Lattice Parameter Of Nanoparticles Research Articles

Au-Pt alloy nanoparticles obtained by nanosecond laser irradiation of gold and platinum bulk targets in an ethylene glycol solution

Au-Pt alloy nanoparticles (NPs) of different compositions ( Au0Pt100 , Au30Pt70 , Au50Pt50 , Au70Pt30 , and Au100Pt0 were obtained using the nanosecond laser ablation of gold and platinum bulk targets in ethylene glycol, followed by mixing highly monodisperse Au and Pt nanocolloids, for the first time. UV-vis absorption spectra of NPs showed that by increasing the Au content in the Au-Pt NPs, the surface plasmon resonance (SPR) peak red-shifted, from 260 to 573nm in a nonlinear way. In addition, the mean crystalline size, crystal structure, d-spacing, and lattice parameters of NPs were estimated from the XRD spectra. Microscopy studies revealed the most NPs have a spherical or near-spherical shape, and the average sizes of Au0Pt100 , Au30Pt70 , Au50Pt50 , Au70Pt30 , and Au100Pt0 NPs were calculated to be 12.50, 14.15, 18.53, 19.29, and 26.38nm, respectively. Also, the chemical identity of the molecules adhering to the NPs surface was considered by Raman and FT-IR spectroscopy techniques. Among different synthesis methods, the demonstrated technique allows easy synthesis of alloy NPs in aqueous media at room temperature with no formation of by-products.

Microwave-assisted hydrothermal synthesis of nanocrystalline lithium-ion sieve from biogenic manganese oxide, its characterization and lithium sorption studies

Biogenic birnessite (BB) is a stable form of manganese oxide. It is widely distributed in the natural environment and originates from microbial oxidation. It has potential applications in functional material fabrication because of its unique morphology. Using a microwave-assisted hydrothermal method, nano-sized lithium-ion sieves were prepared from BB with a short reaction time. A combination of sorption experiments and structural characterization was used to compare Li uptake by nanoparticles with that by microparticles. X-ray diffraction (XRD) patterns showed that the nano- and microparticles had similar fundamental structures, but the lattice parameter of nanoparticles is smaller than microparticles. Mn K-edge X-ray absorption fine structure (XAFS) spectroscopy showed that the oxidation state of Mn increased from 3.50 to 3.69 with decreasing crystal size, and the Mn–Mn atomic distance decreased from 2.92 to 2.89Å. Li extraction resulted in significant cleavage of the microparticle surfaces. The oxidation state of Mn increased to 4.0, and the Mn–Mn atomic distance decreased to 2.86Å. XRD showed that dissolution of the polycrystalline phase of the nanoparticles occurred during acid washing. However, the EXAFS spectrum was similar to that of the original material before acid washing. The specific surface areas and Li-sorption capacities of the nano-sized lithium-ion sieves prepared from manganese carbonate were significantly higher than those of a similarly prepared micro-sized lithium-ion sieve. The results obtained in this work suggest that BB is a promising starting material for the energy-saving fabrication of functional materials for highly efficient Li recovery.

Size and shape dependent lattice parameters of metallic nanoparticles

A model is developed to account for the size and shape dependent lattice parameters of metallic nanoparticles, where the particle shape difference is considered by introducing a shape factor. It is predicted that the lattice parameters of nanoparticles in several nanometers decrease with decreasing of the particle size, which is consistent with the corresponding experimental results. Furthermore, it is found that the particle shape can lead to 10% of the total lattice variation. The model is a continuous media model and can deal with the nanoparticles larger than 1 nm. Since the shape factor approaches to infinity for nanowires and nanofilms, therefore, the model cannot be generalized to the systems of nanowires and nanofilms. For the input parameters are physical constants of bulk materials, therefore, the present model may be used to predict the lattice variation of different metallic nanoparticles with different lattice structures.