Rapid and continuous reduction of silicon nanoparticles’ size and crystallinity through the interaction with multistage atmospheric-pressure microwave plasma system

Silicon nanomaterials have significant applications in energy, semiconductor, and life-science fields, where they are in strong demand, yet still lack robust, scalable, and high-quality large-scale production methods. This study demonstrates the size reduction of micrometer-sized silicon particles using a three-stage atmospheric-pressure microwave-plasma system, with a processing time of approximately 100 ms. The plasma temperature field was measured using an optical emission spectroscopy method. SEM (scanning electron microscopy) and TEM (transmission electron microscopy) were utilized to examine the surface morphology of the products, and the particle size distribution of the prepared products was statistically analyzed with a minimum mean diameter of 20.71 nm and a standard deviation of 11.51 nm. XRD (x-ray diffraction) and Raman spectroscopy confirmed the continuous reduction of silicon nanoparticles’ size and crystallinity. The experimental results indicate that multistage atmospheric microwave-plasma treatment can reduce the size of silicon nanoparticles in an ultra-fast, continuous, one-step process, offering promising prospects and developmental potential for the economical, high-throughput production of quantum-dot-scale silicon nanoparticles. The simultaneous reduction of particle size and crystallinity demonstrated here is of particular relevance to silicon-based lithium-ion battery anodes, where amorphous nanoparticles below 30 nm exhibit markedly superior cycling stability, and to silicon quantum dot photonic applications, where sub-30-nm diameters activate quantum confinement effects that shift the photoluminescence into the visible range.