphate adsorption onto acid-activated Bauxsol was investigated by using response surface methodology with central composite design. The maximum phosphate adsorption capacity of 192.94 mg g −1 was achieved with an initial solution pH of 4.19 and an adsorption temperature of 52.18 °C, which increased by 7.61 times compared with that of Bauxsol (22.40 mg g −1 ), and was higher than other adsorbents. Furthermore, the desorption studies demonstrated that the acid-activated Bauxsol was successfully regenerated with 0.5 mol L −1 HCl solution. The adsorption capacity and desorption efficiency of acid-activated Bauxsol maintained at 80.48% and 93.02% in the fifth adsorption–desorption cycle, respectively, suggesting that the acid-activated Bauxsol could be repeatedly used in wastewater treatment with high phosphate concentration. [ABSTRACT FROM AUTHOR]

Acid-activated neutralized red mud (AaN-RM) has become a promising adsorbent for phosphate adsorption. The maximum phosphate adsorption capacity of AaN-RM reached 492.46 mg g −1 in this study, which was much higher than that of many other adsorbents. However, no study has specifically investigated how the phosphate reacted with AaN-RM. For the first time the interaction between phosphate and AaN-RM during adsorption process was investigated in this research. Kinetic models and isotherms were used to analyze the possible reaction pathways between AaN-RM and phosphate. Particularly, the phosphate complexes on AaN-RM surface, and the exact role of different adsorption mechanisms were systemically identified. The phosphate adsorption was well described by pseudo second-order kinetic model and Langmuir–Freundlich isotherm, which suggested that chemisorption occurred between the phosphate and AaN-RM, and the phosphate adsorption was governed by heterogeneous processes. Furthermore, the phosphate complexes of Fe–P, Al–P, Fe–P–H 3 PO 4 and Al–P–H 3 PO 4 were formed on AaN-RM surface through ion exchange, precipitation and surface deposition mechanisms. XPS analysis of P 2p peak showed that 59.78% of the phosphate was adsorbed through the ion exchange and precipitation with strong chemical bonds, and 40.22% was adsorbed through the surface deposition with weak chemical bonds. [ABSTRACT FROM AUTHOR]

Abstract: Ir–Zr co-deposition coatings with 71at% Zr were deposited on graphite by double glow plasma at 1073–1123K. The structure and composition of the coatings were confirmed by FE-SEM, XRD, XPS and EDS. The hardness and the elastic modulus of the coatings were estimated by nanoindentation instrument. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. The results showed that the coating was composed of nanocrystalline grains with a size of 80–90nm compared with 0.5μm for the pure Ir coating. The fine grains of the coatings might be attributed to the additional Zr element. New phases IrZr and ZrC were formed due to the high content of Zr and high deposition temperature. The hardness and elastic modulus of the coatings were about 7.5GPa and 388GPa, respectively. The adhesive force between the coating and the substrate was about 10N. [Copyright &y& Elsevier]

Abstract: Ir–Zr gradient coating was obtained on the Mo substrate by double glow plasma. The structure and composition of the coatings were confirmed by SEM, AFM, XRD and EDS, respectively. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. Compared with preferential growth orientation of (220) crystal plane of Ir coating, the Ir–Zr coating had a random orientation structure. The RMS roughness value of the Ir–Zr coating is 19.3nm, which was lower than the roughness value of 45nm for Ir coating. The Ir–Zr coating with the thickness of 5.0μm was composed of two distinct layers. The proportion of Ir decreased gradually from the surface of the coating to the coating/substrate interface. The Zr distribution decreased slightly in the coating. The adhesive force of the Ir–Zr coating was 15N. [Copyright &y& Elsevier]

