Successful direct route production of silicon nanostructures from diatomaceous earth (DE) on a single crystalline silicon wafer via the magnesiothermic reduction reaction is reported. The formed porous coating of 6 µm overall thickness contains silicon as the majority phase along with minor traces of Mg, as evident from SEM-EDS and the Focused Ion Beam (FIB) analysis. Raman peaks of silicon at 519 cm−1 and 925 cm−1 were found in both the film and wafer substrate, and significant intensity variation was observed, consistent with the SEM observation of the directly formed silicon nanoflake layer. Microstructural analysis of the flakes reveals the presence of pores and cavities partially retained from the precursor diatomite powder. A considerable reduction in surface reflectivity was observed for the silicon nanoflakes, from 45% for silicon wafer to below 15%. The results open possibilities for producing nanostructured silicon with a vast range of functionalities.
The use of aluminum alloy AA2024-T4 (Russian designation D16T) in applications requiring a high strength-to-weight ratio and fatigue resistance such as aircraft fuselage often demands the control and modification of surface properties. A promising route to surface conditioning of Al alloys is laser treatment. In the present work, the formation of ripples and conical microstructures under scanning with femtosecond (fs) laser pulses was investigated. Laser treatment was performed using 250 fs pulses of a 1033 nm Yb:YAG laser. The fluence of the pulses varied from 5 to 33 J/cm2. The scanning was repeated from 1 to 5 times for different areas of the sample. Treated areas were evaluated using focused ion beam (FIB)- scanning electron microscopy (SEM) imaging and sectioning, energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), and confocal laser profilometry. The period of laser-induced periodic surface structures (LIPSS) and the average spacing of conical microstructures were deduced from SEM images by FFT. Unevenness of the treated areas was observed that is likely to have been caused by ablation debris. The structural and elemental changes of the material inside the conical microstructures was revealed by FIB-SEM and EDX. The underlying formation mechanisms of observed structures are discussed in this paper.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.