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31.
《Calphad》2019
Mg–Zn–Ca alloys are representative Mg alloys with high formability at room temperature. Their high formability is thought to be related to slip, twinning, and recrystallization of the alloys, but the detailed mechanisms have not yet been clarified. To enable atomistic simulations for investigating those behaviors, an interatomic potential for the Mg–Zn–Ca ternary system was developed. The development was based on the second nearest-neighbor modified embedded-atom method formalism, combining previously developed Mg–Zn and Mg–Ca potentials with the newly developed Zn–Ca binary potential. The Zn–Ca and Mg–Zn–Ca potentials reproduce structural, elastic, and thermodynamic properties of compounds and solution phases of relevant alloy systems in reasonable agreement with experimental data, first-principles and CALPHAD calculations. The applicability of the developed potentials is demonstrated through calculations of the effects of Zn and Ca solutes on the generalized stacking fault energy for various slip systems, segregation energy on twin boundaries, and volumetric misfit strain. 相似文献
32.
《International Journal of Hydrogen Energy》2021,46(64):32403-32412
Porous carbon nanostructures are promising supports for stabilizing the highly dispersed metal nanoparticles and facilitating the mass transfer during the reaction, which are critical to achieve the high efficiency of hydrogen generation from sodium borohydride dehydrogenation. Herein, the catalytically active porous architectures are simply prepared by using 2-methylimidazole and melamine as reactive sources. The structural and compositional characterizations reveal the coexistence of metallic cobalt and N-doped carbon in porous architectures. Electron microscopy observations indicate that the synthesized products are smartly constructed from the carbon nanosheets with densely dispersed Co nanoparticles. Due to the notable structural features, the prepared Co@NC-600 sample presents the highly efficient activity for catalytic hydrolysis of NaBH4 with a hydrogen generation rate of 2574 mL min−1 gcat−1 and an activation energy of 47.6 kJ mol−1. The catalytically active metallic Co and suitable support-effect of N-doped carbon are responsible for catalytic dehydrogenation. 相似文献
33.
Serdar Akbayrak Yalçın Tonbul Saim Özkar 《International Journal of Hydrogen Energy》2021,46(27):14259-14269
Herein, we report the use of tungsten(VI) oxide (WO3) as support for Rh0 nanoparticles. The resulting Rh0/WO3 nanoparticles are highly active and stable catalysts in H2 generation from the hydrolysis of ammonia borane (AB). We present the results of our investigation on the particle size distribution, catalytic activity and stability of Rh0/WO3 catalysts with 0.5%, 1.0%, 2.0% wt. Rh loadings in the hydrolysis reaction. The results reveal that Rh0/WO3 (0.5% wt. Rh) is very promising catalyst providing a turnover frequency of 749 min?1 in releasing 3.0 equivalent H2 per mole of AB from the hydrolysis at 25.0 °C. The high catalytic activity of Rh0/WO3 catalyst is attributed to the reducible nature of support. The report covers the results of kinetics study as well as comparative investigation of activity, recyclability, and reusability of colloidal(0) nanoparticles and Rh0/WO3 (0.5 % wt. Rh) catalyst in the hydrolysis reaction. 相似文献
34.
35.
BaTiO3基Au纳米颗粒复合薄膜的制备及其光学性质研究 总被引:1,自引:1,他引:0
采用溶胶-凝胶(sol-gel)方法,成功的将高体积面分比的Au纳米颗粒复合到BaTiO3的非晶薄膜中,并对其光学性质进行了研究。用XRD、TEM、椭偏仪、吸收光谱、光克尔效应OKE(Optical Kerr Effcet)方法对薄膜进行了表征和测试。从吸收光谱观察到表面等离子体共振SPR(Surface Plasma Resonance)峰随热处理温度升高而红移的现象。光学非线性测试表明薄膜具有高的三阶非线性极化率Χ^(3)和超快的响应时间。 相似文献
36.
L. Sheeney‐Haj‐Ichia S. Pogorelova Y. Gofer I. Willner 《Advanced functional materials》2004,14(5):416-424
Three different configurations of Au‐nanoparticle/CdS‐nanoparticle arrays are organized on Au/quartz electrodes for enhanced photocurrent generation. In one configuration, Au‐nanoparticles are covalently linked to the electrode and the CdS‐nanoparticles are covalently linked to the bare Au‐nanoparticle assembly. The resulting photocurrent, φ = 7.5 %, is ca. 9‐fold higher than the photocurrent originating from a CdS‐nanoparticle layer that lacks the Au‐nanoparticles, φ = 0.8 %. The enhanced photocurrent in the Au/CdS nanoparticle array is attributed to effective charge separation of the electron–hole pair by the injection of conduction‐band electrons from the CdS‐ to the Au‐nanoparticles. Two other configurations involving electrostatically stabilized bipyridinium‐crosslinked Au/CdS or CdS/Au nanoparticle arrays were assembled on the Au/quartz crystal. The photocurrent quantum yields in the two systems are φ = 10 % and φ = 5 %, respectively. The photocurrents in control systems that include electrostatically bridged Au/CdS or CdS/Au nanoparticles by oligocationic units that lack electron‐acceptor units are substantially lower than the values observed in the analogous bipyridinium‐bridged systems. The enhanced photocurrents in the bipyridinium‐crosslinked systems is attributed to the stepwise electron transfer of conduction‐band electrons to the Au‐nanoparticles by the bipyridinium relay bridge, a process that stabilizes the electron–hole pair against recombination and leads to effective charge separation. 相似文献
37.
王芬 《武汉理工大学学报(材料科学英文版)》2005,20(Z1)
1Introduction Harmfulbacteriaexistanywhereintheworldsuchas soil,air,water,surfacesofobjectsandourskins,etc.Thenumberofbacteriumisenormous,withmanydiffer entspecies.Theyhavethreatenedthehealthofhuman beingsseriously.Withthedevelopmentofeconomyand environme… 相似文献
38.
纳米颗粒的测量与表征 总被引:2,自引:0,他引:2
介绍了用于纳米颗粒测量的电镜观察法、X射线衍射线宽法、激光粒度分析法、比表面积法、颗粒沉降法、扫描探针显微术以及小角X射线散射等,并对其测量原理、测量过程、适用范围及测量方法的优缺点进行了讨论。 相似文献
39.
Silver metal has been synthesized in form of a finely divided loose nanopowder, 10–30 nm particle sizes, using a simple polyol process. In hot water, polymer molecules of polyvinyl alcohol (PVA) induce Ag+ → Ag reaction as a weak reducer (suitable to control the final particle size), forming a nanofluid of Ag nanoparticles in situ dispersing in part of PVA molecules. Ag nanoparticles do not aggregate much when casting a viscous Ag–PVA nanofluid (hot) onto a substrate in thin laminates or films. Freestanding Ag–PVA films could be obtained of 1–5 mm thickness after drying at room temperature. Dried sample can be easily peeled from a silicate glass substrate. As small as 5–10 mm Ag–PVA pieces were heated in air in order to recollect Ag nanoparticles by burning off the polymer. At 300–400 °C, Ag–PVA disintegrates and encounters combustion in air, resulting in a pure Ag-powder. As analyzed by X-ray diffraction, a single crystalline phase of an Fm3m cubic crystal structure formed. Lattice parameter a = 0.4071 nm and density ρ = 10.61 g/cm3 compare well the bulk values a = 0.4086 nm and ρ = 10.50 g/cm3. 相似文献
40.