查看更多>>摘要：Hybrid nanostructures composed of a plasmonic noble metal and a semiconductor have been studied intensively because of their unusual properties and wide range of potential applications. However, preparing these hybrid nanostructures with a precisely controlled shape, composition, heterostructure, and internal structure remains a challenge. Here, we describe a method for synthesizing new metal-semiconductor? bimetal hybrid nanostructures. Specifically, Ag-Ag_2S nanoplates were first prepared by site-controlled sulfidation, and these nanoplates were then used as seeds to synthesize Ag-Ag_2S@Ag-Au hybrid nanostructures with unique porous architectures through seed-mediated growth and a galvanic replacement reaction. The composition of the ternary alloy combined with the unique porous structure of the hybrid nanostructures resulted in excellent broadband absorption in the UV-Vis-NIR region (300-1100 nm), and hence a black color, without an additional post-treatment process. When used as photothermal conversion materials, the hybrid nanostructures showed good photothermal conversion activity, with a maximum efficiency of 76.1% under irradiation with an 808 nm near-infrared laser. A mechanism for the high photothermal conversion activity is proposed on the basis of experimental and simulation results.
查看更多>>摘要：The chemistry of metal borohydrides and their derivatives has expanded signficantly during the past decade involving new compositions, structures, and the diversity of associated properties. Here we provide an overview of interesting results mainly from the past few years, discussed relative to previously published results. A range of new synthesis strategies has been developed to obtain pure samples, which has allowed very detailed structural, physical, and chemical investigations. A short overview of mono- and dimetallic borohydrides is provided, including a description of the complete series of rare-earth metal borohydrides and the recently discovered ammonium metal borohydrides, where the latter has attracted interest due to an extreme hydrogen content. Metal borohydrides appear to be the most promising class of materials to achieve high cationic conductivity of divalent metals, and particularly derivatives of metal borohydrides with neutral molecules show promise as future electrolytes for new types of solid-state batteries. Furthermore, metal borohydrides display a wide range of other properties, including optical, magnetic, semi conduction and possibly superconducting properties, and are also used as a new approach for carbon capture and conversion. The aim of the present review is to highlight new trends in properties and provide an outlook with possible future applications. Here, we focus on the more recently discovered materials.
查看更多>>摘要：Recently, additive manufacturing (AM), being part of IR4.0, received great attention for the fabrication of customized implants with outstanding quality, which are used in hard tissue replacement. For an orthopedic application, the titanium alloy implants, especially those that use Ti-6Al-4V manufactured by selective laser melting (SLM), should facilitate maximum osteointegration between the implant and corresponding bone. However, the superior mechanical characteristics, poor surface integration, antibacterial performance, and readiness of SLM Ti-6Al-4V for use in advanced implants are still not comparable to those of anatomical bone. This review focused on the current issue of stress-shielding limitations in SLM Ti-6Al-4V owing to failures in load-bearing applications. The surface treatment and modification strategy that might improve the osseointegration of the implant were discussed. The corrosion resistance of SLM Ti-6Al-4V which could significantly affect antibacterial capability, improve cell adherence and apatite formation on the bone remodeling surface was also addressed. Finally, the current challenges, prospects and applications for SLM Ti-6Al-4V development were presented.
查看更多>>摘要：In the present study, the amorphous Ti-Ni-Zr-Cu thin ribbons were successfully prepared through rapid spinning technology. The crystallization temperature of Ti-Ni-Zr-Cu thin ribbon increased with the increasing of heating rate. The activation energy of crystallization for Ti-Ni-Zr-Cu thin ribbon is calculated to be 156 kj/mol, which is remarkably lower than that of the reported Zr-Cu based metal glass due to the smaller negative enthalpy of mixing atomic pairs. The phase constituents of annealed Ti-Ni-Zr-Cu thin ribbons were largely related to the annealing temperatures. The phase constitutes of Ti-Ni-Zr-Cu thin films annealed at the temperatures lower than 850 °C is almost equal, but the lattice constant of various phases is gradually reduced with the increasing of annealing temperatures. In proportion, Ti-Ni-Zr-Cu thin ribbons annealed at the temperatures lower than 750 °C show the higher Vickers hardness, while a noteworthy reduction of Vickers hardness is observed in Ti-Ni-Zr-Cu thin ribbon annealed at 850 °C. Besides, the annealing temperature has a significant effect on the specific heat and corrosion properties, which can be attributed to the distinction of phase constituents.