Abstract In the present contribution, we describe the successful development of two ternary Mo-Si-Ti alloys with two-phase eutectic and eutectoid microstructure, respectively. In the case of Mo-20.0Si-52.8Ti (at.%), a fully eutectic microstructure consisting of body-centered cubic (bcc) solid solution (Mo,Ti,Si) and hexagonal (Ti,Mo) 5 Si 3 can be obtained in very good agreement with thermodynamic calculations. A fully eutectoid decomposed microstructure is observed subsequent to heat-treatment at 1300 °C for 200 h in the case of Mo-21Si-34Ti (at.%). For this alloy, bcc (Mo,Ti,Si) and tetragonal (Mo,Ti) 5 Si 3 appears after decomposition from the A15-type (Mo,Ti) 3 Si. Besides that, a small amount of hexagonal (Ti,Mo) 5 Si 3 forms in the silicide lamellae, too, which is attributed to Ti segregations in the as-cast microstructure. In addition to the focus on microstructure, both oxidation and creep behavior were preliminarily investigated and compared to other state-of-the-art Mo-based alloys. In the case of the eutectic alloy, a promising and unexpected oxidation resistance at 800 °C is observed whereas the eutectoid alloy exhibits catastrophic oxidation; a behavior that is typically observed under these conditions in alloys containing Mo-rich solid solution. The eutectic alloy shows an approximately one order of magnitude higher creep rate within the investigated temperature and stress range as compared to the eutectoid decomposed counterpart. This is attributed to the rather low intrinsic creep resistance of the hexagonal (Ti,Mo) 5 Si 3 and generally lower melting point of the former alloy, whereas in the latter case, creep seems to be controlled by the deformation of the bcc solid solution (Mo,Ti,Si) and the tetragonal (Mo,Ti) 5 Si 3. Graphical abstract Image 1 Highlights • Compositions for fully eutectic and eutectoid Mo-Si-Ti alloys were determined. • The eutectic alloy consists of (Mo,Si,Ti) and (Ti,Mo) 5 Si 3. • The eutectic alloy does not exhibit pesting at 800 °C. • The eutectoid alloy consists of (Mo,Si,Ti) and mostly (Mo,Ti) 5 Si 3. • The eutectoid alloy exhibits good creep resistance. [ABSTRACT FROM AUTHOR]

In this paper, a platinum coating was deposited on titanium alloy substrate by a double glow plasma. Phase and microstructure of platinum coating were examined by X-ray diffraction and scanning electron microscopy, respectively. The microhardness of the coating was estimated by nanoindentation instrument. The adhesive force between the coating and the substrate was performed with scratch tester. The electrochemical behavior of the platinum coating in 3.5 wt % sodium chloride solution was investigated by potentiodynamic polarization. The results indicated that an adherent platinum coating could be successfully obtained on titanium alloy substrates. Compared with the titanium alloy substrate, the platinum coating had a relative low corrosion current density and high corrosion potential. It indicated that the platinum coating had a better corrosion resistance than the titanium alloy substrate. [ABSTRACT FROM AUTHOR]

Abstract: The effect of two different fiber architectures on the mechanical properties of the quartz fiber-reinforced silica composites processed by silicasol-infiltration-sintering (SIS) has been investigated. The composites were sintered at relatively low temperature (450°C). The characteristics of 2.5D (shallow bend-joint) structure and 3D orthogonal structure were determined. The microstructures, flexural strength, shear strength and failure mechanisms of both 2.5D (shallow bend-joint) and 3D orthogonal composites were characterized. It was found that the fiber placement in the preform will strongly affect the mechanical property and failure behavior of the composite. The results of the tests and microstructural observations indicated that 2.5D (shallow bend-joint) quartz f /silica (Q f /S) composites had better mechanical properties than 3D orthogonal quartz f /silica composites. [Copyright &y& Elsevier]

Abstract: Zirconium carbide doped carbon/carbon (ZrC–C/C) composites were prepared by the polymer impregnation and pyrolysis process. Carbon fiber preforms were firstly immersed into zirconium acetate solution/phenolic resin impregnant, and then carbonized at 1000°C. After four cycles of impregnation/carbonization, they were finally graphitized at 2000°C. The phase composition of the composites was examined by X-ray diffraction. Microstructural characterization of the composites were investigated by scanning electron microscopy and transmission electron microscopy. The results indicated that ZrC particles with sub-micron size were well dispersed in carbon matrix. ZrC particles were encapsulated by highly oriented carbon, and there existed a well bonded interface between ZrC particles and highly oriented carbon. The formation mechanism of the encapsulated structure was proposed. [Copyright &y& Elsevier]

Abstract: Iridium coating was produced on various substrates using a double glow plasma. The effects of bias voltage and gas pressure on orientation and microstructure of the coating were studied. The orientation, microstructure and composition of the coating were evaluated by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results showed that iridium coatings on various substrates all exhibited the preferred (220) orientation under the same deposition conditions. The microstructure of the coating was affected by bias voltage, gas pressure and substrate effects. The bias voltages had a significant impact on the crystal orientation of the coating. The increase of bias voltage resulted in high substrate temperature and large deposition rate. An increase in the coating thickness can affect the microstructure and orientation of the coating. [Copyright &y& Elsevier]