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Three kinds of high-entropy metal diboride composites were successfully prepared by pressureless sintering. The as-synthesized (Hf 0.2 V 0.2 Ta 0.2 Ti 0.2 Nb 0.2)B 2 (HEB-Hf), (Zr 0.2 V 0.2 Ta 0.2 Ti 0.2 Nb 0.2)B 2 (HEB-Zr) and (Cr 0.2 V 0.2 Ta 0.2 Ti 0.2 Nb 0.2)B 2 (HEB-Cr) powders were used as the matrix, and Ni metal was used as the binder phase. The results demonstrated that three kinds of single-phase high-entropy metal diboride powders (HEB-Hf, HEB-Zr, and HEB-Cr) were successfully synthesized by a facile high-energy ball milling-assisted boro/carbothermal reduction method, at 1600 °C for 2 h. Each HEB powder had a hexagonal structure, and the five main elements were evenly distributed. Further, Ni as the binders effectively improved the density and fracture toughness of the sintered HEB composites. In the case of maintaining high hardness, the fracture toughness of the HEB composites was greatly improved. Meanwhile, The composites exhibited excellent properties when the heat-treating temperature was increased to 1600 °C. The hardness of the HEB-Hf, HEB-Zr, and HEB-Cr composites were 24.2 ± 0.6, 23.8 ± 1.2 and 21.8 ± 0.8 GPa, and their fracture toughness were 9.2 ± 0.3, 7.1 ± 0.7 and 7.3 ± 0.5 MPa∙m1/2, respectively. This manuscript reports a novel method for future commercial production of high-entropy diboride. Further, there will be more applications for high-entropy diborides because of their increased toughness when prepared by this method. [Display omitted] • Three single-phase high entropy diboride powders were successfully prepared by boro/carbothermic reduction reaction. • High-dense high-entropy boride composites were successfully prepared using Ni metal as the additive by pressureless sintering at 1600 °C. • The Vickers hardness of HEB-Hf composites, HEB-Zr composites and HEB-Cr composites are 24.2 ± 0.6, 23.8 ± 1.2 and 21.8 ± 0.8 GPa, respectively and the fracture toughness values are 9.2 ± 0.3, 6.1 ± 0.7 and 7.3 ± 0.5 MPa∙m1/2, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Bi3+ doped Ca12Al14O32Cl2 series were successfully synthesized by conventional solid-state reaction method and their luminescence properties have been investigated in detail. Crystallographic parameters of the refinement structure with cubic space group I-43d were obtained by XRD refinement as a =12.0183(3)Å and V (cell volume)=1735.93(1)Å3. The resulting phosphors absorb ultraviolet (UV) light (240–400nm) and show a single intense broad emission band in the wavelength range of 400–600nm with maximum intensity at 483nm. The Commission Internationale de 1’Eclairage (CIE) chromaticity coordinates are about x =0.185, y =0.306. Thus, the novel light blue-emitting phosphor Ca12Al14O32Cl2:Bi3+ could be potentially applied in UV white light-emitting diodes. [Copyright &y& Elsevier]

Abstract: Yellow-orange oxynitride Ca-α-SiAlON: Eu2+ phosphors with the compositions of Ca0.8Si9.2Al2.8O1.2N14.8: xEu2+ (x =0–0.24) were obtained via carbothermal reduction and nitridation method. Crystallographic parameters of the refinement structure with triclinic space group P31c (159) were obtained by XRD refinement as a = b =7.8859(3)Å, c =5.7336(2)Å, V =308.7915(3)Å3, Z =1. The resulting phosphors can absorb light in the range of 300–500nm efficiently and show a single intense broad emission band in the wavelength range of 500–700nm with maximum intensity at 580–601nm. The chromaticity coordinates of the synthesized Ca-α-SiAlON: Eu2+ phosphors can be tailored by simply controlling the activator concentration. All the results show that Ca-α-SiAlON: Eu2+ phosphors can be a candidate for warm white LEDs. [Copyright &y& Elsevier]

In this paper, we present a simple way to achieve the controllable synthesis of composite ZnO@SiO 2 materials. γ-aminopropyltriethoxysilane (APTES) was chosen as the silicon source, and pre-synthesized zinc bromoacetate (ZnBA) was selected the functional metal precursor. By simply regulating the water–ethanol volume ratio, it was possible to simultaneously regulate the sizes of both the composite material and the metal nanoparticles. With an increase in the hydroalcoholic volume ratio from 1:1–3:1, the sizes of the silica materials were increased from 615 to 3020 nm, while the sizes of the ZnO nanoparticles were increased from 3.75 to 6.25 nm. Three ZnO@SiO 2 materials with blue, green, and yellow fluorescence were obtained. More importantly, the hydroalcoholic volume ratio and the particle size of the material showed a good linear relationship. In addition, a "rapid nucleation–aggregation growth" mechanism was proposed, and the controlled growth of metal oxide nanoparticles was explored. [Display omitted] • The sizes of silica matrix and metal oxide nanoparticles can be regulated simultaneously. • A "rapid nucleation-aggregation growth" mechanism was proposed to explain the growth process of nanocomposites. • The controlled growth of metal oxide nanoparticles was discussed in terms of thermodynamics and kinetics. • Three ZnO@SiO 2 material with blue, green and yellow fluorescence were obtained. [ABSTRACT FROM AUTHOR]