Evgeny V. ZharikovValentina B. DudnikovaNina G. Zinovieva
8页
查看更多>>摘要：The content of all matrix elements, including oxygen, was determined by X-ray spectral microanalysis in series of single crystals of sodium-gadolinium molybdates (NGM) grown from melt by Czochralski technique. All grown NGM crystals, including those grown from stoichiometric charge, are non-stoichiometric and contain a molybdenum deficiency of about 3% in average. The NGM congruently melting composition has been determined. For crystals grown from melt of equimolar (stoichiometric) composition, the content of cationic vacancies in the (Gd + Na) sublattice is close to zero, while the composition of crystal differs from the initial melt. As the Gd excess increases, the content of cationic vacancies in the (Gd + Na) sublattice increases up to 10%. It has been found that cation-deficient NGM crystals are also ahion-deficient. The concentration of oxygen vacancies varies from 0.5% to 5% of the amount of anion sites. Possible mechanisms responsible for the formation of cationic and anionic vacancies in NGM crystals are discussed.
查看更多>>摘要：In this work, we have studied the preparation and properties of an alumino-phosphate glass with composition 13Na_2O-13K_2O-16BaO-4Al_2O_3-54P_2O_5 (mol%). The first part of the work deals with the study of the processing conditions of the dehydroxylation of the phosphate glass, which was performed by remelting under N_2 flow using graphite crucibles. Glass samples from 5 to 50 g and Nd_2O_3 doped were submitted to dehydroxylation and the influence of temperature, time, mass of glass and viscosity were correlated with the content of water in the glasses through the coefficient of absorption of OH ions. The network structure of the glasses was also determined by means of ~(31)P and ~(27)A1 1D/2D nuclear magnetic resonance and the local environment of Nd~(3+) ions was probed by electron paramagnetic resonance. The optimized conditions of processing were then used to obtain a dehydroxylated glass with a 2.5 wt% Nd_2O_3 whose spectroscopic and laser emission properties were studied. The spectroscopic properties of Nd~(3+) ions which include, Judd-Ofelt calculation, stimulated emission cross-section of the laser transition, lifetime, and quantum efficiency are presented. Site-selective laser spectroscopy and stimulated emission obtained under selective wavelength pumping along the ~4I_(9/2)→~4F_(5/2) absorption band were performed to determine the distribution of crystal field in which the rare earth is located, together with its influence in the pump wavelength dependence of the spontaneous and laser emissions of Nd~(3+) in this glass matrix.
查看更多>>摘要：Interfacial defects and electrical characteristics were analyzed to confirm the formation of dipole due to the densification of the SiO_2 buffer layer and the resulting movement of the flat-band voltage. Through the NAOS, the SiO_2 layer was densified without any change in thickness, and the suboxide density after the NAOS decreased from 2.23 × 10~(14) atoms/cm~2 (PE-CVD) to 1.33 × 10~(14) atoms/cm~2 (PE-CVD+NAOS). In addition, both electrical and interfacial defects decreased after NAOS and PMA. From these results, the SiO_2 buffer layer through the NAOS was densified and the interface defect state density was reduced. The PE-CVD sample with low atomic density had a dipole layer strength of 0.799 V before PMA, but it was 0.457 V in the case of PE-CVD+NAOS with high atomic density due to the densification of the SiO_2 buffer layer. Also, both samples were reduced to 0.488 V and 0.422 V after PMA. Based on this, the leakage current of PE-CVD was measured to be 3.05 × 10~(-5) A/cm~2, and the leakage current of PE-CVD+NAOS was measured that the difference in about four orders of magnitude was 1.64× 10~(-9) A/cm~2. Through the densification of the SiO_2 layer, the interface atomic density increased, and consequently, the dipole layer strength decreased, thereby improving the electrical properties.
