Silver nano-particles with average diameter of about 60 nm were compacted in a high-strength mold under different pressures at 523 K to produce nano-structured Ag solid materials. The structure and characteristic of the nano-structured Ag solid materials (NSS-Ag) were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectrometer. The NSS-Ag could be used as highly efficient surface-enhanced Raman scattering (SERS) active substrates. The common probe molecules Rhodamine 6G (R6G, 1×10-10 mol/L) were used to test the SERS activity on these substrates at very low concentrations. It is found that the SERS enhancement ability is dependent on the density of NSS-Ag. When the relative density of NSS-Ag is 83.87%, the materials reveal great SERS signal.
The synthesis of high purity intermetallic FeAl nanoparticles using the flow-levitation (FL) method was reported. Iron and aluminium droplets were levitated stably at about 2 230℃. The morphology, crystal structure and chemical composition of FeAl nanoparticles were investigated by transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction and energy dispersive spectrometry. The results show that the average particle size of these nanoparticles is about 34.5 nm. Measurements of the d-spacing from X-ray diffraction and electron diffraction studies confirm that the intermetallic nanoparticles have the same crystal structure (B2) as the bulk FeAl. A thin oxidation coating is formed around the particles when being exposed to air. Based on the XPS measurements, the surface coating of the FeAl nanoparticles is composed of Fe2O3 and FeAl2O4 . Besides, hysteresis curve reveals that saturation magnetization (Ms ) of FeAl is 1.66 A/m2 , and the coercivity is about 1.214 103 A/m.
Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method.The effects of heat treatment of Mn-Cu precursors on alloy phase,morphology and composition of the resultant nanoporous copper were investigated.It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors,which consequently results in a more fully dealloying for forming nanoporous copper.The alloy phase changes from Cu0.49Mn0.51 and Cu0.21Mn0.79 of non-thermally treated precursor to Cu0.33Mn0.67 of heat treated alloy.The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04%(molar fraction) made from the precursor without and with 95 h heat treatment.The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones:the uniform bi-continuous structure zone and the blurry or no pore structure zone.Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor,and the average ligament diameter is 40 nm,far smaller than that from the non-thermally treated precursor,in which the average ligament diameter is estimated to be about 70 nm.