The silicone resin was used to modify ceramic shells for investment casting. SiC nanowires were in-situ formed by the carbothermal reduction method. The pyrolysis of silicone resin and the formation mechanism of SiC nanowires were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that the shells had the maximum sintering bending strength of 7.35 MPa when the silicone resin content and the sintering temperature were 20 wt% and 1300 °C, respectively. The phase of β-cristobalite during the transformation from amorphous SiOC to fused SiO 2 after the pyrolysis of silicone resin impacted the bending strength. In addition, the iron oxide in corundum sand was used as the catalyst in the VLS mechanism to form the ball-stick-shaped SiC nanowires at 1000 °C–1100 °C. However, the necklace-like and rod-like SiC nanowires were formed at 1200 °C–1300 °C in the VS mechanism, which replaced the VLS mechanism. [Display omitted] • The sintering strength of the modified shell was increased by 40.8% over the original shell. • The thickness of the ceramic shell at the optimal process is 6.18 mm. • The fused SiO 2 can inhibit and retard the expansion of cracks in ceramic matrix. • SiC nanowires were in-situ formed by the pyrolysis of silicone resin. • SiC nanowires were in-situ formed without catalysts by VLS and VS mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: A novel yellow phosphor of Dy3+ activated YNbTiO6 has been prepared by high temperature solid-state reaction, and its luminescence properties have been investigated. The excitation spectra monitored at 575nm have several strong peaks from 350 to 480nm. Under 365nm excitation, the emission spectra of composition-optimized (Y0.9Dy0.1)NbTiO6 phosphor exhibit a dominant peak located at about 575nm with the Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of (0.385, 0.411). The energy transfer between Dy3+ is found to be through exchange interaction. [ABSTRACT FROM AUTHOR]

Abstract The microstructural evolution of a nickel-based heat resistant alloy during long term aging (10000 h) at 700 °C was systematically investigated. Experimental results showed that the main precipitates after pre-aging treatments were MC, M 23 C 6 and homogeneous γ’. The weight fraction of γ′ increased continuously with the aging time up to 5000 h, while an obvious coarsening was observed after aging for 100 h. The grain sizes of γ′ precipitates from all aged samples exhibited unimodal distributions, and their coarsening behavior showed good agreement with the LSW model. Compared to the MC carbides, the weight fraction of the M 23 C 6 carbides increased significantly with the increase of the aging time. This could be attributed to their precipitation from the supersaturated matrix. Due to the precipitation and coarsening of γ′, the hardness of the aged samples increased sharply during the first 100 h of aging and then decreased with the increase of the aging time (up to 10000 h). Highlights • All aged samples were quantitatively studied by the phase analysis. • The sizes of γ′ precipitates from all aged samples exhibited unimodal distributions. • The increase of M 23 C 6 during the aging time could be attributed mainly to their precipitation from the supersaturated matrix. [ABSTRACT FROM AUTHOR]

We report a facile and eco-friendly approach to the synthesis of carbon nanofibers (CNFs), using cornstalks as carbon precursors and pinewood-derived carbon powders with inherent rough surfaces as catalytic substrates during chemical vapor deposition. Then, we annealed the CNFs in the presence of ammonia to impart them nitrogen doping (NCNFs), large surface areas, hydrophilicity and underwater oleophobicity. As a result, the NCNF networks achieved via vacuum filtration could work as oil/dye dual-functional filtration membranes for simultaneous removal of crude oil droplets, methylene blue and reactive violet K-3R from water with high flux up to 4950 L m−2 h−1, high efficiency of 99.82% and excellent recyclability. Finally, cobalt oxide (Co x O y) nanoparticles were deposited on NCNFs to prepare Co x O y /NCNF composites, which exhibited higher electrocatalytic activity (overpotential at current density of 10 mA cm−2: 290 mV) and better durability towards the oxygen evolution reaction than the state-of-the-art precious iridium oxide catalysts. This may be attributable to nitrogen doping, synergistic effect between Co x O y and NCNFs, as well as the superior structural and compositional stability of the Co x O y /NCNF composites. [Display omitted] • CNFs are synthesized using biomass as both carbon precursor and catalytic substrate. • NCNFs are hydrophilic/underwater oleophobic and have large surface areas. • NCNF networks can simultaneously separate crude oil droplets, MB and RV from water. • CoxOy/NCNF composites exhibit better OER activity and durability than IrO2 catalysts. [ABSTRACT FROM AUTHOR]