查看更多>>摘要：Molybdenum disulfide (MoS_2) nanosheets were prepared by the method of liquid phase ultrasonic separation. It is coated on the surface of single mode-no-core-single mode (SNS) fiber structure by drip coating method, which realizes the detection of formic acid gas under room temperature. The corresponding sensing performance has been discussed in the concentration range of 0-250 ppm and 0-1100 ppm, respectively. The good selectivity, repeatability and response/recovery characteristics have been experimentally demonstrated and used for exploring an effect method to greatly improve the sensitivity of the formic acid gas sensor. This passive optical fiber probe has the promising potential application in medical and industrial production process for determining the formic acid concentration at room temperature.
查看更多>>摘要：Polycrystalline Mg_(1-x)Zn_xFe_2O_4 (0 ≤ x ≤1) ferrites were prepared with sol-gel method. The obtained samples were characterized by powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mossbauer spectrometry. The X-ray diffraction analysis combined with the Rietveld refinement confirmed that the samples crystallize in a single-phase cubic spinel structure with (SG: Fd3m) and an average grain size in the range of 29.1-40 nm. Lattice parameter increases with increasing Zn concentration, due to the larger ionic radius of Zn~(2+) ions in regard of Mg~(2+) ions. The Curie temperature T_c decreases linearly with substitution. Saturation magnetization (M_s), magnetic moment of iron (u_Fe)) and magnetic entropy change (-ΔS_M) increase for x≤ 0.5 and decrease for x≥ 0.5, this behavior is attributed to the cationic distribution of the ions on tet-rahedral [A] and octahedral [B] sites, where the structure turns from partially inverse spinel to normal spinel, affecting the remanent magnetization and the coercitive field. Moreover, a new empirical relation is acquired performing linear relation between magnetic moment and the inversion parameter 6. Mossbauer spectra show a transformation from sextuple to an only a doublet which indicates a transformation from ferrimag-netic to paramagnetic phase, this ferrimagnetism degradation is confirmed by the negative values of-ΔS_M and the transition of the magnetocaloric effect from normal to inverse through substitution.
查看更多>>摘要：As a compelling complement to lithium batteries, rechargeable aluminum batteries (RABs) have attracted considerable attention because of abundant natural resources, high volumetric capacity, and safety property of aluminum metal. However, the deployment of RABs is hampered by the lack of favorable cathodes with high capacity and rapid kinetics. To address the long-unresolved issue of aluminum-storage capacity and rate, here we design a heterostructured g-C_3N4/Ti_3C_2T_x hybrid which offers a conductive supporting framework to maintain structural integrity and accelerate electronic transport. The energy storage mechanism of the heterostructured g-C_3N_4/Ti_3C_2T_x cathode was demonstrated as the reversible intercalation of AlCl_4~-during cycling. Moreover, the battery-capacitance model mechanism in the heterostructured g-C_3N_4/Ti_3C_2T_x hybrids may accelerate the kinetics of the electrode reactions. Furthermore, DFT calculations certify that heterostructured g-C_3N_4/Ti_3C_2T_x possesses enhanced electrical conductivity and Al trapping capability. Accordingly, the heterostructured g-C_3N_4/Ti_3C_2T_x cathode affords RABs with an excellent Al-storage property (237 mAh g~(-1) at 0.5 Ag~(-1)) and considerable rate capabilities (174 mAh g~(-1) at 4 A g~(-1)) among state-of-the-art cathode materials for aluminum batteries.
NSTL
Elsevier